Understanding the complex plasma dynamics in ultra-intense relativistic laser-solid interactions is of fundamental importance for applications of laser-plasma-based particle accelerators,the creation of high-energy-de...Understanding the complex plasma dynamics in ultra-intense relativistic laser-solid interactions is of fundamental importance for applications of laser-plasma-based particle accelerators,the creation of high-energy-density matter,understanding planetary science,and laser-driven fusion energy.However,experimental efforts in this regime have been limited by the lack of accessibility of over-critical densities and the poor spatiotemporal resolution of conventional diagnostics.Over the last decade,the advent of femtosecond brilliant hard X-ray free-electron lasers(XFELs)has opened new horizons to overcome these limitations.Here,for the first time,we present full-scale spatiotemporal measurements of solid-density plasma dynamics,including preplasma generation with tens of nanometer scale length driven by the leading edge of a relativistic laser pulse,ultrafast heating and ionization at the main pulse arrival,the laser-driven blast wave,and transient surface return current-induced compression dynamics up to hundreds of picoseconds after interaction.These observations are enabled by utilizing a novel combination of advanced X-ray diagnostics including small-angle X-ray scattering,resonant X-ray emission spectroscopy,and propagation-based X-ray phase-contrast imaging simultaneously at the European XFEL-HED beamline station.展开更多
X-ray free-electron lasers(XFELs)can generate bright X-ray pulses with short durations and narrow bandwidths,leading to extensive applica-tions in many disciplines such as biology,materials science,and ultrafast scien...X-ray free-electron lasers(XFELs)can generate bright X-ray pulses with short durations and narrow bandwidths,leading to extensive applica-tions in many disciplines such as biology,materials science,and ultrafast science.Recently,there has been a growing demand for X-ray pulses with high photon energy,especially from developments in“diffraction-before-destruction”applications and in dynamic mesoscale materials science.Here,we propose utilizing the electron beams at XFELs to drive a meter-scale two-bunch plasma wakefield accelerator and double the energy of the accelerated beam in a compact and inexpensive way.Particle-in-cell simulations are performed to study the beam quality degradation under different beam loading scenarios and nonideal issues,and the results show that more than half of the accelerated beam can meet the requirements of XFELs.After its transport to the undulator,the accelerated beam can improve the photon energy to 22 keV by a factor of around four while maintaining the peak power,thus offering a promising pathway toward high-photon-energy XFELs.展开更多
Fe-based layer with Ti（CxN1-x） particulates on Adamite roller surface was obtained by a 5 kW traverse-flowing CO2 laser cladding technology. The microstructures of the layer were detected by optical microscopy （OM...Fe-based layer with Ti（CxN1-x） particulates on Adamite roller surface was obtained by a 5 kW traverse-flowing CO2 laser cladding technology. The microstructures of the layer were detected by optical microscopy （OM）,X-ray diffraction （XRD）,scanning electron microscopy （SEM）,and electron probe microscopy analysis （EMPA）. The tests of wear resistance was carried out on the test machine. It was seen that a good metallurgical bonding between the coating and the substrate was achieved. The microstructure contains bulky dendritic crystal and small size Ti（CxN1-x） grains that are uniformly distributed in the solid solution matrix. The wear tests showed that the laser coating provided an excellent wear resistance property at room temperature.展开更多
In most collisional schemes of x-ray laser （XRL） experiments, a bow-like intensity distribution of XRL is often observed, and it is generally ascribed to the two-dimensional hydrodynamic behaviour of expanding plasm...In most collisional schemes of x-ray laser （XRL） experiments, a bow-like intensity distribution of XRL is often observed, and it is generally ascribed to the two-dimensional hydrodynamic behaviour of expanding plasma. In order to better understand its essence in physics, a newly developed two-dimensional non-equilibrium radiation hydrodynamic code XRL2D is used to simulate a quasi-steady state Ni-like Ag XRL experiment on ShenGuang-Ⅱfacility. The simulation results show that the bow-like distribution of Ni-like ions caused by over-ionization in the central area of plasma is responsible for the bow-like shape of the XRL intensity distribution observed.展开更多
