Diamond hollow cathode with axial magnetic field for high-density cold plasma source

We present a high-density plasma source using a hollow cathode with an axial magnetic field. The hollow cathode consists of molybdenum plates coated by polycrystalline boron-doped diamond (PBDD) with a high yield of ion-induced secondary electrons. Impact ionization was promoted by gyromotion in the hollow cathode with a magnetic field. A normalized current density four orders of magnitude larger than that of a planar cathode without a magnetic field was obtained. The high-quality PBDD cathode enables lower discharge sustain voltage and higher current density without glow-to-arc transition compared with low-quality PBDD and other cathode materials.