High Energy Density Physics最新文献

{"title":"Machine learning assisted bayesian inference of mix and hot-spot conditions in NIF implosions","authors":"B.A. Hammel,&nbsp;B.D. Hammel,&nbsp;H.A. Scott,&nbsp;J. Luc Peterson","doi":"10.1016/j.hedp.2024.101077","DOIUrl":"10.1016/j.hedp.2024.101077","url":null,"abstract":"<div><p>Experiments on the National Ignition Facility (NIF) have provided clear evidence of ablator material mixing into the Hot-Spot, leading to degraded performance. However, inferring the amount of mix and Hot-Spot conditions from typical experimental observations (e.g. x-ray spectra and images) is highly challenging. We have developed an analysis method that utilizes machine learning assisted Bayesian inference to find the probability distributions of the Hot-Spot and mix conditions. This approach uses a neural network, trained on an idealized 2-dimensional representation of the Hot-Spot and mix distribution, and Bayesian inference to find the statistical distributions of Hot-Spot conditions that provide a match with observations. We have tested this method with synthetic data from simulations.</p></div>","PeriodicalId":49267,"journal":{"name":"High Energy Density Physics","volume":"50 ","pages":"Article 101077"},"PeriodicalIF":1.6,"publicationDate":"2024-01-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139517472","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Comparison of second-order spectral line widths formulae","authors":"Carlos A. Iglesias ,&nbsp;Thomas A. Gomez","doi":"10.1016/j.hedp.2024.101080","DOIUrl":"10.1016/j.hedp.2024.101080","url":null,"abstract":"<div><p><span>Frequently used second-order spectral line width formulae from the projector operator and </span>kinetic theory methods have not been formally compared previously. It is shown that a systematic second-order expansion of the projection operator expression including initial correlations agrees with the second-order kinetic theory result. The agreement assumes a common approximation in the projector operator method that introduces a screened radiator–perturber interaction to account for neglected electron–electron correlations. On the other hand, it is shown that the usual width expression from the projection operator approach neglecting initial correlations differs from kinetic theory. The differences, however, are at least third order in the radiator–perturber interaction. The comparisons suggest using the more compact width expression from kinetic theory, which includes initial correlations and a systematic screening of the radiator–perturber interactions, as the starting point for second-order width calculations.</p></div>","PeriodicalId":49267,"journal":{"name":"High Energy Density Physics","volume":"50 ","pages":"Article 101080"},"PeriodicalIF":1.6,"publicationDate":"2024-01-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139500270","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Toward constraint of ionization-potential depression models in a convergent geometry","authors":"D.T. Bishel ,&nbsp;P.M. Nilson ,&nbsp;D.A. Chin ,&nbsp;J.J. Ruby ,&nbsp;E. Smith ,&nbsp;S.X. Hu ,&nbsp;R. Epstein ,&nbsp;I.E. Golovkin ,&nbsp;J.R. Rygg ,&nbsp;G.W. Collins","doi":"10.1016/j.hedp.2024.101076","DOIUrl":"10.1016/j.hedp.2024.101076","url":null,"abstract":"<div><p>We demonstrate the value of inner-shell X-ray absorption spectroscopy for dense-plasma atomic physics and explore the coupling between constraint of the thermodynamic state and constraint of ionization-potential depression models. Synthetic K-shell absorption spectra are generated along a radius from a point-like core and analyzed using different ionization-potential depression models. Within this synthetic analysis framework, we identify plasma conditions (<span><math><mrow><msub><mrow><mi>T</mi></mrow><mrow><mi>e</mi></mrow></msub><mo>=</mo><mn>400</mn></mrow></math></span> eV, <span><math><mrow><mi>ρ</mi><mo>=</mo><mn>40</mn></mrow></math></span> g/cm<span><math><msup><mrow></mrow><mrow><mn>3</mn></mrow></msup></math></span>) accessible by spherical implosions where K-shell absorption spectra discriminate between models if the material temperature is measured to a precision of 20%. The analysis is extensible to a finite-sized core and can be used to guide future studies of ionization-potential depression, informing material and radiative properties of matter in fusion plasmas and stellar interiors.