Fusion Science and Technology / Volume 53 / Number 2 / February 2008 / Pages 699-750
Technical Paper / Plasma Diagnostics for Magnetic Fusion Research
In this chapter, we consider generic issues affecting the implementation of diagnostics in a burning plasma experiment (BPX). These are, directly or indirectly, caused by the radiation environment. In the first instance, handling nuclear radiation issues becomes a dominant factor in the choice of machine and diagnostic layout, construction, and maintenance. We discuss these integration issues first as they set the background against which more specific issues must be addressed. These include nuclear radiation effects on specific types of components and assemblies such as cables, fibers, and mirrors, and also thermal and mechanical degradation issues that must be considered in all component designs. One important consequence of the maintenance challenges brought about by the radiation environment is that degradation of front-line optical components by particle bombardment, normally handled by component replacement, also becomes far more challenging and in situ mitigation techniques must be sought. For the same reason, recalibration techniques become more difficult. At the same time, BPX operation time is precious and extracting the optimum performance from the device may require the use of more sophisticated diagnostic techniques. Therefore, the requirements on reliability and data availability are more stringent and must be applied more widely than is common on present devices. An important goal of BPX operation is to enable the design of future power plants. We consider briefly the development needs for diagnostics for these and conclude with an assessment of the present state of readiness of the diagnostic community for the detailed design and construction of a full diagnostic set for a BPX.