Density evolution measurement of hydrogen plasma in capillary discharge by spectroscopy and interferometry methods

Plasma density is one of the most important parameters for laser wakefield acceleration using a gas-filled capillary waveguide. We measured the evolving hydrogen plasma densities in capillary discharge by using two different diagnostics methods at the same time, i.e., the Stark-effect-based spectroscopy and the transverse interferometry methods. It was found that there is a rather large difference between two methods and the phenomenon is explained in view of self-absorption. The correlation was obtained and the result is quite useful for capillary-plasma-based laser wakefield acceleration research. (C) 2011 American Institute of Physics. [doi:10.1063/1.3643134]