</p></div>","PeriodicalId":49267,"journal":{"name":"High Energy Density Physics","volume":"50 ","pages":"Article 101076"},"PeriodicalIF":1.6,"publicationDate":"2024-01-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S1574181824000016/pdfft?md5=3638bbcfcaddbd90bd36b1e25905472a&pid=1-s2.0-S1574181824000016-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139102391","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The STAG code: A fully relativistic super transition array calculation using Green’s functions","authors":"N.M. Gill,&nbsp;C.J. Fontes,&nbsp;C.E. Starrett","doi":"10.1016/j.hedp.2024.101078","DOIUrl":"10.1016/j.hedp.2024.101078","url":null,"abstract":"<div><p><span>Calculating opacities for a wide range of plasma conditions (i.e. temperature, density, element) requires detailed knowledge of the plasma configuration space and electronic structure. For plasmas composed of heavier elements, relativistic effects are important in both the electronic structure and the details of opacity spectra. We extend our previously described superconfiguration and super transition array capabilities (Gill et al., 2023) to include a fully relativistic formalism. The use of hybrid bound-continuum supershells in our superconfigurations demonstrates the importance of a consistent treatment of bound and continuum electrons in </span>dense plasma<span> opacities, and we expand the discussion of these consequences to include issues associated with equation of state and electron correlations between bound and continuum electrons.</span></p></div>","PeriodicalId":49267,"journal":{"name":"High Energy Density Physics","volume":"50 ","pages":"Article 101078"},"PeriodicalIF":1.6,"publicationDate":"2024-01-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139102227","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Observations of multi-ion physics and kinetic effects in a surrogate to the solar CNO reactions","authors":"J. Jeet ,&nbsp;A.B. Zylstra ,&nbsp;M. Gatu Johnson ,&nbsp;N.V. Kabadi ,&nbsp;P. Adrian ,&nbsp;C. Forrest ,&nbsp;V. Glebov","doi":"10.1016/j.hedp.2023.101066","DOIUrl":"10.1016/j.hedp.2023.101066","url":null,"abstract":"<div><p><span>The ‘CNO process’ occurs in heavier stars with finite metallicity<span> in which hydrogen burning is catalyzed in the presence of </span></span>¹²<span><span><span>C. These reactions are more strongly dependent on temperature than the pp cycle reactions, and thus the CNO cycle dominates only in massive stars. For these types of reactions to be studied at </span>ICF<span> facilities such as OMEGA, an implosion platform using heavier nuclei in the fuel and capable of creating </span></span>ion temperatures on the order of at least 20 keV is required. A potential route to reach these conditions is to take advantage of kinetic effects in low-convergence shock-driven ‘exploding pusher’ implosions. In this experiment, shots were conducted at the OMEGA laser facility using the surrogate reaction </span>¹³C + D. Its cross section is substantially higher than the actual astrophysical CNO reactions. The yield of this reaction in these implosions was much lower than expected. Physical explanations are discussed, with significant species stratification the likely explanation.</p></div>","PeriodicalId":49267,"journal":{"name":"High Energy Density Physics","volume":"49 ","pages":"Article 101066"},"PeriodicalIF":1.6,"publicationDate":"2023-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135656063","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Quantitative proton radiography and shadowgraphy for arbitrary intensities","authors":"J.R. Davies ,&nbsp;P.V. Heuer ,&nbsp;A.F.A. Bott","doi":"10.1016/j.hedp.2023.101067","DOIUrl":"10.1016/j.hedp.2023.101067","url":null,"abstract":"<div><p>Charged-particle radiography and shadowgraphy data can be directly inverted to obtain a line-integrated transverse Lorentz force<span><span><span><span> or a line-integrated transverse refractive index gradient if </span>intensity modulations due to scattering and absorption are negligible, and angular deflections are small. We develop a new direct-inversion algorithm based on </span>plasma physics and compare it to a new Monge–Ampère code and an existing power diagram code (Kasim et al., 2017). The measured or source intensity is represented by