On neutron generation in beryllium plasma under the effect of a fast-electron beam

Abstract

1. The overwhelming majority of present-day neutron sources belong to the type of solid-state generators where neutrons are produced in solid-state targets via nuclear reactions induced by fast ions or energetic bremsstrahlung photons. Plasma neutron sources, whose operation is based on initiating reactions in a relatively cold plasma upon irradiation with a particle beam, have not yet received adequate study. At the same time, reactions in plasmas possess important special features, themain of these being the suppression of the channel of ionization losses—that is, of the useless loss of the charged-particle energy by medium ionization. This leads to an increase in the projectile-particle range and to the enhancement of the yield of nuclear reactions in plasma targets. For example, it was shown in [1, 2] that plasma sources of neutrons can ensure sizable fluxes; therefore, they can be applied in solving a number of scientific and technological problems. Employing electron beams in creating neutron sources may prove to be efficient, at least from the economic point of view. At present, relatively cheap and reliable facilities for producing intense beams of fast electrons have been developed, the efficiency of the input-energy transformation into the beam energy being there as high as 85 to 90%. In neutron sources, an electron beam can perform two functions. First, it is able to transform the target into a plasma state; second, it can initiate nuclear processes in the target that are accompanied by neutron generation. These are the electrodisintegration of target nuclei via (e, e′n) reactions and secondary photonuclear reactions (γ, n) induced by bremsstrahlung photons. Photonuclear reactions have already been employed in experimental neutron sources. As to electrodisintegration processes, the question of whether their application will be promising has so far received very little study. However, the traditional opinion is that, in all probability, their role cannot be significant because of the smallness of the cross sections for (e, e′n) reactions.