Dependence of ponderomotive acoustic signal amplitude in NaCl on specimen conductivity under irradiation by nanosecond electron beams

Abstract

Experimental studies of the amplitude of the ponderomotive acoustic signal (PAS) in NaCl as a function of surface electron-current density and irradiation pulse length are reported. Published experimental data on radiation-induced conductivity in NaCl subjected to strong electron fluxes are used to analyze nonlinear PAS generation under the same irradiation. It is shown that the maximum PAS amplitude is determined by the rapidly varying strong electric field set up in the specimen by the charge in the beam of irradiating electrons and depends on the charge drain due to the radiation-induced conductivity of the NaCl in that field. The satisfactory agreement of the NaCl conductivity calculated with consideration of the PAS amplitude variations with published direct-method data conductivity in strong electric fields indicates that the coefficient K_c of PAS generation is constant in fields with E up to 3 · 10⁵ V/cm. This makes it possible to determine K_c in electric fields E<10⁵ V/cm and establish variations in the conductivity of the material from PAS amplitudes under irradiation with nanosecond electron beams.