Abstract
This work presents a study on laser wakefield electron acceleration in the self-modulated regime (SM-LWFA) using 50-fs laser pulses with energy on the mJ scale, at λ = 0.8 µm, impinging on a thin H2 gas jet. Particle-in-cell simulations were performed using laser peak powers ranging from sub-terawatt to a few terawatts and plasma densities varying from the relativistic self-focusing threshold up to values close to the critical density. The differences in the obtained acceleration processes are discussed. Results show that bunched electron beams with full charge on the nC scale and kinetic energy in the MeV range can be produced and configurations with peak density in the range 0.5–5 × 1020 atoms/cm3 generate electrons with maximum energies. In this range, some simulations generated quasimonoenergetic bunches with ∼0.5% of the total accelerated charge and we show that the beam characteristics, process dynamics, and operational parameters are close to those expected for the blowout regime. The configurations that led to quasimonoenergetic bunches from the sub-TW SM-LWFA regime allow the use of laser systems with repetition rates in the kHz range, which can be beneficial for practical applications.
Highlights
While in conventional electron accelerators the energy gain is based on resonant radio frequency (RF) cavities,1 a new generation of accelerators uses plasmas to produce strong driving electric fields.2,3 Superconducting RF cavities reach and can exceed 100 MV/m, but plasma-based systems4 provide accelerating fields up to TV/m
The perturbation can be induced by a charged particle beam, as in plasma wakefield accelerators (PWFAs), or by a laser pulse, as in laser wakefield accelerators (LWFAs)
We describe the parameter ranges for SMLWFA that led to similar behaviors in processes and results, as stated in Sec
Summary
While in conventional electron accelerators the energy gain is based on resonant radio frequency (RF) cavities, a new generation of accelerators uses plasmas to produce strong driving electric fields. Superconducting RF cavities reach and can exceed 100 MV/m, but plasma-based systems provide accelerating fields up to TV/m. Superconducting RF cavities reach and can exceed 100 MV/m, but plasma-based systems provide accelerating fields up to TV/m. In the latter, a perturbation is introduced in the plasma to cause local electron displacements, generating non-equilibrium local electric fields, which, in turn, oscillate at the plasma frequency. The perturbation can be induced by a charged particle beam, as in plasma wakefield accelerators (PWFAs), or by a laser pulse, as in laser wakefield accelerators (LWFAs) In the latter, the oscillating transverse field of the laser pulse is converted by the plasma into a longitudinal accelerating field with an amplitude that scales with the square root of the plasma density. The high accelerating gradients in these systems allow the production of high-energy bunched electron beams, up to GeV, in compact systems. Many facilities worldwide continue to explore the frontiers for producing even stronger wakefields to reach 10 GeV electrons and beyond.
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