We have used the ShenguangⅡlaser in third harmonic(351 nm)to investigate the emission of L-shell radiation in the 3.3–4.4 ke V range generated using thin foils of Sn coated onto a parylene substrate with irradiation...We have used the ShenguangⅡlaser in third harmonic(351 nm)to investigate the emission of L-shell radiation in the 3.3–4.4 ke V range generated using thin foils of Sn coated onto a parylene substrate with irradiation of order 1015 W cm-2 and nanosecond pulse duration.In our experiment,we have concentrated on assessing the emission on the non-laser irradiated side as this allows an experimental geometry relevant to experiments on photo-ionised plasmas where a secondary target must be placed close to the source,to achieve x-ray fluxes appropriate to astrophysical objects.Overall L-shell conversion efficiencies are estimated to be of order 1%,with little dependence on Sn thickness between 400 and 800 nm.展开更多
The specific angular momenta(j_(t))of stars,baryons as a whole and dark matter halos contain clues of vital importance about how galaxies form and evolve.Using a sample of 70 spiral galaxies,we perform a preliminary a...The specific angular momenta(j_(t))of stars,baryons as a whole and dark matter halos contain clues of vital importance about how galaxies form and evolve.Using a sample of 70 spiral galaxies,we perform a preliminary analysis of j_t,and introduce a new quantity,e.g.,areal density of angular momentum(ADAM)(j_(t)M_(*)/(2R_(d))^(2))as an indication for the existence of jet(s)in spiral galaxies.The percentage of spiral galaxies having jet(s)shows a strong correlation with ADAM,although the present sample is incomplete.展开更多
As a promising new way to generate a controllable strong magnetic field, laser-driven magnetic coils have attracted interest in many research fields. In 2013, a kilotesla level magnetic field was achieved at the Gekko...As a promising new way to generate a controllable strong magnetic field, laser-driven magnetic coils have attracted interest in many research fields. In 2013, a kilotesla level magnetic field was achieved at the Gekko XII laser facility with a capacitor-coil target. A similar approach has been adopted in a number of laboratories, with a variety of targets of different shapes. The peak strength of the magnetic field varies from a few tesla to kilotesla, with different spatio- temporal ranges. The differences are determined by the target geometry and the parameters of the incident laser. Here we present a review of the results of recent experimental studies of laser-driven magnetic field generation, as well as a discussion of the diagnostic techniques required for such rapidly changing magnetic fields. As an extension of the magnetic field generation, some applications are discussed.展开更多
Astrophysical collisionless shocks are amazing phenomena in space and astrophysical plasmas, where supersonic flows generate electromagnetic fields through instabilities and particles can be accelerated to high energy...Astrophysical collisionless shocks are amazing phenomena in space and astrophysical plasmas, where supersonic flows generate electromagnetic fields through instabilities and particles can be accelerated to high energy cosmic rays. Until now, understanding these micro-processes is still a challenge despite rich astrophysical observation data have been obtained. Laboratory astrophysics, a new route to study the astrophysics, allows us to investigate them at similar extreme physical conditions in laboratory. Here we will review the recent progress of the collisionless shock experiments performed at SG-II laser facility in China. The evolution of the electrostatic shocks and Weibel-type/filamentation instabilities are observed. Inspired by the configurations of the counter-streaming plasma flows, we also carry out a novel plasma collider to generate energetic neutrons relevant to the astrophysical nuclear reactions.展开更多
In this paper, we present a reanalysis of the silicon He-α X-ray spectrum emission in Fujioka et al.’s 2009 photoionization experiment. The computations were performed with our radiative-collisional code, RCF. The c...In this paper, we present a reanalysis of the silicon He-α X-ray spectrum emission in Fujioka et al.’s 2009 photoionization experiment. The computations were performed with our radiative-collisional code, RCF. The central ingredients of our computations are accurate atomic data, inclusion of satellite lines from doubly excited states and accounting for the reabsorption of the emitted photons on their way to the spectrometer. With all these elements included, the simulated spectrum turns out to be in good agreement with the experimental spectrum.展开更多
We present laboratory measurement and theoretical analysis of silicon K-shell lines in plasmas produced by Shenguang II laser facility, and discuss the application of line ratios to diagnose the electron density and t...We present laboratory measurement and theoretical analysis of silicon K-shell lines in plasmas produced by Shenguang II laser facility, and discuss the application of line ratios to diagnose the electron density and temperature of laser plasmas.Two types of shots were carried out to interpret silicon plasma spectra under two conditions, and the spectra from 6.6 ?A to6.85 ?A were measured. The radiative-collisional code based on the flexible atomic code(RCF) is used to identify the lines, and it also well simulates the experimental spectra. Satellite lines, which are populated by dielectron capture and large radiative decay rate, influence the spectrum profile significantly. Because of the blending of lines, the traditional G value and R value are not applicable in diagnosing electron temperature and density of plasma. We take the contribution of satellite lines into the calculation of line ratios of He-α lines, and discuss their relations with the electron temperature and density.展开更多
