Abst_book_draft-120920

International e-Conference on Plasma Theory and Simulations (PTS-2020), September 14 & 15, 2020, Bilaspur, India Oral-13 Theoretical Study of the Energy and Luminosity of an Ion Beam Accelerated in the Radiation Pressure Dominated (RPD) Region Shalu Jain1, Krishna Kumar Soni1, N. K. Jaiman1, K. P. Maheshwari1 1Department of Pure & Applied Physics, University of Kota, Kota, India e-mail: [email protected] The study of the interaction between an ultra intense laser pulse with a thin dense plasma foil is of fundamental importance for different research fields such as efficient ion acceleration, high frequency intense radiation sources, medical applications, investigation of high energy collective phenomena in relativistic astrophysics [1]. We consider the interaction of ultra short, ultra intense laser with ultrathin plasma layer and evaluate the energy and luminosity with their dependence on the parameters of laser and target. In this paper we present our analytical and numerical results for the energy of laser induced accelerated ions. The ion beam is generated as a result of intense laser interacting with plasma [2]. In this reference, we estimate laser pulse intensity, its power, pulse duration, pulse shape, polarization of the incident laser pulse, the luminosity of the beam of ions and their dependence on the parameters of laser and target. References [1] S. V. Bulanov, T. Zh. Esirkepov, M. Kando, A. S. Pirozhkov, and N. N. Rosanov, Phys. Uspekhi, 56, 429-464 (2013). [2] T. Zh. Esirpekov, M. Borghesi, S. V. Bulanov, G. Mourou, and T. Tajima, Phy. Rev. Lett., 92, 175003 (2004). Department of Pure and Applied Physics Guru Ghasidas Central University, Bilaspur (C.G.)-495009, India 36

Poster Presentations

Basic Plasma Phenomena

International e-Conference on Plasma Theory and Simulations (PTS-2020), September 14 & 15, 2020, Bilaspur, India BP-01 Numerical Studies of Dissipative Instabilities in Hall Thruster Plasma Sukhmander Singh Department of Physics, Central University of Rajasthan, Ajmer, Kishangarh, India e-mail: [email protected] In Hall thrusters, thrust is generated by the acceleration of ions by the external electric field in a discharge chamber. Hall thrusters uses electricity from solar energy, so it's weighs significantly lighter and is 10 times more efficient than liquid fuelled satellites. A voltage difference is imposed between the inlet and outlet sections and an almost radial magnetic field is generated by means of magnetic coils in order to trap the electrons, leaving the ions only slightly affected by the magnetic field [1-4]. There is an increasing interest for a correct understanding of purely growing electromagnetic and electrostatic instabilities driven by a plasma gradient in a Hall thruster device [1-7]. The goal of this paper is to study the dissipative instabilities due to the collisional of electrons with the neutral particles in plasmas. An analytical model is derived for the growth arte and real frequency for such type of growing waves in a Hall thruster. References [1] E. Ahedo, J. M. Gallardo, and M. Marti´nez-Sánchez. Phys. Plasmas 10, 3397 (2003). [2] L. Garrigues, G. J. M. Hagelaar, C. Boniface, and J. P. Boeuf. J. Appl. Phys. 100, 123301 (2006). [3] E. Y. Choueiri. Phys. Plasmas 8, 1411 (2001). [4] S. Singh and H. K. Malik. J. Appl. Phys. 112, 013307 (2012). [5] H. K. Malik and S. Singh. Phys. Rev. E 83, 036406 (2011). [6] S. Singh, H. K. Malik and Y. Nishida. Phys. Plasmas 20, 102109 (2013). [7] S. Singh and H.K. Malik. IEEE Trans. Plasma Sci. 39, 1910 (2011). Department of Pure and Applied Physics Guru Ghasidas Central University, Bilaspur (C.G.)-495009, India 37

International e-Conference on Plasma Theory and Simulations (PTS-2020), September 14 & 15, 2020, Bilaspur, India BP-02 Head-on and Overtaking Collision of Kinetic Alfven Solitons Shahida Parveen Shaheed Benazir Bhutto Women University, Peshawar-25000, Pakistan e-mail: [email protected] , [email protected] The interaction of Kinetic Alfven (KA) wave solitons is examined in a finite β (me /mi < β < 1) electron-ion plasma with kappa distributed electrons. Following the extended Poincare-Lighthill-Kuo method, coupled Korteweg–de Vries (KdV) equations are derived for the interaction of two moving opposite Kinetic Alfvenic solitons and the corresponding phase shifts are estimated. The procedure is then extended to the multiple soliton interaction of Kinetic Alfven waves. By using the Hirota bilinear method, the solution of two-sided double and two-sided triple KA KdV solitons and their corresponding phase shifts are obtained. The profiles of head-on collision in multiple soliton situations areshown; the present model supports only compressive sub-Alfvenic soliton structures. It is found that plasma β, obliqueness, and the superthermality index significantly alter the phase shifts (due to head-on and overtaking collisions). The magnitude of the phase shift due to overtaking collision is more compared to that with the head-on collision. The present study is relevant to space and laboratory plasma underpinning sub-Alfvenic soliton. Department of Pure and Applied Physics Guru Ghasidas Central University, Bilaspur (C.G.)-495009, India 38

International e-Conference on Plasma Theory and Simulations (PTS-2020), September 14 & 15, 2020, Bilaspur, India BP-03 Molecular Cloud Formation Via Thermal Instability of Viscous Partially-Ionized Plasma with Neutral Collision and Radiative Heat-loss Function in Interstellar Medium Sachin Kaothekar Department of Physics, Mahakal Institute of Technology & Management, Ujjain-456664, Madhya Pradesh, India e-mail: [email protected] The problem of thermal instability is investigated for a partially ionized plasma which has connection in astrophysical condensations for the formation of molecular clouds in interstellar medium (ISM). The normal mode analysis technique is used in this problem. The general dispersion relation is obtained from linearized perturbation equations of the problem. Effects of collisions with neutrals, radiative heat-loss function, viscosity, thermal conductivity and magnetic field strength, on the thermal instability of the system are discussed. The conditions of instability are obtained for heat-loss function with thermal conductivity. Numerical computations have been performed to calculate the effect of different physical parameters on the growth rate of the thermal instability of considered system. The heat-loss function, thermal conductivity, viscosity, magnetic field and neutral collision have stabilizing effect, while finite electrical resistivity has a destabilizing effect on the growth rate of the thermal instability. Routh-Hurwitz’s criterion is used to calculate, the stability of the system. The results presented in this problem are helpful in understanding the molecular cloud formation and star formation in ISM. Department of Pure and Applied Physics Guru Ghasidas Central University, Bilaspur (C.G.)-495009, India 39

International e-Conference on Plasma Theory and Simulations (PTS-2020), September 14 & 15, 2020, Bilaspur, India BP-04 Effect of mechanical, barrier and adhesion properties on oxygen plasma surface modified polypropylene Vishnuvarthanan. M Department of Printing Technology, College of Engineering, Guindy, Anna University, Chennai – 600 025. TamilNadu. India e-mail: [email protected] In this work, the Polypropylene (PP) film was surface modified by oxygen plasma treatment and the effect of mechanical, barrier and adhesion properties was studied. The PP film was plasma treated with various RF power settings of 7.2 W, 10.2W and 29.6W in various time intervals of 60 s, 120 s, 180 s, 240 s and 300 s. To characterize the wettability, the contact angle was measured and the surface energy values were estimated with different test liquids. The generation of oxygen functional groups on the surface of plasma modified PP and the surface change characterization were observed by attenuated total reflection-Fourier transform infrared spectroscope (ATR - FTIR) and they resulted in wettability improvement. The roughness of the PP film and the surface morphology were analyzed by Atomic Force Microscopy (AFM). It was found that the roughness value increased from 1.491 nm to 7.26 nm because of the increase of treatment time and RF power. The PP crystalline structure of the untreated and treated PP was evaluated by X-ray diffraction analysis (XRD). The bond strength of the untreated and surface modified films was measured by T-peel test method. For the untreated and oxygen plasma treated sample, the mechanical properties like Tensile Strength and the barrier properties like oxygen transmission rate (OTR),Water vapour transmission rate (WVTR) were also calculated. From the results, the tensile strength reduced from 6 MPa to 1.350 MPa because of polypropylene etching and degradation. The OTR increased from 1851.2 to 2248.92 cc/m2/24 h and the Water vapour transmission rate increased from 9.6 to 14.24 g/m2/24 h. Department of Pure and Applied Physics Guru Ghasidas Central University, Bilaspur (C.G.)-495009, India 40

International e-Conference on Plasma Theory and Simulations (PTS-2020), September 14 & 15, 2020, Bilaspur, India BP-05 Energy Generation Using Nuclear Fusion: A Study Alok Kumar Chaudhary Department of Mechanical Engineering, UCET, VBU, Hazaribag (Jharkhand) e-mail: [email protected] The whole universe is continuously running due to energy. Earth has also owned a huge demand for energy which is being fulfilled by various type of fossil fuel, renewable source of energy etc. But still, we want another alternate source of energy which not only fulfil huge demand of us but also should clean and green. Sun is the main source of energy on earth and if such like energy source could be created it will be long-lasting and efficient. Which reaction happens on the surface of the sun is nuclear fusion and if we can use this reaction for our energy need it can be the energy source of the future. International Thermonuclear and Experimental Reactor (ITER) Organization are one of the leading organizations which is continuously working for the same. China, the European Union, Japan, Korea, Russia, United States and also India are involved in this project of ITER for the clean, green and efficient source of energy. Some country like China and the United Kingdom are also trying to make its nuclear fusion machine. The world reached much far to generate energy from this reaction but still facing a different kind of difficulty and issues. If we will resolve these and will able to generate energy by this method then it will be the best source of energy without pollution and upcoming generation will thank us Department of Pure and Applied Physics Guru Ghasidas Central University, Bilaspur (C.G.)-495009, India 41

International e-Conference on Plasma Theory and Simulations(PTS-2020), September 14 & 15, 2020, Bilaspur, India BP-06 Exchange of Wave Energy Among Two Orthogonally Propagating Waves Through Wave-particle Interactionin aMagnetised Plasma Banashree Saikia, P.N.Deka Department of Mathematics,Dibrugarh University ,Dibrugarh, India e-mail: [email protected] In this paper, we have considered wave energy exchange mechanism[1][2] among two electrostatic waves propagating in mutually perpendicular directions in a magnetized plasma based on wave-particle interaction process[3]. For this, we have considered one of the wave as ion-acoustic turbulence which is a low frequency wave and a large portion of its spectrum is found to be in resonance mode. This wave can accelerate plasma particles through wave- particle interaction process. The accelerated plasma particles may transfer their energy to the other wave which is non-resonant wave through a modulated wave. This non-resonant wave is considered as the upper hybrid wave. We consider a Maxwellian particle distribution function for this study and Vlasov{Maxwell system of equations[4] are taken as governing system of equations. The uctuating parts of the distribution function corresponding to turbulence are obtained by solving linearized Vlasov equation[5]. Further, we take Upperhybrid wave as perturbation to the system and corresponding non-linear uctuating parts of non resonant waves and modulated waves are obtained. The non-linear dispersion relation of Upper hybrid wave is obtained by using Poisson equation. We have obtained expression forgrowth rate of unstable upper hybrid waves which is growing at the expense of ion-acousticwave energy. References [1] P.N.Deka, PRAMANA-Journal of physics, 50, 345-354(1998). [2] P.N.Deka, A.Borgohain, Physics of Plasmas,18, 042311 (2011). [3] F.Chen, Introduction to Plasma Physics, Plenum, New York, (1974). [4] S.J.Gogoi, P.N.Deka , Physical Science International Journal,23(3), 1-10 (2019). [5] N A Krall and A W Trivelpiece, Priciples of Plasma Physics McGraw-Hill, New York, (1973). Department of Pure and Applied Physics Guru Ghasidas Central University, Bilaspur(C.G.)-495009, India 42

