Measurements of non-axisymmetric halo currents with and without ``killer`` pellets during disruptions in the DIII-D tokamak
- General Atomics, San Diego, CA (United States)
- Institut National de la Recherche Scientifique, Varennes, PQ (Canada)
- Oak Ridge National Lab., TN (United States)
Non-axisymmetric halo currents are always observed during disruptive instabilities in DIII-D. These halo currents appear to have a helical structure which rotates toroidally in the electron current drift direction with frequencies ranging between 200 and 400 Hz prior to and during the initial plasma current quench phase of the disruption. Sometimes the halo. current rotation locks at random toroidal phase angles during the plasma current quench. The total halo current rarely exceeds 30% of the pre-disruptive plasma current (I{sub po}) and peak-to-average toroidal peaking factors (TPF) are usually less than 3 during most disruptions. Neon ``killer`` pellets have proven very effective in reducing both the total halo current amplitude, often by as much as 50%, and the TPF from {approximately}3 to {approximately}1. 2.
- Research Organization:
- General Atomics, San Diego, CA (United States)
- Sponsoring Organization:
- USDOE Office of Energy Research, Washington, DC (United States)
- DOE Contract Number:
- AC03-89ER51114
- OSTI ID:
- 438536
- Report Number(s):
- GA-A-22344; CONF-960569-14; ON: DE97001154
- Resource Relation:
- Conference: 12. international conference on plasma surface interactions in controlled fusion devices, Saint-Raphael (France), 20-26 May 1996; Other Information: PBD: May 1996
- Country of Publication:
- United States
- Language:
- English
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