Application of liquid low-temperature cooling in a multi-disk ytterbium laser head under conditions of multi-joule pumping at a high pulse repetition rate

We have investigated the possibility of low-temperature liquid cooling of a multi-disk laser head, as well as the main advantages of this approach. The active zone of the laser head was modelled: the temperature, coolant velocity, inversion, gain, stored energy in the active medium, and thermally induced phase distortions were calculated. It was shown that such cooling can be accomplished with ethyl alcohol; there also are more preferred liquids, which are more difficult in use. The optimal parameters of the active zone were found for using pump pulses with an energy of several J. A significant increase in the gain and stored energy were shown upon cooling from 300 to 200 K, as was a decrease in thermally induced phase distortions.