International e-Conference on Plasma Theory and Simulations (PTS-2020), September 14 & 15, 2020, Bilaspur, India BP-07 Effect of Dust Concentration on the Characteristics of Rogue Waves in a Dusty Plasma with Maxwellian Negative Ions Rajkamal Kakoti and K. Saharia Department of Physics, North Eastern Regional Institute of Science and Technology, Nirjuli, Arunachal Pradesh-791109, India e-mail: [email protected] We present an investigation for the formation of dust ion acoustic rogue waves (DIARWs) in an unmagnetized, collisionless plasma comprising Maxwellian electrons, Maxwellian negative ions, cold mobile positive ions and negatively charged stationary dust. We have considered an electronegative plasma (ENP) owing to its numerous applications in laboratory as well as space plasmas. The assumption of Maxwellian negative ions in our model is inspired by the Ghim and Hweshkowitz [1] experiment for low pressure ENPs. In most of the cases, ENPs are contaminated by dust particles or solid impurities.[2] We have derived a nonlinear Schrodinger equation (NLSE) by using reductive perturbation technique to study DIARWs.[3] The modulational instability (MI) has been regarded as a well-known mechanism for the formation of rogue waves in various systems ranging from condensed matter to optics, biophysics and plasma physics in the past. In investigating the modulational stability/instability region, the variation of the coefficient of nonlinearity is plotted against wave number k for different values of the physical parameters. The critical wavenumber threshold kc at which modulational instability sets in, is raised by the increasing value of dust particle density. Further, in the modulational instability region, the coefficient of nonlinearity increases with the increase of dust particle density. Our present investigation may be helpful for basic characteristic study of DIARWs in the laboratory and space plasmas. References [1] Y. Ghim and N. Hershkowitz, Appl. Phys. Lett. 94, 151503 (2009). [2] A. A. Mamun, P. K. Shukla, and B. Eliasson, Phys. Rev. E 80, 046406 (2009). [3] W. M. Moslem, R. Sabry, S. K. El-Labany, and P. K. Shukla, Phys. Rev. E 84, 066402 (2011). Department of Pure and Applied Physics Guru Ghasidas Central University, Bilaspur (C.G.)-495009, India 43

International e-Conference on Plasma Theory and Simulations (PTS-2020), September 14 & 15, 2020, Bilaspur, India BP-08 FLR effect on the Rayleigh-Taylor Instability in Strongly coupled Rotating Magnetized Viscoelastic Fluids P.K. Sharma, Nusrat khan, Shraddha Argal and Anita Tiwari UIT, Barkatullah University Bhopal (M.P.) India 462026 e-mail: [email protected] In the present work, the effect of Finite larmor radius (FLR) corrections is studied on Rayleigh-Taylor (R-T) instability propagating in a strongly coupled, magnetized plasma medium. We have use the (GHD) generalized hydrodynamic model to derive the analytical dispersion relation. The dispersion relation is modified due to the presence of magnetic field and FLR effects. The dispersion relation is also discussed in strongly coupled (kinetic) limits. Numerical calculations are discussed and it is examined that the FLR effect suppresses the growth rate of R-T instability. The Rayleigh-Taylor (R-T) instability has been recently investigated in strongly coupled plasma looking to its importance in Inertial Confinement Fusion reactions and in dense stellar systems. Department of Pure and Applied Physics Guru Ghasidas Central University, Bilaspur (C.G.)-495009, India 44

International e-Conference on Plasma Theory and Simulations (PTS-2020), September 14 & 15, 2020, Bilaspur, India BP-09 Terahertz Radiation Propagation through Double Layered Metallic Plasmonic Waveguide R. Kaur1,2, S. Kaur1, G. Kumar3 1Department of Physics, GuruNanak Dev University, Amritsar,143008 Punjab, India 2S. L. Bawa DAV College, Batala, 142505, Punjab, India 3Department of Physics, Indian Institute of Technology Guwahati, Guwahati, 781039, Assam, India e-mail: [email protected] We analytically and numerically demonstrate a three-dimensional Double Layered Metallic Plasmonic waveguide by Patterning the surface of metallic plates with an array of rectangular corrugations with a motive of obtaining low loss and highly confined THz propagation. Here we demonstrate that the corrugations on metallic surface is assumed as lossy medium which support confined surface wave propagation in THz range which are otherwise not supported by smooth metallic surface. The theoretical dispersion relation is obtained by using effective medium approximation. The comparison of surface modes is observed in the structure by patterning one plate and both plates by using finite difference time domain numerical simulation. Further we observe that the resonant behaviour of surface plasmons depends on the gap between the plates. This type of waveguide structures is useful for THz sensing applications. Department of Pure and Applied Physics Guru Ghasidas Central University, Bilaspur (C.G.)-495009, India 45

International e-Conference on Plasma Theory and Simulations (PTS-2020), September 14 & 15, 2020, Bilaspur, India BP-10 Linear Dispersion Characteristics and Shock Fronts of EAW in Semi Classical Plasma Mrittika Ghosh, Debiprosad Dutta and Swarniv Chandra Behala College, Calcutta University, Kolkata (W.B.), India e-mail: [email protected] In this paper, we consider the propagation of electron acoustic solitary waves in semi-classical plasma. Using the quantum hydrodynamic model, we obtain the dispersion relation and study the parametric variations of the dispersion curve. We further study the solitary profiles and their evolution by using the Korteweg-de Vries Burger equation. The results provide interesting findings that have laboratory and astrophysical importance. References [1] Chen, F. Francis, Introduction to Plasma Physics and Controlled Fusion. [2] V. K Tripathi Lectures at NPTEL. [3] S. Chandra, S. N. Paul and B. Ghosh, Springer Science Business Media Dordrecht (2012). [4] B. Ghosh, S. Chandra, and S. N. Paul, Phys. Plasmas. 18, 012106 (2011). Department of Pure and Applied Physics Guru Ghasidas Central University, Bilaspur (C.G.)-495009, India 46

International e-Conference on Plasma Theory and Simulations (PTS-2020), September 14 & 15, 2020, Bilaspur, India BP-11 Non-thermal Plasma Technology for the Improvement of Hydrogel Surface towards Biomedical Applications P. Panda, R. Mahanta and S. P. Das Plasma Research Laboratory, Dept. of Chemistry, Ravenshaw University, Cuttack, Odisha, India. e-mail: [email protected] Of the several approaches utilized for surface tailoring of polymeric composites; cold/ non- thermal plasma technology has blossomed into an effectual, facile and economical methodology and gained thrust lately [1]. The treatment is more appealing for materials intended towards biomedical applications since it guarantees a higher degree of bio-activity, bio-selectivity and environment friendly process [2]. In this piece of work bio-degradable hydrogels comprising of chitosan and gelatin (Cs/Gel) composites have been synthesized using a nontoxic cross linker, tetraethyl orthosilicate. For enhancing various surface properties such as surface wettability, topographical study, different biological applications, we have chosen non-thermal plasma technology for surface modification in two different environments i.e., one at He and second one is at He + O2 as carrier gas. The Enhanced hydrophilicity was observed after plasma treatment. Also, topographical changes of the hydrogels were found from AFM and FE-SEM study. Non-thermal plasma technology is considered to be the best (safe and green) method for surface modification of hydrogels as it does not have any adverse effect on the bulk properties; it only shows modification on the surface. Also, the tensile strength of the hydrogels was increased which indicates the enhancement of hardness and stability of the hydrogels for post plasma treatment. Different biological Applications of these bio-degradable hydrogels were also performed. The hydrogels displayed good antibacterial features against S. aureus and E. coli and Better inhibition was found in case of He + O2. Also, we checked antioxidant property of the hydrogels which shows a good result in presence of O2 for post plasma treatment. The hydrogels were found to be remarkably biodegradable and pH sensitive. So non-thermal plasma treated Cs/Gel hydrogels can be explored for diverse biomedical applications, drug delivery and also in food packaging industry. References [1] T. Desmet, R. Morent, N. De Geyter, C. Leys, E. Schacht and P. Dubruel, Bio-macromolecules, 10, 2351-2378, (2009). [2] A. Abdulkhani, E. H. Marvast, A. Ashori, Y. Hamzeh, A. N. Karimi, Int. J. Biol. Macromol. 62, 379– 386, (2013). Department of Pure and Applied Physics Guru Ghasidas Central University, Bilaspur (C.G.)-495009, India 47

International e-Conference on Plasma Theory and Simulations (PTS-2020), September 14 & 15, 2020, Bilaspur, India BP-12 PLASMA IS NEED OF AN HOUR Ramlal, Akhilesh Singh Rajput, A.K.Shrivastava DR.C.V.Raman University Kota Bilaspur Chhattisgarh, India e-mail: [email protected] In this paper an attempt has been made to illustrate about plasma.The word plasma comes from the Greek and means something molded. It was applied for the first time by Tonks and Lngmuir in 1929. The word plasma is used to describe a wide variety of macroscopically neutral substances containing many interacting free electrons and ionized atoms or molecules. Plasma is a quasi-neutral gas of charged and neutral particles which exhibits collective behaviour. Plasma is as the fourth state of matter. Natural plasma exists in some cosmic objects like interiors and atmospheres of hot stars, planetary nebulae and the upper atmosphere of the earth. On the earth, plasma can however be produced in the laboratories. In 1922, Irving Langmuir deduced plasma. In 1940 ,H.Alfven developed a theory of hydro magnetic waves, now called Alfven waves. In 1960, Fusion progress developed. In 1980 Plasma Processing described. In 1990, Dusty Plasma introduced. As the plasma is found in a natural form in a number of cosmic objects and in the upper atmosphere of the earth. Therefore it is sometimes defined as the fourth state of matter. When the gas is ionized, its dynamical behaviour is influenced by the external electric and magnetic fields. Moreover, the separated charged particles within the plasma give rise to new forces between the constituents particles. Thus the properties of the plasma become quite different from those of neutral atoms and molecules. There are three condition for plasma as: Macroscopic Neutrality, Debye Shielding, Plasma frequency. The Debye length is an important physical parameter for description of a plasma. It provides a measure of the distance over which the influence of the electric field of an individual charged particle is felt by the other charged particles inside the plasma. Mean Free Paths, Mobility of Charged Particles, Effect of magnetic field on mobility of electrons, Thermal Conductivity, Dielectric constant of plasma, Optical properties of plasma. The molecules/electrons/ions have a small , but finite size. These molecules collide with one another after short intervals. Since the molecules exert no force on one another. They move in straight lines with constant speeds between two successive collisions. Plasma is a diamagnetic material. Plasma might be transparent or opaque. molecule is a series of short zigzag paths of different lengths. References [1] F.F.Chen, Plasma Physics and Controlled Fusion,2nd ed, Springer, NewYork (2006). [2] J.D.Huba, NRL Plasma Formulary(Naval Research Laboratory), Washington, DC(2006) [3] J.A.Bittencourt, Fundamentals of Plasma Physics, Third Edition, Springer, Brazil (2017). Department of Pure and Applied Physics Guru Ghasidas Central University, Bilaspur (C.G.)-495009, India 48

