PLANS FOR 2-DIMENSIONAL STEADY-STATE BOLOMETRIC MEASUREMENTS OF THE LARGE HELICAL DEVICE

Preliminary plans for two-dimensional steady state bolometric measurem ents of core plasma and divertor regions have been made for the Large Helical Device (LHD) under construction at the National Institute for Fusion Science. Using a semi-tangential plane through the plasma volum e, a two-dimensional view of the core plasma is achieved from the outb oard, upper and lower diagnostic ports. Divertor regions will also be viewed from the upper, lower and outboard ports. In the case of divert or and core plasma arrays, duplicate detector arrays will alternate in turn between viewing and active cooling phases, using fast shutters t o enable continuous detection during long-pulse (30 min) operation of the LHD. Each detector array will consist of 32 metal him bolometers a nd 64 XUV photodiode arrays, resulting in a spatial resolution of abou t 2-4 cm. The temporal resolution should be about 1 ms for the film bo lometers and 1 mu s for the photodiodes. Additional arrays will includ e a one-dimensional array that views from an outboard port, and an arr ay of toroidally spaced detectors for investigating the toroidal varia tion of the radiated power. During the present stage of development, v arious detector samples are being acquired and tested. Schematics of t he bolometer arrays, as well as plans for the complete bolometer diagn ostic system will be shown. (C) 1997 Elsevier Science S.A.