(OV/1-4) Development in the DIII-D Tokamak of Advanced Operating Scenarios and Associated Control Techniques for ITER
1) General Atomics, San Diego, California, United States of America
Abstract. The DIII-D research program is focused on providing solutions to issues critical to the future success of ITER, both in achieving its basic mission goal of Q = 10 operation and in enhancing the ITER physics program through development of operating regimes capable of sustaining higher Q values. Significant progress has been made in the ability to control key plasma features and using such control to expand the operational limits of stationary and steady-state tokamak operation. Recent experiments have demonstrated the capability to suppress the key plasma instabilities of concern for ITER (including ELMs, neoclassical tearing modes, and resistive wall modes) by external means, techniques for mitigating the effects of disruptions, and control of the current profile evolution. The use of these techniques has allowed an expansion of the envelope of viable, stationary tokamak operation, highlighted by the demonstration of sustained (∼2 s) operation with normalized
β∼4 (50% above the no-wall stability limit) as well as fully noninductive operation with toroidal
β∼3.5%. This developmental research is supported by a vigorous basic physics program, which also addresses several key ITER issues. These include edge carbon transport and tritium co-deposition on plasma facing surfaces, fast-ion instabilities and their effects on the fast ion population, and identification of the underlying mechanisms responsible for transport in a tokamak plasma. Highlights of recent research in these areas will be presented. In addition, experiments in the coming year will seek to take advantage of extensive upgrades recently made to the DIII-D facility. These include the reorientation of a neutral beam to allow counter- and low-rotation plasmas, a new lower divertor for density control in double null plasmas, and increased EC power. It is anticipated that these upgrades will increase the flexibility in controlling and optimizing of plasma operation in DIII-D.
* Work supported by the US DOE under DE-FC02-04ER54698.
Full paper and slides available (PDF)