We present a parameter estimate for continua, and He-like triplets of the high resolution X-ray spectra with a Bayesian inference and a Markov Chain Monte Carlo(MCMC) tool. The method is applied for Vela X-1 with thre...We present a parameter estimate for continua, and He-like triplets of the high resolution X-ray spectra with a Bayesian inference and a Markov Chain Monte Carlo(MCMC) tool. The method is applied for Vela X-1 with three different orbital phases(φ), Eclipse, φ = 0.25, and φ = 0.5, which are adopted from the Chandra High-Energy Transmission Grating Spectrometer(HETGS). A parameterized two-component power-law model [Sako et al., Astrophys. J. 525, 921(1999)] and a multi-Gaussian model are applied to model these continua and He-like triplets, respectively. A uniform distribution over each parameter is used as the prior belief. Posterior probability distribution functions of parameters and the covariances among them are explored by using the MCMC method. The main advantages are(i) all model-based parameters are set to be free instead of artificially fixing some of the parameters during the data-model fitting;(ii) the contributions from satellite lines are considered;(iii) backgrounds are treated as a correction to the observation errors;and(iv) the confidence interval of each parameter is given. The fitted results show that the column density of scatter component(N_H^(scat)) varies from phase to phase, which imply a non-spherical structure of the stellar wind in Vela X-1.Moreover, the wind velocities derived from main lines of each set of He-like triplets show better self-consistency than those in previous publications, which could provide a reliable approach for the diagnostics of photoionized plasma in astrophysical objects and the laboratory.展开更多
基金supported by the UK Science and Technology Facilities Council,National Natural Science Foundation of China(No.11573040)Science Challenge Project(No.TZ2016005)The Royal Society International Exchange(No.IE161039).
文摘We have used the ShenguangⅡlaser in third harmonic(351 nm)to investigate the emission of L-shell radiation in the 3.3–4.4 ke V range generated using thin foils of Sn coated onto a parylene substrate with irradiation of order 1015 W cm-2 and nanosecond pulse duration.In our experiment,we have concentrated on assessing the emission on the non-laser irradiated side as this allows an experimental geometry relevant to experiments on photo-ionised plasmas where a secondary target must be placed close to the source,to achieve x-ray fluxes appropriate to astrophysical objects.Overall L-shell conversion efficiencies are estimated to be of order 1%,with little dependence on Sn thickness between 400 and 800 nm.
基金supported by the National Natural Science Foundation of China(NSFC,grant Nos.11988101 and 12073043)National Key Research and Development Program of China No.2019YFA0405500the support from CAS Project for Young Scientists in Basic Research grant No.YSBR-062。
文摘The specific angular momenta(j_(t))of stars,baryons as a whole and dark matter halos contain clues of vital importance about how galaxies form and evolve.Using a sample of 70 spiral galaxies,we perform a preliminary analysis of j_t,and introduce a new quantity,e.g.,areal density of angular momentum(ADAM)(j_(t)M_(*)/(2R_(d))^(2))as an indication for the existence of jet(s)in spiral galaxies.The percentage of spiral galaxies having jet(s)shows a strong correlation with ADAM,although the present sample is incomplete.
基金supported in part by the Science Challenge Project(No.TZ2016005)the CAS-JSPS Joint Research Program(External Cooperation Program of the BIC,Chinese Academy of Sciences,No.112111KYSB20160015)+1 种基金the National Natural Science Foundation of China(Nos.11520101003,11535001 and11861121001)the Strategic Priority Research Program of the Chinese Academy of Sciences(Nos.XDB16010200 and XDB07030300)
文摘As a promising new way to generate a controllable strong magnetic field, laser-driven magnetic coils have attracted interest in many research fields. In 2013, a kilotesla level magnetic field was achieved at the Gekko XII laser facility with a capacitor-coil target. A similar approach has been adopted in a number of laboratories, with a variety of targets of different shapes. The peak strength of the magnetic field varies from a few tesla to kilotesla, with different spatio- temporal ranges. The differences are determined by the target geometry and the parameters of the incident laser. Here we present a review of the results of recent experimental studies of laser-driven magnetic field generation, as well as a discussion of the diagnostic techniques required for such rapidly changing magnetic fields. As an extension of the magnetic field generation, some applications are discussed.
