Investigation of Sub-Terawatt Laser Wakefield Acceleration
C.-Y. Hsieh1*, M.-W. Lin2, S.-H. Chen1
1Department of Physics, National Central University, Jhongli, Taiwan
2Institute of Nuclear Engineering and Science, National Tsing Hua University, Hsinchu, Taiwan
* Presenter:C.-Y. Hsieh
Laser wakefield accelerator (LWFA) can be achieved by directing a sub-terawatt (TW) laser pulse into a thin, high-density gas target. In this way, the laser peak intensity can be greatly enhanced by the effects of self-focusing and the self-modulation, to a level capable of driving a non-linear plasma wave for accelerating electrons. This work focuses on studying how the variations of the density profiles and peak densities of them can ultimately affect the performance of sub-TW LWFA. Gas targets having a Gaussian density profile or a flat-top distribution that resembles the properties of gas targets produced by a gas jet or a gas cell respectively are defined for investigations. Our three-dimensional particle-in-cell simulations show that the plateau region of a flat-top density distribution can be favorable for the growth of self-focusing and self-modulation of a sub-TW laser pulse. When using the laser peak power PL= 0.6 TW ~ 2Pcr of the self-focusing critical power, well-established plasma bubbles can be produced to accelerate electrons with a higher efficiency. Therefore, a gas cell represents a more suitable device than a gas jet to produce gas targets in the sub-TW LWFA experiments.

Keywords: Laser Wakefield Accelerator, Self-Focusing Effect, Self-Modulation Effect, Particle-In-Cell Simulations