碘化铯(CsI)光阴极响应灵敏度是软X射线条纹相机用于X射线能谱定量诊断的重要参数,其理论计算具有重要指导意义.目前的理论解析模型基于薄膜光阴极产生次级电子的一维随机行走模型发展而来,具体包括X射线正入射、能量大于1 ke V条件下的...碘化铯(CsI)光阴极响应灵敏度是软X射线条纹相机用于X射线能谱定量诊断的重要参数,其理论计算具有重要指导意义.目前的理论解析模型基于薄膜光阴极产生次级电子的一维随机行走模型发展而来,具体包括X射线正入射、能量大于1 ke V条件下的Henke模型,以及变角度入射、光阴极厚度大于100 nm条件下的Fraser模型,都存在一定局限性.本文进一步引入次级电子输运概率的基础表达式,推导了CsI光阴极在更大参数范围内(X射线能量0.1—10 ke V、光阴极厚度10—200 nm)响应灵敏度随X射线能量E、光阴极厚度t、X射线与阴极表面夹角θ变化的一般表达式.最后,将本文的理论计算结果与Henke模型、Fraser模型、文献及北京同步辐射的实验数据分别进行了比较和讨论分析,验证了计算模型的准确性和普适性,并且为高时间分辨光谱定量测量实验中Cs I光阴极的优化设计提供了理论参考.展开更多
A technique of flat crystal x-ray spectrometer for quantitative spectral measurement is described.For the flat crystal spectrograph geometry,the quantitative reduction of relating the CCD counts back to the photon flu...A technique of flat crystal x-ray spectrometer for quantitative spectral measurement is described.For the flat crystal spectrograph geometry,the quantitative reduction of relating the CCD counts back to the photon flux from the x-ray source is established.The absolute calibrations of the integral diffraction coefficients of the crystal and the CCD sensitivity make it possible to measure absolute photons flux within the energy range of 2000–5000 eV.The uncertainty analysis of the calibrations is carried out to obtain the energy resolved uncertainties of crystal and CCD.Thus,the experimental spectra with spectral resolved intensity uncertainties are available.Then,a performing experiment of laser-produced Ti plasma is carried out and the absolute x-ray spectra with intensity uncertainty less than 8.5%are obtained.The technique is promising for absolute spectral measurement of high temperature plasmas in a kilo-electron-volt region.展开更多
High-resolution transmission spectra of radiatively-heated low-z C10H16O6 plasma have been measured on‘Xingguang II’laser facility by using flat field grating spectrometer.Absorption lines of oxygen and carbon ions ...High-resolution transmission spectra of radiatively-heated low-z C10H16O6 plasma have been measured on‘Xingguang II’laser facility by using flat field grating spectrometer.Absorption lines of oxygen and carbon ions in the region of 1.6 to 5.0 nm have been observed clearly and identified.Using the unresolved transition array model,we also calculated the transmission spectra of C10H16O6 plasma.The measured transmission spectrum has been compared with the calculated ones.展开更多
Radiation flow through gold-doped hydrocarbon foam is investigated and a model is presented to calculate effective opacity for an inhomogeneous,pressure-equilibrated gold/foam mixture based on the Levermore–Pomraning...Radiation flow through gold-doped hydrocarbon foam is investigated and a model is presented to calculate effective opacity for an inhomogeneous,pressure-equilibrated gold/foam mixture based on the Levermore–Pomraning method for binary stochastic media.The effective opacity dependance on the size of the gold particles and the foam temperature are studied.The results suggest that when the mixture temperature is lower than 250 eV,the opacity difference between the 5μm particle mix case and the atomic mix case is large enough to induce a significant discrepancy in radiation transport,which is confirmed by the hydrodynamic simulation.展开更多
Hot dense titanium plasma was produced by irradiating a CH foam coated titanium layer with nanosecond laser pulses.The time-integrated emission spectra of He-like titanium were measured by using an absolutely calibrat...Hot dense titanium plasma was produced by irradiating a CH foam coated titanium layer with nanosecond laser pulses.The time-integrated emission spectra of He-like titanium were measured by using an absolutely calibrated flat crystal spectrometer.The synthetic spectra obtained by the steady collisional-radiative(CR)equilibrium model associated with the hydrodynamic simulations were compared with the experimental spectra.The results show that the electron density increases up to 5×10^(21) cm^(-3) with CH foam of density 40 mg/cc.This work indicates that an overlay of CH foam on a solid target is beneficial to create an optimum condition for K-shell emissions from a high density plasma region.展开更多
The K−shell emission spectra of laser-produced aluminum plasma are measured by a space-resolved spectrometer consisting of a flat crystal spectrometer with a 20μm wide space−resolved slit.By using the approximation o...The K−shell emission spectra of laser-produced aluminum plasma are measured by a space-resolved spectrometer consisting of a flat crystal spectrometer with a 20μm wide space−resolved slit.By using the approximation of the steady collisional-radiative equilibrium model,the interstage line intensity ratios of Ly-αresonance line to He−αresonance line are given as a function of electron temperature.The spectra profiles are decomposed to resonance line and the overlapped high-order satellites manifold.Thus reliable electron temperature is deduced from the interstage line intensity ratios of the decomposed resonance lines.The results of spaced-resolved temperature are compared with the hydrodynamic simulations.The diagnostics of electron temperature for laser-produced plasma is developed.展开更多
The width of an unresolved transition array, which was once regarded as insensitive to electron temperature by Audebert et al. [Phys. Rev. A 32 (1985) 409], is found to be a temperature-sensitive function to a certain...The width of an unresolved transition array, which was once regarded as insensitive to electron temperature by Audebert et al. [Phys. Rev. A 32 (1985) 409], is found to be a temperature-sensitive function to a certain extent and has the potential of being used in plasma diagnostics. In this letter, on the assumption that the plasma has achieved the local thermodynamical equilibrium and that each of the subarray has a Gaussian shape, the electron temperature of a gold plasma produced by laser irradiation of a microdot is obtained by comparing the experimental width with the theoretical width. The full widths at half maximum of the unresolved transition arrays are computed in the formalism of the spin-orbit-split arrays.展开更多
文摘碘化铯(CsI)光阴极响应灵敏度是软X射线条纹相机用于X射线能谱定量诊断的重要参数,其理论计算具有重要指导意义.目前的理论解析模型基于薄膜光阴极产生次级电子的一维随机行走模型发展而来,具体包括X射线正入射、能量大于1 ke V条件下的Henke模型,以及变角度入射、光阴极厚度大于100 nm条件下的Fraser模型,都存在一定局限性.本文进一步引入次级电子输运概率的基础表达式,推导了CsI光阴极在更大参数范围内(X射线能量0.1—10 ke V、光阴极厚度10—200 nm)响应灵敏度随X射线能量E、光阴极厚度t、X射线与阴极表面夹角θ变化的一般表达式.最后,将本文的理论计算结果与Henke模型、Fraser模型、文献及北京同步辐射的实验数据分别进行了比较和讨论分析,验证了计算模型的准确性和普适性,并且为高时间分辨光谱定量测量实验中Cs I光阴极的优化设计提供了理论参考.
