Theory Weekly Highlights for March 2003

March 28 2003

A milestone was reached in the development of a new version of the GLF23 transport model. A new method for including the effect of trapped particles on driftwave instabilities was found. A good fit to the modification of the plasma dispersion function due to trapped particles was obtained from a four-moment set of gyrofluid equations. This was accomplished without introducing a separate set of fluid moment equations for the trapped particles. The detrapping due to electron-ion collisions can also be included in a simple way. This work will be reported at the upcoming Transport Task Force workshop.

March 21 2003

Version v1.60 of the TORAY ECH/ECCD code is now available. This new Fortran 90 version no longer requires any preprocessing to handle precision and has been successfully built and tested on HP, Linux (Portland, Lahey-Fujitsu), and Alpha (Tru 64) platforms. TORAY now includes the recently developed ECCD module by Y.R. Lin-Liu, which includes an adjoint formulation, with collisionality correction factors that reduce the trapped electron fraction and increase the current drive efficiency. Other revisions include improving the power integration along the arc length, the addition of an aspect ratio in the J/P current drive efficiency, and an improved evaluation of the poloidal angle used to calculate the local value of the major radius.

March 14 2003

A new general equation for the resistive wall mode (RWM) in a rotating plasma and in the presence of an external resonant field has been derived. An analysis shows that the growth and damping of the RWM result from the balance of the energy flux and the dissipation torques from both the plasma and the resistive wall. However, in steady state, only the dissipation in the plasma to the damped RWMs contributes to the phase shift between the external resonant field and the resonant plasma response. Further, the phase and amplitude of the plasma resonant response is related to the damping rate and mode frequency of the RWM through a complex amplification factor. These conclusions can provide an explanation of the experimental observations of the resonant field amplification phenomenon.

March 07 2003

A new IDL data retrieval code GADAT2 was created to replace the existing code GADAT. This will make it easier for the DIII-D team to retrieve PTDATA from off-site by not relying on client side shared libraries. It also posts no limitation on the size of data and will further increase portability and reliability by separating data processing from data retrieval. The replacement of GADAT by the new code will take place gradually.

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