Processes in hollow cathode discharge excited by steady-state and pulse currents

Abstract

A semi-analytical method to simulate the local and integral pumping rates of spectral lines in multi-component hollow cathode discharge plasma has been proposed. The contribution of different mechanisms into pumping rate of upper level of laser line 441 .6 rim Cdli in He-Cd mixture is discovered for CW regime. The excitation of discharge by current pulses has been analyzed. The results oftheoretical calculations are in good agreement with experimental measurements.

About creation of population inversion in mixture of inert noble gas and metal vapor

“…Besides, value of U CF increases with a decrease of the pulse length, and exceeds several times than the U CF value in a stationary discharge. Energy ε 0 and number of fast electrons accordingly increase too [3,4]. Optimum value of HCD current (and optimum electron density) for certain laser transition depends on pumping rate of metal atom by second kind col lisions in NG plasma, i.e.…”

“…Optimum value of HCD current (and optimum electron density) for certain laser transition depends on pumping rate of metal atom by second kind col lisions in NG plasma, i.e. on the buffer gas rate of ionization (for CT) and rate of excitation (for PI), and also depends on intensity of processes of excitation and deexcitation of upper and lower laser levels at the expense of collisions with plasma thermal electrons whose density is proportional to cathode current den sity [3,4].…”

“…In this type of discharge most effectively excited the ion quan tum transitions of metals by means of the second kind collisions in a plasma of the metal atoms with the ions or excited atoms of buffer gas [2,3]. Advantage of NG HCD plasma before PC plasma is existence at electron energy distribution (EED) in NG excess both fast, and thermal slow electrons in comparison with Maxwell EED in PC [3].…”