Heating of D/sub 2/ gas targets by intense tritium ion beams

Abstract

This study examines the problem of heating due to bombarding a D/sub 2/ gas with a T/sup +/ beam to produce 14-MeV neutrons. Such a neutron source is proposed for testing the effects of neutrons on materials to be used in a fusion reactor. Ionization and electronic state excitation by the beam and ionization, electronic and vibrational excitation, dissociation, momentum transfer, and dissociative recombination by secondary electrons are considered. For most beam energies of interest, ionization will play the dominant role in transferring energy from the beam to the target gas. Dissociative electron recombination is particularly important because it allows the energy involved in overcoming the ionization threshold to be released very rapidly as kinetic energy. The results of our study are applied to a specific Intense Neutron Source design in which approximately 60% of the energy deposited by the beam will emerge as heat while the supersonic D/sub 2/ gas remains in the target interaction region. Less than 10% of the energy is given off as radiation.