Resonance microwave volume plasma source
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MPERATURE PLASMA
Resonance Microwave Volume Plasma Source N. K. Berezhetskayaa, V. A. Kop’eva, I. A. Kossyia, N. I. Malykha, M. A. Misakyana, M. I. Taktakishvilia, S. M. Temchina, and Young Dong Leeb a Prokhorov
Institute of General Physics, Russian Academy of Sciences, ul. Vavilova 38, Moscow, 119991 Russia b Samsung Advanced Institute of Technology, Mt. 14-1, Nongseo-dong, Giheung-gu, Yongin-si Gyunggi-do, 446-712 South Korea Received September 21, 2006
Abstract—A conceptual design of a microwave gas-discharge plasma source is described. The possibility is considered of creating conditions under which microwave energy in the plasma resonance region would be efficiently converted into the energy of thermal and accelerated (fast) electrons. Results are presented from interferometric and probe measurements of the plasma density in a coaxial microwave plasmatron, as well as the data from probe measurements of the plasma potential and electron temperature. The dynamics of plasma radiation was recorded using a streak camera and a collimated photomultiplier. The experimental results indicate that, at relatively low pressures of the working gas, the nonlinear interaction between the microwave field and the inhomogeneous plasma in the resonance region of the plasmatron substantially affects the parameters of the ionized gas in the reactor volume. PACS numbers: 52.50.Dg, 52.80.Pi DOI: 10.1134/S1063780X07070094
1. INTRODUCTION The aim of the present work was to design and investigate a new type of microwave gas-discharge plasma source employing nonlinear processes that occur in the plasma resonance region, in which the density of a nonuniform plasma is close to the critical den2 2 m ( ω 0 + ν eff ) - [1], sity of an unmagnetized plasma, nec = ----------------------------2 4πe where ω0 is the microwave circular frequency and νeff is the effective electron–neutral collision frequency. In a narrow region around the resonance surface, the microwave energy can be efficiently absorbed and converted into the kinetic energy of plasma electrons. The generation of accelerated electrons in plasma under the action of an intense electromagnetic field is a fundamental phenomenon, which has been thoroughly investigated both experimentally and theoretically (see, e.g., [2–4]). It should be noted that most of the studies on this subject were concerned with an inhomogeneous plasma in a highly rarified gas, in which the generation of fast electrons in the resonance layer and their escape into the surrounding medium can be analyzed without allowance for the interaction between electrons and gas molecules (atoms). In the present work, we attempted to create conditions under which the energy of the electrons accelerated in the plasma resonance region was primarily spent on gas ionization, thereby leading to the formation of a plasma halo around this region.
In gas-discharge applications concerned with the plasma resonance phenomenon, the main variable parameter is the gas pressure, which should be low enough for the resonance not to be suppre
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