Frequency-energy characteristics of the ion He-Ca lasers
Abstract
Frequency-energy characteristics of the ion He-Ca lasers
Incoming article date: 07.07.2017An analysis of the mechanisms limiting the growth of the output characteristics of ion recombination He-Ca lasers with an increase in the active medium volume and frequency of pulse repetition is carried out. It was established that by a growing laser tube diameter and a growing frequency of pulse repetition the average power of He-Ca lasers saturates and then decreases due to the formation of radial non-uniformity of the active medium as a result of its overheating on the axis and of the radial cataphoresis, as well as because of the raise of the electron temperature level in early afterglow, conditioned by the grow of gas temperature. It is pointed out that as possible ways of increasing the output characteristics can be used the blackening of the laser tube surface, the use of an independent input of calcium vapours, the use of a forced cooling, while the application of a tube with rectangular cross-section will allow to maximally increasing the energy characteristics. Based on numerical computations it is shown that the attainable maximum of running power of He-Ca lasers amounts to: ~ 4.4 W/m for self-heating active elements from BeO-ceramics and ~ 5.2 W/m – on blackening their surface; ~ 5.3 W/m for an independent calcium vapours input and ~ 6.2 W/m – for its combination with blackening; ~ 9.5 W/m for an intensive forced cooling of active elements with cylindrical geometry; ~ 16 W/m – with active elements of rectangular cross-section at a ratio of wall sizes 1:3.
Keywords: metal vapor laser, the ion recombination He-Ca laser, pulse-periodic discharge, gas-discharge plasma, self-heating regime, mathematical modeling