Ultra-intense laser pulses in near-critical underdense plasmas – radiation reaction and energy partitioning

Erik Wallin,Arkady Gonoskov,Olle Lundh,Mattias Marklund,Christopher Harvey

doi:10.1017/s0022377817000320

Abstract

Although, for current laser pulse energies, the weakly nonlinear regime of laser wakefield acceleration is known to be the optimal for reaching the highest possible electron energies, the capabilities of upcoming large laser systems will provide the possibility of running highly nonlinear regimes of laser pulse propagation in underdense or near-critical plasmas. Using an extended particle-in-cell (PIC) model that takes into account all the relevant physics, we show that such regimes can be implemented with external guiding for a relatively long distance of propagation and allow for the stable transformation of laser energy into other types of energy, including the kinetic energy of a large number of high energy electrons and their incoherent emission of photons. This is despite the fact that the high intensity of the laser pulse triggers a number of new mechanisms of energy depletion, which we investigate systematically.

Highlights

Laser wakefield acceleration (LWFA) is a means for utilising the extreme fields accessible in plasmas for the purpose of accelerating electrons to very high energies over short distances (Tajima & Dawson 1979)
Wakefield acceleration with radiation reaction included As we increase the intensity of the laser pulse generating the wake field, we expect that the electrons will be further accelerated
We compare, for a number of different intensities, how the inclusion of the radiation reaction (RR) force affects the time it takes for the laser pulse to be depleted

Summary

Introduction

Laser wakefield acceleration (LWFA) is a means for utilising the extreme fields accessible in plasmas for the purpose of accelerating electrons to very high energies over short distances (Tajima & Dawson 1979). At high enough intensities of the laser radiation, this classical description is not applicable as the energies of electrons and emitted photons become comparable. Wakefield acceleration with radiation reaction included As we increase the intensity of the laser pulse generating the wake field, we expect that the electrons will be further accelerated.

Results

Conclusion