On the electromagnetic-electron rings originating from the interaction of high-power short-pulse laser and underdense plasma

Abstract

We investigate the evolution of radial profile of a high-power short-pulse laser interacting with underdense plasma, and in particular, we concentrate on the transverse electromagnetic rings, which are formed due to the laser radiation defocusing induced by the excitation of Langmuir waves. We illustrate the physical processes involved in the formation of such structures analytically and use the three-dimensional numerical simulations to reveal the relationships among the electromagnetic ring properties and the parameters of laser and plasma. Within the studied parameter range, we find that up to ≈70 % of the total initial driver pulse energy can be carried off by the electromagnetic rings having the opening angles ≈45–115 mrad. Furthermore, we show that the electromagnetic rings can become a source of high-energy ring-shaped electron beams.