Plasma-surface diagnostics in LAPPS

Abstract

Summary form only given. In situ mass and energy resolved measurements of ion and neutral fluxes to a conducting electrode surface in NRL's Large Area Plasma Processing System (LAPPS) are presented. LAPPS uses a magnetically confined sheet of high-energy electrons to ionize a background gas, producing a high-density (10/sup 9/-10/sup 12/ cm/sup -3/) planar plasma that is scalable to large areas (meters/sup 2/). The electron beam is produced by a hollow cathode, collimated by a 100-300 Gauss magnetic field and injected into 20-200 mTorr of background gas. Hence, plasma production is decoupled from the reactor geometry, allowing independent positioning and biasing of electrode surfaces. The relative fluxes and energy distributions art reported for a grounded and RF-biased electrode and as a function of plasma-electrode separation. Ion and neutral species are sampled through a small orifice (sub-Debye length diameter) located in the center of the electrode and analyzed via an energy selector in series with a mass spectrometer. Relative fluxes and energy distributions are presented for discharges in Ar, O/sub 2/, Ne, and their mixtures over a range of plasma conditions (pressure, B). The results are discussed in terms of materials processing. Additional details concerning LAPPS and its processing applications are presented at this conference.