Investigation of cold cathode for nanosecond electron accelerators

Abstract

In many technological applications, electron beams of large size are required on one of the coordinates. The cold cathode used for this purpose has to possess high stability of characteristics, durability and be able to generate a uniform distribution of the electron beam current density. Comprehensive research into the properties of the metal dielectric (MD) cathode on the URT-1M accelerator was conducted. The influence of quantity and the relative positioning of the emission elements on the beam parameters and distribution of the electron beam current density were established. The influence of the shape of the cathode case on stability of operation at a high repetition rate was also investigated. A measurement technique using pulsed cathode luminescence (PCL) of phosphorus to estimate the distribution of the electron beam current density was developed. This PCL technique was tested by a dosimetry technique using plastic detectors. The qualitative compliance of the results from both techniques was established. By selecting the number and arrangement of MD plates, it was possible to obtain a more or less uniform (15%) electron beam current density distribution on the output foil.It was set so that falling of emission MD cathode by operation at high repetition rates (>100 pps) occurs rather slowly, thus ensuring continuous functioning for 40 h.