Near-GeV Electron Beams at a Few Per-Mille Level from a Laser Wakefield Accelerator via Density-Tailored Plasma

Snowmass 2021 Accelerator Frontier White Paper: Near Term Applications driven by Advanced Accelerator Concepts

“…Dense relativistic electron beams or ultra-intense laser pulses can drive charge separation in meter-scale plasmas that can support accelerating fields over 2-3 orders of magnitude larger than with RF-based technology. For laser-driven wakefield accelerators (LWFAs), energies up to 8 GeV energy gain have been reported [31] in a 20cm plasma structure, as well as per-mille level energy spread [32], 10-100 pC charge, few-fs beam duration [33], sub-mrad divergence, few-µm source size [34], and repetition rates up to 10 Hz and planned for multi-kHz with laser improvement projects underway. For beam-driven wakefield accelerators (PWFAs), energies up to 84 GeV (42 GeV energy Snowmass2021 Accelerator Frontier White Paper: Near Term Applications driven by Advanced Accelerator Concepts gain) have been reported [35], as well as per-mille-level energy spread [36,37], 10-100 pC charge, tens of fs beam duration [38,39], µm-level normalized emittance [40], 10 µm level source size, and few Hz repetition rates with plans for kHz repetition rates.…”

Multi-GeV Laser Wakefield Electron Acceleration with PW Lasers

“…For example, the use of density up-ramp medium [47] or multijets configuration [48] has been recently employed, albeit they have been done in a low laser power regime and with short distance. The careful shaping of the profile can produce beams with energy spread below 1% [49]. We, thus, foresee that longitudinal control of the plasma density profile over a wide density range (10 14 -10 19 cm −3 ) is a necessity for improving the energy and quality of electron beams produced with multi-PW lasers.…”

Scissor-cross ionization injection in laser wakefield accelerators

“…For example, an electron beam with energy of 7.8 GeV has been generated in 20 cm [2]. The electron beams with energy spread in the sub-percentage level have been produced using density-tailored plasma [3]. The 24-hour stable LWFA has been achieved by decoding sources of energy drift and jitter [4].…”

“…The ionization injection has the advantage of high reproducibility, but its energy spread is usually large. To reduce the energy spread, one may use the self-dechirping effect [3,25], and/or reduce the electrons injection length [26,27]. For example, an electron beam with slice energy spread of 13 keV and charge of 0.4 pC can be produced by ionization injection of counter-propagating laser pulse [28].…”