Temporal evolution of electron density and temperature in capillary discharge plasmas

摘要

Time-resolved spectroscopic measurements of a capillary discharge plasma of helium gas were carried out to obtain detailed information about dynamics of the discharge plasma column, where the fast plasma dynamics is determined by the electron density and temperature. Our measurements show that the electron density of the capillary plasma column increases sharply after gas breakdown and reaches its peak of the order of 10~(18) cm~(-3) within less than 100 ns, and then it decreases as time goes by. The result indicates that a peak electron density of 2.3 × 10~(18) cm~(-3) occurs about 65 ns after formation of the discharge current, which is ideal for laser wakefield acceleration experiments reported by Karsch et al. [New J. Phys. 9, 415 (2007)].