1.06μm激光辐照金盘靶的软X光转换

在１．０６μｍ激光辐照金盘靶实验中，利用坪响应Ｘ光二级管探测器测量了软Ｘ光能量（０．１－１．５ｋｅＶ）角分布，得到了软Ｘ光转换效率。实验条件：激光波长λＬ＝１．０６μｍ，ＥＬ＝６０－５００Ｊ，τｐｍ≈８００ｐｓ，ｆ／１．７，ＩＬ＝１０＾１＾３－１０＾１＾４Ｗ／ｃｍ＾２。实验结果表明：软Ｘ光能量角分粗略呈α＋ｂｃｏｓθ分布，软Ｘ光转换效率随激光强度的增加而降低。当靶面激光焦斑直径２３５μｍ，激光强度     

激光等离子体衰减系数的测量

利用“星光”激光装置的线聚焦激光束辐照碳铝组合靶，形成Ｘ光点源及铝等离子体的衰减区。用带时间分辨的平场光栅谱仪测量由碳等离子体发射的Ｘ射线在穿过长为３ｍｍ的铝等离子体后强度随时间的变化。测量结果表明该方法用于激光等离子体衰减系数测量是可行的。     

高能X射线源焦斑尺寸的时间分辨诊断

将门控分幅相机与快闪烁晶体结合,构成时间分辨X射线诊断系统,对神龙一号直线感应加速器产生的高能脉冲X射线源焦斑进行了测量,在时间间隔为10 ns的情况下,获得了焦斑尺寸随时间的变化曲线。在此基础上,设计了单像素尺寸为0.78 mm×0.78 mm的LYSO闪烁晶体阵列,并进行了X射线照射晶体阵列发光的初步实验,结果表明该阵列可用于高能X射线源焦斑的时间分辨诊断,并能显著提高成像的空间分辨力。     

测定微束微区X射线探针分析仪焦平面的实验研究

微束微区X射线探针分析仪借助会聚X光透镜把X射线聚焦.针对仪器调试过程中需确定出口焦平面位置的难题.采用拟合曲线荧光分析方法方便快速地确定出口焦平面的位置.方法是用直径小于X焦斑直径的金属丝在不同测量平面上进行微动测量,因X光强度沿径向呈高斯分布,所以金属丝中元素荧光强度随位移也呈高斯分布.通过计算得出不同测量平面上同...     

基于光克尔效应的径向光束匀滑新方案

针对惯性约束聚变装置中提高靶面辐照均匀性的要求, 提出了一种基于光克尔效应的径向光束匀滑方案, 其基本原理是利用光克尔介质和周期性高斯脉冲光束相互作用实现对激光束透射波前附加周期性的球面位相调制, 以周期性地改变激光束远场焦斑尺寸, 进而引起远场焦斑内部散斑的快速径向扫动, 从而在积分时间内抹平靶面焦斑的强度调制, 实现径向方向的光束匀滑. 通过建立基于光克尔效应的径向光束匀滑的理论模型, 分析了焦斑形态及其径向匀滑特性, 并讨论了光克尔介质的选取和径向扫动特性. 结果表明, 基于光克尔效应的径向光束匀滑方案可以有效地实现远场焦斑内部散斑的周期性径向扫动, 从而在积分时间内快速改善靶面辐照均匀性.     

黑洞靶X光产生机制实验研究

本文报导了黑洞靶Ｘ光产生机制实验研究。实验采用波长为１．０５３μｍ，能量为３００－７００Ｊ／束，脉宽为６００－１０００ｐｓ的高斯型激光脉冲。利用三台亚千Ｘ光能谱仪，三台软Ｘ光针孔相机、一台软Ｘ光透射光栅谱仪和十个平响应亚千Ｘ射线二极管对十余种结构、尺寸腔靶实验进行测量。实验给出了腔靶发射Ｘ光的空间分辨像、时间过程、光谱结构及空间角分布测量结果。通过分析，基本弄清了黑洞靶Ｘ光产生机制。     

