| Laser inertial confinement fusion(ICF)research has become one of the most active frontier research directions,which is of great significance to solve the energy crisis and consolidate national defense.At present,the main reason why mankind has not been able to achieve fusion ignition is that we have an insufficient cognition and poor control effect on some complicated physical problems in the process of fusion.In order to more accurately understand and control these processes,it is often necessary to use a variety of advanced diagnostic equipment to quantitatively measure various important physical quantities in the process of fusion.We have developed a variety of X-ray diagnostic equipment,and they have played an extremely important role in the ICF diagnosis.However,the research on the absolute spectral response characteristics of the above diagnostic equipment is insufficient.So they usually do not have the precision quantify diagnostic capabilities.At present,in fact,this issue is a key obstacle to further deepening our ICF research.In view of the above problems,under the auspices of the National Youth Fund Project(No.11405158),this paper has studied on the absolute spectral response characteristics of the representative active diagnostic equipment XSC and the passive diagnostic equipment XFF based on the laser-plasma X-ray source.Thence XSC and XFF have a precision quantify diagnostic capabilities in the 177eV~1.24 keV energy region.Based on the whole research process,a systematic theoretical research method has been proposed to study on the absolute spectral response characteristics of an active and passive X-ray diagnostic equipment,and simultaneously,an advanced experimental measurement system for the absolute spectral response measurements of these X-ray diagnostic equipment has been established.The main research contents and related research results of this paper are as follows:(1)Theoretical research of the XSC absolute spectral response characteristics.The whole response process of XSC to incident X-ray photon was analyzed.The expression of mathematical function of XSC absolute spectral response was established.It was proved that the XSC absolute spectral response curve and the photocathode quantum efficiency curve are consistent in shape.Based on the theoretical model of the secondary electron emission and the one-dimensional stochastic step size analysis method,the mathematical function expression of thephotocathode quantum efficiency was deduced and the corresponding numerical simulation was also carried out.Finally,this paper summarized the systematic theoretical research methods on the absolute spectral response characteristics of large active X-ray diagnostic equipment such as XSC.(2)Experimental measurement of the XSC absolute spectral response sensitivity.Based on the advantages and disadvantages of the measurement methods at home and abroad,a new experimental scheme for XSC absolute spectral response measurement was introduced,and its measurement principle and advantages were also analyzed in detail.Under the guidance of the experimental scheme,the main tasks that were completed are as follows:1)Two sets of high-resolution holographic flat-field grating spectrometers weredesigned.2)Two sets of X-ray CCD cameras were absolutely calibrated on the 4B7Bbeamline station of the synchrotron radiation source in Beijing.3)Au and CsI photocathode were prepared,and the absolute calibrations werealso performed on the 4B7 B beamline station.4)Based on the 2×100J small laser facility,the double branch optical experimentmeasurement system for the XSC absolute spectral response was built up,and thecorresponding precision aiming method of experimental light path was alsodesigned.5)Based on the C16H6O4N2 planar target experiment,the multi-parameter fittingmethod was used to accurately calibrate the geometric relationship between thecorresponding X-ray wavelength and the pixel position of the spectrometers.6)Based on the Cu planar target experiment,the absolute spectral sensitivity ofthe XSC in the 177eV~1.24 keV energy region was measured.The results showed that the absolute sensitivity of the XSC measured in this experiment are consistent with the quantum efficiency curve of the photocathode obtained by theoretical calculation,and the maximum deviation between the two is15%.The relative uncertainty of all experimental data is less than 12%.Compared with the similar measurement results in foreign countries,this experiment not only has a higher measurement accuracy,but also can obtain more absolute sensitivity data points near the absorption edge(284eV)of C element.(3)Theoretical and experimental study of the XFF absolute spectral response(transmittance).1)The application background and design principle of the XFF were analyzed,and a number of XFF were prepared in laboratory.The mathematical function expression of the XFF absolute transmittance was deduced and the corresponding numerical simulation was carried out.In addition,the influence of various factors on the absolute transmittance was also discussed.Finally,a set of systematic research methods for the absolute spectral response of small passive X-ray diagnostic equipment such as XFF was summarized.2)The absolute transmittance data of XFF in the 177 eV ~ 1.24 keV energy region was measured with high precision on 4B7 B beamline station of the Beijing synchrotron source,and the problems faced by the current measurement work on the synchronous radiation source were analyzed.In order to solve this problem,the experimental methods of double-branch and single-branch for the XFF absolute transmittance measurement which are based on laser plasma X-ray source were introduced.The absolute transmittance of No.23 and No.48 XFF in the 177 eV ~1.24 keV energy region were measured by these two methods based on the Al and C16H6O4N2 planar-target experiments.The results show that the experimental results obtained by the single-branch and double-branch method can be consistent with the high precision data measured using the synchrotron radiation source,but the single-branch measurement results have a better consistent.The relative measurement uncertainties of all the experimental data obtained by the single-branch and double-branch measurement methods were less than 14.3% and 9%,respectively. |
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