Lower hybrid wave coupling in Tore Supra through multijunction launchers
The Tore Supra lower hybrid current drive experiments use large phased waveguide arrays to couple the waves to the plasma. These launchers are based on the "multi-junction" principle. Extensive coupling measurements have been performed in order to study the radio-frequency characteristics of the plasma loaded multi-junction antennae. The dominant scattering coefficients of the waveguide arrays have been measured in various edge plasma conditions. Excellent agreement has been obtained between all these measured scattering coefficients, including their phase, and those deduced from the linear coupling theory (SWAN code). The detailed coupling analysis is performed on the basis of Langmuir probe measurements of the plasma density in front of the antennae. For a total injected power of less than 1 MW, modifications of the scrape-off layer have not been observed. For larger RF power (P > 1 MW), a significant heating (50%) and a decrease by a factor of two of the edge density were measured. Global power reflection coefficients of about 3% have been obtained in a large range of edge plasma densities and antennae positions. A detailed analysis provides a check of the phase difference between adjacent waveguides and the deduced experimental radiated power spectra. Power densities up to 40 MW/m2 have been reached with good linear coupling characteristics and spectrum control.
Bibliographic Reference: Paper presented: 18th European Conference of the EPS-Plasma Physics Division, Berlin (DE), June 3-7, 1991
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Record Number: 199110375 / Last updated on: 1994-12-02
Original language: en
Available languages: en