The Ni-like Ag 13.9 nm x-ray laser has been previously demonstrated that the higher gain near critical surface contributes little to the amplification of the x-ray laser because of severe refraction. In this paper, th...The Ni-like Ag 13.9 nm x-ray laser has been previously demonstrated that the higher gain near critical surface contributes little to the amplification of the x-ray laser because of severe refraction. In this paper, the transient collision excitation （TCE） Ni-like Ag 13.9 nm x-ray laser is simulated, driven by two 3 ps short pulse preceded by a 330 ps long prepulse, optimization of the peak to peak delay time of the two short pulses is made to get the best results. Simulation indicates that by producing lowly ionized preplasma with smoothly varying electron density, it is possible to decrease electron density gradient in higher density region, and thus higher gains near this region could be utilized, and if the main short pulse is delayed by 900ps, local gains where electron density larger than - 4 × 10^20 cm^-3 could be utilized.展开更多
We investigate the Ne-like Cr x-ray laser at 28.6 nm by using a modified ID lagrangian hydrodynamic code MEDI03 coupled with an atomic physics data package and a 2D ray tracing code as a post-processor. The laser pump...We investigate the Ne-like Cr x-ray laser at 28.6 nm by using a modified ID lagrangian hydrodynamic code MEDI03 coupled with an atomic physics data package and a 2D ray tracing code as a post-processor. The laser pumping configuration includes two prepulses and one main pulse. The first prepulse normally irradiates the target, while the second prepulse and the main pulse irradiate the target at grazing-incident angles. We predict that saturation can be achieved for the Ne-like Cr x-ray lasers with a total pumping energy of 125mJ, Good beam qualities with no deflecting angle and a small divergence angle of 5 mrad are observed.展开更多
For experiments such as on Ni-like Ag x-ray laser, driven by 1ω laser, the gain region is only several nm depth near the target surface, this paper proposes a new two-layer target, in which a thin layer （several nm ...For experiments such as on Ni-like Ag x-ray laser, driven by 1ω laser, the gain region is only several nm depth near the target surface, this paper proposes a new two-layer target, in which a thin layer （several nm depth） of silver is plated on the surface of some other materials. Furthermore, the Ni-like Ag 13.9 nm x-ray laser produced by three new kinds of two-layer target with CH, Al and Ge as foundation, was theoretically studied.展开更多
A method of studying a non-equilibrium x-ray laser plasma is developed by extending the existing one-dimensional similarity equations to the case of two-dimensional plasma study in the directions perpendicular to the ...A method of studying a non-equilibrium x-ray laser plasma is developed by extending the existing one-dimensional similarity equations to the case of two-dimensional plasma study in the directions perpendicular to the slab and along a focal line. With this method the characteristics of pre-plasma are optimized for transient neon-like Cr x-ray laser. It is found that when the duration and the intensity of 1.053μm pre-pulse are 1.2 ns and 6.5 TW/cm^2 respectively with a delay time of 1.5 ns, the temperature and the temperature discrepancy each approach a proper state, which will provide a uniform distribution of properly ionized neon-like Cr ions before the arrival of pumping pulse.展开更多
Based on the two-dimensional model, this paper compares the hydrodynamics of slab x-ray laser plasma produced by different nonuniform line focused irradiations. It finds that the average intensity and the duration of ...Based on the two-dimensional model, this paper compares the hydrodynamics of slab x-ray laser plasma produced by different nonuniform line focused irradiations. It finds that the average intensity and the duration of laser pulse and the overall shape of the intensity distribution in the focal line have different influences on the plasma. Calculations show that the evolution of temperature variation is more sensitive to the pulse duration and the electron density variation is more sensitive to the pulse intensity. Pulses with duration of 200 ps to 500 ps and with intensity of 0.2 TW/cm2 to 1.0 TW/cm2 are proved acceptable in slab x-ray lasers.展开更多
