Ponderomotive acceleration of hot electrons in tenuous plasmas

Abstract

The oscillation-center Hamiltonian is derived for a relativistic electron injected with an arbitrary momentum in a linearly polarized laser pulse propagating in tenuous plasma, assuming that the pulse length is smaller than the plasma wavelength. For hot electrons generated at collisions with ions under intense laser drive, multiple regimes of ponderomotive acceleration are identified and the laser dispersion is shown to affect the process at plasma densities down to 10 17 cm −3 . Assuming a/γg 1, which prevents net acceleration of the cold plasma, it is also shown that the normalized energy γ of hot electrons accelerated from the initial energy γ0 Γ does not exceed Γ ∼ aγg, where a is the normalized laser field, and γg is the group velocity Lorentz factor. Yet γ ∼ Γ is attained within a wide range of initial conditions; hence a cutoff in the hot electron distribution is predicted.

A critical analysis of the ‘ponderomotive snowplow’ concept in direct laser acceleration of electrons

“…which is now superponderomotive by a factor of four. In the papers by Geyko et al [22,23], the snowplow theory is derived by a different approach, however when it is re-cast in the terms used in this paper we have found that equation ( 8) in [23] is identical to equation (7) for Π = 1. We have also found that, from equation (5) in [23] one can obtain equation (6).…”

“…Independently of Sazegari, Mendonca et al proposed nearly the same concept around the same time [21]. The idea has also appeared in the work of Geyko and coworkers [22,23]. Discussion of this, and similar ideas, can be found in [24].…”

Plasma Physics in Strong Field Regimes

“…More interesting phenomena happen when the laser field becomes strong. For example, when a ≈ 1 is relativistically strong but the resulting E x ≈ 0.3E c is below the Schwinger field, the simulation recovers what happens in classical plasmas (McKinstrie and Startsev, 1996;Naumova et al, 2004;Geyko et al, 2009). First, let us look at what happens to charged particles.…”

Electron Acceleration in Wakefield and Supra-Bubble Regimes by Ultraintense Laser with Asymmetric Pulse

“…[12] It is noted that δ can significantly affect the dynamics of hot electrons. [13] For simplicity we ignore it because we just discuss problem in this paper for the cold electron and circular polarized laser pulses, thus, the Hamiltonian is reduced to…”