Effects of Weibel-type instabilities in laser-produced plasmas

摘要

In laser-produced plasmas, self-induced magnetic fields have been demonstrated both experimentally and theoretically. It is sure that these fields play an important role, for example, in the anomalous reduction of thermal conductivity and in dynamic behaviors of spherical compression of pellets. Recently, it is reported that electromagnetic waves with relatively low velocities are obserbed just in front of the target, when the intensity of the irradiated laser light exceeds some threshold. These electromagnetic waves excited in the target may have a possibility not only to give rise to a new type of energy loss mechanism but also to influence the implosion characteristics. We have already published that the Weibel-type electromagnetic instabilities[1] can be theoretically excited by electrons in a velocity distribution with an anisotropic temperature[2, 3]. In this work, the particle-in-cell (PIC) simulation results are presented for laser-produced plasmas with non-vanishing thermal flux, vanishing current and vanishing temperature anisotropy. These results agree well with typical experimantal values.