International e-Conference on Plasma Theory and Simulations (PTS-2020), September 14 & 15, 2020, Bilaspur, India BP-13 A Collisional Radiative Model for the Diagnostics of Ar-CO2 Mixture Plasma Neelam Shukla1, R K Gangwar2 and R Srivastava1 1Department of Physics, Indian Institute of Technology Roorkee, Roorkee, India 2Department of Physics, Indian Institute of Technology Tirupati, Tirupati, India e-mail: [email protected] We develop a comprehensive collisional radiative (CR) model for the Ar-CO2 mixture plasma. Our model is extension of our earlier work [1] which uses our calculated complete set of electron impact excitation cross sections of several fine structure levels of argon using relativistic distorted wave (RDW) theory[2] and represent the ground and excited state of magnesium through multi configuration Dirac-Fock (MCDF) wave functions which are calculated using GRASP2K code[3]. These calculated cross-sections have been used to incorporate excitation and de-excitation of argon due to its collision with electrons in the plasma. Radiative absorption and decay, ionization and recombination (two and three body both) processes are also included in the model. The model is applied to the diagnostics of a recently reported low-pressure DC generated Ar-CO2 plasma of Rodriguez et al. [4] utilizing their spectroscopic measurements. The plasma parameters viz. electron density (ne) and electron temperature (Te) are obtained as a function of different pressures (0.2, 0.3, and 0.6 mbars) and discharge powers at 25 and 50% concentrations of CO2 in argon. These results are determined using measured intensities of seven intense emission lines out of 3p54p (2p) → 3p54s (1s) fine-structure transitions. It is observed that both the electron density and electron temperature increase with the increase of CO2 concentration, which is in confirmation with experimental predictions. The populations obtained for 1si and 2 pi levels from our CR Model are also reported and compared respectively with the corresponding available values from the simple CR Model and experiment of Rodriguez et al. [3]. References [1] S Gupta et. al., Plasma Sources Sci. Technol. 28 (2019) [2] R Srivastava et. al., Phys. Rev. A - At. Mol. Opt. Phys. 74 1–10 (2006) [3] P Jönsson et. al., Comput. Phys. Commun. 177 597–622 (2007) [4] J Rodriguez et al. Phys. Plasmas 25, 053512 (2018) Department of Pure and Applied Physics Guru Ghasidas Central University, Bilaspur (C.G.)-495009, India 49

International e-Conference on Plasma Theory and Simulations (PTS-2020), September 14 & 15, 2020, Bilaspur, India BP-14 Small Amplitude Ion-acoustic Soliton in Unmagnetized Plasmas with Superthermal Electrons and Negative Ions J. K. Chawla Govt. College Tonk, Rajasthan, India-304001 e-mail: [email protected] Small amplitude ion-acoustic soliton in a plasma consisting of positive and negative ions and superthermal electrons. For this purpose, the hydrodynamics equations for positive and negative ions, superthermal electron density distribution are used the reductive perturbation method (RPM) to derive the Korteweg de Vries (KdV). The presences of ions have finite temperatures, then there exist two types of modes, namely slow and fast ion-acoustic modes. Variation of amplitude and width for the compressive (rarefactive) solitons are graphically represented to different values of negative ions, spectral index and ionic temperature ratio. The amplitude (width) of the compressive and rarefactive solitons increases (decreases) with increase the values of spectral index are discussed in details. The effect of negative ion concentration on characteristics of ion-acoustic soliton discussed in details. References [1] B. Buti, J. Plasma Phys. 24, 169 (1980). [2] Y. Nishida and T. Nagasawa, Phys. Fluids 29, 345 (1986). [3] R. A. Cairns, A. A. Mamun, R. Bingham, R. Bostrom, R. O. Dendy, C. M. C. Nairn and P. K. Shukla, Geophys. Rev. Lett. 22, 2709 (1995). [4] R. Sabry, W. M. Moslem and P. K. Shukla, Physics of Plasmas 16, 032302 (2009). [5] S. K. Jain and M. K. Mishra, Astrophys. Space Sci. 346, 395 (2013). [6] S. K. El-Labany, R. Sabry, E. F. El-Shamy and D. M. Khedr, J. Plasma Physics 79, 613 (2013). [5] K. Kumar and M. K. Mishra, AIP Advances 7, 115114 (2017). [6] J. K. Chawla, P. C. Singhadiya and R. S. Tiwari, Pramana J. Phys. 94, 13 (2020). Department of Pure and Applied Physics Guru Ghasidas Central University, Bilaspur (C.G.)-495009, India 50

International e-Conference on Plasma Theory and Simulations (PTS-2020), September 14 & 15, 2020, Bilaspur, India BP-15 Role of Localized Structures and Associated Turbulence Generation at Magnetopause Reconnection Sites Neha Pathak1, R. P. Sharma2 and S.C. Sharma1 1Department of Applied Physics, Delhi Technological University, New Delhi, India 2Centre for Energy Studies, Indian Institute of Technology Delhi, New Delhi, India e-mail: [email protected] Turbulence plays a crucial role in space plasmas. There are lots of observation of whistler waves and kinetic Alfven waves (KAWs) in the framework of turbulence and magnetic reconnection. The present study is concerned with the role of electron to ion scale localized structures in particle acceleration and heating at magnetopause reconnection sites. Here, we have derived the field evolution equations of powerful whistler waves and weak KAW, taking into account the density modification and magnetic field fluctuations. Moreover, numerical techniques and analytical model are used to solve dynamical equations for magnetopause parameters. The main emphasis of the present study is on the development of electron and ion scale structures having the important role in turbulence generation at magnetopause reconnection sites. Department of Pure and Applied Physics Guru Ghasidas Central University, Bilaspur (C.G.)-495009, India 51

International e-Conference on Plasma Theory and Simulations (PTS-2020), September 14 & 15, 2020, Bilaspur, India BP-16 Azimuthal Drift of Magnetized Electrons in a Hall Thruster Dusty Plasma Jasvendra Tyagi Department of Applied Sciences (Physics), IMS Engineering College, Ghaziabad Uttar Pradesh, India e-mail: [email protected] The Hall current plasma thruster is a crossed field discharge device in which quasineutral plasma is accelerated by axial electric and radial magnetic field in an annular channel. There is substantial interest in improving the performance of the Hall thruster as a propulsion engine by reducing the divergence of the plume that could damage the solar panels and other parts of the satellite [1]. The magnetic field configuration was expressly important parameter deciding all sorts of performances [2]. The thruster’s operating conditions and performance are very sensitive to the magnetic field topology. In modern Stationary Plasma Thruster, the magnetic circuit consists of two systems of magnetic coils and poles, external and internal. This magnetic system creates a quasiradial magnetic induction in the exhaust region with a magnitude maximum in the exit plane. Due to the coupling of electron drift velocity with the oscillations in the presence of collisions, plasma of the channel becomes unstable. In the plasma of Hall thrusters, dust contamination is generated due to ions sputtering the walls owing to a radial component of electric field which is generated during the motion of ions as well as electrons and takes ions toward the walls [3]. In this work, the oscillations of charged dust, ions and electrons along with their finite temperatures is taken. With the help of linearized form of fluid equations, the perturbed ion, electron and dust density is obtained. The growth of coupling is realized to be directly proportional to the collision frequency of the electrons. This is possible as the coupling of electrons with the wave oscillations is enhanced in the presence of more collisions. References [1] H. K. Malik, J. Tyagi, and D. Sharma, AIP Advances 9, 055220 (2019). [2] J. Bak, B. Van Loo, R. Kawashima, and K. Komurasaki, J. Appl. Phys. 128, 023302 (2020). [3] D. M. Goebel, R. R. Hofer, I. G. Mikellides, I. Katz, J. E. Polk, and B. N. Dotson, IEEE Trans. Plasma Sci. 43, 118 (2015). Department of Pure and Applied Physics Guru Ghasidas Central University, Bilaspur (C.G.)-495009, India 52

International e-Conference on Plasma Theory and Simulations (PTS-2020), September 14 & 15, 2020, Bilaspur, India BP-17 Large Amplitude Ion-acoustic Solitons in Plasmas with Positrons and Nonthermal Electrons S. K. Jain Govt. College Dhoplur, Rajastan, India e-mail: [email protected] The large amplitude of an ion-acoustic soliton in a plasma consisting of ions, positrons and nonthermal electrons is considered the pseudo-potential method (SPM). An energy integral equation for the system has been derived with the help of SPM. It is found that compressive and rarefactive solitons exist in the plasma system for selected set of plasma parameters. It is also found that the effect of nonthermal parameters (β) positron concentration (α) ionic temperature ratio (σ) positron temperature ratio (γ) and Mach number (M) on the characteristics of the large amplitude ion-acoustic compressive and rarefactive solitons are discussed in detail. The amplitude of the ion-acoustic compressive/rarefactive soliton decreases with increase in nonthermal parameters (β) and ionic temperature ratio (σ), however an increase in positron temperature ratio (γ) and Mach number (M) increases the amplitude of the on-acoustic compressive/rarefactive solitons. The present investigation may be helpful in space and astrophysical plasma system where positrons and nonthermal electrons are present. References [1] P. Goldreich and W. H. Julian, Astrophys. J. 157, 869 (1969). [2] R. Bharuthram and P. K. Shukla, Phys. Fluids 29, 3214 (1986). [3] S. K. Jain and M. K. Mishra, Astrophys Space Sci 346, 395 (2013). [4] S. K. Jain and M. K. Mishra, J Plasma Physics 79, 661 (2013). [5] K. Kumar and M. K. Mishra, AIP Advances 7, 115114 (2017). [6] J. K. Chawla, P. C. Singhadiya and R. S. Tiwari, Pramana J. Phys. 94, 13 (2020). Department of Pure and Applied Physics Guru Ghasidas Central University, Bilaspur (C.G.)-495009, India 53

