Orifice probe for plasma diagnostics. IV. Ion density determination

Abstract

For Pt. III see abstr. A24317 of 1974. The ion number density ni is determined by the orifice probe using a method independent of the electrons. The quantities measured experimentally through the orifice are the number of ions per unit time (ion saturation current ii) divided by the volume flow rate V of neutral gas. In the molecular flow region where V is constant, ni is simply obtained from a measurement of ii. This determination of ni is potentially adaptable to a wide pressure and density range. The method has been applied here to an RF plasma in argon with an input power of 25 W for pressures from 0.001-10 Torr and number densities from 108-1011 cm-3. For pressures between 0.02 and 0.2 Torr, ni obtained in this way is in good agreement with ne obtained from the probe characteristics. This determination of ni is much simpler and inherently more accurate (<15%) than that for ne using the orifice probe or Langmuir probes (>20%).

$ G$-identities of non-associative algebras

“…Such orifice probes have been studied by numerous authors (Tonks et a1 1926, Ionov and Tontegode 1964, Bohm and Goodings 1966a,b, Williams 1966,' Franklin et aZ1968, Bakulin et aZl969, Okamoto and Tamagawa 1969, 1970, Amemiya and Dote 1970, Hiraoka and Kamada 1971, Coburn and Kay 1971, SCguin et a1 1972, Prokopenko et a1 1972, 1974a,b, Chang et aZ 1973, 1976, Goldan 1970, Vasile and Smolinsky 1973, Amemiya 1974, Prokopenko and Goodings 1975, Hasted 1975. Most of these papers deal with non-magnetised plasmas.…”