Multicapillary and carbon fiber cathodes for high-current electron beam generation

We report results of investigation of a high-current electron diode with multicapillary cordierite and glass cathodes assisted by velvet-type and ferroelectric plasma source igniters, and carbon fiber cathodes. Parameters of the plasma inside the capillary channels and in the vicinity of the cathode surface were studied during the accelerating pulse in a diode powered by a ~200 kV, ~300 ns pulse. The nature of uniformity in emission current density distribution and possibility of electron beam control duration for multicapillary cathode will also be presented. For carbon fiber cathodes it was found that application of the accelerating pulse leads to generation of the surface plasma in a form of several mm size plasma spots. The cathode plasma density and temperature were measured using non-disturbing spectroscopic methods.