Toroidal pinch experiments. Annual progress report, November 24, 1992--November 23, 1993
The effect of boundary conditions on plasma confinement in the reversed field pinch (RFP) was studied. Early theoretical studies of the magnetohydrodynamic stability of the reversed field pinch had shown that the pinch was unstable unless it was surrounded by a conducting shell which prevented the penetration of the magnetic field during the lifetime of the pinch. The presence of the sheer, however, complicated construction and prevented control of the plasma equilibrium by feedback systems. This research project was undertaken to determine the effect on confinement of varying the magnetic penetration time of the shell. A reversed field pinch, the Reversatron, was constructed so that shells of varying thickness could be installed. Shells were made with magnetic penetration times both longer and shorter than the duration of the plasma discharge. These shells allowed the performance to be determined as a function of the magnetic penetration time of the shell. This research showed that a shell with a short penetration time degraded the discharges. Diagnostic measurements showed reductions in plasma current, discharge duration, and the Doppler temperature of impurity ions and showed increases in the plasma resistivity and loop voltage. The greater power input and lower temperature implied a reduced energy confinement time. Magnetic diagnostics showed that two classes of MHD instabilities with poloidal mode number m = 1 were responsible for the degraded confinement. These were the dynamo modes resonant on the magentic axis (with toroidal mode numbers -9, -10, -11, -12) and the external kink modes (with toroidal mode numbers 3, 4, 5, and 6).
- Research Organization:
- Colorado Univ., Boulder, CO (United States). Dept. of Astrophysical, Planetary, and Atmospheric Sciences
- Sponsoring Organization:
- USDOE, Washington, DC (United States)
- DOE Contract Number:
- FG02-87ER53244
- OSTI ID:
- 10118567
- Report Number(s):
- DOE/ER/53244-20; ON: DE94005876; BR: AT051011A/AT0530020
- Resource Relation:
- Other Information: PBD: 24 Jan 1994
- Country of Publication:
- United States
- Language:
- English
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