Physics requirements for ITER engineering systems

Specific performance from imposes loads on other supporting subsystems and subsystems. This paper overviews system requirements dictated by the plasma's needs and impacts. Overall device parameters have been derived from the performance goals using plasma transport and stability models based on physics R and D results. Most transport issues relate to the extrapolation of the plasma behavior to ITER's large size (especially relative to the gyroradius). Plasma control systems must achieve shape and position flexibility sufficient for the performance of the power handling and auxiliary power systems. Induced currents in the conducting structures between the poloidal coils and the plasma both provide passive stabilization of plasma disturbances and delay plasma responses to external magnetic controls. Auxiliary power systems must heat the plasma to ignition and drive noninductive currents for steady state operation, and may have to drive plasma rotation if physics confirms the need for rotation indicated by recent theories of resistive wall stabilization. Diagnostics must support plasma control and performance assessment and contribute to physics understanding. The first wall must handle steady state power and energetic neutral bombardment, and will experience transient power and runaway electron loads. The divertor system must disperse the incoming power while confining the divertor's higher concentration neutral gas and pumping the helium. In-vessel structural design is driven by the forces related to plasma disruptions, which induce currents in the conducting structures and drive non-axisymmetric "halo currents" between the plasma and the conductors. Such plasma control needs and impacts from power and disruption handling are described.