11. Plasma Diagnostics

Diagnostic instruments are needed to provide measurements for machine protection (magnet systems, vacuum systems, heating and cooling systems, safety systems, etc.); for plasma control; and for plasma performance evaluation. Plasma diagnostic systems include electrostatic probes, magnetic probes, measurement of particles emitted from the plasma, spectroscopy of waves emitted by the plasma, probing the plasma with injected particle beams, and probing the plasma with waves, such as microwaves and laser beams. For ITER, the next major step in magnetic fusion, diagnostics must be hardened to survive in a hot, high-radiation environment, and designed to minimize neutron streaming through ducts. Many adverse effects must be mitigated, such as radiation-induced spurious signals, erosion of windows and mirrors, and deposition of films on them. This is new territory for diagnostics and many challenges have to be overcome.