Development of a soft X-ray tomography device with variable field of view for plasma diagnostics

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1. Development of small size diode array with pre-amplifiers Five small size diode arrays with pre-amplifiers (height 63 mm X width 26 mm X depth 69 mm) which are composed of small size diode arrays and pre-amplifiers with high time resolution, are developed. The diode array are made of silicon wafer by use of the ion-plantation method. Each diode array has 20 channels. The time resolution of these small size diode arrays with pre-amplifiers is less than 5 mus and is sufficient for plasma diagnostics. The time evolution is measured with time response for amplitude modulated sample light (wavelength 850 nm). The level of cross talk among each channel is measured with pin-spot light (diameter 0.1 mm). The measured value of the level of cross talk is less than 1% and this value is insignificant for the spatial resolution of these diode arrays.2. Development of a pinhole camera for soft X-ray with variable range of view. Five pinhole cameras for soft X-ray with variable range of view, whic … More h can equip the small size diode arrays with pre-amplifiers, are developed The test of these pinhole cameras is carried out on the WT-3 tokamak. In the maximum range of view, the pinhole cameras can observe the whole of the WT-3 tomakak plasma and the range of view can be changed continuously down to the minimum range of view. In the minimum range of view, the pinhole cameras can observe the half of the plasma.3. Development of a calculation code for computer tomography A calculation code for analysis of data from 5 port , that is, 100 channel is developed. The method of reconstruction is Fourier spline method which give satisfactory results in 3 port computer tomography on WT-3.4. Test of the device for soft X-ray tomography The clear signal with low noise level can be observed in the WT-3 tokamak plasma which has two types of the MHD oscillation. The detected signal are reconstructed. The information on the position and structure of the oscillations is provided from the reconstructed images and it is sure the two types of MHD oscillations have M=1 and 2 structure, respectively. Less