CW cathode development for LAPPS

Summary form given only, as follows. NRL is developing a Large Area Plasma Processing System (LAPPS) for materials processing applications. The plasma generation technique utilizes a sheet electron beam to ionize a low pressure, neutral background gas such as oxygen, nitrogen or argon at a pressure of 20-100 mTorr. The beam electrons are generated by a separate hollow-cathode diode located outside the processing region and confined to a narrow channel by a axial magnetic field of 100-300 Gauss. Plasma production is confined to the beam channel. A hollow-cathode which produces a 5 kV, 1 cm wide by 30 cm long continuous (CW) beam has been fielded and a 50 cm wide cathode is under design. Langmuir probe data indicates the plasma density within the plasma sheet is >2 × 10/sup 12/ cm/sup -3/ with T/sub e/ = 0.5 eV in a 50 mTorr oxygen background. Plasma density measurements inside and outside the beam region have been made in both oxygen and argon as a function of distance from the beam and are in agreement with a diffusion model. Plasma density and temperature measurements for various gases and cathode configurations will be presented.