ITER软X射线检测系统及其电磁兼容设计

ITER detection system of soft X-ray and electro-magnetic compatibility design

国际热核聚变实验反应堆是世界上在建的最大的磁约束聚变装置托克马克装置,通过对其中软X射线的测量,可实现等离子体辐射对锯齿、色骨模等磁流体现象的物理研究和成像反演。软X射线诊断系统就是用来检测软X射线的设备。由于热核聚变时恶劣电磁环境及远距离传输,在设计信号检测系统时必须进行电磁兼容设计,以降低系统噪声、提高检测精度。本文中使用的检测电路采用差分结构实现电流信号到电压信号的转换,重点研究检测电路的实现及其电磁兼容设计。从电磁抗干扰的三要素出发,结合实验测试,针对电磁干扰的特殊性,讨论了滤波电路设计、印制电路板(Printed Circuit Board,PCB)走线、电磁屏蔽及信号接地在系统中实现。本文采用32通道板卡集成设计;信号增益提高至107 V?A-1;放大器带宽达到120 k Hz。通过测试结果可以看出,信号噪声降至8 mV。通过优化设计提高了检测电路的集成度和放大电路的增益及带宽,同时降低了检测电路的噪声。

Background： The primary diagnostic role of radial X-ray camera （RXC） includes measuring low （re,n） magnetohydrodynamic modes, sawteeth and disruption precursors, H-mode, edge-localized modes, and L-H transition. Purpose： According to the soft X-ray weak signal detection requirements of international thermonuclear experimental reactor （ITER） tokamak, considering the harsh electro-magnetic environment and long distance transmission of signal, some appropriate electromagnetic protection measurements must be took in the design of soft X-ray diagnosis system in order to suppress circuit noise. Methods： In this thesis, a differential circuit structure has been designed to accomplish current-to-voltage conversion, and studying the electro-magnetic compatibility is the point. Results： Associated with experimental test and complied with three factors of electro-magnetic interference, the paper has discussed the application of shielding, grounding, filtering, and printed circuit board （PCB） layout methods in circuit, and completed the circuit requirements of system miniaturization, high parameters with quantity of 32 channels per PCB board, gain of 107V·A-1, width of 120 kHz, and noise of 8 mV. Conclusion： The effective detection of weak current signal and steady performance are proved by test results. The effect of electromagnetic protective measurements adopted is reasonable and obvious.