1. Stable TAE n Discrimination with Plasma Rotation
J. A. Snipes, A. Fasoli*, J. E. Rice, J. A. Sears
MIT Plasma Science and Fusion Center, Cambridge, MA USA
*CRPP-EPFL Association Euratom, Lausanne, Switzerland
J A Snipes, Alcator C-Mod Ideas Forum, MIT PSFC, Cambridge, MA – 15 December 2006

2. Improved Toroidal Mode Number Measurements
New pick-up coil limiters at four toroidal locations will improve low n resolution for all MHD modes  If multiple n’s are simultaneously excited by the TAE antennas, a large plasma rotation should separate the modes in frequency
J A Snipes, Alcator C-Mod Ideas Forum, MIT PSFC, Cambridge, MA – 15 December 2006

3. Plasma Rotation in Ohmic H-mode Reaches 40 km/s ~ 9.5 kHz
Motivation: Actively excited TAE measured phases often show no clear n number. The broad antenna spectrum may excite multiple n’s simultaneously. Knowing n is essential to compare with theory.
Goals: Excite stable TAEs with the active MHD antennas during high plasma rotation • Look for closely frequency spaced multiple n modes with spacing proportional to plasma rotation • Attempt to discriminate the various n values and determine the damping rate as a function of n • Compare high n damping rate with theoretical expectation of increased radiative damping at high n
Plan of execution: In Ohmic H-mode plasmas: • Sweep active MHD antenna frequency through the real-time TAE frequency and look for resonances
• Attempt to maximize plasma rotation in H-mode
• Look for frequency splitting of each resonance
• Sweep through frequencies associated with high n>10 to attempt to drive higher n modes
J E Rice, et al, 2004 Phys Plasmas 11, 2427
J A Snipes, Alcator C-Mod Ideas Forum, MIT PSFC, Cambridge, MA – 15 December 2006