Controlling Hot Electrons by Wave Amplification and Decay in Compressing Plasma

Abstract

Through particle-in-cell simulations, it is demonstrated that a part of the mechanical energy of compressing plasma can be controllably transferred to hot electrons by preseeding the plasma with a Langmuir wave that is compressed together with the medium. Initially, a wave is undamped, so it is amplified under compression due to plasmon conservation. Later, as the phase velocity also changes under compression, Landau damping can be induced at a predetermined instant of time. Then the wave energy is transferred to hot electrons, shaping the particle distribution over a controllable velocity interval, which is wider than that in stationary plasma. For multiple excited modes, the transition between the adiabatic amplification and the damping occurs at different moments; thus, individual modes can deposit their energy independently, each at its own prescribed time.

Axiomatic geometrical optics, Abraham-Minkowski controversy, and photon properties derived classically

“…We also suggest Refs. [66,144,160,163] as recent illustrations of how advantageous it is for analyzing the linear wave dynamics in plasmas. In addition, the nonlinear Lagrangian theory has been getting a new spin recently, namely, in the context of plasma waves carrying autoresonantly trapped particles [106][107][108][109]161].…”

Nonlinear Amplification and Decay of Phase-Mixed Waves in Compressing Plasma

“…At the early stage, G(N ) is hence the same as at parallel compression [17]. (Keep in mind that Ref.…”

“…In particular, the averaged-Lagrangian theory of Refs. [11][12][13] renders analytical transparency, while, numerically, one-dimensional (1D) particle-in-cell (PIC) simulations are distinctly enlightening [7,[16][17][18]. Below we combine these tools to explore the dynamics of BGK-like waves in time-evolving plasma, which exhibit a host of interesting paradigmatic phenomena.…”

“…(Keep in mind that Ref. [17] discusses the wave total energy rather than the energy density, so an extra factor of N must be taken into account when comparing with that paper.) However, since κ ∝ n −1/2 decreases, collisionless damping is now suppressed at all times.…”

“…Also, ions are modeled as a uniform charge-neutralizing background, the justification being as in Ref. [17]. Electrons are initialized as a 1D homogeneous Maxwellian distribution with parallel thermal speed v T , which is approximately conserved during compression.…”