共查询到20条相似文献,搜索用时 187 毫秒
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从等离子体的流体动力学方程出发,导出了描述激光辐照平板靶条件下产生X射线激光物理过程的自相似方程。由于方程得到了不同等离子体参数Tc、L、ne等,这些参数地平板靶坶激光的实验设计提供了有参考价值的结果。并为快速定量地解释实验结果提供了一套完整的数学物理工具,使在实验中调整参数成为可能。 相似文献
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研究了在最佳除焦、预脉冲光束单独散焦及主预脉 时散焦三种不同抽运激光聚焦条件下,预脉冲诱导的类氖铁和锌J=0→1X射线激光的近场像。本实验是在Asteri iv磺激光装置上进行的,实验中主、预脉冲间的时间间隔为5ns。实验发现在抽运激光主、预脉冲最佳聚焦条件下,X射线激光束在2.5cm长的线状等离子体输出端沿靶面(垂直)方向分裂成两束;在抽运预脉冲单独散焦条件下,仍然观察到这一分裂现象;但是当抽运 相似文献
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激光腔靶辐射时间特性研究 总被引:2,自引:1,他引:1
介绍了激光加热腔靶辐射时间特性研究。实验采用滤长为1.053μm,能量为30-750J,脉宽为600-1100ps的高斯型激光脉冲,辐照柱型腔靶,用两台具有一定和时间分辨的亚千X射线能谱仪,分别观察激光入射口和X光输运口的辐射时间特性,实验结果给出了腔靶源区发射X光时间过程及其与发射口面积,形状,发射能区等的关系。 相似文献
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冯贤平 《原子与分子物理学报》2005,22(1):30-33
本文的基本思想是设计双层金铝薄膜靶以检测激光脉冲宽度与等离子体消融深度的关系,找出有效的等离子体加热方法以产生更强更亮的等离子体辐射源.由于有预脉冲激光的存在,表层金薄膜首先被消融,由主脉冲携带的大能量就能较易穿过表层金等离子体将能量聚焦在内层铝靶上,由此产生内层高温等离子体.又由于外层低温等离子体存在,其将有效的阻碍内高温等离子体因膨胀而引起的能量损失.对无预脉冲而言,直接入射激光能量都沉积在靶表层形成表层高温等离子体.但是激光直接入射而产生的等离子体辐射总强度只比由预脉冲情况下产生的金等离子体辐射强度增加15%.而预脉冲能量只占激光总能量的2%.实验结果显示Al光谱线主要来自类氢,类氦离子跃迁.Au等离子体光谱线主要来自它的N带,O带和P带谱.我们也观察到一个明显的软X射线短波发射极限.所有结果显示由于预脉冲的存在将对靶各层等离子体辐射产生极大的影响 相似文献
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介绍了在“神光”装置上进行的不同类型腔靶X射线面、体发射物理机制的实验研究。实验采用波长为1.053μm的激光,脉冲波形为高斯型,能量为500一700J/束,脉冲宽度为600一1000ps.典型靶由三个柱型腔组成,采取双束对打,两端的腔为吸收-转换区(源区),中间腔为辐射加热的内爆区。给出源区及内爆区X射线面、体发射测量结果,并通过分析、估算给出面、体发射强度比。
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用一维流体力学程序MEDUSA耦合原子物理程序NIMP,对超短脉冲激光辐照Mylar纤维靶和平面靶产生复合泵浦O~(17)X射线激光的物理过程进行了理论研究,探讨了利用VULCAN激光装置的CPA皮秒脉冲光束进行饱和增益实验的可行性.结果表明,超短脉冲辐照激光靶可能是产生饱和增益的复合泵浦X射线激光的一条有效途径. 相似文献
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Tabulated mass absorption coefficient data from the XCOM, Chantler and ion beam analysis (IBA) Handbook are compared, and differences are shown against X‐ray energy and target atomic number. Over the X‐ray energy range 1–40 keV systematic differences of several tens of percent are noted between these datasets, particularly for the earlier IBA Handbook dataset. The influence of these different mass absorption coefficients on the X‐ray yields for thick target proton‐induced X‐ray emission (PIXE) are investigated and compared as a function of X‐ray energy and target atomic number. For contemporary experimental PIXE users trying to work quantitatively over a broad range of elements and X‐ray energies, differences between PIXE results obtained using these three separate mass attenuation coefficient datasets can be larger than the typical accuracy limits of ±3% to ±5%. There are systematic differences in the mass attenuation coefficients of 5–10% between the XCOM and Chantler, while the differences for the IBA Handbook dataset can be larger (up to 40% and greater) at high X‐ray energies. At this time, we recommend the dataset of Chantler as it is more recent, and the synchrotron experimental results seem to favour it over the older XCOM and IBA Handbook data. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
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We have found that it is possible to preserve the temporal waveform of the reflected wave generated from stimulated Brillouin scattering (SBS) by using a prepulse technique. The waveform of the SBS wave usually shows a steep rising edge in the ordinary SBS process. It has been found that the waveform of the reflected wave depends on both the prepulse energy and the time delay between the main pulse and the prepulses. A prepulse energy of 5 mJ and a time delay of 5 ns have been measured to be the optimum values under the experimental conditions. This prepulse method is useful in developing a multistage system employing several SBS cells in series for high-power laser applications. 相似文献
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基于反冲质子法建立了一种测量D-T中子与平板型宏观样品作用的次级中子角度谱的实验方法.为保证探测器的能量线性并在较低的中子有效测量下阈(0.5 MeV)情况下获得好的中子-伽马射线甄别性能,采用高、低能段分别测量的方法.采用事件记录法,同时记录了次级中子和伴随伽马射线的脉冲形状甄别和脉冲幅度二维信息,利用基于ROOT数据分析平台编写的离线数据分析程序,完成了伴随伽马射线的挑选和扣除,以及高、低两能段反冲质子谱的拼接,并成功的将神经网络技术应用于中子能谱的解谱,获得了D-T中子与9和18 cm厚平板型聚乙烯材料作用的0.5-15 MeV的次级中子角度谱实验结果.实验模型的MC模拟由MCNP5完成,数据库采用ENDF-VI,实验结果和MC计算结果在实验不确定度范围内一致.