基金supported by the Science Challenge Project (No. TZ2016005)the National Basic Program of China (No. 2013CBA01501/03)+2 种基金the National Natural Science Foundation of China (Nos. 11503041, 11522326, 11622323, and 11573040)the Strategic Priority Research Program of the Chinese Academy of Sciences (Nos. XDB16010200 and XDB07030300)the Project Funded by China Postdoctoral Science Foundation (No. 2015M571124)
文摘Astrophysical collisionless shocks are amazing phenomena in space and astrophysical plasmas, where supersonic flows generate electromagnetic fields through instabilities and particles can be accelerated to high energy cosmic rays. Until now, understanding these micro-processes is still a challenge despite rich astrophysical observation data have been obtained. Laboratory astrophysics, a new route to study the astrophysics, allows us to investigate them at similar extreme physical conditions in laboratory. Here we will review the recent progress of the collisionless shock experiments performed at SG-II laser facility in China. The evolution of the electrostatic shocks and Weibel-type/filamentation instabilities are observed. Inspired by the configurations of the counter-streaming plasma flows, we also carry out a novel plasma collider to generate energetic neutrons relevant to the astrophysical nuclear reactions.
基金supported by the Science Challenge Project(No.TZ2016005)the National Natural Science Foundation of China(Nos.11903006,12073043 and U1930108)the Strategic Priority Research Program of Chinese Academy of Sciences(No.XDA25030700)。
文摘In this paper, we present a reanalysis of the silicon He-α X-ray spectrum emission in Fujioka et al.’s 2009 photoionization experiment. The computations were performed with our radiative-collisional code, RCF. The central ingredients of our computations are accurate atomic data, inclusion of satellite lines from doubly excited states and accounting for the reabsorption of the emitted photons on their way to the spectrometer. With all these elements included, the simulated spectrum turns out to be in good agreement with the experimental spectrum.
基金supported by the Science Challenge Project(No.TZ2016005)the National Basic Research Program of China(No.2013CBA01503)+1 种基金the National Natural Science Foundation of China(Nos.10905004,11220101002,and11622323)the Fundamental Research Funds for the Central Universities
文摘We present laboratory measurement and theoretical analysis of silicon K-shell lines in plasmas produced by Shenguang II laser facility, and discuss the application of line ratios to diagnose the electron density and temperature of laser plasmas.Two types of shots were carried out to interpret silicon plasma spectra under two conditions, and the spectra from 6.6 ?A to6.85 ?A were measured. The radiative-collisional code based on the flexible atomic code(RCF) is used to identify the lines, and it also well simulates the experimental spectra. Satellite lines, which are populated by dielectron capture and large radiative decay rate, influence the spectrum profile significantly. Because of the blending of lines, the traditional G value and R value are not applicable in diagnosing electron temperature and density of plasma. We take the contribution of satellite lines into the calculation of line ratios of He-α lines, and discuss their relations with the electron temperature and density.
基金supported by the Science Challenge Project(No.TZ2016005)the National Natural Science Foundation of China(NSFC)(Nos.11573040,11773033,11390371/2,and 11233004)support from the Recruitment Program of Global Youth Experts of China
文摘We present a parameter estimate for continua, and He-like triplets of the high resolution X-ray spectra with a Bayesian inference and a Markov Chain Monte Carlo(MCMC) tool. The method is applied for Vela X-1 with three different orbital phases(φ), Eclipse, φ = 0.25, and φ = 0.5, which are adopted from the Chandra High-Energy Transmission Grating Spectrometer(HETGS). A parameterized two-component power-law model [Sako et al., Astrophys. J. 525, 921(1999)] and a multi-Gaussian model are applied to model these continua and He-like triplets, respectively. A uniform distribution over each parameter is used as the prior belief. Posterior probability distribution functions of parameters and the covariances among them are explored by using the MCMC method. The main advantages are(i) all model-based parameters are set to be free instead of artificially fixing some of the parameters during the data-model fitting;(ii) the contributions from satellite lines are considered;(iii) backgrounds are treated as a correction to the observation errors;and(iv) the confidence interval of each parameter is given. The fitted results show that the column density of scatter component(N_H^(scat)) varies from phase to phase, which imply a non-spherical structure of the stellar wind in Vela X-1.Moreover, the wind velocities derived from main lines of each set of He-like triplets show better self-consistency than those in previous publications, which could provide a reliable approach for the diagnostics of photoionized plasma in astrophysical objects and the laboratory.
