REVERSED FIELD PINCH EXPERIMENT ON A NEW LARGE MACHINE, TPE-RX

摘要

Reversed field pinch (RFP) experiment on a new large machine, TPE-RX has been started from Marchrn1998. Major and minor radii of TPE-RX are 1.7175m and 0.45m, and the maximum designed plasma currentrn(I_p) and discharge duration are 1MA and 100ms, respectively. TPE-RX is being operated in the medium I_prnregion (I_p < 500kA) with discharge duration about 80ms and RFP discharges with good reproducibility arernroutinely obtained, where the precise compensation of error field at poloidal gap of thick shell is indispensable.rnIn a series of initial phase of experiment, following results are obtained. Non-inductive part of toroidal looprnvoltage (RpI_p) as low as 12 V is obtained at low I_p (～150kA), but it increases with I_p and becomes 22V at I_prn~450kA. However, it is shown that R_pI_p is gradually decreasing as the discharge cleaning has been continued.rnFurther decrease of RpI_p will be expected under the improved wall condition. In almost of all discharges,rnespecially with large I_p (>250kA) the wall and phase locking of the MHD fluctuations is observed. However,rnseveral discharges without this mode locking are found in low I_p and low filling pressure cases. Measurementsrnof electron density () by CO2 laser interferometer, electron temperature (T_e) by soft x-ray pulse heightrnanalysis and ion temperature (T_i) by CV Doppler broadening have been started. Measured values are ～rn5×10~(18)m~(-3), T_e ～1000-1200eV and T_i ～ 130±50eV for the discharge with I_p～ 270kA and reversal/pinchrnparameters ～ -0.1/1.6, although it is possible that this high Te may correspond to high energy part and low T_irnmay correspond to the value near the edge since the radiation profile of CV line is very hollow. An interestingrndependence of plasma rotation on I_p is found in the Doppler shift measurement of CV line.