基于光克尔效应的径向匀滑方案参数优化

在基于光克尔效应的径向匀滑方案中,抽运光脉冲序列利用非线性介质的光克尔效应对激光束附加周期性的球面位相调制,从而使激光束远场焦斑内部散斑产生周期性的径向扫动,以改善远场焦斑均匀性。为了分析抽运光时间特性的改变对匀滑效果的影响,建立了径向匀滑方案的理论模型,并利用该模型对抽运光的时间特性参数进行了分析及优化。结果表明,在抽运光子脉冲之间的延迟时间一定时,子脉冲的脉宽过大或过小均会降低激光束远场的辐照均匀性,而随着子脉冲脉宽的增大,激光束远场的辐照均匀性随积分时间的波动相对趋于稳定,因而在避免产生明显"拍频"现象的前提下,选取较大的抽运光子脉冲脉宽更有利于实现稳定的匀滑效果。激光束与抽运光的时间同步精度对初期的匀滑效果有较大的影响,当抽运光提前1/5个周期左右时,可以在更短的积分时间内达到较好的径向匀滑效果。此外,不同的抽运光时间波形所获得的匀滑效果也有所不同,当抽运光的时间波形为三角波时,焦斑内部散斑的径向扫动速度较为稳定,可以使径向匀滑的整体效果及稳定性得到有效改善。     

用于超快束匀滑的动态波前调控新方案

提出了利用光克尔效应实现激光束波前动态调控,进而实现焦斑超快束匀滑(ps量级)的方案,其原理是利用抽运光动态改变光克尔介质的折射率分布,以对透射主激光束附加时空耦合的动态波前,进而使激光束在靶面的焦斑散斑产生更加快速、多样的变化,最终实现焦斑的超快束匀滑.当抽运光时间波形为高斯脉冲序列,且以小角度倾斜入射至光克尔介质时,由于抽运光和光克尔介质对主激光附加随时间横向移动的周期性球面相位,且球面相位的幅值随时间不断变化,因而可以同步实现激光束焦面散斑的横向和径向超快速扫动,从而更为有效地改善靶面辐照均匀性.     

基于锥形单玻璃管X射线聚焦镜表征X射线光源参数

X射线光源的焦斑尺寸和焦深对X射线光谱学,尤其是对于微区X射线衍射与荧光分析等领域十分重要的参数。如何高效而准确的表征这些参数对于X射线光源的应用和发展至关重要。现有的光源参数表征方法,尤其在表征微焦斑光源的参数时,都存在自身的局限性。锥形单玻璃管X射线聚焦镜是一种常用的X射线聚焦器件。根据锥形单玻璃管X射线聚焦镜滤波特性和几何特点,分析得到聚焦镜的聚焦光能量上限的大小受到光源焦斑尺寸的影响,提出这个能量上限与光源尺寸和光源到聚焦镜入口的距离之间的数学关系。设计了一种基于锥形单玻璃管X射线聚焦镜的表征X射线光源参数的方法。对锥形单玻璃管X射线聚焦镜的参数进行测量和确定后,将聚焦镜放置要测量的光源前,与光源形成聚焦光路。在光路准直并确保只有在聚焦镜内发生单次全反射的X射线射出聚焦镜的情况下,通过改变聚焦镜与光源焦斑距离并利用能谱探测系统来探测聚焦光并得到多个对应的聚焦光能谱。对所得能谱进行计算与分析,得到各能谱中的能量最大值,即聚焦光的能量上限。利用聚焦光能量上限、光源焦斑尺寸和光源到聚焦镜的距离之间的关系并结合线性拟合法,可同时得到光源焦斑尺寸和焦深。选用制造商给出焦斑尺寸约60 μm,焦深为20 mm的微焦斑钼靶光源作为测量对象,利用基于锥形单玻璃管X射线聚焦镜的表征方法测量的结果为焦斑尺寸为60.1 μm,焦深为19.7 mm。用小孔成像法表征该光源焦斑尺寸为60.3 μm,焦深为20.1 mm。相较于现有的方法,基于锥形单玻璃管X射线聚焦镜的表征X射线光源参数方法对表征微焦斑光源有一定优势,对表征高能X射线光源有潜在发展和利用价值。     

