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 paper describes a model of electron energization and cyclotron-maser emission applicable to astrophysical magnetized collisionless shocks. It is motivated by the work of Begelman, Ergun and Rees [Astrophys. J. 62...This paper describes a model of electron energization and cyclotron-maser emission applicable to astrophysical magnetized collisionless shocks. It is motivated by the work of Begelman, Ergun and Rees [Astrophys. J. 625, 51(2005)] who argued that the cyclotron-maser instability occurs in localized magnetized collisionless shocks such as those expected in blazar jets. We report on recent research carried out to investigate electron acceleration at collisionless shocks and maser radiation associated with the accelerated electrons. We describe how electrons accelerated by lower-hybrid waves at collisionless shocks generate cyclotron-maser radiation when the accelerated electrons move into regions of stronger magnetic fields. The electrons are accelerated along the magnetic field and magnetically compressed leading to the formation of an electron velocity distribution having a horseshoe shape due to conservation of the electron magnetic moment. Under certain conditions the horseshoe electron velocity distribution function is unstable to the cyclotron-maser instability [Bingham and Cairns, Phys. Plasmas 7, 3089(2000); Melrose, Rev. Mod. Plasma Phys. 1, 5(2017)].展开更多
Magnetic field measurements in turbulent plasmas are often difficult to perform. Here we show that for kG magnetic fields, a time-resolved Faraday rotation measurement can be made at the OMEGA laser facility. This dia...Magnetic field measurements in turbulent plasmas are often difficult to perform. Here we show that for kG magnetic fields, a time-resolved Faraday rotation measurement can be made at the OMEGA laser facility. This diagnostic has been implemented using the Thomson scattering probe beam and the resultant path-integrated magnetic field has been compared with that of proton radiography. Accurate measurement of magnetic fields is essential for satisfying the scientific goals of many current laser–plasma experiments.展开更多
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.
基金funding from the Engineering and Physical Sciences Research Council(grant Nos.EP/N014472/1,EP/R004773/1and EP/N013298/1)the Science and Technologies Facilities Council of the United Kingdom.F.C.+2 种基金support from the European Research Council(InPairs ERC-2015-AdG 695088)FCT Portugal(grant No.PD/BD/114307/2016)supported in part at the University of Chicago by the US DOE NNSA ASC through the Argonne Institute for Computing in Science under FWP 57789 and the US DOE Office of Science through grant No.DE-SC0016566
文摘This paper describes a model of electron energization and cyclotron-maser emission applicable to astrophysical magnetized collisionless shocks. It is motivated by the work of Begelman, Ergun and Rees [Astrophys. J. 625, 51(2005)] who argued that the cyclotron-maser instability occurs in localized magnetized collisionless shocks such as those expected in blazar jets. We report on recent research carried out to investigate electron acceleration at collisionless shocks and maser radiation associated with the accelerated electrons. We describe how electrons accelerated by lower-hybrid waves at collisionless shocks generate cyclotron-maser radiation when the accelerated electrons move into regions of stronger magnetic fields. The electrons are accelerated along the magnetic field and magnetically compressed leading to the formation of an electron velocity distribution having a horseshoe shape due to conservation of the electron magnetic moment. Under certain conditions the horseshoe electron velocity distribution function is unstable to the cyclotron-maser instability [Bingham and Cairns, Phys. Plasmas 7, 3089(2000); Melrose, Rev. Mod. Plasma Phys. 1, 5(2017)].
基金funding from the European Research Council under the European Community Seventh Framework Programme(FP7/2007-2013)/ERC grant agreement No.256973the U.S.Department of Energy under Contract No.B591485 to Lawrence Livermore National Laboratory,Field Work Proposal No.57789 to Argonne National Laboratory,grant Nos.DE-NA0002724and DE-SC0016566 to the University of Chicago,and Cooperative Agreement DE-NA0001944 to the Laboratory for Laser Energetics University of Rochester+5 种基金support from the National Science Foundation under grant PHY-1619573supported in part by National Institutes of Health through resources provided by the Computation Institute and the Biological Sciences Division of the University of Chicago and Argonne National Laboratory,under grant S10 RR029030-01the U.S.Department of Energy Innovative and Novel Computational Impact on Theory and Experiment(INCITE)and ASCR Leadership Computing Challenge(ALCC)programmessupported by the Office of Science of the U.S.Department of Energy under contract DE-AC02-06CH11357Support from AWE plc.,the Engineering and Physical Sciences Research Council(grant Nos.EP/M022331/1 and EP/N014472/1)the Science and Technology Facilities Council of the United Kingdom is acknowledged
文摘Magnetic field measurements in turbulent plasmas are often difficult to perform. Here we show that for kG magnetic fields, a time-resolved Faraday rotation measurement can be made at the OMEGA laser facility. This diagnostic has been implemented using the Thomson scattering probe beam and the resultant path-integrated magnetic field has been compared with that of proton radiography. Accurate measurement of magnetic fields is essential for satisfying the scientific goals of many current laser–plasma experiments.
