Intense charged-particle emission in a diffuse vacuum discharge

The effects of plasma-assisted emission of electrons from a cathode and of ions from an anode are used in experiments to generate intense particle beams in a vacuum gap. The plasma is produced by sputtering of the electrons and ions impinging on the electrode surfaces. When the initial electron beam, which is generated by ferroelectric emission, reaches a current density of about 1 A/cm2, a homogeneous vacuum discharge takes place provided an electric field of the order of 10 kV/cm is applied between the anode and the cathode. The vacuum gap is short circuited and the sum of the electron and ion beam currents is determined by the charging voltages and by the parameters of the external electric circuit. Beam currents of electrons and ions are extracted through holes or grids in the corresponding electrodes