On understanding of a magnetically enhanced hollow cathode arc plasma

Hollow cathode arc discharges have been studied for decades, particularly in the field of physical vapor deposition, but the underlying physics of these discharges is still not fully understood. In this work, the hollow cathode arc discharge with a strong axial magnetic field was investigated analytically and by means of particle-in-cell/Monte Carlo method. The models relate input parameters such as cathode geometry, magnetic field, discharge voltage, and feed gas flow rate with cathode electron emission, ionization, and particles fluxes. The dynamics of energetic electrons, i. e., cathode-emitted thermionic electrons after acceleration in the cathode fall, is studied by considering Coulomb collisions with Maxwellian bulk electrons and inelastic collisions with neutrals. The axial magnetic field within the cathode not only allows a discharge operation at a very low gas flow rate, but also presents a cross-field discharge in which the electron mobility decreases and instabilities may occur. The voltage-current and voltage-gas flow characteristics obtained by the analytical model are in good agreement with available experimental data.