Ion temperature at the plasma centre has been measured from Doppler broadening of Ti XXI (2.61 Å) and Ar XVII (3.95 Å) x-ray lines using a newly installed crystal spectrometer with CCD detector in ECH, NBI and ICRF plasmas of Large Helical Device (LHD). The ion temperature obtained in a range of 0.6 and 3.5 kev was analysed with electron density and compared with electron temperature. A new parameter range of Ti > Te was found in low-density (ne < 1013 cm-3) H-minority ICRF discharges operated in the ion-heating regime (Pi ≥ Pe), whereas the ion temperature was roughly equal to the electron temperature in NBI discharges operated in the electron-heating regime (Pi < Pe). The ion temperature in the ICRF and ICRF + NBI discharges was correlated with the input power to bulk ions over the ion density (Pi/ni). As a result, a good correlation was obtained between them and it also indicated a clear rise of the ion temperature for the increasing Pi in a range of Pi/ni < 5 (MW/1013 cm-3).
All Science Journal Classification (ASJC) codes
- Nuclear and High Energy Physics
- Condensed Matter Physics