ISSN:
1077-3118
Source:
AIP Digital Archive
Topics:
Physics
Notes:
Spatial distributions of electron density ne, electron temperature Te, and wave field intensity in a planar microwave discharge at low pressures (10–100 mTorr) are measured with the discharge power as a parameter. Two different modes of electron heating are found: a bulk heating mode characterized with high Te(∼10 eV) in underdense plasma, and a surface heating mode with low Te(∼3 eV) in overdense plasma with a hot layer near the plasma-dielectric boundary. Abrupt transition between the two modes takes place near the cutoff density nc where the electron plasma frequency coincides with the discharge frequency (2.45 GHz). In the underdense case (ne〈nc), the microwave penetrates the bulk plasma and heats the majority of electrons confined in the dc ambipolar potential well, leading to high Te. In the overdense case (ne〉nc), the evanescent wave (surface wave) near the microwave window strongly heats the electrons in the boundary layer, which are transported to the bulk region and ionize the neutral particles to therein produce relatively cold electrons. © 2000 American Institute of Physics.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1063/1.1329322
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