Speaker
Description
The plasma accelerator community has made impressive strides in developing methods to optimize beam injection schemes needed to make laser wakefield accelerators (LWFAs) viable for collider applications. One such technique is two-color flying-focus ionization injection, where a drive laser partially ionizes a gas and excites a nonlinear wake, and an injector laser with a much shorter wavelength focuses inside the wake. The injector further ionizes the gas and generates an electron beam that can be trapped and accelerated. The flying-focus technique allows us to control the spatiotemporal profile of the injector in order to maintain a near-constant intensity peak which propagates at a programmable velocity. Controlling the injector's properties in this way allows us to generate a beam with a trapezoidal linear charge density, which flattens the wake's electric field and results in very low energy spread. This method was previously investigated in simulations with a 20 TW, 9.2 $\mu$m CO$_2$ drive laser and a 400 nm Ti:Sapphire (second harmonic) injector, achieving $\sim$200 pC of injected charge with an energy spread below 1\% and $\sim$100 nm$\cdot$rad normalized emittances (https://doi.org/10.1103/q36y-6jqn). In this study, we explore the viability of this technique using a more typical PW-class near-IR laser. We perform quasi-3D particle-in-cell simulations with experimentally-relevant parameters for testing this method at Lawrence Berkeley National Laboratory (LBNL). We use an 800 nm Ti:Sapphire laser to drive the wake and a 267 nm (third harmonic) flying-focus laser as the injector, with the parameters of both LBNL's 100-TW and 1-PW systems considered. We will show preliminary simulation results and discuss the challenges with designing an experiment to demonstrate injection and acceleration of a high quality beam with this configuration.
This material is based upon work supported by the National Science Foundation under Grant No. PHY-2238840. This material is also based on resources of the NERSC facility, operated under Contract No. DE-AC02-5CH11231
| Working group | WG1 |
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