Laser shaping and optimization of the laser-plasma interaction

Abstract

Abstract. The physics of energy transfer between the laser and the plasma in laser wakefield accelerators is studied. We find that wake excitation by arbitrary laser shapes can be parameterized using the total pulse energy and pulse depletion length. A technique for determining laser profiles that produce the required plasma excitation is developed. We show that by properly shaping the longitudinal profile of the driving laser pulse, it is possible to maximize both the transformer ratio and the wake amplitude, achieving optimal laser-plasma coupling. The corresponding family of laser pulse shapes is derived in the nonlinear regime of laser-plasma interaction. Such shapes provide theoretical upper limit on the magnitude of the wakefield and efficiency of the accelerating stage by allowing for uniform photon deceleration inside the laser pulse. We also construct realistic optimal pulse shapes that can be produced in finitebandwidth laser systems and propose a two-pulse wake amplification scheme using the optimal solution.

Relativistic laser plasma interactions

“…It has been observed in PIC-code simulations that self-focusing and ponderomotive blow-out can be suppressed by the occurrence of Raman scattering and plasma heating [59]. It has been shown theoretically that non-Gaussian-shaped pulses can drive wakefields more effectively than Gaussian-shaped pulses [60]. Similar improvements might be obtained by the use of pulse shapes that are more easily produced experimentally using a genetic algorithm [61].…”

“…Proof-of-principle experiments are underway at various laboratories to use multiple synchronized laser pulses [170] to simultaneously channel-guide intense laser pulses [110][111][112][113] and coherently control wakefields [60,61,18] and electron injection [28][29][30][31][32][33]. The near-term milestone goal is to accelerate electrons monoenergetically up to an energy of 1 GeV in a single 1 cm long plasma channel.…”

Nonlinear wakefields and electron injection in cluster plasma

“…When a wakefield is driven by a short laser pulse a red-shift can be observed. This effect is also called "photon deceleration" and is associated with the energy loss from driving the wakefield whilst preserving the photon number within the pulse [58,59]. Here, we will show how this process scales with cluster parameters.…”

Nonlinear wakefields and electron injection in cluster plasma

“…When a wakefield is driven by a short laser pulse a redshift can be observed. This effect is also called "photon deceleration" and is associated with the energy loss from driving the wakefield while preserving the photon number within the pulse [59,60]. Here, we will show how this process scales with cluster parameters.…”