ELMy H-mode in unfavorable grad-B drift plasmas Type I ELMy - PowerPoint PPT Presentation

ELMy H-mode in unfavorable grad-B drift plasmas • Type I ELMy H-mode is a common regime which can be studied on C-Mod, DIII-D and NSTX as part of the FY11 Joint Research Target on pedestal physics • Generally challenging to obtain Type I ELMs on C-Mod; done with atypical shaping (JFT-2M shape) – Requires non-standard diagnostic setup – Power supply limitations prevent high-I P operation • But, access could potentially be enhanced by operating in low- collisionality regimes – ELMs have been seen in I-mode – Some older data show ELMs in reversed-field H-modes with typical shaping and lower H- mode collisionality J.W. Hughes, 2011 C-Mod Ideas Forum, Jan 10—12, 2011 0

ELMy H-mode in unfavorable grad-B drift plasmas • Type I ELMy H-mode is a common regime which can be studied on C-Mod, DIII-D and NSTX as part of the FY11 Joint Research Target on pedestal physics • Generally challenging to obtain Type I ELMs on C-Mod; done with atypical shaping (JFT-2M shape) – Requires non-standard diagnostic setup – Power supply limitations prevent high-I P operation • But, access could potentially be enhanced by operating in low- collisionality regimes – ELMs have been seen in I-mode – Some older data show ELMs in reversed-field H-modes with typical shaping and lower H- mode collisionality J.W. Hughes, 2011 C-Mod Ideas Forum, Jan 10—12, 2011 1

ELMy H-mode in unfavorable grad-B drift plasmas • Idea: Reverse field and study ELMy H-mode at increased power, lower collisionality (1 run day) – Begin with LSN JFT-2M shape (5.4T, 0.9MA). This was done once, on 1070724029 – Scan shape, current to determine ELMing boundary (similar to what was done in normal B T under MP578, earlier MPs); is there a more desirable shape that can give us the regular ELMing condition? 1080130007 1080304029 – Generate data set for a new test of ELITE and EPED J.W. Hughes, 2011 C-Mod Ideas Forum, Jan 10—12, 2011 2