electrons subject to drag, and the other intensity by fixed ions. The decrease in kinetic plus </span>electrostatic energy determines convergence. The displacement of the electrons from their initial to their equilibrium positions determines the line-integrated force or refractive index gradient. We have implemented two approaches: PIC (particle in cell) and Lagrangian fluid, in 1-D and 2-D. The PIC code works for arbitrary intensities, can work efficiently in parallel, and can make use of existing codes. The Lagrangian code requires less memory and is faster than the PIC code without massively parallel processing, but fails in 2-D for large intensity modulations. The Monge–Ampère code is by far the fastest in 2-D, without massively parallel processing, but fails for intensities with large voids, high contrast ratios and large deflections across the boundaries, and could not obtain the degree of convergence possible with the PIC code. The power diagram code was by far the slowest and most memory intensive, and failed for large peaks in the measured intensity.</span></p></div>","PeriodicalId":49267,"journal":{"name":"High Energy Density Physics","volume":"49 ","pages":"Article 101067"},"PeriodicalIF":1.6,"publicationDate":"2023-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135760588","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Optical depth measurement of self-reversed line emitted from in-homogenous plasma in laser induced breakdown spectroscopy","authors":"Jalloul Trabelsi,&nbsp;Mounir Esboui,&nbsp;Neïla Terzi","doi":"10.1016/j.hedp.2023.101069","DOIUrl":"10.1016/j.hedp.2023.101069","url":null,"abstract":"<div><p>In this work, an original method is proposed and used for measurement of the optical depth of a self-reversed spectral line. A theoretical approach is utilized in an inhomogenous laser induced plasma at local thermodynamic to simulate self-reversed line and then to get the main line profile without self-absorption. The spatial and temporal evolution of optical depth of two spectral lines of Ca II at 393.4 nm and 396.9 nm is studied. Furthermore, the variation of optical depth versus the concentration of species emitter inside of plasma plume is investigated. In addition, the validity of this method is affirmed during comparison with results obtained by other techniques.</p></div>","PeriodicalId":49267,"journal":{"name":"High Energy Density Physics","volume":"49 ","pages":"Article 101069"},"PeriodicalIF":1.6,"publicationDate":"2023-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135614584","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"High-precision room temperature Fe opacity measurements at 1000-2000eV photon energies","authors":"Malia L. Kao ,&nbsp;Guillaume P. Loisel ,&nbsp;James E. Bailey ,&nbsp;Patrick W. Lake ,&nbsp;Paul D. Gard ,&nbsp;Gregory A. Rochau ,&nbsp;George R. Burns ,&nbsp;William R. Wampler ,&nbsp;Haibo Huang ,&nbsp;Michael N. Weir","doi":"10.1016/j.hedp.2023.101064","DOIUrl":"10.1016/j.hedp.2023.101064","url":null,"abstract":"<div><p>Prior measurements of room temperature (cold) Fe opacity have errors as high as <em>±</em>10 % and a spread in values that exceeds the uncertainties. These data, along with current cold opacity databases, were used for comparison with experimental solar Fe opacity. The solar Fe opacity is expected to be lower than cold Fe opacity in the <em>∼</em>1500–2000 eV photon energy range. However, results from this comparison contradicted this assumption and prompted an investigation of the precision and accuracy of cold Fe opacity measurements. Cold Fe opacity is determined here with high precision using transmission measurements of Fe foils at three characteristic line energies in the soft X-ray range (1000–2000 eV). The present opacities are determined with ≲1 % overall uncertainties. This is achieved through precise measurements of transmission and areal density which are related to opacity by the Beer-Lambert Law. Transmission is measured with overall individual uncertainties of ≲1 % and is obtained through simultaneous measurements of attenuated and unattenuated spectra using an X-ray source and a Bragg crystal spectrometer. The required areal density is indepen-dently measured using two different techniques: Rutherford Backscattering Spectroscopy and a recently-developed technique using calibrated cold absorption in the 