Laser irradiation of solid targets can drive short and high-charge relativistic electron bunches over micron-scale acceleration gradients.However,for a long time,this technique was not considered a viable means of ele...Laser irradiation of solid targets can drive short and high-charge relativistic electron bunches over micron-scale acceleration gradients.However,for a long time,this technique was not considered a viable means of electron acceleration due to the large intrinsic divergence(∼50°half-angle)of the electrons.Recently,a reduction in this divergence to 10°–20°half-angle has been obtained,using plasma-based magnetic fields or very high contrast laser pulses to extract the electrons into the vacuum.Here we show that we can further improve the electron beam collimation,down to∼1.5°half-angle,of a high-charge(6 nC)beam,and in a highly reproducible manner,while using standard stand-alone 100 TW-class laser pulses.This is obtained by embedding the laser-target interaction in an external,large-scale(cm),homogeneous,extremely stable,and high-strength(20 T)magnetic field that is independent of the laser.With upcoming multi-PW,high repetition-rate lasers,this technique opens the door to achieving even higher charges(>100 nC).展开更多
With the latest configuration,the Ti:Sa laser system ARCTURUS(Düsseldorf University,Germany)operates with a double-chirped pulse amplification(CPA)architecture delivering pulses with an energy of 7 J before compr...With the latest configuration,the Ti:Sa laser system ARCTURUS(Düsseldorf University,Germany)operates with a double-chirped pulse amplification(CPA)architecture delivering pulses with an energy of 7 J before compression in each of the two high-power beams.By the implementation of a plasma mirror system,the intrinsic laser contrast is enhanced up to 10^-12 on a time scale of hundreds of picoseconds,before the main peak.The laser system has been used in various configurations for advanced experiments and different studies have been carried out employing the high-power laser beams as a single,high-intensity interaction beam(I≈1020 W/cm^2),in dual-and multi-beam configurations or in a pump–probe arrangement.展开更多
Engineered targets are expected to play a key role in future high-power laser experiments calling for joined, extensive knowledge in materials properties, engineering techniques and plasma physics. In this work, we pr...Engineered targets are expected to play a key role in future high-power laser experiments calling for joined, extensive knowledge in materials properties, engineering techniques and plasma physics. In this work, we propose a novel patterning procedure of self-supported 10 μm thick Au and Cu foils for obtaining micrometre-sized periodic gratings as targets for high-power laser applications. Accessible techniques were considered, by using cold rolling, electronbeam lithography and the Ar-ion milling process. The developed patterning procedure allows efficient control of the grating and foil surface on large area. Targets consisting of patterned regions of 450 μm × 450 μm, with 2 μm periodic gratings, were prepared on 25 mm × 25 mm Au and Cu free-standing foils, and preliminary investigations of the microtargets interacting with an ultrashort, relativistic laser pulse were performed. These test experiments demonstrated that,in certain conditions, the micro-gratings show enhanced laser energy absorption and higher efficiency in accelerating charge particle beams compared with planar thin foils of similar thickness.展开更多
The process of high energy electron acceleration along the surface of grating targets(GTs)that were irradiated by a relativistic,high-contrast laser pulse at an intensity I=2.5×10^20 W/cm^2 was studied.Our experi...The process of high energy electron acceleration along the surface of grating targets(GTs)that were irradiated by a relativistic,high-contrast laser pulse at an intensity I=2.5×10^20 W/cm^2 was studied.Our experimental results demonstrate that for a GT with a periodicity twice the laser wavelength,the surface electron flux is more intense for a laser incidence angle that is larger compared to the resonance angle predicted by the linear model.An electron beam with a peak charge of∼2.7 nC/sr,for electrons with energies>1.5 MeV,was measured.Numerical simulations carried out with parameters similar to the experimental conditions also show an enhanced electron flux at higher incidence angles depending on the preplasma scale length.A theoretical model that includes ponderomotive effects with more realistic initial preplasma conditions suggests that the laser-driven intensity and preformed plasma scale length are important for the acceleration process.The predictions closely match the experimental and computational results.展开更多
基金supported by Grant Nos.11-IDEX-0004-02 and ANR-17-CE30-0026-Pinnacle from Agence Nationale de la Recherchethe European Union’s Horizon 2020 research and innovation program under Grant Agreement No.654148 Laserlab-Europe+3 种基金the European Research Council(ERC)under the European Union’s Horizon 2020 research and innovation program(Grant Agreement No.787539)This work was supported by the Ministry of Education and Science of the Russian Federation under Contract No.14.Z50.31.0007The work of JIHT RAS team was done under financial support of the Russian Science Foundation(Grant No.17-72-20272)The research leading to these results is supported by Extreme Light Infrastructure Nuclear Physics(ELI-NP)Phase I,a project co-financed by the Romanian Government and European Union through the European Regional Development Fund.
