(EX/P4-25) Impurity Accumulation in the Main Plasma and Radiation Processes in the Divetor Plasma of JT-60U
1) Japan Atomic Energy Institute, Naka, Japan
Abstract. Two studies are included: tungsten accumulation in the main plasma and radiation processes of carbon ions in the detached plasma of JT-60U.
It has been found that tungsten accumulation becomes more significant with increasing plasma rotation velocity against the plasma current direction, where negative radial electric field is formed.
The accumulation level does not depend on the tungsten generation flux, suggesting the transport plays a dominant role to determine the accumulation level.
In a high density plasma at 63% of the Greenwald density, the tungsten accumulation levels decreased siginificantly, suggesting a shielding effect of the peripheral plasma.
The spectral lines of
C3+ emitted around the X-point in the detached plasma with MARFE are measured with a VUV spectrometer and a 2-dimensional visible spectrometer in order to compare the generation flux of
C3+ ( ionization of
C2+ and recombination of
C4+ ) and the loss flux of
C3+ ( ionization and recombination of
It has been found that
C3+ is produced by the volume recombination of
C4+ and the ionization of
In contrast, the volume recombination of
C3+ is not detected, and the ionization flux of
C3+ is less than 1% of the
C3+ generation flux.
C3+ generation flux is higher by two orders of magnitude than the loss flux.
This result suggests that another loss mechanism of
C3+ such as transport loss from the X-point is significant.
Full paper available (PDF)