International e-Conference on Plasma Theory and Simulations (PTS-2020), September 14 & 15, 2020, Bilaspur, India BP-18 Collisional Radiative Model for Laser Induced Mg Plasma using Calculated Detailed Electron Excitation Cross-sections and Self-absorption Correction S. S. Baghel11, S. Gupta1, R. K. Gangwar2 and R. Srivastava1 1Indian Institute of Technology Roorkee, Roorkee-247667, India 2Indian Institute of Technology Tirupati, Tirupati-517506, India e-mail: [email protected] Laser Induced Plasmas (LIPs) are of great importance due to their application in material processing, biomedical, military, industrial analysis, pharmaceutical studies, environmental monitoring, laser propulsion, aerodynamic flow control and laser triggered gas switches etc [1,2]. A very efficient tool for diagnosis of these plasmas is Laser Induced Breakdown Spectroscopy (LIBS) in which emitted light from plasma plume after ablation of the target surface through high power laser pulse is collected and analyzed to characterize and investigate the sample composition, electron temperature and electron density[3]. Most of the earlier LIBS works consider Local Thermodynamic Equilibrium (LTE) models[1,4] to extract the plasma parameters rather than using Collisional-Radiative (CR) models which are relatively more efficient. A few CR models have been used to study the laser induced Zn and Al plasmas [5–7]. In the present work we develop CR model to study the laser induced Magnesium plasma. We calculate the electron impact excitation cross-section of Magnesium from its ground state into 34 different energy levels corresponding to configuration 3s3p, 3s4s, 3s3d, 3s4p, 3s5s, 3s4d, 3s5p, 3s6s, 3s5d, 3s6p and also from levels of configuration 3s3p into 3s4s, 3s5s, 3s6s, 3s3d, 3s4d, 3s5d for electron energy from threshold to 500 eV. We use relativistic distorted wave (RDW) theory[8] and represent the ground and excited state of magnesium through multi configuration Dirac-Fock (MCDF) wave functions which are calculated using GRASP2K code[9]. These calculated cross-sections have been used to incorporate excitation and de-excitation of magnesium due to its collision with electrons in the plasma. Radiative absorption and decay, ionization and recombination (two and three body both) processes are also included in the model. The model has been coupled with laser induced breakdown spectroscopy measurements of Delserieys et al. [10] to extract the electron temperature, electron density and levels population of magnesium atoms. The measured line intensities have also been corrected through internal reference self-absorption correction method [11]. The calculated electron temperature has been compared with that of calculated by Delserieys et al. [10] using the Boltzmann plot and Thomson scatter approach at different time delay (100-700 ns) of plasma evolution. The calculated plasma temperatures through the present CR model are in good agreement with Thomson scatter results particularly at higher time delays. The results suggest that our model can be further applied to characterize the other reported laser induced Mg plasmas and also the calculated cross-sections can be used for different atomic physics applications. [1] Y Hongbing and, et. al., J. Lasers, Opt. Photonics, 05, 2–7 (2018). [2] H Zhang, et. al, Spectrochim. Acta - Part B At. Spectrosc., 157, 6–11 (2019). [3] D W Hahn, et. al., Appl. Spectrosc., 66 347–419 (2012). [4] M Milán, et. al., Spectrochim. Acta - Part B At. Spectrosc,. 56, 275–88 (2001). [5] S Gupta, et. al., Plasma Sources Sci. Technol., 28, (2019). [6] L D Pietanza, et. al., Spectrochim. Acta - Part B At. Spectrosc., 65, 616–26 (2010). [7] G Travaillé, et. al., Spectrochim. Acta - Part B At. Spectrosc., 64, 931–7 (2009). [8] R Srivastava, et. al., Phys. Rev. A - At. Mol. Opt. Phys., 74, 1–10 (2006). [9] P Jönsson, et. al., Comput. Phys. Commun., 177, 597–622 (2007). [10] A Delserieys et al. J. Appl. Phys., 106, 083304 (2009). [11] L Sun, et. al., Talanta 79, 388-395 (2009). Department of Pure and Applied Physics Guru Ghasidas Central Univ5e4rsity, Bilaspur (C.G.)-495009, India

International e-Conference on Plasma Theory and Simulations (PTS-2020), September 14 & 15, 2020, Bilaspur, India BP-19 Surface Modification of Chitosan/Starch Biocomposites by Non-thermal Ar, Ar+O2 and He+O2 Plasma Treatment: A Comparative Study and Towards Biological Applications Rajesh k.Mahanta, Pranita Panda, Smrutiprava Das Ravenshaw University, Cuttack 753003, Odisha, India e-mail: [email protected] Polymers have become an indispensable part of mankind; be it electronics, energy or medicine. In particular, polymers obtained from natural sources have profound applicability in biomedical sectors. Plasma treatment has gained widespread significance since it is solvent-free, fast, devoid of any by-products and thus, environmentally more benign. Particularly in surface treatment; gases such as argon, helium, nitrogen, oxygen, and hydrogen react with the polymer substrate and modify its surface properties like topography, wettability and printability. Depending on the plasma exposure, the surface properties can be engineered. In this work bio-composites thin film comprising of chitosan and starch(C/S) were fabricated using a non-toxic tetraethyl orthosilicate as a cross linker. The resulting composites are subjected to Non thermal plasma to enhance wettability, topographical study and different biological applications. An improvement in wettability or hydrophilic character ensuring from NTP treatment was confirmed by contact angle measurement. Topological studies like SEM and AFM studies shows surface nanotexturing while the bulk attributes remain unaffected. An insignificant aging effect was observed upon exposure to air for 30 days which indicated the high stability of the NTP-modified film composites. Tensile strength data shows the hardness and stability of film which are highest in Ar+O2 gas mixture. The film composites displayed good antibacterial features against bacteria like E.coli and S.aurious which are confirmed by measuring its inhibition zone. Antioxidant property showed a good result in presence of Ar+O2 mixture which will help in future research for food packaging industry. By looking at this type of properties non-thermal plasma has shown greater significance in all application and it can be applied in future for diverse biomedical application. References [1] Meyers, M.A.; Chen, P.Y.; Lin, A.Y.M.; Seki, Y. Biological materials: Structure and mechanicalproperties. Prog. Mater. Sci. 2008, 53, 1–206. [2] Faruk, O.; Bledzki, A.K.; Fink, H.P.; Sain, M. Biocomposites reinforced with natural fibers:2000–2010. Prog. Polym. Sci. 2012, 37, 1552–1596. [3] Koronis, G.; Silva, A.; Fontul, M. Green composites: A review of adequate materials forautomotive applications. Compos. B Eng. 2013, 44, 120–127. Department of Pure and Applied Physics Guru Ghasidas Central University, Bilaspur (C.G.)-495009, India 55

International e-Conference on Plasma Theory and Simulations (PTS-2020), September 14 & 15, 2020, Bilaspur, India BP-20 Study of the Low Latitude Plasma Bubbles Irregularities Climatology using SWARM Satellite A-Alpha A.Shaker1, 3, Ayman Mahrous2, 3, Ibrahim Fathy1, 3 1 Egyptian Academy of Engineering and Advanced Technology affiliated to Ministry of Military Production, Cairo, Egypt. 2Institute of Basic and Applied Sciences, Egypt-Japan University of Science and Technology, 21934 Alexandria, Egypt 3Space Weather Monitoring Center, Faculty of Science, Helwan University, Ain Helwan, 11795 Egypt. e-mail: [email protected] Ionospheric scintillation occurs when radio signals propagate through an irregular ionosphere (e.g., plasma bubbles). Since plasma bubbles are regions of depleted ion and electron densities, a plasma bubble located on the satellite-to-ground signal path will cause radio signals to fluctuate in phase and amplitude. The seasonal, annual and solar cycle variation of scintillation occurrence is investigated together with the Total Electron Content (TEC), to put in evidence the relation between the electron density gradients and the ionospheric irregularities causing scintillation. Emphasis will be placed on characterization of the relevant phenomena under geomagnetic quiet and disturbed conditions due to space weather phenomena, which are the main cause of increased ionospheric variability, and their associated consequences which will enable the mitigation of the deleterious ionospheric propagation effects on practical terrestrial, Earth-space communication and navigation systems. This is of considerable interest for space programs. This study aims to evaluate and improve ionospheric models for the region to facilitate better ionospheric predictions. References [1] Woodman, R. F., and C. LaHoz (1976), Radar observations of F region equatorial irregularities, J. Geophys. Res., 81(31), 5447–5461. [2] Sultan, P. J. (1996), Linear theory andmodeling of the Rayleigh-Taylor instability leading to the occurrence of equatorial spread F, J. Geophys.Res., 101(A12), 26,875–26,891, doi:10.1029/96JA00682. [3] Burke, W. J. (2004), Longitudinal variability of equatorial plasma bubbles observed by DMSP and ROCSAT-1, J. Geophys. Res., 109, A12301, doi:10.1029/2004JA010583. Department of Pure and Applied Physics Guru Ghasidas Central University, Bilaspur (C.G.)-495009, India 56

International e-Conference on Plasma Theory and Simulations (PTS-2020), September 14 & 15, 2020, Bilaspur, India BP-21 Electron-acoustic solitary waves in Fermi plasma with two-temperature electrons S. Pramanick1, A. Dey2, S. Chakraborty3, M. Sarkar3, S. Chandra4 1Indian Institute of Technology Kharagpur, Kharagpur, West Bengal, India 2Lady Brabourne College, Kolkata, West Bengal, India 3Jadavpur University, Kolkata, West Bengal, India 4Physics Department Government General Degree College at Kushmandi, Dakshin Dinajpur, India e-mail: [email protected] Electron Acoustic waves in Fermi Plasma with two temperature electrons have various applications in space and laboratory-made plasmas. In some dense plasma systems like the inside of compact stars, Fermi plasma is important. We have studied Fermi plasma system with three components, two temperature electrons, and ions. The hot electrons are mobile and produce restoring force to the system while cold electrons are immobile and produce inertia to the system. We have studied the dispersion behavior of electron acoustic waves in Fermi plasma with two temperature electrons and investigated its dependence with various plasma parameters. we have investigated Korteweg-de Vries Burger’s equation for the solitary profile of Fermi plasmas with two temperature electrons and investigated its dependence with various plasma parameters. References [1] Chandra, S.; Paul, S.N.; Ghosh, B.; “Electron-acoustic solitary waves in a relativistically degenerate quantum plasma with two-temperature electrons”, Astrophys Space Sci ,343:213–219, (2013) [2] Ali, S., Shukla, P.K.: Phys. Plasmas 13, 022313 (2006) [3] Bains, A.S., Tribeche, M., Gill, T.S.: Phys. Lett. A 375, 2059 (2011) Department of Pure and Applied Physics Guru Ghasidas Central University, Bilaspur (C.G.)-495009, India 57

International e-Conference on Plasma Theory and Simulations (PTS-2020), September 14 & 15, 2020, Bilaspur, India BP-22 Coupled KP Equation in Non-Maxwellian Plasmas with two Temperature Electrons Manveet Kaur and N. S. Saini Department of Physics, Guru Nanak Dev University, Amritsar-143005, India e-mail: [email protected] Most of the astrophysical, space and laboratory environments have confirmed the occurrence of superthermal charged particles due to different mechanisms. Lorentzian distribution function is the most common distribution function used to illustrate such superthermal particles. Due to non-equilibrium behaviour the space possesses the non- Maxwellian distribution. Vasyliunas first time reported that the velocities of high-energy electrons do not follow the simple well-known Maxwellian distribution but rather follow a non-Maxwellian power law distribution, known as kappa (κ) distribution. Over the last many years, the hybrid distribution provides more general platform to analyse different kinds of nonlinear structures in space and astrophysical plasma environments. The Vasyliunas-Cairns (VC) distribution function contains two spectral indices κ (given by Vasyliunas) for superthermal and α (given by Cairns) for nonthermal. For realistic situations, α < 1 and κ > 3/2. It is also believed that many space and astrophysical environments witness the presence of two temperature electrons (e.g., Saturn’s magnetosphere etc.). In the present investigation, we have studied the characteristics of two-dimensional small amplitude dust-ion-acoustic waves in multicomponent plasma having ion fluid, dust, and two temperature electrons obeying Vasyliunas-Cairns (VC) distribution. The MKP equations have been derived using reductive perturbation technique. Further, coupled KP equation is derived to study the characteristics of small amplitude dust-ion acoustic solitary structures. Only negative potential solitary structures are formed. It is discerned that the characteristics of dust-ion acoustic solitary waves are significantly influenced by the variation in different physical parameters. The findings of this investigation may be useful in understanding the nonlinear structures in space dusty plasma like Saturn’s magnetosphere. References [1] W. S. Kadomstev, V. Petviashvili, Soviet Physics 15, 539 (1970). [2] V. M. Vasyliunas, J. Geophys. Res.73, 2839 (1968). [3] N. S. Saini, Nimardeep Kaur, T. S. Gill, Adv. Space Research, 55, 2873 (2015). Department of Pure and Applied Physics Guru Ghasidas Central University, Bilaspur (C.G.)-495009, India 58

