Integrated Physics Advances in Simulations of Wave Interactions on Extended MHD Phenomena D. B. Batchelor, ORNL (representing the SWIM team)

The broad scientific objectives of the SWIM (Simulation of Wave Interaction with MHD) project are: (A) To improve our understanding of interactions that both RF wave and particle sources have on extended-MHD phenomena, and to substantially improve our capability for predicting and optimizing the performance of burning plasmas in devices such as ITER: and (B) To develop an integrated computational system for treating multi-physics phenomena with the required flexibility and extensibility to serve as a prototype for the Fusion Simulation Project (FSP). The SWIM Center consists of three elements:

(1) Development of a computational platform referred to as the Integrated Plasma Simulator (IPS) that will allow efficient coupling of the full range of required fusion codes or modules.

(2) A physics campaign addressing long timescale discharge evolution in the presence of sporadic fast MHD events. This involves interfacing the IPS to both linear and 3D non-linear extended MHD codes and carrying out a program of research related to use of RF and other driving sources to study and control fast time-scale MHD phenomena such as optimizing burning plasma scenarios and improving the understanding of how RF can be employed to achieve long-time MHD stable discharges and control sawtooth events.

(3) A physics campaign for modeling the direct interaction of RF and extended MHD for slowly growing modes. This requires development of new approaches to closure for the fluid equations and the interfacing of RF modules directly with the extended MHD codes and with code modules that implement the fluid closures. The primary physics focus of this campaign is to improve the understanding of how RF can be employed to control neoclassical tearing modes.

The key massively parallel physics codes have now been ported to the “leadership class” computer facilities and performance issues addressed, the design of the IPS has been completed and initial testing is ongoing, and a staged strategy has been developed to explore ways to close the MHD fluid equations including the RF effects necessary to treat RF stabilization of neoclassical tearing modes. The IPS design is based on a component architecture in which the various required physics functionalities have been abstracted at a high level and formal interfaces defined such that the components can be implemented by any code that provides the required functionality, and so that multiple code implementations can be used. An important feature of the IPS is the exchange of simulation data between components using an intermediate Plasma State component presenting a simple user interface with a standardized data format, and whose code is automatically generated allowing for ease of modification and extensibility. A computational framework, built upon existing developments in computer science, provides such services as portal access, event logging, data management and workflow management. Details of the IPS and initial physics results modeling RF heating and transport on ITER will be presented.