DIII-D RESEARCH OPPORTUNITIES FORUM FOR THE 2008 EXPERIMENTAL CAMPAIGN
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| Title | 277: Test of Neoclassical Toroidal Viscosity theory using modulated I-coil currents | ||
| Name: | Keith Burrell ( |
Affiliation: | General Atomics |
| Research Area: | Rotation Physics | Presentation time: | Requested | Co-Author(s): | A. Garofalo, G. Jackson, M. Schaffer, |
| Description: | Use modulated I-coil currents to investigate the theory of braking of plasma toroidal rotation by non-resonant error fields | ||
| Experimental Approach/Plan: | Create non-resonant, n=3 error fields in L-mode and/or QH-mode plasmas using the I-coil. Modulate the I-coil currents to modulate the non-resonant drag on the plasma. Investigate the effects as a function of modulation frequency, background plasma rotation, collisionality and I-coil parity. | ||
| Background: | The theory of braking of plasma rotation by non-resonant error fields predicts that the magnitude of the drag on the plasma increases with the square of the error field amplitude and that the drag vanishes when the plasma rotates toroidally at a non-zero, offset velocity related to the ion temperature gradient. By creating non-resonant, n=3 error fields using the I-coil and then modulating these at frequencies up to 100 Hz, we can impose a periodic variation in the drag term. By analyzing the amplitude and phase of the resulting changes in the toroidal rotation, we can determine the size of the drag term. In addition, by doing this experiment at various different toroidal rotation speeds, we can investigate the offset velocity. The results can then be compared with theoretical predictions to test the theory. | ||
| Resource Requirements: | I-coil system connected to do both error field correction and n=3 braking, if possible. If not, use C-coil for error correction and I-coil for n=3 braking. Reversed plasma current is needed for the QH-mode portion of the experiment. 7 NBI sources needed for rotation scan. | ||
| Diagnostic Requirements: | All profile diagnostics. CER at high enough speed to have 10 samples per I-coil modulation period. | ||
| Analysis Requirements: | -- | ||
| Other Requirements: | -- | ||
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