DIII-D RESEARCH OPPORTUNITIES FORUM FOR THE 2008 EXPERIMENTAL CAMPAIGN
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| Title | 392: Resonant and Non-resonant magnetic braking | ||
| Name: | Matthew Lanctot ( |
Affiliation: | Columbia University |
| Research Area: | Error Fields | Presentation time: | Not requested | Co-Author(s): | A. M. Garofalo, H. Reimerdes, Gary Jackson |
| Description: | The purpose of this experiment is to investigate the effect of non-axisymmetric magnetic fields on rotating plasmas. This experiment is a continuation of previous efforts (MP 2007-04-04) to amass data from discharges where both resonant and non-resonant magnetic braking is applied to plasmas above and below the no-wall n=1 kink stability limit. To date, this experiment has received only 1/2 day of runtime. Data from discharges in both normal and reverse plasma current configurations are needed to compare with predictions from the neoclassical toroidal viscosity model of momentum dissipation. Analysis of these results may also indicate the presence of a significant n=3 error field on DIII-D. | ||
| Experimental Approach/Plan: | Using both normal-Ip and reverse-Ip configurations, we will measure the evolution of the plasma rotation while applying n=1 and n=3 magnetic braking using the I-coil. The phasing and/or the polarity of the I-coil configuration will be chosen to complement previous data. Magnetic, ECE and SXR data will be analyzed to detect the possible presence of error field induced magnetic islands after the braking phase of the discharge. | ||
| Background: | Operation in the high-beta regime, where plasmas exhibit a paramagnetic response to field asymmetries, is made possible by minimizing magnetic field errors. The optimal error field correction helps to maintain the plasma toroidal rotation, which has has been shown to have a stabilizing effect on potentially catastrophic MHD instabilities such as RWMs and tearing modes. A full understanding of the mechanism by which naturally occurring or injected angular momentum is lost from the plasma is lacking. Results from NSTX suggest the NTV theory should be considered when investigating questions of torque balance in toroidal plasmas. DIII-D results from this experiment will be compared with these NSTX results and similar experiments in JET. | ||
| Resource Requirements: | Toroidal field at 1.95 T for ECE measuremens. Normal and reversed Ip configurations. | ||
| Diagnostic Requirements: | Magnetics, ECE, SXR, MSE | ||
| Analysis Requirements: | -- | ||
| Other Requirements: | -- | ||
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