A new type of soft X-ray source, i.e. a plasma-based X-ray laser, is found to be promising to conduct transient measurement. By means of picosecond X-ray laser speckles, the dynamic microscopic polarization clusters w...A new type of soft X-ray source, i.e. a plasma-based X-ray laser, is found to be promising to conduct transient measurement. By means of picosecond X-ray laser speckles, the dynamic microscopic polarization clusters within cubic (paraelectric) BaTiO3 was directly observed and characterized in a microscopic scale for the first time. This opens a way to study this type of clusters, which usually manifest large external-field response for ferroelectric materials.展开更多
A simple modified model is presented based on R. A. London＇s self-similarity model on time-independent ionization hydrodynamics of exploding foil X-ray lasers. In our model, the time-dependent ionization effect is un...A simple modified model is presented based on R. A. London＇s self-similarity model on time-independent ionization hydrodynamics of exploding foil X-ray lasers. In our model, the time-dependent ionization effect is under consideration and the average ion charge depends on the temperature. Then we obtain the new scaling laws for temperature, scale length and electron density, which have better agreement with experimental results.展开更多
A new method for micro-beam XRF localiztion is presented.A laser beam along with an incident X-ray hits on the surface of a sample.The micro region on the sample that reached by X-ray beam can be localized by means of...A new method for micro-beam XRF localiztion is presented.A laser beam along with an incident X-ray hits on the surface of a sample.The micro region on the sample that reached by X-ray beam can be localized by means of the visible spot of the laser beam.This method is suitable for X-ray microprobes using an X-ray tube or synchrotron radiation as excitation sources.展开更多
X射线作为一种探测原子尺度物质结构的重要工具,已广泛应用于前沿科学研究、医疗诊断、工业检测等领域。X射线自由电子激光器(X-ray free electron laser,XFEL)作为目前世界上最先进的光源之一,以其超高峰值亮度、飞秒级脉冲和全相干特...X射线作为一种探测原子尺度物质结构的重要工具,已广泛应用于前沿科学研究、医疗诊断、工业检测等领域。X射线自由电子激光器(X-ray free electron laser,XFEL)作为目前世界上最先进的光源之一,以其超高峰值亮度、飞秒级脉冲和全相干特性极大推动了X射线技术的发展与应用。全球众多国家和研究机构正积极推进XFEL设施的建设与技术进步。该文论述了XFEL的基本原理、国际上的研究进展与最新技术突破,以及我国在XFEL技术方面的研究进展,并对我国未来的XFEL技术进行了展望。展开更多
Investigations show that X-ray-boosted photoionization （XBP） has the following advantages for in-situ measurements of ultrahigh laser intensity 1 and field envelope F（t） （time t, pulse duration VL, carrier-envelo...Investigations show that X-ray-boosted photoionization （XBP） has the following advantages for in-situ measurements of ultrahigh laser intensity 1 and field envelope F（t） （time t, pulse duration VL, carrier-envelope-phase Ф）： accuracy, dynamic range, and rapidness. The calculated XBP spectra resemble inversely proportional functions of the photoelectron momentum shift. The maximum momentum p and the observable value Q （defined as a double integration of a normalized photoelectron energy spectrum, PES） linearly depend on I^1/2 and τL, respectively. Ф and F（t） can be determined from the PES cut-off energy and peak positions. The measurable laser intensity can be up to and over 1018 W/cm2 by using high energy X-rays and highly charged inert gases.展开更多
Energy levels, transition probability and oscillator strengths have been calculated for the Ar XIII, Ti XVII and Fe XXI. The configurations included in the calculations are 2s<sup>2</sup> 2p<sup>2<...Energy levels, transition probability and oscillator strengths have been calculated for the Ar XIII, Ti XVII and Fe XXI. The configurations included in the calculations are 2s<sup>2</sup> 2p<sup>2</sup>, 2s<sup>2</sup> 2p 3l (l = s, p & d) and 4l (l = s, p, d, & f) of C-like Ar XIII, Ti XVII & Fe XXI which has 69 fine structures by using the fully relativistic flexible atomic code (FAC) program. These data are used in the determination of the reduced population and gain coefficients over a wide range of electron densities from (10<sup>+18</sup> to 10<sup>+23</sup>) and at various plasmas temperatures. The results show that the transitions in Ar<sup>18+</sup>, Ti<sup>22+</sup>, and Fe<sup>26+</sup> ions are the most promising laser emission lines in the XUV and soft X-ray spectral regions.展开更多
基金funding from Grant No. HIDSS-0002 DASHH (Data Science in Hamburg-Helmholtz Graduate School for the Structure of Matter)partially supported by the Helmholtz Imaging platform through the project “Smart Phase.”
