Laser beam deflection by flow and nonlinear self-focusing

Abstract

In general, it is found that the plasma density response to a laser beam’s ponderomotive force is shifted in the direction of a transverse flow, which in turn deflects the laser beam in that direction, and retards the flow at a temporal rate which is proportional to the beam’s spatial deflection rate. This rate is a rapidly increasing function of 〈I〉, the average laser intensity. This may result in finite beam deflections after propagation over a distance of a few speckle lengths for random phase plate optics. In current gas filled hohlraum experiments, the estimated magnitude of these effects is consistent with their experimental observation and one may need to include this physics in order to predict beam pointing which results in a symmetric capsule implosion. Flow retardation may be sufficient to exclude flow from the beam, self‐limiting the deflection process.