Title :
Electron Cyclotron emission diagnostics for helical plasma in the large helical device
Author :
Nagayama, Yoshio ; Kawahata, K. ; Inagaki, Shigeru ; Morisaki, Tomohiro ; Narihara, K.
Author_Institution :
Large Helical Device Group, Nat. Inst. for Fusion Sci., Toki, Japan
Abstract :
Electron cyclotron emission (ECE) diagnostics have been developed in the large helical device (LHD). The ECE is transmitted over 80 m from the antenna to the spectrometer with the corrugated waveguide system, which has a low transmission loss (∼30%). The polarization of ECE is identical for all frequencies, while the field angle varies from -40° to +30° on the ECE sight line. The ECE temperature measured by the Michelson, which is calibrated with a hot source, agrees well with Thomson scattering measurement in a wide range of the electron density. Magnetic island formation is investigated using the electron temperature profile measured with the Michelson. The radiometer is cross-calibrated to the Michelson and is employed for the study of fast phenomena, such as the sawtooth oscillation. Besides the normal ECE, tangential ECE is investigated in LHD in order to explore the potential of ECE diagnostics.
Keywords :
Michelson interferometers; antennas in plasma; plasma density; plasma diagnostics; plasma filled waveguides; plasma oscillations; plasma temperature; plasma toroidal confinement; sawtooth instability; stellarators; 80 m; Michelson measurement; Thomson scattering; corrugated waveguide system; electron cyclotron emission diagnostics; electron density; electron temperature profile; helical plasma; large helical device; magnetic island formation; radiometer; sawtooth oscillation; transmission loss; Cyclotrons; Density measurement; Electron emission; Magnetic field measurement; Plasma devices; Plasma diagnostics; Plasma temperature; Plasma waves; Temperature measurement; Transmitting antennas; Diagnostics; ECE; LHD; electron cyclotron emission; large helical device; microwave; plasma; temperature;
Journal_Title :
Plasma Science, IEEE Transactions on
DOI :
10.1109/TPS.2004.833380
