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

J.W. Hughes, 2011 C-Mod Ideas Forum, Jan 10—12, 2011

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-IP

• peration
• 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

• 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-IP

• peration
• 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 2

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 BT under MP578, earlier MPs); is there a more desirable shape that can give us the regular ELMing condition? – Generate data set for a new test of ELITE and EPED

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