SOFT-X-RAY AND BOLOMETRIC TOMOGRAPHY IN RFX

The article presents the design and the first results of a new eight c amera, soft x-ray (SXR) and bolometric tomography which has been insta lled in RFX, a large (R = 2 m, a = 0.46 m), high current reverse held pinch experiment operating in Padova. The main features of the diagnos tic, which has been designed with standards compatible with the requir ements of large fusion experiments, are: (a) it allows simultaneous re construction of both SXR and total radiation emissivity structures wit h high spatial and time resolution (bandwidth up to 200 kHz for SXR an d 10 kHz for bolometry). Moreover, computer controlled remote actions which interchange up to five material filters in front of the detector s allow the exploration of different energy ranges; (b) it can be easi ly decoupled from the machine without breaking the main vacuum and can be operated during first wall baking up to 300 degrees C thanks to a cooling circuit; (c) the detection chain is designed to measure very l ow signals [in the order of 1 nA for SXR diodes and of 100 mu V for bo lometers]; (d) it is equipped with a VME based 1 MHz data acquisition system which allows on-line processing of a large amount of data. To a ccomplish these features the diagnostic consists of eight fully remote ly controlled manipulators which can insert eight photocameras, carryi ng 78 top-rated Si SXR and 48 miniaturized metal firm bolometric detec tors in their operating positions. Initial results are presented. (C) 1997 American Institute of Physics.