文摘Understanding the complex plasma dynamics in ultra-intense relativistic laser-solid interactions is of fundamental importance for applications of laser-plasma-based particle accelerators,the creation of high-energy-density matter,understanding planetary science,and laser-driven fusion energy.However,experimental efforts in this regime have been limited by the lack of accessibility of over-critical densities and the poor spatiotemporal resolution of conventional diagnostics.Over the last decade,the advent of femtosecond brilliant hard X-ray free-electron lasers(XFELs)has opened new horizons to overcome these limitations.Here,for the first time,we present full-scale spatiotemporal measurements of solid-density plasma dynamics,including preplasma generation with tens of nanometer scale length driven by the leading edge of a relativistic laser pulse,ultrafast heating and ionization at the main pulse arrival,the laser-driven blast wave,and transient surface return current-induced compression dynamics up to hundreds of picoseconds after interaction.These observations are enabled by utilizing a novel combination of advanced X-ray diagnostics including small-angle X-ray scattering,resonant X-ray emission spectroscopy,and propagation-based X-ray phase-contrast imaging simultaneously at the European XFEL-HED beamline station.
基金supported by the National Grand Instrument Project No. SQ2019YFF01014400the Natural Science Foundation of China (Grant Nos. 12375147, 12435011, 12075030)+2 种基金the Beijing Outstanding Young Scientist Project, Project for Young Scientists in Basic Research of Chinese Academy of Sciences (YSBR-115)the Beijing Normal University Scientific Research Initiation Fund for Introducing Talents No. 310432104the Fundamental Research Funds for the Central Universities, Peking University
文摘X-ray free-electron lasers(XFELs)can generate bright X-ray pulses with short durations and narrow bandwidths,leading to extensive applica-tions in many disciplines such as biology,materials science,and ultrafast science.Recently,there has been a growing demand for X-ray pulses with high photon energy,especially from developments in“diffraction-before-destruction”applications and in dynamic mesoscale materials science.Here,we propose utilizing the electron beams at XFELs to drive a meter-scale two-bunch plasma wakefield accelerator and double the energy of the accelerated beam in a compact and inexpensive way.Particle-in-cell simulations are performed to study the beam quality degradation under different beam loading scenarios and nonideal issues,and the results show that more than half of the accelerated beam can meet the requirements of XFELs.After its transport to the undulator,the accelerated beam can improve the photon energy to 22 keV by a factor of around four while maintaining the peak power,thus offering a promising pathway toward high-photon-energy XFELs.
基金Sponsored by Shandong Natural Science Foundation of China (Z2006F07)
文摘Fe-based layer with Ti（CxN1-x） particulates on Adamite roller surface was obtained by a 5 kW traverse-flowing CO2 laser cladding technology. The microstructures of the layer were detected by optical microscopy （OM）,X-ray diffraction （XRD）,scanning electron microscopy （SEM）,and electron probe microscopy analysis （EMPA）. The tests of wear resistance was carried out on the test machine. It was seen that a good metallurgical bonding between the coating and the substrate was achieved. The microstructure contains bulky dendritic crystal and small size Ti（CxN1-x） grains that are uniformly distributed in the solid solution matrix. The wear tests showed that the laser coating provided an excellent wear resistance property at room temperature.
