As computing capabilities have increased, the coupling of computational models has become an increasingly viable and therefore important way of improving the physical fidelity of simulations. Applications currently using some form of multicode or multi-component coupling include climate modeling, rocket simulations, and chemistry. In recent years, the plasma physics community has also begun to pursue integrated multiphysics simulations for space weather and fusion energy applications. Such model coupling generally exposes new issues in the physical, mathematical, and computational aspects of the problem. This paper focuses on the computational aspects of one such effort, detailing the design, and implementation of the Integrated Plasma Simulator (IPS) for the Center for Simulation of Wave Interactions with Magnetohydrodynamics (SWIM). The IPS framework focuses on maximizing flexibility for the creators of loosely-coupled component-based simulations, and provides services for execution coordination, resource management, data management, and inter-component communication. It also serves as a proving ground for a concurrent ¿multi-tasking¿ execution model to improve resource utilization, and application-level fault tolerance. We also briefly describe how the IPS has been applied to several problems of interest to the fusion community.

Obtaining energy from nuclear fusion requires heating the fuel to about 100 times the temperature of the sun to produce a plasma, and holding the hot plasma long enough for fusion reactions to produce a net energy gain. In a magnetic fusion device, this plasma is maintained in a largely self-organized state that far from equilibrium the mathematical description of which is characterized by high dimensionality, nonlinearity, extreme range of time and space scales, and sensitivity to geometric details. High-performance computing plays an essential role in fusion research not just to understand the theory and make quantitative comparison to experiments, but also to provide direct support to the experiments by interpreting measurements and designing experiments. The fusion community has begun a major new phase of research with ITER, an international prototype fusion energy reactor. This talk will review recent advances in the computational modeling of fusion plasmas and describe the challenges of simulating a reactor scale experiment such as ITER.