1. NTM Stability at Low Collisionality
J. A. Snipes, T. C. Hender*, S. M. Wolfe
MIT Plasma Science and Fusion Center, Cambridge, MA USA
*UKAEA-Euratom, Culham Science Centre, Culham, UK
J A Snipes, Alcator C-Mod Ideas Forum, MIT PSFC, Cambridge, MA – 15 December 2006

2. Can we Approach NTM Stability Limits at Low *?
Previous NTM threshold scalings on DIII-D and AUG indicated C-Mod approaches the NTM threshold  Recent JET scalings differ:
C-Mod is still far from the N scaling
C-Mod surpasses the p scaling without NTM's
J A Snipes, Alcator C-Mod Ideas Forum, MIT PSFC, Cambridge, MA – 15 December 2006

3. NTM Stability at Low Collisionality
Motivation: C-Mod’s unique operational range can help distinguish between various NTM threshold dimensionless scalings through multi-machine comparisons (JET, DIII-D, AUG). This will be important to correctly predict NTM stability in ITER.
Goals: Operate at high  and low collisionality to approach or surpass the various NTM threshold scalings. Look for unstable low frequency MHD activity and try to distinguish NTMs from classical modes.
Plan of execution: Begin with then reduce the density • Use the divertor cryopump to maintain density control at low density
• Will require PICRF > 4 MW preferably up to 6 MW
• Use DNB to measure q(r) with MSE to determine the MHD 
• Scan ne down to 4  1020 m-3 to cross * NTM threshold scalings
• Scan Ip to vary the p scaling more than the N scaling to further distinguish the two scalings ~
J A Snipes, Alcator C-Mod Ideas Forum, MIT PSFC, Cambridge, MA – 15 December 2006