Control and optimization of a staged laser-wakefield accelerator

Abstract

We report results of an experimental study of laser-wakefield acceleration of electrons, using a staged device based on a double-jet gas target that enables independent injection and acceleration stages. This novel scheme is shown to produce stable, quasi-monoenergetic, and tunable electron beams. We show that optimal accelerator performance is achieved by systematic variation of five critical parameters. For the injection stage, we show that the amount of trapped charge is controlled by the gas density, composition, and laser power. For the acceleration stage, the gas density and the length of the jet are found to determine the final electron energy. This independent control over both the injection and acceleration processes enabled independent control over the charge and energy of the accelerated electron beam while preserving the quasi-monoenergetic character of the beam. We show that the charge and energy can be varied in the ranges of 2-45 pC, and 50-450 MeV, respectively. This robust and versatile electron accelerator will find application in the generation of high-brightness and controllable x-rays, and as the injector stage for more conventional devices.

High quality electron bunches for a multistage GeV accelerator with resonant multipulse ionization injection

“…Advanced acceleration techniques are being pursued via different approaches, aiming at compact, more affordable systems to drive secondary radiation sources [1][2][3][4][5][6][7][8][9][10] or even future particle colliders [11][12][13]. In this context, laser wakefield acceleration (LWFA) of electrons offers a very promising path, with experiments showing further increase of maximum energy, now approaching 8 GeV [14], including staging exploration [15][16][17][18][19] and high repetition rate operation at the lower energy end [20]. In view of the construction of the first user facility based on plasma acceleration, effort is now directed toward the demonstration of stable operation of a GeV scale electron beam at high specification, as those needed for an x-ray free electron laser (FEL) in the EuPRAXIA project [21].…”

Coupling Effects in Multistage Laser Wake-field Acceleration of Electrons

“…This technique, providing potentially jitter-free sources of radiation and electrons, has already demonstrated the electron acceleration over 4 GeV [13] in a single stage with laser pulse energy less than 100 J. However, similar to vacuum acceleration schemes, the staging schemes in plasma (an injector, a buster, and so on) seem to be more practical providing better stability and reproducibility of the acceleration process [17,18].…”

The resonant multi-pulse ionization injection

“…High-quality Laser Wake Field Accelerated (LWFA) electron bunches are nowdays requested for several applications including Free Electron Lasers [1][2][3], X/γ radiation sources [4][5][6][7][8] and staged acceleration [9][10][11][12][13]. While performances of self-injected bunches generated in the socalled bubble-regime [14,15] continue to improve, other promising injection schemes, including injection via density downramp [16][17][18][19][20], colliding pulses injection [21][22][23] and ionization injection [24][25][26][27][28][29][30][31][32], are under active theoretical and experimental investigation.…”