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D-T中子
积分中子学
反冲质子法
次级中子能谱 相似文献
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Lα and Lβ X‐ray fluorescence spectra of a lead metallic sheet were measured using an energy dispersive X‐ray spectrometer by changing the X‐ray tube voltage and the material of the primary filter. The Lα to Lβ intensity ratio changed from Lα: Lβ = 3: 1 at 15 kV to Lα: Lβ = 1: 1 at 50 kV depending on the X‐ray tube voltage and the filter. The scattered X‐ray spectra of an acrylic slab instead of the sample in the sample holder were measured by changing the applied voltage and the material of the primary filter. The calculated values of the Pb Lα/Lβ intensity ratio of the metallic sheet using the Shiraiwa–Fujino formula by inserting the scattered X‐ray spectra of an acrylic plate as incident X‐ray spectra and the fundamental parameters taken from the Elam database were in good agreement with the experimental ones. We conclude that we can obtain an incident X‐ray spectrum approximately by measuring the scattered X‐ray spectrum without measuring the direct incident beam. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
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电视导引头的激光回波分析 总被引:2,自引:1,他引:1
阐述了用激光主动扫描法侦察远方飞航导弹来袭方位的原理及实验技术。以电视导引头光学系统为例,运用矩阵光学追迹法对影响“猫眼效应”回波强度的因素进行了定性和定量的分析。研究结果表明:回波强度受导引头光路中光学镜头的相对孔径、摄像管靶面倾斜和离焦的影响较大;扫描激光光束的入射角等因素对回波强度也有一定的影响。在主动扫描装置与被探测导引头相距约5000m、扫描光束的入射角为0.1rad的条件下,导引头光学系统反射面倾斜和离焦使得侦察装置接收到的回波能量与发射脉冲能量之比由理想条件下的1.0%分别下降到了0.004%和0.3%。 相似文献
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Pauline Fournier Iwan Cornelius Mattia Donzelli Herwig Requardt Christian Nemoz Marco Petasecca Elke Bräuer-Krisch Anatoly Rosenfeld Michael Lerch 《Journal of synchrotron radiation》2016,23(5):1180-1190
Microbeam radiation therapy (MRT) is a novel irradiation technique for brain tumours treatment currently under development at the European Synchrotron Radiation Facility in Grenoble, France. The technique is based on the spatial fractionation of a highly brilliant synchrotron X‐ray beam into an array of microbeams using a multi‐slit collimator (MSC). After promising pre‐clinical results, veterinary trials have recently commenced requiring the need for dedicated quality assurance (QA) procedures. The quality of MRT treatment demands reproducible and precise spatial fractionation of the incoming synchrotron beam. The intensity profile of the microbeams must also be quickly and quantitatively characterized prior to each treatment for comparison with that used for input to the dose‐planning calculations. The Centre for Medical Radiation Physics (University of Wollongong, Australia) has developed an X‐ray treatment monitoring system (X‐Tream) which incorporates a high‐spatial‐resolution silicon strip detector (SSD) specifically designed for MRT. In‐air measurements of the horizontal profile of the intrinsic microbeam X‐ray field in order to determine the relative intensity of each microbeam are presented, and the alignment of the MSC is also assessed. The results show that the SSD is able to resolve individual microbeams which therefore provides invaluable QA of the horizontal field size and microbeam number and shape. They also demonstrate that the SSD used in the X‐Tream system is very sensitive to any small misalignment of the MSC. In order to allow as rapid QA as possible, a fast alignment procedure of the SSD based on X‐ray imaging with a low‐intensity low‐energy beam has been developed and is presented in this publication. 相似文献