Abstract
The production of GeV electron beam with narrow energy spread and high brightness is investigated using particle-in-cell simulations. A controlled electron injection scheme and a method for phase-space manipulation in a laser plasma accelerator are found to be essential. The injection is triggered by the evolution of two copropagating laser pulses near a sharp vacuum-plasma transition. The collection volume is well confined and the injected bunch is isolated in phase space. By tuning the parameters of the laser pulses, the parameters of the injected electron bunch, such as the bunch length, energy spread, emittance and charge, can be adjusted. Manipulating the phase-space rotation with the rephasing technique, the injected electron bunch can be accelerated to GeV level while keeping relative energy spread below 0.5% and transverse emittance below $1.0\text{ }\text{ }\ensuremath{\mu}\mathrm{m}$. The results present a very promising way to drive coherent x-ray sources.
Highlights
Laser plasma accelerators (LPAs) are of great interest because of their abilities to sustain extremely large acceleration fields, typically 1000-fold higher than that of the conventional accelerators [1,2,3,4]
We show that with a controlled injection scheme and a method for phase-space manipulation, brilliant GeV electron beam with narrow energy spread can be generated by a LPA
We show that with a controlled injection scheme and the phase-space manipulation, the electron energy spread can be reduced to below 0.5% at GeV level
Summary
Laser plasma accelerators (LPAs) are of great interest because of their abilities to sustain extremely large acceleration fields, typically 1000-fold higher than that of the conventional accelerators [1,2,3,4]. Modern FELs based on conventional accelerators are the brightest x-ray sources ever and are indispensable tools for material science, medicine, biology and chemistry Their applications are limited by the sizes and expenses of the driving accelerators, whereas LPAs may overcome. In the laser wakefield acceleration (LWFA) regime, self-injected electron beams with energy up to 4.2 GeV have been experimentally demonstrated [8,9,10,11], but the relative energy spread is typically a few percent, which is more than 10 times larger than the Pierce parameter. We show that with a controlled injection scheme and a method for phase-space manipulation, brilliant GeV electron beam with narrow energy spread can be generated by a LPA. The longitudinal electric and magnetic fields of the laser pulses are included in the simulation and their expressions can be derived from Eq (1) [62]
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