3–17 keV range. The final areal density used in the opacity determination is an average between both methods. The measured opacity at 1188 eV is in agreement with current opacity databases but is higher by around 5–10 % at the highest photon energy (1924 eV) and lower by around 2–4 % at the lowest photon energy (1012 eV). A caveat is that opacity accuracy is linearly dependent on the areal density. We performed the first direct comparison between the two areal density methods which revealed a 7–11 % discrepancy. If one of the methods is proven correct in future studies, it may impact the opacity accuracy reported here since we use the average of the two methods. This result affects the solar Fe opacity measurements as they also rely on the accuracy of these areal density measurement techniques.</p></div>","PeriodicalId":49267,"journal":{"name":"High Energy Density Physics","volume":"49 ","pages":"Article 101064"},"PeriodicalIF":1.6,"publicationDate":"2023-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S1574181823000307/pdfft?md5=985ad748bad3faeb094a9e63ef90556d&pid=1-s2.0-S1574181823000307-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135705867","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Simulation of dissociation effect at high temperature and high pressure by REMC method","authors":"Mingrui Li ,&nbsp;Na Feng ,&nbsp;Pengfei Gao ,&nbsp;Gang Zhou ,&nbsp;Chunlin Chen ,&nbsp;Bingwen Qian","doi":"10.1016/j.hedp.2023.101068","DOIUrl":"10.1016/j.hedp.2023.101068","url":null,"abstract":"<div><p>Considering the zero-point vibration energy of fluid H₂, the dissociation process of fluid H₂ at different temperatures and densities under 10000 K was studied by using the REMC (reaction ensemble Monte Carlo) method based on classical theory, and the results of different methods were compared and analyzed. The variation of the dissociation degree with temperature predicted by the REMC method is similar to that of the DM method, and the value of the dissociation degree is closest to that of the TB-II method. The dissociation degree of fluid H₂ is less than 38% at 10000 K. According to this REMC method, the fluid D₂ begins to dissociate when the shock pressure reaches 20 GPa. When the shock pressure is 50 GPa, the dissociation degree is 23.88%; At 100 GPa, the dissociation degree is 61.30%. The calculated dissociation value of fluid D₂<span> is lower than that of the QMD method under high temperature and high pressure, while it is in good agreement with the experimental results derived from light gas gun under low temperature and low pressure.</span></p></div>","PeriodicalId":49267,"journal":{"name":"High Energy Density Physics","volume":"49 ","pages":"Article 101068"},"PeriodicalIF":1.6,"publicationDate":"2023-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135656069","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Fast approximation to supershell partition functions: Explicit forms of the coefficients","authors":"Jean-Christophe Pain ,&nbsp;Brian G. Wilson","doi":"10.1016/j.hedp.2023.101065","DOIUrl":"10.1016/j.hedp.2023.101065","url":null,"abstract":"<div><p>In a previous work, we derived a formula for supershell partition functions, which are the cornerstone of the Super-Transition-Array approach to radiative-opacity calculations. The new expression takes the form of a functional of the distribution of energies within the supershell and allows for fast and accurate computations, truncating the number of terms in the expansion. The latter involves coefficients (denoted <span><math><msub><mrow><mi>Γ</mi></mrow><mrow><mi>k</mi></mrow></msub></math></span>) for which we obtained a recursion relation. In the present short paper, as a complement of the previous one, we give an explicit formula for the coefficients <span><math><msub><mrow><mi>Γ</mi></mrow><mrow><mi>k</mi></mrow></msub></math></span>. Another recursion relation is also provided, as well as an alternative expression involving Bell polynomials. The connections with cycle indexes of permutation groups and with elementary symmetric polynomials are outlined.</p></div>","PeriodicalId":49267,"journal":{"name":"High Energy Density Physics","volume":"49 ","pages":"Article 101065"},"PeriodicalIF":1.6,"publicationDate":"2023-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135660807","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}