Reversed Shear Experiments with ICRF Heating in Alcator C-Mod
Abstract
Initial scoping experiments were performed to obtain the enhanced reversed shear (ERS) mode in Alcator C-Mod using current ramp and early ICRF heating. Typical plasma parameters at the end of the 0.23 s sawtooth free period were barne = 1 × 10^20 m-3, Bt = 5.3 T, T_e0 = 5 keV, T_i0 = 2.5 keV, n_H/ne ~= 0.02 - 0.10, and Ip = 0.8 MA. During the ramping phase, 0.08 - 0.15 s into the discharge initiation phase, MHD oscillations were observed on both poloidal field pick-up coils and ECE diagnostics just as q_95 dropped below 5. Equilibrium reconstruction using the EFIT code is consistent with a reverse shear q-profile or a nearly flat q-profile near the center, with q_0>= 3.0, q_95>= 4.5. The MHD modes have been interpreted with the linear code MARS as single layer resistive tearing modes.(J. Ramos, et al., this conference.)
- Publication:
-
APS Division of Plasma Physics Meeting Abstracts
- Pub Date:
- November 1997
- Bibcode:
- 1997APS..DPPoTP211P