Production of a quiescent plasma by a rf discharge

Abstract

Quiescent argon plasmas of densities of 109–1011 electrons/cm3 with a symmetric radial density profile and a Maxwellian electron velocity distribution (Te≃5 eV) have been produced by a rf discharge for neutral gas pressures of 1×10−4 to 2×10−3 mm Hg and magnetic fields in the range 0.2–0.5 kG. The main sources of density inhomogeneities and noise, which can arise from the formation of a plasma in regions of strong rf field inhomogeneities, have been eliminated by appropriate construction of the rf wave structure. The rms density fluctuation level δn/n is in the range 2×10−3 to 5×10−2, and decreases with increasing neutral gas pressure.