Thermal Properties of an Intense Relativistic Electron Beam Collector Under Repetitive Pulse Operation

With the increase in power and miniaturization in a size of repetitively operated high-power microwave (HPM) sources, such as relativistic backward-wave oscillators, the thermal control and cooling methods for a collector have the great effects on efficient operations of these devices. In this paper, the thermal properties of an intense relativistic electron beam collector under repetitive operation were studied. The bombardment area caused by energetic electrons was experimentally quantified, and the pulsed thermal loading for a 700-keV and 7-kA beam current was calculated. With an ANSYS multiphysics package, the typical results of temperature history of the collector under 10-100-Hz operation were presented. The dependence of peak temperatures on forced cooling conditions at different pulse repetition rates was also obtained. Comparison results show that the cooling process is influenced by collector thermophysical parameters, interface thickness, and convective factor of the forced water cooling. Finally, the hydraulic system necessary to achieve appropriate cooling fluid flow was discussed. These results may supply an efficient reference to the optimization and reasonable use of a repetitively operated beam collector in the HPM tubes.