Efficient generation of mid-IR radiation due to the Doppler effect under the reflection of intense laser pulses from near-critical plasma

The possibility of generating radiation of the mid-IR range due to the Doppler effect under the reflection of relativistic intense laser radiation in the planned XCELS facility from near-critical dense plasma is considered. It is shown that the greatest efficiency of the order of tenths of percent is observed at the maximum short duration of the incident laser pulse and its ultra-sharp focusing into a spot with a diameter of less than 2 μm. The use of two pulses allows one to increase the efficiency by 1.5 – 2 times. Thus, it is possible to generate the radiation pulses in the region above 3 μm with the energy of several joules.