Generation of Alfvén waves in magnetized plasma by laser plasma bunches at Mach numbers much less than unity

Abstract

In this paper, we examine a torsional Alfvén wave produced by periodic plasma bunches in a magnetized plasma flux tube. A new effect has been revealed: the wave is generated not only during the action of bunches, but also for a long time after the termination, which makes it possible to increase the wavelength by several times. We have determined the conditions under which the wave contains η~40 % of the total bunch energy. The wave radius depends on the energy of one bunch; and the length, on their number. The optimum number of bunches is 15. Simultaneously with the Alfvén wave, a bunch plasma jet (η~35 %) and a slow magnetosonic wave (η~10 %) propagate in the force tube. Similarity parameters scale the results to laboratory and near-Earth magnetized plasma.