The interaction between a molecular cloud and an external agent(e.g.,a supernova remnant,plasma jet,radiation,or another cloud)is a common phenomenon throughout the Universe and can significantly change the star forma...The interaction between a molecular cloud and an external agent(e.g.,a supernova remnant,plasma jet,radiation,or another cloud)is a common phenomenon throughout the Universe and can significantly change the star formation rate within a galaxy.This process leads to fragmentation of the cloud and to its subsequent compression and can,eventually,initiate the gravitational collapse of a stable molecular cloud.It is,however,difficult to study such systems in detail using conventional techniques(numerical simulations and astronomical observations),since complex interactions of flows occur.In this paper,we experimentally investigate the compression of a foam ball by Taylor–Sedov blast waves,as an analog of supernova remnants interacting with a molecular cloud.The formation of a compression wave is observed in the foam ball,indicating the importance of such experiments for understanding how star formation is triggered by external agents.展开更多
We have developed a new radiography setup with a short-pulse laser-driven x-ray source. Using a radiography axis perpendicular to both long- and short-pulse lasers allowed optimizing the incident angle of the short-pu...We have developed a new radiography setup with a short-pulse laser-driven x-ray source. Using a radiography axis perpendicular to both long- and short-pulse lasers allowed optimizing the incident angle of the short-pulse laser on the x-ray source target. The setup has been tested with various x-ray source target materials and different laser wavelengths.Signal to noise ratios are presented as well as achieved spatial resolutions. The high quality of our technique is illustrated on a plasma flow radiograph obtained during a laboratory astrophysics experiment on POLARs.展开更多
This article describes the fabrication of a suite of laser targets by the Target Fabrication group in the Central Laser Facility(CLF), STFC Rutherford Appleton Laboratory for the first academic-access experiment on th...This article describes the fabrication of a suite of laser targets by the Target Fabrication group in the Central Laser Facility(CLF), STFC Rutherford Appleton Laboratory for the first academic-access experiment on the Orion laser facility(Hopps et al., Appl. Opt. 52, 3597–3601(2013)) at Atomic Weapons Establishment(AWE). This experiment, part of the POLAR project(Falize et al., Astrophys. Space Sci. 336, 81–85(2011); Busschaert et al., New J. Phys. 15, 035020(2013)),studied conditions relevant to the radiation-hydrodynamic processes occurring in a remarkable class of astrophysical star systems known as magnetic cataclysmic variables. A large number of complex fabrication technologies and research and development activities were required to field a total of 80 high-specification targets. Target design and fabrication procedures are described and initial alignment and characterization data are discussed.展开更多
A new target design is presented to model high-energy radiative accretion shocks in polars. In this paper, we present the experimental results obtained on the GEKKO XII laser facility for the POLAR project. The experi...A new target design is presented to model high-energy radiative accretion shocks in polars. In this paper, we present the experimental results obtained on the GEKKO XII laser facility for the POLAR project. The experimental results are compared with 2 D FCI2 simulations to characterize the dynamics and the structure of plasma flow before and after the collision. The good agreement between simulations and experimental data confirms the formation of a reverse shock where cooling losses start modifying the post-shock region. With the multi-material structure of the target,a hydrodynamic collimation is exhibited and a radiative structure coupled with the reverse shock is highlighted in both experimental data and simulations. The flexibility of the laser energy produced on GEKKO XII allowed us to produce high-velocity flows and study new and interesting radiation hydrodynamic regimes between those obtained on the LULI2000 and Orion laser facilities.展开更多
The influence of a strong external magnetic field on the collimation of a high Mach number plasma flow and its collision with a solid obstacle is investigated experimentally and numerically. The laser irradiation （I ...The influence of a strong external magnetic field on the collimation of a high Mach number plasma flow and its collision with a solid obstacle is investigated experimentally and numerically. The laser irradiation （I - 2 × 10^14 W. cm-2） of a multilayer target generates a shock wave that produces a rear side plasma expanding flow. Immersed in a homogeneous 10 T external magnetic field, this plasma flow propagates in vacuum and impacts an obstacle located a few mm from the main target. A reverse shock is then formed with typical velocities of the order of 15-20 4- 5 km/s. The experimental results are compared with 2D radiative magnetohydrodynamic simulations using the FLASH code. This platform allows investigating the dynamics of reverse shock, mimicking the processes occurring in a cataclysmic variable of polar type.展开更多
基金the support of Investissements d’Avenir of LabEx PALM(Grant No.ANR-10-LABX-0039-PALM)the Ministry of Science and Higher Education of the Russian Federation(Agreement with Joint Institute for High Temperatures RAS No.075-15-2020-785)G.G.acknowledges support from the UK EPSRC(Grant Nos.EP/M022331/1 and EP/N014472/1)。
文摘The interaction between a molecular cloud and an external agent(e.g.,a supernova remnant,plasma jet,radiation,or another cloud)is a common phenomenon throughout the Universe and can significantly change the star formation rate within a galaxy.This process leads to fragmentation of the cloud and to its subsequent compression and can,eventually,initiate the gravitational collapse of a stable molecular cloud.It is,however,difficult to study such systems in detail using conventional techniques(numerical simulations and astronomical observations),since complex interactions of flows occur.In this paper,we experimentally investigate the compression of a foam ball by Taylor–Sedov blast waves,as an analog of supernova remnants interacting with a molecular cloud.The formation of a compression wave is observed in the foam ball,indicating the importance of such experiments for understanding how star formation is triggered by external agents.
