Enhancement of Electron Energy to the Multi-GeV Regime by a Dual-Stage Laser-Wakefield Accelerator Pumped by Petawatt Laser Pulses

Laser-wakefield acceleration offers the promise of a compact electron accelerator for generating a multi-GeV electron beam using the huge field gradient induced by an intense laser pulse, compared to conventional rf accelerators. However, the energy and quality of the electron beam from the laser-wakefield accelerator have been limited by the power of the driving laser pulses and interaction properties in the target medium. Recent progress in laser technology has resulted in the realization of a petawatt (PW) femtosecond laser, which offers new capabilities for research on laser-wakefield acceleration. Here, we present a significant increase in laser-driven electron energy to the multi-GeV level by utilizing a 30-fs, 1-PW laser system. In particular, a dual-stage laser-wakefield acceleration scheme (injector and accelerator scheme) was applied to boost electron energies to over 3 GeV with a single PW laser pulse. Three-dimensional particle-in-cell simulations corroborate the multi-GeV electron generation from the dual-stage laser-wakefield accelerator driven by PW laser pulses.

Figure 1

Experimental layout. The dipole magnet has length of 30 cm and magnetic field strength of 1.33 T, which was installed 1 m away from the gas-jet target. Two Lanex screen have been installed at the entrance and exit of the magnet to measure electron beam profile and energy, respectively. The ICT was installed between gas jet and dipole magnet to measure the charge of the electron beam.

Figure 2

(a) Electron energy spectrum for 10-mm [red line and image (i)] and 4-mm [blue line and image (ii)] gas jets. (b) Electron energy with respect to the electron density.

Figure 3

(a) Electron energy spectrum and (b) spatial profile for the seed beam from the 4-mm target [red line and (i)] and the accelerated electrons from the dual-stage target [black line and (ii)].

Figure 4

Electron density distribution at (a) $t=3.5\mathrm{ps}$ and (b) $t=6.2\mathrm{ps}$ and (c) the electron energy spectrum of the seed beam and accelerated beam in the dual-stage accelerator calculated by 3D PIC simulation in the boost frame ($\gamma =8$).

Figure 5

Electron energy map as a function of electron densities of the two gas jet media.