Infrared camera and data-acquisition system in Doublet III

Thermal imaging cameras sensitive to 3--5 μ radiation are routinely used to measure heat flow to the main limiter, to the vacuum vessel wall behind the main limiter, and to the divertor plate limiters. The cameras are equipped to provide either a standard television image, one frame per approx.16.7 ms, or a surface temperature profile on one line of the image with a time resolution of approx.125 μs. In the former mode, we can determine both the location and the intensity of the heating on the main limiter during multimegawatt neutral-beam injection into plasma; in the latter mode, we can measure heat pulses striking the limiter from plasma processes occurring on fast timescales (e.g., D/sub α/ spikes of approx.500 μs duration). Data is stored in both video image and digitized forms. In the latter, a ''peak-sample-hold'' circuit electronically records the maximum signal of each line sweep and stores this data in digitized form on magnetic tape. This facilitates later comparisons of infrared camera data with other diagnostic signals using plotting packages on the DEC-10