On the nature of emissions of polymethyl methacrylate excited by an electron beam of subnanosecond or nanosecond duration

The results of studies of the physical nature of emissions produced in polymethyl methacrylate excited by electron beams of a subnanosecond or a nanosecond duration are presented. The spatial, amplitude, and spectral-kinetic properties of emissions have been examined under an electron beam energy density varying from 10$^{-4}$ to 4 $\times$ 10$^{-1}$ J/cm$^2$. It has been found that cathodoluminescence is the primary type of emission under low energy densities of the electron beam. When the energy density of a nanosecond electron beam and/or the number of pulses of excitation by a subnanosecond electron beam were increased, an electrical breakdown of polymethyl methacrylate occurred in the irradiated region. This process was accompanied by a burst of emission of dense, low-temperature plasma.