International e-Conference on Plasma Theory and Simulations (PTS-2020), September 14 & 15, 2020, Bilaspur, India BP-23 Gravitational Instability in Viscoelastic Medium with Non-Uniform Rotation and Magnetic Field under Dissipative Energy Effects Joginder Singh Dhiman and Mehak Mahajan Department of Mathematics, Himachal Pradesh University, Summerhill, Shimla-171005, India e-mail: [email protected] The effect of dissipative processes due to viscosity on self-gravitational instability of viscoelastic medium in the presence of non-uniform rotation and magnetic field is analyzed using standard Jeans mechanism. The modified Jeans instability criterions are derived from the dispersion relations, which are obtained from the linearized perturbation equations of the problem for transverse and longitudinal modes of wave propagation using normal mode analysis method. It is found that both the dissipative energy effect and the magnetic field respectively represented by the Stokes-Kirchhoff factor and Alfven’s wave velocities, reduce the critical Jeans wave number and thus enhance the critical Jeans mass. It is also observed that non-uniform rotation has no effect on the Jeans instability criterion; however, the dissipative energy and non-uniform magnetic field has stabilizing influence on the onset of gravitational instability. Further, the presence of dissipative energy in viscoelastic medium retards the gravitational collapse. References: [1] K. V. Roberts and J. B. Taylor, Phys. Rev. Lett. 8, 197 (1962). [2] P. A. Damiano, A. N. Wright and J. F. McKenzie, Phys. Plasmas 16, 062901 (2009). [3] P. K. Bhatia, Z. Astrophys. 69, 363 (1968). [4] P. Sharma, IEEE International Conference on Plasma Sciences (ICOPS), Antalya, Turkey (2015). Department of Pure and Applied Physics Guru Ghasidas Central University, Bilaspur (C.G.)-495009, India 59

International e-Conference on Plasma Theory and Simulations (PTS-2020), September 14 & 15, 2020, Bilaspur, India BP-24 Study of Floating Potential Oscillations of Anodic Double Layers Produced in a Typical DC Glow Discharge Plasma Thangjam Rishikanta Singh and Suraj Kumar Sinha Department of physics, Pondicherry University, Puducherry, 605014 (India) e-mail: [email protected] In this paper, we discuss about the formation of anodic double layers in typical DC glow discharge plasma and study its floating potential oscillations by varying different discharge parameters like pressures, cathode voltage and anode voltage. The observed oscillations and time series data with respect to these corresponding parameters are investigated and analyzed by using Fast Fourier Transform and Wavelet transform to ascertain the formation of time domain structures. The floating potential oscillations observed under MADL condition showed some striking similarity with the bipolar time domain structures of electric pulse in auroral double layer as observed by FAST (Fast Auroral SnapshoT ) satellite. This research would give an insight about the possibility of scaling down of space and astrophysical structures to laboratory scale and model the governing processes, which is otherwise not possible and it may be applicable to study acceleration mechanism of charge particles in the space for solar flare, solar wind and auroral discharge in ionosphere. References [1] Lars. P. Block, Astrophysics and space science 55, 59-83, 1978. [2] C Charles, Plasma Sources Sci. Technol. 16 (2007) R1–R25 [3] Torven and Babic, Proc. Twelfth Int.Conf. On Phenomena in ionized gases, Eindhoven, The Netherland, Pt I, p.124 (1976). [4] Anderson, Tech.Retp TRITA-EPP-76-10, Dept. of Electron Physics, Royal Inst. Of Tech.Stockholm (1976). [5] Quon and Wong, Phys.Rev.Letters, 36, 1393 (1976). [6] Micheal A. Raadu, Physics Reports, 178, 2, pp.25-97 (1989). [7] R. E. Ergun, C. W. Carlson, J. P. McFadden, F. S. Mozer, L. Muschietti, I. Roth, and R. J. Strangeway, Phys. Rev. Lett. 81, 826 (1998). [8] Prince Alex, Saravanan Arumugham and Suraj Kumar Sinha, Physics Letters A 381 (2017) 3652-3658 Department of Pure and Applied Physics Guru Ghasidas Central University, Bilaspur (C.G.)-495009, India 60

International e-Conference on Plasma Theory and Simulations (PTS-2020), September 14 & 15, 2020, Bilaspur, India BP-25 Head-on Collision of Electron Acoustic Solitary Waves in a Plasma with Generalized (r, q) Distribution Rupinder Kaur, N. S. Saini Department of Physics, Guru Nanak Dev University, Amritsar-143005, India e-mail: [email protected] Over the last few decades, studies on the nonlinear propagation of electron acoustic waves (EAWs) have received a great deal of attention. Electron acoustic waves are high frequency waves and can be generated in a plasma which contains two populations of electrons (cold and hot) with stationary background of ions [1]. The thermal pressure of the hot electrons is a source of the restoring force and cold electrons provide inertia. Numerous investigations have been reported to study electron acoustic solitary waves and shocks in different kinds of plasmas. A limited number of investigations have been reported to study head on collision of electron acoustic solitons in nonrelativistic or weakly relativistic plasmas. The significance of considering the relativistic dynamics of electrons arises due to the fact that the effect of relativistic streaming electrons on the large electric field observed in the polar cusp regions of the pulsar magnetosphere can make the cold electron species to achieve relativistic velocities [2]. A theoretical investigation is carried out to study head-on collision among electron acoustic solitary waves (EASWs) with collisionless, homogenous and unmagnitized relativistic plasma comprising inertial cold electrons, hot electrons obeying (r, q) distribution and immobile ions. By employing the extended Poincarѐ-Lighthill-Kou (PLK) method, two sided KdV equations are derived. The Hirota direct method is used to obtain multi-soliton solutions for each KdV equation [3]. Plasma parameters, typically found in Saturn’s magnetosphere and the Earth’s auroral region, where two populations of electrons exist, are considered for numerical analysis. It has been found that the flatness parameter (r), tail parameter (q) and other plasma parameters affect significantly the propagation properties of nonlinear electron acoustic solitary waves (EASWs). The findings of this investigations may be useful in illustrating nonlinear phenomena for the formation of electrostatic excitations in space and astrophysical plasma environments. References: [1] P. K. Shukla, L. Stenflo, and M. Hellberg, Physical Review E, 66, 2000. [2] N. S. Saini, and Kuldeep Singh, Physics of Plasmas, 23, 103701(1-10) 2018. [3] Kuldeep Singh, Papihra Sethi and N. S. Saini, Physics of Plasmas, 25, 033705 (1-11), 2018. Department of Pure and Applied Physics Guru Ghasidas Central University, Bilaspur (C.G.)-495009, India 61

Dusty (Complex) Plasmas

International e-Conference on Plasma Theory and Simulations (PTS-2020), September 14 & 15, 2020, Bilaspur, India DP-01 Collective Excitation of Dust Grains in 3D Complex Plasma P. Bezbaruah1 and N. Das2 1Biswanath College, Biswanath Chariali, India 2Tezpur University, Tezpur, India e-mail: [email protected] In a three-dimensional system of dust particles, the physical properties of the dust ensemble are sensitive to phase behavior and collective effect in complex plasma. The characteristics of the longitudinal wave modes due to dust oscillation are affected by the nature of interaction potential operative between the dust grains. In presence of ion flow the combined role of Yukawa and modified Debye Hückle interaction is observed in the dispersion of the dust acoustic mode. The role of Coulomb Coupling parameter on dispersive property is investigated in solid and fluid phase of the assembly of dust particles. Brownian Dynamics Simulation is performed to yield Longitudinal Current Autocorrelation Function (LCAF) which is analyzed to obtain the wave spectrum. It is revealed that the asymmetry, contributed through the modified Debye Hückle potential may become effective in the fluid phase and it may be responsible for energy exchange between collective mode and the dust particles in the system. References [1] Z. Donko, G. J. Kalman, and P. Hartmann, J. Phys. Condens. Matter 20, 413101 (2008). [2] P. K. Kaw, and A. Sen, Phys. Plasmas 5(10), 3552-3559 (1998). [3] B. Liu, and J. Goree, Phys. Rev. E 75, 016405 (2007). Department of Pure and Applied Physics Guru Ghasidas Central University, Bilaspur (C.G.)-495009, India 62

International e-Conference on Plasma Theory and Simulations (PTS-2020), September 14 & 15, 2020, Bilaspur, India DP-02 Evolution of Dusty Plasma: From Challenges to Opportunities Avik Kr. Basu1,2 and M. Bose1 1 Department of Physics, Jadavpur University, Kolkata-700032, India 2Department of Physics, Raja Peary Mohan College, Uttarpara, Hooghly- 712258, India e-mail: [email protected] An admixture of charged particulates, electrons, ions, and neutrals in a partially or fully- ionized gas forms a ‘Dusty (or Complex) Plasma’. These particulates may have sizes ranging from nanometers to microns in the probable shapes of spheres or rods or irregularly shaped. They may be composed of dielectric or conducting materials. Although the particles are commonly solid, they might also be fluffy ice crystals or even liquid droplets. Long before Langmuir (1923) first coined the term ‘plasma’, the history of dust-laden objects began with the observation of the zodiacal light, the Orion nebula, the noctilucent clouds, etc. by our ancestors and this particular field, later termed as dusty plasma, is still of major interest in a wide range of applications from dry powder coatings, upper atmospheric research to the microelectronics industry. Dust is a very common medium and turns out to be ubiquitous in nature such as in an astrophysical plasma environment (planetary nebula, planetary rings) or planetary upper atmosphere as well as in human-made plasma (laboratory or industrial discharges, fusion plasmas, etc.). In any case, charged dust particles can be useful or harmful, and consequently, a lot of studies are devoted to them. These particles are an annoyance in the plasma of fusion energy schemes and semiconductor manufacturing whereas, the nanoparticles grown in plasma discharges are seen as the building blocks of nanotechnology. From the unique pieces of information of very basic experiments on the dusty plasma in the laboratory system, we can actually predict several phenomena in fusion devices as well as in space. Recently in our lab, we observed a mysterious dust ring inside a dust void. We need the theoretical plasma physicist community to come forward and to provide a proper explanation regarding this astonishing experimental finding. Department of Pure and Applied Physics Guru Ghasidas Central University, Bilaspur (C.G.)-495009, India 63

International e-Conference on Plasma Theory and Simulations (PTS-2020), September 14 & 15, 2020, Bilaspur, India DP-03 Instabilities in Magnetized Inhomogeneous Plasmas with Effect of Recombination Shachi Pachauri1, Kamakhya Prakash Misra1 and Jyoti2 1Department of Physics, Manipal University Jaipur, Jaipur, Rajasthan, India-303007 2Government College for Women, Gurawara, Haryana, India-123035 e-mail: [email protected] Inhomogeneous plasma with positive ions and electrons, in which collisions are taking place, is considered. To include the modification due to the magnetized plasma, a static magnetic field B0 is considered to be applied along -direction and the wave propagation is taken at an angle in the plane. The ions are assumed to be cold and singly charged. Fluid equations, which take into account the recombination effects, are formulated for ions and electrons. Potential is deduced from Poisson’s equation using normal mode analysis along with linear approximation, neglecting higher order perturbation terms. From Potential equation, dispersion relation is generated which is solved numerically for obtaining the value of ɷ using typical plasma parameters. From this dispersion relation growth profile of instabilities has been observed using typical plasma parameters. References [1] C. N. Lashmore-Davies, Phys. Plasmas 14, p 092101-8, (2007). [2] Jyoti, Contrb. Plasm. Phys. 56, p 113-125, (2015). [3] W. L. Hogartht and d. L. S. Mcelwaint, Proc. B. Soc. Lond. A. 345, p 251-263, (1975). [4] P. Kaw and R. Singh, Phys. Rev. Lett. 79, p 423-426, (1997). [5] V. P. Lakhin, V. I. Ilgisonis, A. I. Smolyakov, E. A. Sorokina, and N. A. Marusov, Phys. Plasmas 25, 012107 (2018). Department of Pure and Applied Physics Guru Ghasidas Central University, Bilaspur (C.G.)-495009, India 64

