Numerical simulation of high pressure HeCd plasma generated by E-beam or by electrical discharges

Description

This item was taken from the IEEE Periodical ' Numerical simulation of high pressure HeCd plasma generated by E-beam or by electrical discharges ' Summary form only given. A model of an atmospheric pressure HeCd laser pumped by a pulsed electron beam has been developed which makes it possible to calculate temporal and energy characteristics of the laser radiation. Processes restricting the specific pumping energy have been analyzed under optimal conditions of medium excitation. It is shown that the repetitive-pulse operation with a small duty ratio can be realized in the HeCd laser. Time and energy characteristics have been studied numerically of the radiation from a high pressure HeCd laser excited by a microsecond electron beam at wavelengths of 441.6 and 537.3 nm which depends on the pump duration, namely, the efficiency rises as the pump duration is reduced. A method is suggested for enhancement of the laser power at long pump pulses, which consists of increasing the temperature of the HeCd plasma electrons with the use of an external electric field. The optimal field strength has been determined. It is shown that the emitted radiation power can be modulated by means of pulsed switching of the electric field. The shape of the secondary electron degradation spectrum has weak influence on pumping rates of upper laser levels by direct electron impact, therefore lasings are identical in the case of equality of energy depositions.