基金by the National High-Tech Program of China and the National Natural Science Foundation of China under Grant Nos 10734140,10874156 and 10875109.
文摘A technique of flat crystal x-ray spectrometer for quantitative spectral measurement is described.For the flat crystal spectrograph geometry,the quantitative reduction of relating the CCD counts back to the photon flux from the x-ray source is established.The absolute calibrations of the integral diffraction coefficients of the crystal and the CCD sensitivity make it possible to measure absolute photons flux within the energy range of 2000–5000 eV.The uncertainty analysis of the calibrations is carried out to obtain the energy resolved uncertainties of crystal and CCD.Thus,the experimental spectra with spectral resolved intensity uncertainties are available.Then,a performing experiment of laser-produced Ti plasma is carried out and the absolute x-ray spectra with intensity uncertainty less than 8.5%are obtained.The technique is promising for absolute spectral measurement of high temperature plasmas in a kilo-electron-volt region.
基金Supported in part by the National Natural Science Foundation of China under Grant No.19975042.
文摘High-resolution transmission spectra of radiatively-heated low-z C10H16O6 plasma have been measured on‘Xingguang II’laser facility by using flat field grating spectrometer.Absorption lines of oxygen and carbon ions in the region of 1.6 to 5.0 nm have been observed clearly and identified.Using the unresolved transition array model,we also calculated the transmission spectra of C10H16O6 plasma.The measured transmission spectrum has been compared with the calculated ones.
文摘Radiation flow through gold-doped hydrocarbon foam is investigated and a model is presented to calculate effective opacity for an inhomogeneous,pressure-equilibrated gold/foam mixture based on the Levermore–Pomraning method for binary stochastic media.The effective opacity dependance on the size of the gold particles and the foam temperature are studied.The results suggest that when the mixture temperature is lower than 250 eV,the opacity difference between the 5μm particle mix case and the atomic mix case is large enough to induce a significant discrepancy in radiation transport,which is confirmed by the hydrodynamic simulation.
基金Supported by the Foundation of China Academy of Engineering Physics under Grant No 2011A0102005the Foundation of Science and Technology on Plasma Physics Laboratory under Grant No 9140C680203110C6804.
文摘Hot dense titanium plasma was produced by irradiating a CH foam coated titanium layer with nanosecond laser pulses.The time-integrated emission spectra of He-like titanium were measured by using an absolutely calibrated flat crystal spectrometer.The synthetic spectra obtained by the steady collisional-radiative(CR)equilibrium model associated with the hydrodynamic simulations were compared with the experimental spectra.The results show that the electron density increases up to 5×10^(21) cm^(-3) with CH foam of density 40 mg/cc.This work indicates that an overlay of CH foam on a solid target is beneficial to create an optimum condition for K-shell emissions from a high density plasma region.
基金by the National High-Tech Program of Chinathe National Natural Science Foundation of China under Grant Nos 10734140,10874156 and 10875109.
文摘The K−shell emission spectra of laser-produced aluminum plasma are measured by a space-resolved spectrometer consisting of a flat crystal spectrometer with a 20μm wide space−resolved slit.By using the approximation of the steady collisional-radiative equilibrium model,the interstage line intensity ratios of Ly-αresonance line to He−αresonance line are given as a function of electron temperature.The spectra profiles are decomposed to resonance line and the overlapped high-order satellites manifold.Thus reliable electron temperature is deduced from the interstage line intensity ratios of the decomposed resonance lines.The results of spaced-resolved temperature are compared with the hydrodynamic simulations.The diagnostics of electron temperature for laser-produced plasma is developed.
基金Supported by the Fund of Chinese Academy of Engineering Physics(Grant No.20000216)the National Natural Science Foundation of China under Grant No.19674049.
文摘The width of an unresolved transition array, which was once regarded as insensitive to electron temperature by Audebert et al. [Phys. Rev. A 32 (1985) 409], is found to be a temperature-sensitive function to a certain extent and has the potential of being used in plasma diagnostics. In this letter, on the assumption that the plasma has achieved the local thermodynamical equilibrium and that each of the subarray has a Gaussian shape, the electron temperature of a gold plasma produced by laser irradiation of a microdot is obtained by comparing the experimental width with the theoretical width. The full widths at half maximum of the unresolved transition arrays are computed in the formalism of the spin-orbit-split arrays.