International e-Conference on Plasma Theory and Simulations (PTS-2020), September 14 & 15, 2020, Bilaspur, India DP-04 Dynamics of Dust Ion Acoustic Waves in the Low Earth Orbital (LEO) Plasma Region Siba Prasad Acharya1, Abhik Mukherjee2 and M. S. Janaki1 1Saha Institute of Nuclear Physics, Kolkata, India 2National University of Science and Technology, “MISiS”, Moscow, Russia e-mail: [email protected] We consider the system consisting of the plasma environment in the Low Earth Orbital (LEO) region in presence of charged space debris objects. The system is modelled for the first time as a weakly coupled dusty plasma where the charged space debris objects are treated as weakly coupled dust particles. The dynamics of the ion acoustic waves in the system is found to be governed by a forced Kadomtsev-Petviashvili (KP) type model equation, which is derived employing the well-known reductive perturbation technique (RPT). Accelerated planar solitary wave solutions are obtained after solving the KP equation upon transferring the frame of reference. The possibility of accelerated lump solutions, which are happened to be pinned, is also discussed. This is the generalization of precursor line solitons moving ahead of the space debris objects, which is reported in recent years. Our work provides a much clearer insight of the debris dynamics in the plasma medium in the LEO region, revealing some novel results that are immensely helpful for various space missions. References [1] A. Sen, S. Tiwari, S. Mishra, and P. Kaw, Advances in Space Research, Vol. 56, 429-435 (2015). [2] A. R. Seadawy, and K. El-Rashidy, Results in Physics, Vol. 8, 1216-1222 (2018). [3] M. Lin, and W. Duan, Chaos, Solitons and Fractals, Vol. 23, 929-937 (2005). [4] M. S. Janaki, B. K. Som, B. Dasgupta, and M. R. Gupta, Journal of the Physical Society of Japan, Vol. 60, 2977-2984 (1995). [5] S. Reyad, M. M. Selim, A. EL-Depsy, and S. K. El-Labany, Physics of Plasmas, Vol. 25, 083701 (2018). [6] X. Yong, W. X. Ma, Y. Huang, and Y. Liu, Computers and Mathematics with Applications, Vol. 75, 3414-3419 (2018). [7] J. Yu, F. Wang, W. Ma, Y. Sun, and C. M. Khaliue, Nonlinear Dynamics, Vol. 95, 1687-1692 (2019). [8] A. A. Minzoni, and N. F. Smyth, Wave motion, Vol. 24, 291-305 (1996). Department of Pure and Applied Physics Guru Ghasidas Central University, Bilaspur (C.G.)-495009, India 65

International e-Conference on Plasma Theory and Simulations (PTS-2020), September 14 & 15, 2020, Bilaspur, India DP-05 Charging of Dust Particles in Plasma Using h-PIC-MCC Simulation Model Suniti Changmai, Madhurjya P. Bora Physics Department, Gauhati University, Guwahati, India e-mail: [email protected] Here we present the preliminary dust charging results obtained using our newly developed Particle-in-cell (PIC) model. Our hybrid-Particle-in-cell-Monte Carlo Collision (h-PIC-MCC) algorithm can be used to study numerous phenomena that can be developed in various dusty plasma environments ranging from laboratory to space and astrophysical plasma. The approach of estimating the dust-plasma particle interaction in our model is quite different from the available well known Monte Carlo Collision (MCC) algorithms. However, our numerical results are found to be in good agreement with the existing theoretical estimations available for charging mechanism of the dust particles immersed in a plasma. References [1] C. K. Birdsall, IEEE Transactions on Plasma Science, 19, 65 (1991). [2] N. A. Gatsonis, R. E. Erlandson, C.-I. Meng, Journal of Geophysical Research, 99, 8479 (1994). Department of Pure and Applied Physics Guru Ghasidas Central University, Bilaspur (C.G.)-495009, India 66

International e-Conference on Plasma Theory and Simulations (PTS-2020) September 14 & 15, 2020, Bilaspur, India DP-06 Nonlinear Propagation of Dust Acoustic Waves in Dusty Plasma having Nonisothermal Two-Temperature Electrons and Isothermal Positrons S. Chattopadhyay1, S. N. Paul1,2 and S. K. Bhattacharya1,3 1East Kolkata Centre for Science Education Research, Kolkata-700 094, India 2Department of Physics, Jadavpur University, Kolkata-700032, India 3Kalna Polytechnic, Kalna, Purba Bardhaman, West Bengal, Pin-713409, India e-mail: [email protected] In recent years, there have been considerable interests in understanding the different types of collective processes in plasmas containing electrons, ions and charged micron-sized grain particles. Such plasmas occur frequently in many astrophysical systems including the interplanetary medium, planetary rings, asteroids, cometary tails, interstellar clouds, nebulae, aurora etc. and they are also produced in plasma discharges, optical fibers, dusty crystals, semiconductors as well as regions of hot fusion plasma and in devices for plasma-assisted material processing. For low frequency modes, the grain dust can be described as negative ions with large mass and large charge. In particular it has been shown that dusty plasmas with inertial dust fluid and Boltzmann distributed ions admit only negative solitary potentials associated with nonlinear dust acoustic wave. In the present paper, we have theoretically investigated the nonlinear propagation of dust acoustic waves in dusty plasma in a collisionless dusty plasma consisting of non-isothermal two-temperature electrons, negatively charged cold dust, warm positive ion and isothermal positrons by using Sadie’s pseudo- potential method. An exact form of Sagdeev potential ψ(ϕ) has been derived for the propagating dust acoustic wave in such dusty plasma. The solutions of dust acoustic solitary wave for first-, second- and third- orders are obtained using “tanh-method”. Moreover, the conditions for the existence of a potential well for dust acoustic solitary waves are obtained in the dusty plasma. From the third order nonlinear equation the solution of spiky and explosive dust acoustic solitary waves is obtained and graphically discussed. References: [1] W. Malfliet and Willy Hereman, Physica Scripta.54, 563-568 (1996). [2] G.C.Das,J.Sarma and M.Talukdar, Phys. Plasmas, 5, 63-69 (1998). [3] S.N.Paul, A.Chatterjee , Indrani Paul and B.Ghosh, International J. Chemical and Physical Sciences, IJCPS, 4 APST–2015, 38 - 42 (2015). Department of Pure and Applied Physics Guru Ghasidas Central University, Bilaspur (C.G.)-495009, India 67

International e-Conference on Plasma Theory and Simulations (PTS-2020), September 14 & 15, 2020, Bilaspur, India DP-07 Effect of Multiply Charged Xe Ions on a Dusty Hall Discharge Plasma Jasvendra Tyagi Department of Applied Sciences (Physics), IMS Engineering College, Ghaziabad Uttar Pradesh, India e-mail: [email protected] Versatile thrusters with high reliability and performance are required to perform various missions in the space. Compared to chemical propulsion the electric propulsion has the advantage of a low propellant consumption and a significant thrust to power ratio, which result in mass and cost savings. Hall thrusters are the devices which make use of plasma propulsion and are being used in the long-term space missions. In these devices, the radial magnetic field and the axial electric field trap the electrons in an azimuthal closed-drift and according to classical theory, the only mechanism that allows the electrons to drift axially is the collisions with other species. The drop of the axial electron conductivity gives rise to large electric field in the plasma, which accelerates the ions. In the presence of dust contamination, this scenario may change due to the current flowing into the dust particles and the collisions taking place in the acceleration channel [1-3]. On the other hand, the importance of plasma oscillations for the successful operation of Hall current plasma thrusters has been long recognized. Hence, this is obvious that the dust contamination in the thruster plasma will drastically modify the operation of the device and its efficiency. These dust particles are produced due to the collisions of the ions with the walls in view of the radial component of electric field generated in these devices; there is also some level of impurity in the propellant that leads the dust contaminations in the channel plasma. A high fraction of multiply charged Xe ions has found in Hall thruster plasmas, which is related to the performance characteristics of the thruster, such as a high specific impulse [4]. This work is associated with the performance of the Hall thruster plasma in the presence of doubly or multiply charged Xe ions. The oscillations of all contaminated plasma species (ions, electrons and charged dust) is considered. By using the fluid model, the dispersion equation is derived numerically with the help of which the effect of different parameters on the Hall plasma is discussed. References [1] H. K. Malik, J. Tyagi, and D. Sharma, AIP Advances 9, 055220 (2019). [2] J. Bak, B. Van Loo, R. Kawashima, and K. Komurasaki, J. Appl. Phys. 128, 023302 (2020). [3] J. Tyagi, D. Sharma, and H. K. Malik, J. Theor. Appl. Phys. 12, 227 (2018). [4] H. Kim, Y. Lim, W. Choe, and J. Seon, Appl. Phys. Lett. 105, 144104 (2014). Department of Pure and Applied Physics Guru Ghasidas Central University, Bilaspur (C.G.)-495009, India 68

International e-Conference on Plasma Theory and Simulations (PTS-2020), September 14 & 15, 2020, Bilaspur, India DP-08 Molecular Dynamics Simulation of the Kelvin-Helmholtz Instability in Dusty Plasma Layers with Different Velocities and Density Bivash Dolai and R. P. Prajapati Department of Pure and Applied Physics, Guru Ghasidas Vishwavidyalaya, Bilaspur-495009 (C.G.), India e-mail: [email protected] The effect of different velocities and density of flowing dusty plasma layers are investigated on hydrodynamic Kelvin-Helmholtz (K-H) instability. The dust particles are too massive as compared to the electron and ions. Therefore, the electron and ion fluids are taken to be light Boltzmann fluid and they only contributes as the neutralizing background to the charged dust grains. The dust particles are interacting through the Yukawa potential. Thus, the system can be termed as Yukawa one component fluid. The basic fluid equations for this configuration have been formulated. The problem has been simulated using the MD simulation technique through open source LAMMPS code. We consider the two layers of such Yukawa one component fluids with same and different dust density, and different velocity profiles. The effect of different flow velocities, flow direction and different density are studied on the K-H instability. We have calculated the growth rate of the K-H instability for such configurations. It is found that the different dust flow velocities enhance the growth rate of the K-H instability Department of Pure and Applied Physics Guru Ghasidas Central University, Bilaspur (C.G.)-495009, India 69

