Preliminary Study for Improving Electron Emission Threshold of Metallic Electrodes Treated by Intense Pulsed Ion Beam

There exist lots of impurities and micro-protrusions on the surface of metallic electrode, which lower the electron emission threshold. Since intense pulsed ion beam (IPIB) irradiation can melt and vaporize metal material, it is expected to increase the electron emission threshold by removing the impurities and micro-protrusions with this method. In our work, effects of IPIB treatment on electron emission threshold of metallic electrodes were studied. The electron emission threshold tests were done on a platform named 1 MV generator (the output voltage is higher than 1 MV with a rise time of ~25 ns when the load impedance $> 10~\Omega $ ). The pressure of the test vacuum chamber was kept at ~10 ⁻³ Pa. The results show that the electron emission threshold of as-machined 304L SS electrode was ~250 kV/cm, and it increased to 316 kV/cm after polish, and IPIB treatment enhanced the average electron emission threshold to 367 kV/cm. For bare machined aluminum electrodes, the average threshold was 255 kV/cm, and it also increased to 368 kV/cm after IPIB treatment.