文摘In most collisional schemes of x-ray laser （XRL） experiments, a bow-like intensity distribution of XRL is often observed, and it is generally ascribed to the two-dimensional hydrodynamic behaviour of expanding plasma. In order to better understand its essence in physics, a newly developed two-dimensional non-equilibrium radiation hydrodynamic code XRL2D is used to simulate a quasi-steady state Ni-like Ag XRL experiment on ShenGuang-Ⅱfacility. The simulation results show that the bow-like distribution of Ni-like ions caused by over-ionization in the central area of plasma is responsible for the bow-like shape of the XRL intensity distribution observed.
文摘The Ni-like Ag 13.9 nm x-ray laser has been previously demonstrated that the higher gain near critical surface contributes little to the amplification of the x-ray laser because of severe refraction. In this paper, the transient collision excitation （TCE） Ni-like Ag 13.9 nm x-ray laser is simulated, driven by two 3 ps short pulse preceded by a 330 ps long prepulse, optimization of the peak to peak delay time of the two short pulses is made to get the best results. Simulation indicates that by producing lowly ionized preplasma with smoothly varying electron density, it is possible to decrease electron density gradient in higher density region, and thus higher gains near this region could be utilized, and if the main short pulse is delayed by 900ps, local gains where electron density larger than - 4 × 10^20 cm^-3 could be utilized.
基金supported by the National Natural Science Foundation of China ( Grant Nos 60678007,60621063 and 10774184)the State Key Development Program for Basic Research of China (Grant No 2007CB815101)
文摘We investigate the Ne-like Cr x-ray laser at 28.6 nm by using a modified ID lagrangian hydrodynamic code MEDI03 coupled with an atomic physics data package and a 2D ray tracing code as a post-processor. The laser pumping configuration includes two prepulses and one main pulse. The first prepulse normally irradiates the target, while the second prepulse and the main pulse irradiate the target at grazing-incident angles. We predict that saturation can be achieved for the Ne-like Cr x-ray lasers with a total pumping energy of 125mJ, Good beam qualities with no deflecting angle and a small divergence angle of 5 mrad are observed.
文摘For experiments such as on Ni-like Ag x-ray laser, driven by 1ω laser, the gain region is only several nm depth near the target surface, this paper proposes a new two-layer target, in which a thin layer （several nm depth） of silver is plated on the surface of some other materials. Furthermore, the Ni-like Ag 13.9 nm x-ray laser produced by three new kinds of two-layer target with CH, Al and Ge as foundation, was theoretically studied.
基金Project supported by the National Natural Science Foundation of China (Grant Nos 10474137,10874242 and 10775018)the National Basic Research Program of China (Grant No 2007CB815105)the Specialized Research Fund for the DoctoralProgram of Higher Education of China (Grant No 20070290008)
文摘A method of studying a non-equilibrium x-ray laser plasma is developed by extending the existing one-dimensional similarity equations to the case of two-dimensional plasma study in the directions perpendicular to the slab and along a focal line. With this method the characteristics of pre-plasma are optimized for transient neon-like Cr x-ray laser. It is found that when the duration and the intensity of 1.053μm pre-pulse are 1.2 ns and 6.5 TW/cm^2 respectively with a delay time of 1.5 ns, the temperature and the temperature discrepancy each approach a proper state, which will provide a uniform distribution of properly ionized neon-like Cr ions before the arrival of pumping pulse.
