Characteristics and diagnosis of a new type radio frequency driven in vacuum arc ion source

The discharge mechanism of this source is based on the use of both RF- driven (15 MHz -300W) and vacuum arc to create discharge plasma of higher intensity. An internal antenna is used to couple the RF power to the plasma. Lower ignition voltage (50 up to 200V) and higher plasma intensity feature the characteristics of this source. The plasma and beam diagnostics are made for this source. The plasma is diagnosed using Langumier double probes. The plasma intensity could reach ∼ 8x1011 elec./cm3 and the plasma temperature ∼ 14 eV. The source is considered self extracted ion current and could deliver ion currents of ∼10mA for thin beam (φ ∼4mm) and ∼20 mA for broad beam (φ ∼ 6cm) at ∼ 200V extraction voltage. The beam diagnostics (for thin beam) of this source are measured which include: the beam profiles, beam emittance, energy spread and distribution of the ion species in the ion beam. The increase of the anode voltage affects decrease of the beam emittance, while the energy spread increases with the decrease of the discharge pressure. The beam emittance is found to be around 200 up to 400 mm.m.rad. and the energy spread of the ions in the ion beam is around 40 up to 80 eV. The Ar ion specie extracted from the source could reach Ar+5. The beam profiles show that the beam is more convergent with the increase of the accelerating voltage and with the use of proper capacitors between the extraction electrodes. (author)