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Transient setting of relativistic ponderomotive non-linearity and filamentation of ultra-short laser pulses in collisionless plasmas

Published online by Cambridge University Press:  11 July 2019

R.P. Sharma
Affiliation:
Centre for Energy Studies, Indian Institute of Technology, Delhi-110016, India
Narender Kumar*
Affiliation:
Centre for Energy Studies, Indian Institute of Technology, Delhi-110016, India Department of Physics, Sri Venkateswara College, University of Delhi, New Delhi-110021, India
R. Uma
Affiliation:
Centre for Energy Studies, Indian Institute of Technology, Delhi-110016, India
Ram Kishor Singh
Affiliation:
Department of Physics, Shivpati Post Graduate College, Siddharth University, Siddharth Nagar-272205, India
P.K. Gupta
Affiliation:
Centre for Energy Studies, Indian Institute of Technology, Delhi-110016, India
*
Author for correspondence: Narender Kumar, Centre for Energy Studies, Indian Institute of Technology, Delhi-110016, India, E-mail: narenderk@svc.ac.in

Abstract

We study the setting up of relativistic ponderomotive non-linearity in an under-dense collisionless cold plasma. Using the fluid model, coupled system of equations of the laser beam and electron plasma oscillations has been derived. We present the numerical simulation for this coupled system of equations, when the coupling arises through relativistic ponderomotive non-linearity. The filamentation of the laser beam has been found to vary appreciably with perturbation wave number. The results show that with time, localized structures become more complex and the plasma oscillation frequency spectra have several harmonic peaks at terahertz frequencies when the electron plasma frequency is in terahertz range and laser frequency is around 2.35 × 1015 rad/s. We also present the semi-analytical model to capture the underlying physics.

Type
Research Article
Copyright
Copyright © Cambridge University Press 2019 

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