基金the support of RFBR grant 14-29-06099Competitiveness Programme of NRNU MEPhI
文摘We have developed a new radiography setup with a short-pulse laser-driven x-ray source. Using a radiography axis perpendicular to both long- and short-pulse lasers allowed optimizing the incident angle of the short-pulse laser on the x-ray source target. The setup has been tested with various x-ray source target materials and different laser wavelengths.Signal to noise ratios are presented as well as achieved spatial resolutions. The high quality of our technique is illustrated on a plasma flow radiograph obtained during a laboratory astrophysics experiment on POLARs.
文摘This article describes the fabrication of a suite of laser targets by the Target Fabrication group in the Central Laser Facility(CLF), STFC Rutherford Appleton Laboratory for the first academic-access experiment on the Orion laser facility(Hopps et al., Appl. Opt. 52, 3597–3601(2013)) at Atomic Weapons Establishment(AWE). This experiment, part of the POLAR project(Falize et al., Astrophys. Space Sci. 336, 81–85(2011); Busschaert et al., New J. Phys. 15, 035020(2013)),studied conditions relevant to the radiation-hydrodynamic processes occurring in a remarkable class of astrophysical star systems known as magnetic cataclysmic variables. A large number of complex fabrication technologies and research and development activities were required to field a total of 80 high-specification targets. Target design and fabrication procedures are described and initial alignment and characterization data are discussed.
基金supported by the‘Programme National de Physique Stellaire’(PNPS)of CNRS/INSU,Francesupported by ANR Blanc grant No.12-BS09-025-01 SILAMPALABEX Plas@Par grant No.11-IDEX-0004-02 from theFrench agency ANR
文摘A new target design is presented to model high-energy radiative accretion shocks in polars. In this paper, we present the experimental results obtained on the GEKKO XII laser facility for the POLAR project. The experimental results are compared with 2 D FCI2 simulations to characterize the dynamics and the structure of plasma flow before and after the collision. The good agreement between simulations and experimental data confirms the formation of a reverse shock where cooling losses start modifying the post-shock region. With the multi-material structure of the target,a hydrodynamic collimation is exhibited and a radiative structure coupled with the reverse shock is highlighted in both experimental data and simulations. The flexibility of the laser energy produced on GEKKO XII allowed us to produce high-velocity flows and study new and interesting radiation hydrodynamic regimes between those obtained on the LULI2000 and Orion laser facilities.
基金funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement No. 654148 LaserlabEuropesupported by RAS Presidium Program for Basic Research #11+1 种基金by Competitiveness Program of NRNU MEPhIsupported by the NNSA-DS and SC-OFES Joint Program in High Energy Density Laboratory Plasmas, grant No. DENA0002956
文摘The influence of a strong external magnetic field on the collimation of a high Mach number plasma flow and its collision with a solid obstacle is investigated experimentally and numerically. The laser irradiation （I - 2 × 10^14 W. cm-2） of a multilayer target generates a shock wave that produces a rear side plasma expanding flow. Immersed in a homogeneous 10 T external magnetic field, this plasma flow propagates in vacuum and impacts an obstacle located a few mm from the main target. A reverse shock is then formed with typical velocities of the order of 15-20 4- 5 km/s. The experimental results are compared with 2D radiative magnetohydrodynamic simulations using the FLASH code. This platform allows investigating the dynamics of reverse shock, mimicking the processes occurring in a cataclysmic variable of polar type.
