RESISTIVE MODES in REVERSED MAGNETIC SHEAR ALCATOR C-MOD PLASMAS
نویسنده
چکیده
During current ramp-up discharges with early auxiliary RF heating, reversed magnetic shear profiles have been obtained on Alcator C-Mod. MHD oscillations are often observed on ECE diagnostics, as well as magnetics. Although no direct q-profile measurement was available, a hollow current density profile with q min =2.5 was reconstructed by EFIT. The location of the biggest electron temperature fluctuations was close to the outer q = 3 rational surface. Based on a resistive linear stability code (MARS), the MHD oscillations were identified as n=1 resistive " multiple " tearing modes. Since the pressure profile was hollow and q > 1 in the core, a resistive interchange mode was also predicted to be unstable at the inner q = 4 rational surface, despite the low β N .
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