1 - Nuclear Sciences and Applications - IAEA

5. CONCLUSIONS
IAEA-CN-50/A-VH-8 443
The experimental results can be summarized as follows:
Relaxation and self-organization of the q profile are observed. The initial q profiles
of a high jS plasma in TPE-2, which are produced by fast or slow programming
of the toroidal and poloidal fields, relax to a specific final q profile within a short
time. The current density is nearly flat over the cross-section. The profile does not
depend on the initial q profiles, q( or rig either in the slow screw pinch mode or in
the fast screw pinch mode, and does not depend on the plasma histories. The density
profiles also relax to the profiles which depend on the qf value. The configuration
with the specific q and density profiles might be in a minimum energy state of a high
/3 and very low q plasma. The confinement deteriorates in the plasmas when relaxation
oscillations appear. This could be interpreted to mean that the deterioration of
the confinement is caused by the deviation from and the relaxation to the specific q
profile, accompanied by the relaxation oscillations. The formation and the sustainment
of the flat current and flat density profiles are considered to be essential for a
stable confinement of high (3 and low q tokamak plasmas.
ACKNOWLEDGEMENT
This work was supported by the Atomic Energy Bureau, Science and
Technology Agency, Prime Minister's Office, Japan.
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