Optimization of Electron Beams Based on Plasma-Density Modulation in a Laser-Driven Wakefield Accelerator

Abstract

We demonstrate a simple but efficient way to optimize and improve the properties of laser-wakefield-accelerated electron beams (e beams) based on a controllable shock-induced density down-ramp injection that is achieved with an inserted tunable shock wave. The e beams are tunable from 400 to 800 MeV with charge ranges from 5 to 180 pC. e beams with high reproducibility (of ~95% in consecutive 100 shots) were produced in elaborate experiments with an average root- mean-square energy spread of 0.9% and an average divergence of 0.3 mrad. Three-dimensional particle-in-cell (PIC) simulations were also performed to accordingly verify and uncover the process of the injection and the acceleration. These tunable e beams will facilitate practical applications for advanced accelerator beam sources.

Free electron lasers driven by plasma accelerators: status and near-term prospects

“…A laser pulse with 800 nm central wavelength was focused to 38 m (FWHM) onto a gas target by an f /30 off-axis parabolic mirror. The gas target is generated from the cascaded or single-stage gas jets because the supersonic flow can generate shock waves or high-density areas, which can be constructed to improve e-beam quality [ 8 , 70 , 71 ] . In collaboration with SINAP, two sets for FEL experiments have been built, using planar undulators and transverse gradient undulators (TGUs), respectively [ 72 , 73 ] , as shown in Figure 5.…”

Dosimetry and radioprotection evaluations of very high energy electron beams

“…The first limitation, and one of the foremost problems currently facing this technology, is the control and stability of these beams. There are studies that are continually being carried out in an attempt to improve certain characteristics of these beams, such as its reproducibility and beam pointing uncertainty 20 , 21 . Additional physical collimation might therefore still prove necessary in order to better conform the dose to a target.…”

Optimization of the beam quality in ionization injection by a tailoring gas profile*

“…The electron injection means that the moving electrons locate at the accelerating phase of wakefield and are accelerated to high energy. [1] Many effective injection methods have been proposed to achieve this goal, e.g., colliding pulses injection, [11,12] density gradient injection, [13,14] and ionization-induced injection. [15,16] The ionization-induced injection is a typical longitudinal injection, which has been widely used in experiments due to the advantages of simple operation and controllability.…”