Theory Weekly Highlights for February 2009

February 27, 2009

As part of the Simulation of RF Wave Interactions with Magnetohydrodynamics (SWIM) project, interface modules of ORBIT-RF were delivered to a SWIM repository as a new component of the IPS (Integrated plasma simulator). Two F90 programs, “PREPARE_ORBITRF_INPUT” and “PROCESS_ORBITRF_OUTPUT”, were written. The former extracts data from the plasma state to produce an input file for ORBIT-RF, while the latter writes the ORBIT-RF output back to the plasma state. As the output from ORBIT-RF is written, the fast ion distribution function and power deposition by resonant ions species are reconstructed as readable formats by another RF component, AORSA, and the plasma state under IPS. A test run in IPS is underway.

February 20, 2009

In collaboration with on-site colleagues from the Institute of Physics Research (IPR) in India and ASIPP-Hefei, a new F90 unified EFIT version including an option to run under MPI for all platforms hydra, Linux, and between-shot Linux is being developed and tested. This new F90 version is linked with the new MSE library with better estimates of MSE uncertainty as discussed by the MSE team at various meetings. The new version compiled under HP Unix on Hydra and under PGF90 on Linux is now available to DIII-D collaborators. The option to run this new EFIT F90 version under PGF90 MPI on the Linux machines is being tested and will be released when testing is completed. Higher radial grid versions 257×257 and 513×513 will be also released shortly on Linux platforms when testing is completed.

February 13, 2009

A validation of the ORBIT-RF code against DIII-D beam-only heating experiments is underway and preliminary results show good consistency with FIDA measurements of the fast ion distribution. ORBIT-RF was recently improved to read the beam ion distribution function from the NUBEAM module in PTRANSP, which calculates the fast ion distribution averaged in each bin of energy, pitch and space. A Monte-Carlo module was developed to convert the bin averaged distribution function to a particle distribution for use as an initial condition for the beam ion –fast wave interaction simulations using ORBIT-RF. A comparison between the EFIT experimentally reconstructed beam ion pressure profile and the profile calculated from ORBIT-RF is continuing in order to verify the consistency of the PTRANSP bin-averaged distribution function with the converted Monte Carlo particle distribution.

February 06, 2009

A longstanding dimensioning issue in the mapping for the GATO ideal MHD stability code that prevented mapping of arbitrary size direct equilibria from EFIT has now been resolved. The GATO mapping has evolved over the past few decades to accurately and reliably handle the most extreme equilibrium geometries, including very high elongations, low and high aspect ratio extremes, and arbitrary up-down asymmetric cross sections, including mapping through diverted boundaries with an X-point, but was restricted to square (r,z) mesh dimensions of the traditional form Nr = Nz, usually with Nr = 65 or 129 or 257. This was due to thirty year old legacy FORTRAN coding in matrix algebra routines that, while efficient, utilized the once standard technique of passing multidimensional arrays as a single dimension array, with dimension one, threaded through multiple subroutine levels. The entire mapping has been recoded to upgrade the FORTRAN and all nonstandard dimensioning has been identified and eliminated throughout the code; the mapping is now able to handle dimensions of any size with a single compiled executable. With the final restriction removed, the GATO mapping is currently being modified to run as a stand-alone mapping tool to be used to interface other stability codes such as NOVA-k with EFIT equilibria.

Dr. Y.R. Lin-Liu from National Central University in Taiwan is visiting February 5 and 6 to collaborate with former colleagues on various issues of mutual interest.

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