DIII-D RESEARCH OPPORTUNITIES FORUM FOR THE 2013 EXPERIMENTAL CAMPAIGN Review | Direct submission with log-in | Request submission without log-in
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Title	75: Evaluate the potential of correcting more than one mode component of the TBM error field
Name:	Holger Reimerdes reimerdes@fusion.gat.com	Affiliation:	CRPP-EPFL
Research Area:	Stability & Disruption Avoidance	Presentation time:	Requested
Co-Author(s):	J. Hanson, R. La Haye, M. Lanctot, N. Oyama, C. Paz-Soldan, J. Snipes	ITPA Joint Experiment :	No
Description:	This experiment seeks to improve the structure of the TBM correction field. Possible improvements are based on improving the m spectrum of an n=1 correction field, adding n>1 components to the correction field or a combination of both. Here the optimization of m and n components are addressed separately in order to facilitate the link to theory.	ITER IO Urgent Research Task :	No
Experimental Approach/Plan:	The experiment requires a target that clearly shows the effects of the TBM and is reproducible at the same time. The target could be the fast rotating H-mode developed in 2011, but any other scenario that meets the above criteria would work, too. In order to address the poloidal spectrum of an n=1 field, an optimization procedure using external fields that substantially differ from the 240 Deg phasing I-coil field is carried out. This includes an n=1 field applied with the C-coil alone as well as model based (e.g. vacuum, IPEC) C- and I-coil combinations that are predicted to improve the correction. The performance is compared to the standard n=1 I-coil field with 240 Deg phasing. If the poloidal structure of the n=1 field is important, the recoverable rotation should change. In order to address the importance of higher n components the optimization procedure used for n=1 is repeated using an n=2 field. This requires the control of each individual I-coil with an independent power supply. Optimum n=1 and n=2 EFC currents are then applied alone and simultaneously.
Background:	The 2011 TBM experiments showed that in rotating ELMY H-modes at beta normalized of 1.8, n=1 EFC using 240 Deg I-coil phasing can only correct 25% of the TBM induced rotation decrease. The remaining 75% of the rotation decrease must be caused by either secondary n=1 components of the TBM field or by n>1 components of the TBM field [H. Reimerdes, et al., IAEA 2012].
Resource Requirements:	- TBM mock-up coil - 5 co-NBI, 2 ctr-NBI (depending on the target). - Independent control of 12 I-coils
Diagnostic Requirements:	- 3D magnetics
Analysis Requirements:
Other Requirements: