Relativistic laser hosing instability suppression and electron acceleration in a preformed plasma channel

Abstract

The hosing processes of a relativistic laser pulse, electron acceleration, and betatron radiation in a parabolic plasma channel are investigated in the direct laser acceleration regime. It is shown that the laser hosing instability would result in the generation of a randomly directed off-axis electron beam and radiation source with a large divergence angle. While employing a preformed parabolic plasma channel, the restoring force provided by the plasma channel would correct the perturbed laser wave front and thus suppress the hosing instability. As a result, the accelerated electron beam and the emitted photons are well guided and concentrated along the channel axis. The employment of a proper plasma density channel can stably guide the relativistically intense laser pulse and greatly improve the properties of the electron beam and radiation source. This scheme is of great interest for the generation of high quality electron beams and radiation sources.

Forward sliding-swing acceleration: electron acceleration by high-intensity lasers in strong plasma magnetic fields

“…As confirmed by the simulations, the FSSA mechanism is realized due to the relativistically induced transparency [28][29][30] in a structured target that mitigates instabilities [20,[62][63][64]. This implies that the electron density in the propagation region is n e a 0 n cr , where…”

“…The channel inside the target is required for the stable laser pulse propagation. The target structure suppresses the hosing instability that would develop in a uniform target [64]. Additional simulations for a uniform target with n e = 1.5n c confirm that the laser pulse experiences a significant deviation from its original direction after propagating just tens of microns into the target.…”

Radiation reaction as an energy enhancement mechanism for laser-irradiated electrons in a strong plasma magnetic field

“…Additional studies have shown that the laser propagation becomes unstable in a dense relativistically transparent target 54 , which makes the direction of the laser beam propagation unpredictable. One way to suppress the instability while retaining the advantages of laser propagation through a dense plasma is to use structured targets that provide optical guiding to the laser pulse.…”

Collimated gamma-ray beams from structured laser-irradiated targets -- how to increase the efficiency without increasing the laser intensity

“…This fraction increases during the interaction, as the channel expands appreciably. An important consideration for choosing R ch /w 0 is the suppression of instabilities that cause the laser beam to deviate from its original direction of propagation 47 . For example, we found that the propagation becomes unstable at R ch /w 0 ≥ 1.…”

“…Our previously published results indicate that a structured target with a channel serving as an optical wave-guide delivers a well-directed photon beam 11,12 . In contrast to that, laser propagation is unstable in dense relativistically transparent targets 47 , which makes the direction of the emitted photon beam unpredictable. The optical guiding is achieved by filling the channel with a material that becomes very transparent at the peak intensity 48 .…”