### Theory Weekly Highlights for July 2004

##### June 25, 2004

Ideal calculations for a sequence of fully bootstrapped equilibria obtained by scaling the vacuum toroidal field showed instability with no wall but stability with the DIII-D wall and with considerable structure in the growth rates as functions of q_{0}, q_{min}, and q_{edge}. Minima and maxima in the growth rates do not correspond to integer values of any of q_{0}, q_{min}, and q_{edge}. The perturbed flux on the outer, low field side boundary is also remarkably insensitive to these parameters over a wide range (5 5 < q_{0} < 12.05), including the successive maxima and minima in the growth rate. The outboard mode structure is insensitive to the q_{edge} value even though the poloidal m = n* q_{edge} harmonic (n = 1) dominates at the boundary, and is even insensitive to he presence or absence of nearby integer q_{edge} values where there is a strong peeling component. This result implies that active feedback control of the associated RWM should also be quite insensitive to these parameters, which may simplify feedback schemes.

##### June 18, 2004

Based on the assumption that the angular momentum confinement time is the same as the energy confinement time, a formula has been devised for the toroidal rotation frequency expected in ITER. This projects a 2.4 kHz rotation frequency for ITER, given an efficiency of 50% for generating toroidal momentum from a 1 MeV neutral beam. The method also predicts a 21 kHz rotation rate for DIII-D, which is of the order that is generally observed. This should be extremely useful in ITER design work, especially for Resistive Wall Mode stabilization.

##### June 11, 2004

Recent modeling has shown that, given sufficient pulse length, a steady state ITER configuration is achievable assuming the GLF23 energy and toroidal rotation transport model and fixed density profiles. The simulations were based on current 9-MA discharge ITER design parameters and used the ONETWO transport code, together with ECH and ECCD calculations from TORAY-GA and fast wave ICH and ICCD from CURRAY. The steady state configuration features a constant E*, with essentially 100% non-inductive current drive, and is maintained by a total of 73 MW of input power, consisting of 33 MW of 1 MeV NNBI, 20 MW of fast wave and 20 MW of ECH. Optimization of the non-inductive current fraction and fusion gain assuming the initial ITER hardware capabilities is underway.
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**Disclaimer**

These highlights are reports of research work in progress and are accordingly subject to change or modification