滚边法测量高能X射线源焦斑大小

应用于高能闪光X光照相技术的X射线源焦斑大小是闪光照相装置的关键参数, 直接影响成像的分辨能力。由于高能X射线的强穿透性和强辐射环境, 给焦斑测量带来一定困难。介绍了一种间接测量方法, 采用滚边装置(rollbar)成像得到X射线源的边扩展函数, 微分后得到光源的线扩展函数并计算调制传递函数(MTF), 而后从MTF为0.5所对应的空间频率之值确定出光源的光斑大小。给出了神龙二号加速器电子束聚焦调试实验中得到的X射线焦斑测量结果, 分析影响测量结果的因素并提出了解决方法。     

Theoretical consideration of an X‐ray Bragg‐reflection lens using the eikonal approximation

On the basis of the eikonal approximation, X‐ray Bragg‐case focusing by a perfect crystal with parabolic‐shaped entrance surface is considered theoretically. Expressions for focal distances, intensity gain and distribution around the focus spot as well as for the focus spot sizes are obtained. The condition of point focusing is presented. The experiment can be performed using X‐ray synchrotron radiation sources (particularly free‐electron lasers).     

12MeV LIA X射线斑点测试及其调制传递函数

 介绍了测试12MeV LIA X光斑点的测试系统,利用刀口法和大孔成像法测出所成像的黑密度分布, 获得X光斑点大小结果; 根据该光源的近乎轴对称特点和大孔所成像的密度分布,经数值处理拟合出斑点强度的空间分布;利用该系统,获得了判断12MeV LIA X光成像空间分辨能力的调制传递函数。     

1.06μm激光等离子体X光转换实验研究

Ｘ光转换是激光—等离子体相互作用中的一个重要研究课题。文中介绍了在“神光”装置上利用亚千Ｘ光能谱仪测量Ｘ光能谱、辐射温度与Ｘ光转换效率；并给出了转换Ｘ光总量、辐射温度与激光能量、脉冲宽度及腔面积的定标关系。     

A simple calibration procedure of polycapillary based portable micro‐XRF spectrometers for reliable quantitative analysis of cultural heritage materials

Portable micro‐X‐ray fluorescence (micro‐XRF) spectrometers mostly utilize a polycapillary X‐ray lens along the excitation channel to collect, propagate and focus down to few tens of micrometers the X‐ray tube radiation. However, the polycapillary X‐ray lens increases the complexity of the quantification of micro‐XRF data because its transmission efficiency is strongly dependent on the lens specifications and the propagated X‐ray energy. This feature results to a significant and not easily predicted modification of the energy distribution of the primary X‐ray tube spectrum. In the present work, we propose a simple calibration procedure of the X‐ray lens transmission efficiency based on the fundamental parameters approach in XRF analysis. This analytical methodology is best suited for compact commercial and portable micro‐XRF spectrometers. The developed calibration procedure is validated through the quantitative analysis of a broad range of samples with archeological relevance such as glasses, historical copper alloys, silver and gold alloys offering an overall accuracy of less than 10%–15%. Copyright © 2015 John Wiley & Sons, Ltd.     

HL—1M装置器壁硅化对电子速率分布的影响

在欧姆加热和低混杂波电流驱动条件下,利用磺化汞半导体探测器和碘化钠和探测器测出了ＨＬ－１Ｍ装置的Ｘ射线能谱,研究了器壁硅化前后电子速率分布和电子温度变化的特点,给出了Ｘ射线辐射强度与ＬＨＣＤ能量沉积的关系。     

An estimation of EDXRF spectrometer properties,based on a two‐layer composite Si‐Ge detector

A mathematical model for the two‐layer composite Si‐Ge energy dispersive X‐ray detector is proposed, based on analyses of radiation and electron transport in the detector, and a mathematical model of an energy dispersive X‐ray fluorescent spectrometer with the detector is considered. The Monte Carlo method is applied to calculate probabilities of photon detection in different parts of the detector's response function. The composite detector with the time anti‐coincidence scheme is proposed; its first layer is Si detector, and the second layer is Ge detector. It is shown that this composite detector has some advantages, such as reduced Ge photo escape peaks intensities and efficiency of detection of high energy photons similar to efficiency of Ge detector. Applying the X‐ray detector for the energy dispersive X‐ray fluorescent spectrometer provides for a lower background level. Copyright © 2012 John Wiley & Sons, Ltd.     

