Theory Weekly Highlights for April 2009

April 24, 2009

An application was created to visualize real-time data from the NEWSPEC magnetic fluctuation spectrum code. The visualization displays a number of modes that are loaded in from a file using the Time, Frequency and Amplitude axes. In order to better illustrate the path that is followed by a mode, an animation is done making a particular part of the line glow brighter. Several plotting modes are available including a connected line, individual points, and tower-like lines from the data points that provide a similar look to the original contour plots. This visualization is being used for real-time data display in the DIII-D control room.

April 17, 2009

A unified framework to compute either model shape parameters (kappa, delta, squareness) or Fourier coefficients for an arbitrary shape has been completed and added to the GYRO suite (TGYRO/GYRO/NEO). The Fourier method is generally a more faithful representation of the discharge equilibrium. While the capability to treat general flux-surface shape was previously added to the GYRO suite, the new framework uses the mapping from the GATO ideal MHD stability code to provide the required (R,Z) mapping of EFIT flux-surface data. The method has the benefit that precise, direct comparisons between parameterized and general shape are made by changing only a single input parameter. This framework merges data from either ITERDB files generated by the ONETWO code or from plasma state files generated by the TRANSP code with high-resolution geometric data from GATO derived from the original EFIT equilibrium file. This new capability is expected to be important in near edge simulations or for calculations of momentum transport in non-up-down symmetric plasmas.

April 10, 2009

The pellet ablation source module in the ONETWO code, originally developed in the 1980’s, has been successfully updated with the most up-to-date pellet ablation module from ORNL. The new module includes a range of hydrogenic and impurity ablation models, expanding from the hydrogenic Neutral Gas Shielding (NGS) model implemented previously. The new module predicts a slightly different result using the hydrogenic NGS model from the previous version due to the different implementation of the fourth order Runge-Kutta integration routine that updates the pellet radius and the plasma parameters as it passes through a cell. A version of the new ONETWO code will soon be available for public testing. A further update of the pellet ablation source term, using the newest Parks-Rosenbluth ablation model into ONETWO, is also planned. Future tests will include varying the pellet parameters and the plasma conditions to help DIII-D experimentalists determine the appropriate pellet parameters.

April 03, 2009

The 3D variational moment equilibrium code VMOM3D has been reactivated and modified to include an arbitrary number of modes. VMOM3D was developed at GA in the early 1980s but has not been used since then. An interface with EFIT has now been constructed and the code is currently undergoing testing with data from an actual DIII-D discharge.

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