Magnetic Helicity is Conserved at a Tokamak Sawtooth Crash
Abstract
The sawtooth instability causes sudden changes in magnetic topology during combined neutral beam and fast wave heating in the DIII-D tokamak. Measurements with a Motional Stark Effect diagnostic provide accurate determination of the equilibria before and after the sawtooth reconnection events. The global magnetic helicity int A\cdotB dV changes 0.2±0.9% at a sawtooth crash. The local change in helical flux, \chi, is roughly consistent with the Kadomtsev(B.B. Kadomtsev, Sov. J. Plasma Phys. 1) (1975) 389. model within large errors. The volume in which the helical flux changes is 85±15% of the volume predicted by Kadomtsev, while the central value of \chi is within 1% of the predicted value.
- Publication:
-
APS Division of Plasma Physics Meeting Abstracts
- Pub Date:
- October 2000
- Bibcode:
- 2000APS..DPPNP1095D