基金suported by the National Natural Science Foundation of China (Grant No. 10874242)the National Basic Research Program of China (973 Program) (Grant No. 2007CB815105)Research Fund for the Doctoral Program of Higher Education of China (Grant No. 20070290008)
文摘Based on the two-dimensional model, this paper compares the hydrodynamics of slab x-ray laser plasma produced by different nonuniform line focused irradiations. It finds that the average intensity and the duration of laser pulse and the overall shape of the intensity distribution in the focal line have different influences on the plasma. Calculations show that the evolution of temperature variation is more sensitive to the pulse duration and the electron density variation is more sensitive to the pulse intensity. Pulses with duration of 200 ps to 500 ps and with intensity of 0.2 TW/cm2 to 1.0 TW/cm2 are proved acceptable in slab x-ray lasers.
文摘A new type of soft X-ray source, i.e. a plasma-based X-ray laser, is found to be promising to conduct transient measurement. By means of picosecond X-ray laser speckles, the dynamic microscopic polarization clusters within cubic (paraelectric) BaTiO3 was directly observed and characterized in a microscopic scale for the first time. This opens a way to study this type of clusters, which usually manifest large external-field response for ferroelectric materials.
基金supported by National Natural Science Foundation of China(Nos.11574390,11374360,41472130)the National Basic Research Program of China(No.2013CBA01504)
文摘A simple modified model is presented based on R. A. London＇s self-similarity model on time-independent ionization hydrodynamics of exploding foil X-ray lasers. In our model, the time-dependent ionization effect is under consideration and the average ion charge depends on the temperature. Then we obtain the new scaling laws for temperature, scale length and electron density, which have better agreement with experimental results.
文摘A new method for micro-beam XRF localiztion is presented.A laser beam along with an incident X-ray hits on the surface of a sample.The micro region on the sample that reached by X-ray beam can be localized by means of the visible spot of the laser beam.This method is suitable for X-ray microprobes using an X-ray tube or synchrotron radiation as excitation sources.
文摘X射线作为一种探测原子尺度物质结构的重要工具,已广泛应用于前沿科学研究、医疗诊断、工业检测等领域。X射线自由电子激光器(X-ray free electron laser,XFEL)作为目前世界上最先进的光源之一,以其超高峰值亮度、飞秒级脉冲和全相干特性极大推动了X射线技术的发展与应用。全球众多国家和研究机构正积极推进XFEL设施的建设与技术进步。该文论述了XFEL的基本原理、国际上的研究进展与最新技术突破,以及我国在XFEL技术方面的研究进展,并对我国未来的XFEL技术进行了展望。
基金supported by the National Natural Science Foundation of China (Grant No. 11175010)
文摘Investigations show that X-ray-boosted photoionization （XBP） has the following advantages for in-situ measurements of ultrahigh laser intensity 1 and field envelope F（t） （time t, pulse duration VL, carrier-envelope-phase Ф）： accuracy, dynamic range, and rapidness. The calculated XBP spectra resemble inversely proportional functions of the photoelectron momentum shift. The maximum momentum p and the observable value Q （defined as a double integration of a normalized photoelectron energy spectrum, PES） linearly depend on I^1/2 and τL, respectively. Ф and F（t） can be determined from the PES cut-off energy and peak positions. The measurable laser intensity can be up to and over 1018 W/cm2 by using high energy X-rays and highly charged inert gases.
文摘Energy levels, transition probability and oscillator strengths have been calculated for the Ar XIII, Ti XVII and Fe XXI. The configurations included in the calculations are 2s<sup>2</sup> 2p<sup>2</sup>, 2s<sup>2</sup> 2p 3l (l = s, p & d) and 4l (l = s, p, d, & f) of C-like Ar XIII, Ti XVII & Fe XXI which has 69 fine structures by using the fully relativistic flexible atomic code (FAC) program. These data are used in the determination of the reduced population and gain coefficients over a wide range of electron densities from (10<sup>+18</sup> to 10<sup>+23</sup>) and at various plasmas temperatures. The results show that the transitions in Ar<sup>18+</sup>, Ti<sup>22+</sup>, and Fe<sup>26+</sup> ions are the most promising laser emission lines in the XUV and soft X-ray spectral regions.
