Effect of prepulses with various durations on the neutron yield in laser picosecond plasma

Experimental results on the effect of picosecond and nanosecond prepulses on the neutron yield in laser picosecond plasma on the surface of solid (CD2)(n) targets at a laser intensity of 10(18) W/cm(2) are presented. It is demonstrated that the picosecond (nanosecond) prepulse decreases the neutron yield at a laser prepulse intensity of higher than 10(13) (10(12)) W/cm(2). The estimates indicate three possible mechanisms for the realization of the observed effect: stimulated Mandelstam-Brillouin scattering of the main pulse by the preplasma, channels of the generation of fast ions, and their possible deceleration in the preplasma. The results of calculations are compared with the experimental data.