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

1. 研制了5种由小尺寸二极管阵列和高时间分辨率前置放大器组成的前置放大器（高63 mm X宽26 mm X深69 mm）小尺寸二极管阵列。采用离子种植法在硅片上制作二极管阵列。每个二极管阵列有20个通道。这些带前置放大器的小尺寸二极管阵列的时间分辨率小于5 μ s，足以用于等离子体诊断。用时间响应测量了波长为850nm的调幅样品光的时间演化。每个通道之间的串扰水平用针点光（直径0.1 mm）测量。串扰电平的测量值小于1%，这个值对于这些二极管阵列的空间分辨率来说是微不足道的。可变视距软x射线针孔相机的研制。研制了5台可变视距软x射线针孔相机，可在小尺寸二极管阵列上配置前置放大器，并在WT-3托卡马克上进行了试验。在最大视距下，针孔相机可以观察WT-3型等离子体的整体，并且视距可以连续变化到最小视距。在最小视野范围内，针孔照相机可以观察到等离子体的一半。开发了一种对5口即100通道数据进行分析的计算代码。重建方法为傅立叶样条法，在WT-3.4上的三端口计算机断层扫描中得到了满意的结果。在具有两种MHD振荡类型的WT-3型托卡马克等离子体中，可以观察到清晰的低噪声信号。对检测到的信号进行重构。重建图像提供了振荡的位置和结构信息，可以确定两种MHD振荡分别具有M=1和M= 2结构。少

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