Influence of collisions between laser plasma jets in conical targets on the plasma parameters in the final stages of expansion

An investigation was made of the charge, kinetic, and geometric parameters of the ion component of a laser plasma in the final stages of expansion when the radiation was focused into a conical recess in a lead target. The dependences of these parameters on the cone vertex angle were determined and a comparison was made with plane targets. The measurements were made by probe and mass spectrometer techniques. The results suggest that a narrow highly directional plasma jet with a high degree of ionization can be produced by optimizing the target shape and the radiation focusing conditions. A possible mechanism of the influence of collision processes on the resultant plasma parameters is discussed.