Discharge Characteristics of a Gas-Filled Capillary Plasma for Laser Wakefield Acceleration

Abstract

A gas-filled capillary plasma source for potential use in conjunction with laser wakefield acceleration is developed, and its discharge characteristics are presented here. In the capillary, helium or hydrogen gas (similar to 150 torr in pressure) is injected, and a pulsed high voltage (similar to 25 kV) is applied for electrical discharge and plasma production. The discharge properties of the helium and hydrogen gases are compared. The plasma densities inside the capillary hole are measured with a Mach-Zehnder interferometer and are obtained separately by a simple analysis using the diffusion equation and measured current profiles.