Session 6P - TEXT-U, Tore Supra, HBT-EP, and Other Tokamaks.
POSTER session, Wednesday afternoon, November 13
Exhibit Hall - Concourse Level, Adam's Mark
Frequency modulated resonant magnetic perturbations (RMPs) have been successful in controlling the rotation velocity of internal (2,1) modes in the HBT-EP tokamak. The RMPs were produced by a set of compact saddle coils driven in series (single-phase) by a high-current, high-bandwidth power amplifier. The frequency of naturally-occurring internal modes (\(f \approx 7\) kHz) was controlled over the range 3 kHz--15 kHz using five pairs of highly-localized 9-turn coils (total coverage \( \sim 8% \) of the plasma surface) with \( \tilde b_r\ applied^(2,1)\left( a \right)\cong \tilde b_\theta \ MHD^(2,1)\left( a \right)\). The magnitude of the induced rotation velocity for a given applied field was limited by phase slippage of the mode with respect to the applied field, presumably due to plasma viscosity. Rotation control over a smaller frequency range was achieved using only two saddle coil pairs. This technique has been extended with an additional amplifier/saddle coil set (\( m=3 \), \( n=2 \)) to produce differential rotation at separate rational surfaces within the plasma. Measurements of the induced rotational shear including effects on stability and transport will be presented.
\(^*\)Supported by U. S. DOE Grant No. DE--FG02--86ER--53222