Theoretical study of transition radiation from hot electrons generated in the laser–solid interaction

Abstract

Transition radiation from a beam of hot electrons generated in ultraintense laser plasma interaction is theoretically studied. The total radiation is separated into two parts: one is incoherent transition radiation (ITR), the other is coherent transition radiation (CTR). The spectrum of ITR just depends on the particle velocity distribution in the beam. The angular distribution of ITR varies from sin2 θ, and approaches the angular distribution of the beam when the hot electron temperature increases from the nonrelativistic limit (T≪mc2) to the ultrarelativistic limit (T≫mc2). The spectrum of CTR is dependent on the particle configuration as well as their velocities. Any microbunching in the beam can greatly enhance the CTR intensity at the microbunching frequency, from which the dominant heating process can be inferred. The effects of target thickness and hot electron temperature on CTR intensity are also calculated. The simplified model shows that the CTR intensity decreases with the increase of the target thickness, and increases with the hot electron temperature. The divergence of the beam can broaden the CTR spectrum.