Influence of intense soft X-ray radiation on the parameters of tracks induced in CR-39 and PM-355 solid state nuclear track detectors

This paper presents the results of the influence of soft X-ray radiation on craters induced in SSNTDs by energetic α particles and protons of energy in the MeV range. We checked two detectors of the PM-355 and CR-39 types in order to verify and compare their resistance to the harsh conditions of high-temperature plasma experiments. To determine this effect some detector samples were first irradiated with α particles emitted from natural α particle sources and protons delivered by a particle accelerator. After that these samples were exposed to soft X ray radiation emitted from an X ray tube and also from the PF-1000 Plasma Focus facility. Doses during X ray irradiations varied from 0 up to tens of kGy. The irradiated samples were then etched in steps and track diameters were determined versus the absorbed dose and etching time and compared with those measured in samples not exposed to X ray radiation.     

Improvements of the low‐energy performance of a micro‐focus x‐ray source for XRF analysis with the SEM

X‐ray Fluorescence (XRF) with a scanning electron microscope (SEM) is a valuable completion of the analytical capabilities of SEMs. Small and compact micro‐focus x‐ray sources are mounted to the microscope chamber, and the x‐ray spectra are monitored with conventional EDS systems. Up to now the x‐ray tubes used for the micro‐focus x‐ray sources are equipped with beryllium windows about 100 µm thick. The poly‐capillary x‐ray lenses have their transmission maximum at photon energies around 10 keV. It drops down in both low‐ and high‐energy ranges. Hence, L‐radiation from an Mo or Rh target will be strongly attenuated, and the excitation of fluorescence in the soft x‐ray range becomes very ineffective. A new micro‐focus x‐ray source was developed. It is characterised by a lower self‐absorption in the tube target, thin beryllium windows and an x‐ray optics having a large distance between its foci and the maximum of transmission at about 5 keV. Thus K line fluorescence of light elements becomes effectively excited by the L‐radiation from Mo or Rh tube targets. The detection limit for sodium oxide in glass was found to be below 1 mass%. Copyright © 2009 John Wiley & Sons, Ltd.     

Three Dimensional Angular Distributions of X‐Rays in a 4 kJ Plasma Focus Device for Different Anode Tips Using TLD‐100 Dosimeters

Time and energy integrated measurements of the 3‐D angular distribution of X‐rays emission within the chamber of a 4 kJ Mather‐type plasma focus is investigated employing four different anode shapes and using nitrogen as the filling gas by the TLD‐100 thermoluminescence dosimeters. The distributions of X‐ray radiation in the energy range of 5 keV to several hundred keV were bimodal for all of the anode tips, peaked approximately at ±15°. The intensity of X‐rays decreased abruptly along the central axis of the device where the quasi cylindrical plasma pinch was formed. High intensity of X‐ray was observed in the case of a tapered ?at‐end anode, whereas less was obtained with the cylindrical hollow‐end anode. The maximum nitrogen X‐rays were for the tapered flat‐end anode at 4.5 mbar and 13 kV. (© 2014 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

X射线辐射在双孔柱腔靶中传输实验研究

在“星光Ⅱ”装置上,采用双孔柱腔靶研究辐射在空腔中轴向传输变化特性.提出“漏水管”辐射输运的简化模型,用来分析X射线在空腔中的传输的实验结果。分析结果表明,简化模型与实验结果基本相符.X射线输运的结果是输运末端的X射线减弱,辐射持续的时间增大,等离子体弛豫时间增大 关键词： 双孔柱腔靶 辐射传输 “漏水管”模型