文摘Laser irradiation of solid targets can drive short and high-charge relativistic electron bunches over micron-scale acceleration gradients.However,for a long time,this technique was not considered a viable means of electron acceleration due to the large intrinsic divergence(∼50°half-angle)of the electrons.Recently,a reduction in this divergence to 10°–20°half-angle has been obtained,using plasma-based magnetic fields or very high contrast laser pulses to extract the electrons into the vacuum.Here we show that we can further improve the electron beam collimation,down to∼1.5°half-angle,of a high-charge(6 nC)beam,and in a highly reproducible manner,while using standard stand-alone 100 TW-class laser pulses.This is obtained by embedding the laser-target interaction in an external,large-scale(cm),homogeneous,extremely stable,and high-strength(20 T)magnetic field that is independent of the laser.With upcoming multi-PW,high repetition-rate lasers,this technique opens the door to achieving even higher charges(>100 nC).
基金supported by the DFG Transregio SFB/TR18 and GRK 1203 programs
文摘With the latest configuration,the Ti:Sa laser system ARCTURUS(Düsseldorf University,Germany)operates with a double-chirped pulse amplification(CPA)architecture delivering pulses with an energy of 7 J before compression in each of the two high-power beams.By the implementation of a plasma mirror system,the intrinsic laser contrast is enhanced up to 10^-12 on a time scale of hundreds of picoseconds,before the main peak.The laser system has been used in various configurations for advanced experiments and different studies have been carried out employing the high-power laser beams as a single,high-intensity interaction beam(I≈1020 W/cm^2),in dual-and multi-beam configurations or in a pump–probe arrangement.
基金supported by the ELI-NP Phase Ⅱ project,co-financed by the Romanian Government and the European Union through the European Regional Development Fund-the Competitiveness Operational Programme(contract No.1/07.07.2016,COP,ID 1334)Funding from the National Program‘Installations and Strategic Objectives of National Interest’and‘Nucleu’project PN19060105 of the Romanian Governmentfunding from the European Union Framework Programme for Research and Innovation Horizon 2020 under grant agreement No.871161.
文摘Engineered targets are expected to play a key role in future high-power laser experiments calling for joined, extensive knowledge in materials properties, engineering techniques and plasma physics. In this work, we propose a novel patterning procedure of self-supported 10 μm thick Au and Cu foils for obtaining micrometre-sized periodic gratings as targets for high-power laser applications. Accessible techniques were considered, by using cold rolling, electronbeam lithography and the Ar-ion milling process. The developed patterning procedure allows efficient control of the grating and foil surface on large area. Targets consisting of patterned regions of 450 μm × 450 μm, with 2 μm periodic gratings, were prepared on 25 mm × 25 mm Au and Cu free-standing foils, and preliminary investigations of the microtargets interacting with an ultrashort, relativistic laser pulse were performed. These test experiments demonstrated that,in certain conditions, the micro-gratings show enhanced laser energy absorption and higher efficiency in accelerating charge particle beams compared with planar thin foils of similar thickness.
基金Computational support and infrastructure were provided by the Centre for Information and Media Technology(ZIM)of the University of Dusseldorf(Germany).
文摘The process of high energy electron acceleration along the surface of grating targets(GTs)that were irradiated by a relativistic,high-contrast laser pulse at an intensity I=2.5×10^20 W/cm^2 was studied.Our experimental results demonstrate that for a GT with a periodicity twice the laser wavelength,the surface electron flux is more intense for a laser incidence angle that is larger compared to the resonance angle predicted by the linear model.An electron beam with a peak charge of∼2.7 nC/sr,for electrons with energies>1.5 MeV,was measured.Numerical simulations carried out with parameters similar to the experimental conditions also show an enhanced electron flux at higher incidence angles depending on the preplasma scale length.A theoretical model that includes ponderomotive effects with more realistic initial preplasma conditions suggests that the laser-driven intensity and preformed plasma scale length are important for the acceleration process.The predictions closely match the experimental and computational results.