DIII-D RESEARCH OPPORTUNITIES FORUM FOR THE 2008 EXPERIMENTAL CAMPAIGN
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| Title | 275: Optimization w.r.t. plasma rotation of the error field correction from I-coil | ||
| Name: | Andrea M. Garofalo ( |
Affiliation: | Columbia University |
| Research Area: | Error Fields | Presentation time: | Not requested | Co-Author(s): | -- |
| Description: | Use a rotating n=1 field applied with the I-coil to produce fluctuations in the rotation measurements. Exploit DIII-D's capability to measure rotation at different toroidal locations to separate n=1 from n=0 components of the fluctuations and learn what is the optimal correction of the n=1 error field w.r.t. plasma rotation. The error correction is perfect when the plasma becomes insensitive to the phase of an additional, rotating n=1 field. | ||
| Experimental Approach/Plan: | Previous experiment's phase scan: Apply an n=1 rotating field (I1), in addition to the feedback-driven error field correction (I0). Use analysis of the CER fluctuation to determine the times when the phase of the applied n=1 I-coil field is the optimal correction phase. At these times the amplitude and phase of I1 are: A1x, phi1opt. Future experiment's amplitude scan: Vary A1 slowly (over several seconds) from A1x to zero and from zero to maximum allowed. This gives a total apllied field (It) with varying amplitude and phase. In addition to this varying It, again apply an n=1 rotating field, this time at higher frequency, e.g. 20 Hz A time dependent Fourier analysis of the Mirnov loops will give the amplitudes of the n=0 and n=1 magnetic fluctuations. The time of minimum n=0/n=1 amplitude should give the optimal error-field correction. An I-coil helicity scan may then improve the match to the intrinsic error field structure. The error correction is perfect when the plasma becomes insensitive to the phase of an additional, rotating n=1 field. Look for improved angular momentum confinement (at beta above the no-wall limit). | ||
| Background: | Complete 2003 experiment (scan of the toroidal phase) carrying out scan of the amplitude and of the helicity of the n=1 error correction field applyied by the I-coil. | ||
| Resource Requirements: | -- | ||
| Diagnostic Requirements: | -- | ||
| Analysis Requirements: | -- | ||
| Other Requirements: | -- | ||
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