Balmer series H_(β) measurements in a laser-induced hydrogen plasma

摘要

Stark-broadened emission profiles of the Balmer series H_(β) lines are measured subsequent to nanosecond laser-induced optical breakdown in gaseous hydrogen. Electron number densities are found from time-resolved spectra from H_(β) emissions to be in the range 10~(15)-10~(18) cm~(-3). These results are compared with H_(α) measurements for which number densities as high as 10~(19) cm~(-3) are determined from Stark widths and Stark shifts. Good agreement is reported for number densities inferred from H_(α) and H_(β) emissions, down to an electron number density 3×10~(16) cm~(-3), by accurate treatment of ion dynamics in the theory.