Laser Plasma Interactions

International e-Conference on Plasma Theory and Simulations (PTS-2020), September 14 & 15, 2020, Bilaspur, India LP-01 Controlled Tunable Resonant Phase Matching In Laser Plasma Interaction S. Divya Computational Plasma Dynamics Laboratory, Department of Physics & Electronics, Rajdhani College, University Of Delhi e-mail: [email protected] There are various types of applications offered by laser plasma interactions which include nuclear fusion, particle acceleration, heating of ionospheric plasma and laboratory plasmas by radio waves etc. along with controlled fusion applications to ITER (International Thermonuclear Experimental Reactor), frequency upshifting, resonance absorption, laser focusing and defocusing, material processing, generation of X-ray, THz and microwave radiations, higher order harmonic generation, laser filamentation etc. Therefore, it is quite essential to study plasma dynamics upon laser interaction in different regime. When intense lasers are impinged on the plasma, a radiation pressure force is created that impart laser energy to plasma species. There is an essential requirement of phase matching between wave number of laser and excited plasma wave to ensure maximum energy transfer with least dissipation. On the contrary, in case of mismatch of phase, most of the laser energy got dissipated and cause creation of instabilities in plasma. Here, in the present research we suggest to apply external periodic electrostatic field as an extra tool to achieve controlled resonance through phase matching. This achieved resonance can further be tuned to desired range with periodicity of external field. Such approach works well in case of uniform density plasma as well as modulated density plasma. References [1] D. Singh and H. K. Malik, Physics of Plasmas 21, 083105 (2014). [2] D. Singh and H. K. Malik, Plasma Sources Sci. Technol. 24 045001 (2015). [3] D. Singh and H. K. Malik, Asian Journal of Physics 24 3 (2015). [4] D. Singh and H. K. Malik, Nuclear Instruments & Methods in Physics Research A (2016) http://dx.doi.org/10.1016/j.nima.2016.03.108. [5] R. Gill, D. Singh and H. K. Malik, J Theoretical Applied Physics 11:103–108 (2017). [6] D. Sharma, D. Singh and H. K. Malik, Plasmonics (2019), Springer Journal ISSN 1557-1955, doi: 10.1007/s11468-019-01017-5 [7] D. Singh and H. K. Malik, European Physics Letter (2019) ISSN 0295-5075. Department of Pure and Applied Physics Guru Ghasidas Central University, Bilaspur (C.G.)-495009, India 70

International e-Conference on Plasma Theory and Simulations (PTS-2020), September 14 & 15, 2020, Bilaspur, India LP-02 Nonlinear Theory of a Cherenkov Free-electron Laser Hesham Fares1,2, Mohamed Mahmoud2 1Department of Physics, College of Science, Taibah University, P.O. Box 30002, Al Madinah Al Munawwarah, Saudi Arabia 2 Department of Physics, Faculty of Science, Assiut University, Assiut 71516, Egypt e-mail: [email protected] A generalized expression for the high-gain of a Cherenkov Free-Electron Laser (CFEL) is derived. In our treatment, the dynamics of the radiation field and free electrons in the CFEL are described using Maxwell and plasma fluid equations, respectively. The dynamical parameters of electrons such as the velocity and density of electrons are assumed to be spatially dependent. The phase shift (i.e., desynchronization) between the bunched electrons and the electromagnetic wave is also taken into account. The transition of the gain coefficient from the linear to the non-linear regimes is investigated. Then, for optimizing the CFEL operation, the interaction length at which the gain reaches its maximum value at the end of the linear regime can be determined. In linear limit, we confirm that our gain expression is matched with those of previous studies. Department of Pure and Applied Physics Guru Ghasidas Central University, Bilaspur (C.G.)-495009, India 71

International e-Conference on Plasma Theory and Simulations (PTS-2020), September 14 & 15, 2020, Bilaspur, India LP-03 Magnetic Field Generation by Laser-Pulse Interaction with Plasmas Krishna Gopal1 and Devki Nandan Gupta2 1Department of Physics and Electronics, Rajdhani College (University of Delhi), Delhi-110015 2Department of Physics and Astrophysics, University of Delhi, Delhi-110007 E-mail: [email protected] Laser-plasma interaction may be a major source of magnetic field generation through nonlinear processes in plasmas. Magnetic field generation is significant and interesting in the field of laser-plasma interaction because the magnetic field greatly affects the plasma dynamics; consequently it plays a key role in the plasma-based particle accelerators, the formation of plasma channel in context of the fast ignition of fusion target and the process of radiation generation when ultrafast laser interacts with a plasma. Plasmas (magnetic-field free) can give rise to non-zero self-generated magnetic field based on the mechanisms that are responsible for creating the electron current and the electric field. Magnetic field in plasmas can be generated by several mechanisms e.g. due to non-parallel electron density and temperature gradients (known as the Biermann battery), by electron temperature anisotropy (known as the Weibel instability), by counter streaming charge particle beam (known as current filamentation instability), due to inverse Faraday effect, by the ponderomotive force of the intense laser beams and due to dynamo mechanism involving strong axial flow of electrons. Here, we propose two-dimensional particle-in-cell (2D-PIC) simulations to investigate the large-scale magnetic field in plasma density-gradient by a temporally asymmetric laser pulse. References [1] V. K. Tripathi and C. S. Liu, Phys. Plasmas 1, 990 (1994). [2] T. Lehner, Phys. Scr, 49 704(1994). [3] K. Gopal, D. N. Gupta, Y. K. Kim, M. S. Hur, and H. Suk, J. Appl. Phys 119, 123101 (2016). Department of Pure and Applied Physics Guru Ghasidas Central University, Bilaspur (C.G.)-495009, India 72

International e-Conference on Plasma Theory and Simulations (PTS-2020), September 14 & 15, 2020, Bilaspur, India LP-04 Electron Acceleration by Asymmetric Laser Pulses in Vacuum in The Presence of An Axial Magnetic Field Deep Kumar Kuri Department of Physics, Digboi College, Digboi, Assam – 786171, India e-mail: [email protected] With the recent advances in laser technology based on chirped pulse amplification [1], the interaction of electrons with high power laser fields has become possible. The laser-plasma based accelerating schemes such as laser wakefield acceleration (LWFA) [2] can accelerate electrons to high energies. However, electron acceleration in vacuum can have some advantages than in plasma as several effects such as electron dephasing and instabilities arising in a plasma which may limit the electron energy are absent in vacuum [3,4]. The shape of the laser pulse can have a significant impact on the acceleration process [5]. Here, I have numerically studied the electron acceleration in vacuum by laser pulses having different temporal shapes. The laser pulses considered here are asymmetric having an unequal rise and fall time. The influence of an axial magnetic field in the acceleration process has also been investigated. References [1] P. Maine, D. Strickland, P. Bad, M. Pessot, and G. Mourou, IEEE J. Quantum Electron. 24, 398 (1988). [2] T. Tajima and J. M. Dawson, Phys. Rev. Lett. 43, 267 (1979). [3] E. Esarey, P. Sprangle, and J. Krall, Phys. Rev. E 52, 5443 (1995). [4] G. Malka, E. Lefebre, and J. L. Miquel, Phys. Rev. Lett. 78, 3314 (1997). [5] W. P. Leemans, P. Catravas, E. Esarey, C. G. R. Geddes, C. Toth, R. Trines, C. B. Schroeder, B. A. Shadwick, J. van Tilborg, and J. Faure, Phys. Rev. Lett. 89, 174802 (2002). Department of Pure and Applied Physics Guru Ghasidas Central University, Bilaspur (C.G.)-495009, India 73

International e-Conference on Plasma Theory and Simulations (PTS-2020), September 14 & 15, 2020, Bilaspur, India LP-05 Effect of Relativistic Mass Variation of Electron on Raman Amplification Characteristics in semiconductor plasma medium Swati Dubey1, S. Ghosh1 and Subhash Chouhan1 1School of Studies in Physics, Vikram University, Ujjain, India e-mail: [email protected] Electron-phonon coupling is a very important factor in understanding the nonlinear properties of the crystalline materials. Since various collective modes can be excited in plasma, the coupling between these free electron plasma excitations i.e. plasmons and TO phonons leads to stimulated Raman scattering (SRS) in polar semiconductors. The origin of stimulated Raman scattering lies in the third‐order nonlinear optical susceptibility arising due to electron density perturbations and molecular vibrations of the medium. Amplification of an optical signal wave due to an efficient transfer of optical energy from strong pump light wave to the signal wave is possible by means of SRS. Influence of laser beam propagation characteristics in case of relativistic stimulated Raman scattering has got much attention in recent years [1-3]. Since semiconductors are Raman active medium and so they are obvious choice for the study of SRS in semiconductor plasma. Effect of relativistic mass variation (RMV) of electron on threshold electric field and steady state Raman amplification characteristics has been studied by using well-known hydrodynamic model. Rigorous analytical formulations have been carried out to derive expressions for threshold pump electric field and third order nonlinear Raman susceptibility of the medium. Analytical results have been applied to III-V semiconductor (viz., n-InSb) at 77K to demonstrate the practical utility of the theoretical model developed in this work. The dependence of Threshold electric field and steady state Raman gain coefficient on the various parameters (viz., Input pump field Intensity, external magnetic field, carrier concentration and wave vector) is reported. It is found both the threshold electric field and Raman gain coefficient have been affected significantly when RMV is taken to the account. In relativistic regime, higher input pump field amplitude and smaller magnetic is found to be favorable for higher Raman gain whereas higher doping carrier concentration and lower wave vector is required for higher gain. It is observed that magnitude of calculated third order susceptibility arising due to molecular vibration agrees well with other reports [4,5] in the field whereas susceptibility arising due to current density perturbation is found 1000 times higher than earlier works [4]. Raman gain is found to be greatly enhanced as compared to nonrelativistic studies [4,5]. References [1] Saleh T. Mahmoud and R. P. Sharma, Phys. Plasma, 8, 3419 (2001). [2] Yao Zhao et. al., Phys. Plasma, 21,112114 (2014). [3] D. N. Gupta et.al., Phys. Plasmas 22, 052101 (2015). [4] Swati Dubey and S. Ghosh, Physica B 210, 95-103 (1995). [5] A. Neogi and S. Ghosh, Phys. Rev. B, 44 (23) 13074 (1991). Department of Pure and Applied Physics Guru Ghasidas Central University, Bilaspur (C.G.)-495009, India 74

International e-Conference on Plasma Theory and Simulations (PTS-2020), September 14 & 15, 2020, Bilaspur, India LP-06 Strong and Collimated Terahertz Radiation by Photo Mixing of Hermite Cosh Gaussian Lasers in Collisional Plasma Sheetal Chaudhary, Manendra and Anil K. Malik Department of Physics, Ch. Charan Singh University, Meerut. e-mail: [email protected] THz spectral region has become a focus of active and thriving research because of its potential applications in remote sensing, topography, imaging, explosive detection, dentistry, chemical sciences, security identifications, terahertz time-domain spectroscopy (THz-TDS) [1-6]. An analytical model for terahertz (THz) wave emission by frequency difference of Hermite Cosh Gaussian lasers in collisional plasma with periodic density is developed. The effect of laser parameters (mode index s, decentered parameter b and initial phase difference δ) and plasma parameters (plasma density structure, electron-neutral collisions) on emitted THz field profile is investigated. It is found that the highest THz field is obtained for s = 1, b = 0, δ = 0, π, 2π and ω = ωp (resonant excitation) at x = 0. The study also reveals that electron neutral collisions attenuate the field drastically. A very high THz field of G V m-1 and an efficiency of ~ 3% is obtained in our scheme for optimised laser and plasma parameters. References [1] B. Ferguson and X. C. Zhang, Nat. Mater. 1, 26, (2002). [2] D. Dragoman, M. Dragoman, Prog. Quantum Electron. 28, 10, (2010). [3] W. P. Leemans, C. G. R. Geddes, J. Faure, C. Tóth, J. V. Tilborg, C. B. Schroeder, E. Esarey, G. Fubiani, D. Auerbach, B. Marcelis, M. A. Carnahan, R. A. Kaindl, J. Byrd, and M. C. Martin, Phys. Rev. Lett. 91, 074802, (2003). [4] S. Ebbinghaus, K. Schröck, J. C. Schauer, E. Bründermann, M. Heyden, G. Schwaab, M. Böke, J. Winter, M. Tani, M. Havenith, Plasma Sources Sci. Technol. 15, 72, (2006). [5] P. H. Siegel, IEEE Tran. Tera. Sci. Technol. 50, 910, (2002). [6] F. Sizov, Opto. Electron. Rev. 18, 10, (2010). Department of Pure and Applied Physics Guru Ghasidas Central University, Bilaspur (C.G.)-495009, India 75

