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MARFE phenomena on HT-7 tokamak is studied in this paper. A best correlation’ has been found between the total input ohmic power and the product of the .edge line average density and Zeff. MARFEs which is strongly correlated with impurity density, always occurs at Zeff = 3~8 ohmic discharges. In HT-7 tokamak high Zeff discharges, it is found that the MARFEs usually occur at values of : in the range of 0.5~0.7, where p = In the case of good wall condition (Zeff= 1 ~2), the onset of MARFEs have not been observed before reaching the Greenwald density limit’ on HT-7. An improved confinement mode plasma which is induced by the MARFE is observed, the global particle confinement time increases 1.9 times. The relaxation time between the MARFE event trigger and the L-U transition is about 1.4 ms, the followed L-H transition time is 1.9 ms, the improved confinement mode phase is maintained for about 40 ms. MARFE cools the plasma edge, and the electron density profileis observed to become more narrow and peaking.
MARFE phenomena on HT-7 tokamak is studied in this paper. A best correlation ’has been found between total input ohmic power and the product of the .edge line average density and Zeff. MARFEs which is strongly correlated with impurity density, always occurs at Zeff = 3 ~ 8 ohmic discharges. In HT-7 tokamak high Zeff discharges, it is found that the theFEFEs usually occur at values of: in the range of 0.5 ~ 0.7, where p = In the case of good wall condition (Zeff = 1 ~ 2), the onset of MARFEs have not been observed before reaching the Greenwald density limit ’on HT-7. An improved confinement mode plasma which is induced by the MARFE is observed, the global particle confinement time increases 1.9 times. The relaxation time between the MARFE event trigger and the LU transition is about 1.4 ms, the followed LH transition time is 1.9 ms, the improved confinement mode phase is maintained for about 40 ms. MARFE cools the plasma edge, and the electron density profile was observed to become more n arrow and peaking.