脉冲射线束成像关键技术

Key technologies of pulsed radiation beam imaging

脉冲射线束成像是研究惯性约束聚变等核反应装置性能的核心测量技术之一,测量对象为MeV中子、伽马射线束,时间尺度从ns到μs,空间尺度从亚mm到10 cm.本文介绍了西北核技术研究所近年来在发展脉冲射线束成像技术、研制成像系统所取得的主要进展.设计了非对顶双截锥大视场厚针孔和高探测效率编码孔,发展了大面积图像转换屏和阵列式中子图像转换屏,研究了MeV中子、伽马射线束图像转换屏的基本性能,提出了选通型像增强器基本设计要求,系统研究了快响应像增强器的时间选通特性和空间分辨特性,基于一种特殊的全局快门驱动时序设计,研发了百ns曝光双帧CMOS相机,研制了一种针对百ns时间尺度射线源的触发与时间关联系统,包括触发探测器、定时探测器、同步机和快门发生器等,与射线源特征时间关联精度一般为3–5 ns.对超快时间分辨、超高空间分辨、高维成像等脉冲射线束成像技术发展方向进行了讨论.

Pulsed radiation beam imaging is one of the fundamental diagnostic technologies for studying the performance of nuclear reaction devices,such as in the field of inertial confinement fusion.The measurement object is a MeV-scale neutron or gamma ray emitted from a radiation source.The characteristically temporal scale is from nanosecond to microsecond,and the spatial scale is from sub-millimeter to 10 cm.This study introduces the development of pulsed radiation beam imaging technology in recent years at Northwest Institute of Nuclear Technology.A novel non-opposite vertex design of a thick pinhole and a ring aperture with high detection efficiency were explored.Large-area scintillators and a liquidscintillating capillary array for converting radiation to light were developed and investigated.The fast-temporal-response design requirements for an image intensifier were introduced,and the gating properties and dynamical spatial resolution for this kind of image intensifier were comprehensively studied.A dual-frame Complementary Metal Oxide Semiconductor(CMOS)camera with an exposure time of hundreds of nanoseconds was achieved using a specific global gate-driven timing design.A trigger and timing system for relating the image gating time to the characteristic time of radiation sources,consisting of a trigger detector,timing detector,synchronizer,and pulse generator,was explored.The timing precision of the system was approximately 3-5 ns.Advanced technologies,including ultrafast temporal resolution,super spatial resolution,and high-dimensional imaging,were also discussed.