Abstract
A new technique for directly measuring the safety factor, or q, profile in a tokamak is described. A tightly collimated neutral beam capable of injecting approximately 100 mA of 30 keV deuterium atoms was mounted on the Adiabatic Toroidal Compressor tokamak. By proper tangential aiming of the beam a strong concentration of circulating fast ions was created at a chosen plasma minor radius. Through examination of the orbits of these ions with a multi-sight-line charge exchange detector, it was possible to measure the shifts of the orbits off magnetic surfaces, and thereby make local measurements of q. This experiement showed that when q on axis reached unity, strong internal turbulence began, and further lowering of q at the outer edge of the plasma did not lower q(0). A second result was that the measured q(0) was approximately 1.8 times larger than the q(0) deduced from the Tc(r) profile, assuming Z eff to be independent of minor radius. This suggests a significant peaking of Zeff on axis.
Original language | English (US) |
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Pages (from-to) | 2346-2353 |
Number of pages | 8 |
Journal | Physics of Fluids |
Volume | 21 |
Issue number | 12 |
DOIs | |
State | Published - 1978 |
All Science Journal Classification (ASJC) codes
- Computational Mechanics
- Condensed Matter Physics
- Mechanics of Materials
- Mechanical Engineering
- Fluid Flow and Transfer Processes