Prospects and limitations of wakefield acceleration in solids

Abstract

Advances in the generation of relativistic intensity pulses with wavelengths in the X-ray regime, through high harmonic generation from near-critical plasmas, open up the possibility of X-ray driven wakefield acceleration. The similarity scaling laws for laser plasma interaction suggest that X-rays can drive wakefields in solid materials providing TeV/cm gradients, resulting in electron and photon beams of extremely short duration. However, the wavelength reduction enhances the quantum parameter χ, hence opening the question of the role of non-scalable physics, e.g., the effects of radiation reaction. Using three dimensional Particle-In-Cell simulations incorporating QED effects, we show that for the wavelength λ=5 nm and relativistic amplitudes a0=10–100, similarity scaling holds to a high degree, combined with χ∼1 operation already at moderate a0∼50, leading to photon emissions with energies comparable to the electron energies. Contrasting to the generation of photons with high energies, the reduced frequency of photon emission at X-ray wavelengths (compared with that at optical wavelengths) leads to a reduction in the amount of energy that is removed from the electron population through radiation reaction. Furthermore, as the emission frequency approaches the laser frequency, the importance of radiation reaction trapping as a depletion mechanism is reduced, compared with that at optical wavelengths for a0 leading to similar χ.

Employing machine learning for theory validation and identification of experimental conditions in laser-plasma physics

“…The underlying principle of this model states that under the light pressure some varied part of foremost electrons becomes and remains bunched, while the resulted bunch moves so that its radiation precisely cancels out the incident radiation in the plasma bulk. The resulted description agrees well with ab-initio simulations in many aspects in a wide range of conditions and provides several important predictions 62,63 including the possibility of producing unprecedentedly intense and short bursts 60,64,65 of radiation with controllable ellipticity 66 . However, the experimental validation of the RES model is difficult.…”

Plasma Wakes Driven by Photon Bursts via Compton Scattering

“…The interaction of the injected photons with the plasma is solely due to Compton photon-electron scattering. We would like to emphasize that this present work differs fundamentally from previous studies where exotic or nonconventional photon drivers, still interacting with the plasma via the ponderomotive force, such as x-ray pulses [16] or incoherent optical lasers [17] have been considered to drive wakefields. We explore different regimes according to the photon frequency, the photon flux, and the initial magnetization of the plasma.…”

Relativistically intense XUV radiation from laser-illuminated near-critical plasmas

“…For S = 1 the relativistic regime is reached for I 0 > 2×10 20 Wcm −2 , an order of magnitude less than that required if S = 20. At 10 22 Wcm −2 , the current intensity frontier [47], a eff reaches 10, raising the prospect of scaling relativistic laser-plasma phenomena from optical to XUV wavelengths [48].…”