A Study of the Spatial Charge Effect on 2-MeV Proton Beam Transport in an Accelerator-Based Epithermal Neutron Source

A neutron source composed of a tandem accelerator with vacuum insulation and a lithium target is used to develop the boron neutron capture therapy and other applications. The dependence of the proton beam size on the target surface on the beam current is measured with thermocouples inserted inside the target and with a infrared camera. It is found that there is no appreciable influence of the spatial charge on the proton beam transport to a distance of 5 m from the accelerator to the target, which simplifies the neutron source operation.