Research on emission stability of carbon/carbon composite material cathodes

The explosive emission cathode can be used to produce a intense relativistic electron beam. This type of cathode will form a plasma on the cathode surface during the emission process, and the characteristics of the plasma are directly related to the characteristics of the electron beam. In this paper, carbon fiber preforms are densified using isothermal chemical vapor deposition, and a carbon/carbon composite material with a density of $1.9 \mathrm{~g} / \mathrm{cm}^{3}$ was prepared. First, a high-speed framing camera was used to photograph the luminescence of the cathode plasma during the explosion emission process, and the generation and distribution characteristics of the cathode plasma were analyzed. The results showed that the cathode plasma was produced in the form of spots on the cathode emission face during the formation stage. In the subsequent process, the cathode plasma shell is gradually merged to form. During the pulse high voltage loading process, the distribution of cathode plasma maintains a good uniformity, indicating that the cathode electron beam has a good uniformity. After the pulse high voltage loading, the cathode plasma will continue to diffuse between anode and cathode, the duration of tens of microseconds, the diffusion speed is $2 \mathrm{~cm} / \mu \mathrm{s}$. A single capacitance Marx pulse power source is used to carry out the current stability experiment, the load voltage is about 450 kV. The experiments show that the cathode can maintain good beam stability by continuously emitting at 20 Hz for 2 min. It can provide support for the development of stable and reliable HPM source.