Optimization of negative central shear discharges in shaped cross-sections
The advanced tokamak (AT) concept aims at achieving high beta, high confinement, and a well aligned high bootstrap current fraction in a tokamak configuration consistent with steady-state operation. The required improvements over the simple 0D scaling laws, normally used to predict standard, pulsed tokamak performance, are obtained by taking account of the dependence of stability limits and confinement on the 2D equilibrium - both the plasma shape and the plasma profile. The ideal and resistive stability both play important roles in limiting the performance of negative central shear (NCS) discharges. For the ideal limits, there is a clear synergism between profile and cross-section shaping in optimization of the performance of NCS discharges. Optimization of one alone leads to limited gains in performance but optimization of both can lead to dramatic gains. The coupling of the resistive interchange mode with the global doubled tearing and ideal modes is the critical limitation on NCS equilibria with strongly peaked pressure profiles, and is likely associated with the disruptions observed in L-mode NCS experiments.
Bibliographic Reference: Article: Proceedings of the 16th IAEA Fusion Energy Conference (1996) pp. 382-383
Record Number: 199810145 / Last updated on: 1998-02-12
Original language: en
Available languages: en