Characteristics of ion temperature measured with charge-exchange recombination spectroscopy （CXRS） were studied in Ohmic, lower-hybrid-wave （LHW） driven and ion-cyclotron- resonance-frequency （ICRF） heated plasmas in HT-7. The results indicate that the central ion temperature T10 follows the one-third power law in the product of central line-averaged density Ne and plasma current Ip in Ohmic discharges and is therefore consistent with the Artsimovich scaling law T10 = K （Ip Bt ne R2）1/3. It is shown that there is an appreciable increase of ion temperature during the operation with both LHW and ICRF and that the increment of ion temperature in those shots is mainly due to the energy transfer via collisions between ions and electrons rather that by direct heating of the ions.
Charge exchange recombination spectroscopy （CXRS） based on a diagnostic neutral beam （DNB） installed in the HT-7 tokamak is introduced. DNB can provide a 6 A extracted current at 50 kV for 0.1 s in hydrogen. It can penetrate into the core plasma in HT-7. The CXRS system is designed to observe charge exchange （CX） transitions in the visible spectrum. CX light from the beam is focused onto 10 optical fibers, which view the plasma from -5 cm to 20 cm. The CXRS system can measure the ion temperature as low as 0.1 keV. With CXRS, the local ion temperature profile in HT-7 was obtained for the first time.
石跃江符佳李颖颖William ROWAN黄河王福地高慧贤黄娟周倩刘胜张健李军谢远来刘智民黄懿赟胡纯栋万宝年DNB team
