Directed x-rays produced in the interaction of sub-picosecond laser pulses of moderate relativistic intensity with plasma of near-critical density are investigated. Synchrotron-like (betatron) radiation occurs in the ...Directed x-rays produced in the interaction of sub-picosecond laser pulses of moderate relativistic intensity with plasma of near-critical density are investigated. Synchrotron-like (betatron) radiation occurs in the process of direct laser acceleration (DLA) of electrons in a relativisticlaser channel when the electrons undergo transverse betatron oscillations in self-generated quasi-static electric and magnetic fields. In anexperiment at the PHELIX laser system, high-current directed beams of DLA electrons with a mean energy ten times higher than the ponderomotive potential and maximum energy up to 100 MeV were measured at 10^(19) W/cm^(2)laser intensity. The spectrum of directed x-raysin the range of 5–60 keV was evaluated using two sets of Ross filters placed at 0°and 10°to the laser pulse propagation axis. The differential x-ray absorption method allowed for absolute measurements of the angular-dependent photon fluence. We report 10^(13) photons/sr withenergies >5 keV measured at 0°to the laser axis and a brilliance of 10^(21) photons s^(−1) mm^(−2) mrad−2(0.1%BW)−1. The angular distributionof the emission has an FWHM of 14°–16°. Thanks to the ultra-high photon fluence, point-like radiation source, and ultra-short emissiontime, DLA-based keV backlighters are promising for various applications in high-energy-density research with kilojoule petawatt-class laserfacilities.展开更多
Large-amplitude electromagnetic radiofrequency fields are created by the charge-separation induced in interactions of high-intensity,short-pulse lasers with solid targets and have intensity that decreases with the dis...Large-amplitude electromagnetic radiofrequency fields are created by the charge-separation induced in interactions of high-intensity,short-pulse lasers with solid targets and have intensity that decreases with the distance from the target.Alternatively,it was experimentally proved very recently that charged particles emitted by petawatt laser±target interactions can be deposited on a capacitor-collector structure,far away from the target,and lead to the rapid(nanosecond-scale)generation of large quasi-static electric fields(MV/m),over wide regions.We demonstrate here the generation of both these fields in experiments at the PHELIX laser facility,with approximately 20 J energy and approximately 10^(19)W/cm^(2)intensity,for picoseconds laser pulses,interacting with pre-ionized polymer foams of near critical density.Quasi-static fields,up to tens of k V/m,were here observed at distances larger than 1 m from the target,with results much higher than the radiofrequency component.This is of primary importance for inertial-confinement fusion and laser±plasma acceleration and also for promising applications in different scenarios.展开更多
基金supported by the Czech Ministry of Education,Youth and Sports(Project No.CZ.02.2.69/0.0/0.0/18_053/0016980)the Grant Agency of the Czech Republic(Grant No.GM23-05027M).
文摘Directed x-rays produced in the interaction of sub-picosecond laser pulses of moderate relativistic intensity with plasma of near-critical density are investigated. Synchrotron-like (betatron) radiation occurs in the process of direct laser acceleration (DLA) of electrons in a relativisticlaser channel when the electrons undergo transverse betatron oscillations in self-generated quasi-static electric and magnetic fields. In anexperiment at the PHELIX laser system, high-current directed beams of DLA electrons with a mean energy ten times higher than the ponderomotive potential and maximum energy up to 100 MeV were measured at 10^(19) W/cm^(2)laser intensity. The spectrum of directed x-raysin the range of 5–60 keV was evaluated using two sets of Ross filters placed at 0°and 10°to the laser pulse propagation axis. The differential x-ray absorption method allowed for absolute measurements of the angular-dependent photon fluence. We report 10^(13) photons/sr withenergies >5 keV measured at 0°to the laser axis and a brilliance of 10^(21) photons s^(−1) mm^(−2) mrad−2(0.1%BW)−1. The angular distributionof the emission has an FWHM of 14°–16°. Thanks to the ultra-high photon fluence, point-like radiation source, and ultra-short emissiontime, DLA-based keV backlighters are promising for various applications in high-energy-density research with kilojoule petawatt-class laserfacilities.
基金funding from the Euratom research and training programs 2014-2018 and 2019-2020 under grant agreement No.633053funding from LASERLAB EUROPE(grant agreement No.654148,European Union’s Horizon 2020 research and innovation program)supported by the Ministry of Science and Higher Education of the Russian Federation(Agreement with Joint Institute for High Temperatures RAS No.075-15-2020-785,dated September 23,2020)。
文摘Large-amplitude electromagnetic radiofrequency fields are created by the charge-separation induced in interactions of high-intensity,short-pulse lasers with solid targets and have intensity that decreases with the distance from the target.Alternatively,it was experimentally proved very recently that charged particles emitted by petawatt laser±target interactions can be deposited on a capacitor-collector structure,far away from the target,and lead to the rapid(nanosecond-scale)generation of large quasi-static electric fields(MV/m),over wide regions.We demonstrate here the generation of both these fields in experiments at the PHELIX laser facility,with approximately 20 J energy and approximately 10^(19)W/cm^(2)intensity,for picoseconds laser pulses,interacting with pre-ionized polymer foams of near critical density.Quasi-static fields,up to tens of k V/m,were here observed at distances larger than 1 m from the target,with results much higher than the radiofrequency component.This is of primary importance for inertial-confinement fusion and laser±plasma acceleration and also for promising applications in different scenarios.