International e-Conference on Plasma Theory and Simulations (PTS-2020), September 14 & 15, 2020, Bilaspur, India LP-07 Third Harmonic Generation via Interaction of Two-Colour Laser Beams with Plasma E. Agrawal Lucknow, India e-mail: [email protected] Generation of high harmonic radiation is an important subject of laser plasma interaction and attracts great attention due to wide range of applications. Interaction of linearly polarized laser pulses with homogeneous plasma leads to generation of odd harmonics of laser frequency [1]. However, second harmonics have been reported when linearly polarized laser pulses propagate in plasma in presence of density gradients [2] and externally applied magnetic fields [3]. Ganeev et al have experimently demonstrated an enhancement in efficiency of harmonics using two-colour laser beams in plasma plumes [4]. Efficiency enhancement of harmonics have been reported in Helium gas jet by propagation of two-colour laser beams [5]. An analytical study of generation of enhanced third harmonic by interaction of two-colour linearly polarized, laser beams in underdense plasma has been proposed. The frequency of the second laser is considered to be twice that of the first laser. The Lorentz force, continuity and Poisson's equations are perturbatively expanded in orders of the normalized vector potential of the laser field amplitude, to derive the source term driving the wave equation governing the evolution of the amplitude of the third harmonic. Evaluation of third harmonic radiation amplitude and comparison with single beam case has been presented. References [1] W. B. Mori, C. D. Decker, and W. P. Leemans, IEEE Trans. Plasma Sci. 21, 110 (1993). [2] E. Esarey, A. Ting, P. Sprangle, D. Umstadter and X. Liu, IEEE Trans. Plasma Sci. 21, 95 (1993). [3] P. Jha, R. K. Mishra, G. Raj and A. K. Upadhyay, Phys. Plasmas 14, 053107 (2007). [4] R. A. Ganeev, H. Singhal, P. A. Naik, I. A. Kulagin, P. V. Redkin, A. J. Chakera, M. Tayyab, R. A. Khan and P. D. Gupta, Phys. Rev. A 80, 033845 (2009). [5] J. Kim, G. H. Lee, S. B. Park, Y. S. Lee, T. K. Kim, C H. Nam, T. Mocek and K. Jakubczak, App. Phys. Lett, 92, 021125 (2008). Department of Pure and Applied Physics Guru Ghasidas Central University, Bilaspur (C.G.)-495009, India 76

International e-Conference on Plasma Theory and Simulations (PTS-2020), September 14 & 15, 2020, Bilaspur, India LP-08 Laser-plasma Accelerators for Electron Beam Generation D. N. Gupta 2Department of Physics and Astrophysics, University of Delhi, Delhi-110007 E-mail: [email protected] With the advent of laser, these studies underwent an explosive growth and wave-plasma interaction emerged as a major rich field of research. Laser plasma accelerators were proposed as a next generation compact accelerator because of the huge electric fields they can sustain. The accelerating electric fields in conventional accelerators are limited to a few tens of MeV/m, owing to material breakdown at the walls. Laser plasma accelerators can produce accelerating fields of hundreds of GeV/m, which accelerate particles to high energies in distances much shorter than in conventional accelerators. Such laser plasma accelerators are capable of producing beams of energetic electrons, protons and γ-rays. One major laser plasma accelerator is laser wakefield accelerator (LWFA). While an intense short laser pulse is injected in tenuous plasmas, the ponderomotive force of laser light expels electrons both longitudinally and transversely from the high intensity region. Then, a wave of strong electrostatic fields called wakefield is generated behind the pump laser. This is the so-called LWFA. If electrons with sufficient energy matching the accelerating electric fields are injected into the wakefield, they can be trapped by the wakefield and accelerated to high energy. In the last fifteen years, several major injection schemes have been proposed and performed by experiments successfully. The major objective of this talk is to understand the physics of laser plasma interaction via PIC simulation and theoretical analysis, and to explore new ways to increase energy and coupling from laser energy to the accelerated particles under current experimental conditions. This work presents researches on laser plasma acceleration and relevant topics which are of significant importance to many exciting applications such as fast ignition inertial confinement fusion, laboratory astrophysics, medical cancer therapy, and so. References [1] T. Tajima and J. Dawson, Phys. Rev. Lett. 43, 267 (1979). [2] D.N. Gupta, I.H. Nam, H. Suk, Phys. Rev. E 84, 056403 (2011). [2] D. N. Gupta, K. Gopal, V. V. Kulagin, and H. Suk, Laser and Particle Beams 32, 449 (2014). [2] K. Gopal, D. N. Gupta, Phys. Plasmas 24, 103101 (2017), Department of Pure and Applied Physics Guru Ghasidas Central University, Bilaspur (C.G.)-495009, India 77

International e-Conference on Plasma Theory and Simulations (PTS-2020), September 14 & 15, 2020, Bilaspur, India LP-09 Laser Plasma Mediated Synthesis of Ultrathin MoS2-Ag Nano-hybrid for Sensing Applications Parvathy N1, Sivakumaran Valluvadasan3, Ravi A V Kumar3, Sabu Thomas2, Nandakumar Kalarikkal1, 2 1School of Pure and Applied Physics, Mahatma Gandhi University, Kottayam-686560, Kerala 2International and Inter University Centre for Nanoscience and Nanotechnology, Mahatma Gandhi University, Kottayam-686560, Kerala 3Accelerator Division, Institute of Plasma Research, Near Indira Bridge, Gandhinagar District, Bhat, Gujarat 382428 e-mail: [email protected] Pulsed laser ablation (PLA) in liquid has been universally considered to be a physiochemical top-down approach governed by laser plasma and cavitation physics [1]. Herein, we report the influence of laser produced plasma for the improvisation of Molybdenum Disulfide (MoS2) sheets with silver nanoparticles by tuning the plasma parameters like electron temperature (Te) and electron number density (ne). The expansion dynamics of the plasma was characterised using space resolved optical emission spectroscopy [2-3]. Also, MoS2-based nano-hybrids finds extensive research interest in enhancing chemical catalytic performance, biochemical sensing etc. [4-6]. This is a novel laser plasma driven synthesis MoS2-Ag nano-hybrids by using nanosecond laser pulses. TEM, Raman, and XPS characterizations depicts the formation of Ag NPs on MoS2 nano-sheets, the doping effect of metal NPs on MoS2, and the modification of MoS2.The prepared MoS2-Ag hybrid material reveals excellent Surface Enhanced Raman Scattering [SERS] performance and the present study provides a simple and green strategy to decorate MoS2 with size controlled silver nanoparticles by effectively tuning the plasma parameters via liquid phase laser ablation. References [1] Dell′Aglio et al, Appl. Surf. Sci, 4−9, (2015) [2] Griem, H. R, Principles of Plasma Spectroscopy, Cambridge Uni. Press, Cambridge (1997). [3] Nancy, Parvathy, et al. Nano-Structures & Nano-Objects, 16 337-346 (2018). [4] Lee et al, Sci. Rep., 4, 7 (2015) [5] Wu et al, Nature, 514, 470−474 (2014) [6] Yin et al, Small, 10, 3537−3543 (2014) Department of Pure and Applied Physics Guru Ghasidas Central University, Bilaspur (C.G.)-495009, India 78

International e-Conference on Plasma Theory and Simulations (PTS-2020), September 14 & 15, 2020, Bilaspur, India LP-10 Analytical study of Laser matter interaction in magnetized semiconductors in the presence of a hybrid pump field (PTS-2020), Ayushi Paliwal1, Swati Dubey2 and S. Ghosh3 1Govt. PG College, Agar Malwa, India 2,3Vikram University, Ujjain, India e-mail: [email protected] By using Hydrodynamic model for one component plasma along with coupled mode theory, parametric amplification due to polaron mode has been studied in the present therotical study. Most realistic propagation of an intense hybrid pump wave in a magnetized semiconductor plasma has been considered to study some aspects of Laser matter interactions. Expressions for parametric gain coefficient arising due to parametric instability and threshold field required to incite parametric amplification has been derived. The compound semiconductors of group III-V and II-VI are unique within the universe of simple octet compounds, enable them to dominate higher performance electronics and optoelectronics. Present study aims to compare materials for which favourable magnitudes of parametric gain and threshold value could be obtained with suitable values of external parameters. Numerical estimations were carried out using the data of two different group compound semiconductors namely ZnSe and GaAs. Both the gain coefficients and threshold pump field are found to be strongly dependent on the carrier concentration of the medium. Resonance between plasma frequency and collective excitation frequency affects the process of amplification in both the cases. Higher gain is achieved for GaAs which has a smaller coupling coefficient as compared to ZnSe, it indicates that hybrid pump propagation strengthens the electron-LO phonon coupling. Department of Pure and Applied Physics Guru Ghasidas Central University, Bilaspur (C.G.)-495009, India 79

Magnetic Fusion Plasma

International e-Conference on Plasma Theory and Simulations (PTS-2020), September 14 & 15, 2020, Bilaspur, India MF-01 Mechanism of Plasma Blob Formation in the Tokamak Scrape-off Layer (SOL) Vijay Shankar1, Nirmal Bisai 1,2,Shrish Raj1,2, A. Sen2 1Institute for Plasma Research, Bhat Gandhinagar, 382428, INDIA 2Institute for Plasma Research, Homi Bhabha National Institute, Bhat Gandhinagar, 382428, India e-mail: [email protected] The formation of a blob structure [1-3] in the edge region of a tokamak plasma has been found experimentally and numerically. The formation normally takes place when a radially elongated streamer structure breaks due to differential stretching in the radial and poloidal directions. Such a phenomenon has been extensively studied in the past in the edge-to-SOL transition region [1,4]. In this work, we examine the blob formation mechanism in the SOL and far SOL region of a tokamak plasma. The formation mechanism is found to be quite different from those in the edge-to-SOL transition region with the electric field shear related to the poloidal gradient of poloidal electric field playing a major role. We derive a heuristic condition for such a plasma blob formation using a dimensional analysis of the plasma density continuity equation. Blob formation takes place when the amount of shear exceeds the growth rate of the basic interchange instability [5,6] within the radially elongated streamer region. A two- dimensional (2D) numerical simulation study is also carried out to validate our analytic results. In this scenario the parallel plasma dynamics has been neglected since the parallel wave numbers associated with the plasma dynamics are much smaller than the perpendicular wave numbers. Under this approximation we have replaced the parallel dynamics with sheath physics in the scrape-off layer region. In order to incorporate the parallel dynamics a three-dimension (3D) simulation has also been done. It is found that the 3D simulation results also come close to the analytic criterion for plasma blob formation but the parallel dynamics slows down the radial velocity of the blob. The 2D and 3D simulations have been done using the-BOUT++ framework code. References [1] N Bisai, A Das, S. Deshpande, et al. Physics of Plasmas, 12(10):102515 (2005). [2] S. I. Krasheninnikov, D. A. D'Ippolito, and J. R. Myra. Journal of Plasma Physics, 74(5):679-717 (2008). [3] D. A. D'Ippolito, J. R. Myra, and S. J. Zweben.Physics of Plasmas, 18(6):060501 (2011). [4] N. Bisai, S Banerjee, and A. Sen Physics of Plasmas, 26(2):020701 (2019). [5] Y. Sarazin and Ph. Ghendrih Physics of Plasmas, 5(12):4214-4228 (1998). [6] Nirmal Bisai, A. Das, S. Deshpande et al. Physics of Plasmas, 11(8):4018-4024 (2004). Department of Pure and Applied Physics Guru Ghasidas Central University, Bilaspur (C.G.)-495009, India 80