Speaker
Description
The laser wake-field acceleration (LWFA) provides energetic electron beams with higher acceleration gradient. The typical strength of the electrostatic field reaches GV/cm. Significant developments have been achieved in the past decades and various mechanisms have been proposed for beam quality improving. LWFA is expected to deliver high quality electron beams for potential applications. However, it requires high stability and reproducibility of the ejected beam which are still far away from the current laser driven plasma accelerator.
Supersonic nozzles are commonly used in LWFA to provide spatially well-defined gas targets with a plateau density profile and sharp gas-vacuum boundaries. To maintain the reproducibility of the accelerated electron beam, a stable gas target in the vacuum chamber with precise density distribution profile is necessary. It guarantees that the laser-plasma interacts in a proper density region and the relative laser focal point doesn't shift too much from shot to shot. In this work, we focus on the instability originated from the gas jet due to the nonlinear fluid dynamics in the supersonic nozzle. The role of the stilling chamber in a modified Converging-Diverging nozzle is investigated. According to the fluid dynamics simulations, the chamber dissipates the turbulence and stabilizes the gas jets. Via both the numerical simulations and the Mach-Zehnder interferometric measurements, the instability originated from the nonlinear turbulence and the mechanism to suppress the instability are studied.
References
[1] Z. Lei, et al., Rev. Sci. Instrum. 95, 015111 (2024).
[2] Z. Lei, et al., High Power Laser Sci. Eng. 11, e91 (2023).
