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
Z-pinch experiments with a hybrid configuration of a deuterium gas puff have been carried out on theHAWK(NRL,Washington,DC)and GIT-12(IHCE,Tomsk)pulsed power generators at 0.7 MA and 3MA currents,respectively.On GIT-1...Z-pinch experiments with a hybrid configuration of a deuterium gas puff have been carried out on theHAWK(NRL,Washington,DC)and GIT-12(IHCE,Tomsk)pulsed power generators at 0.7 MA and 3MA currents,respectively.On GIT-12,neutron yields reached an average value of 231012 neutrons,and deuterons were accelerated up to an energy of 30 MeV.This was 50 times the ion energy provided by the generator driving voltage of 0.6 MV and the highest energy observed in z-pinches and dense plasma foci.To confirm these unique results independently on another device,we performed several experimental campaigns on theHAWKgenerator.Comparison of the experiments onGIT-12 andHAWKhelped us to understand which parameters are essential for optimized neutron production.Since theHAWKgenerator is of a similar pulsed power architecture as GIT-12,the experiments on GIT-12 and HAWK are important for the study of how charged-particle acceleration scales with the current.展开更多
The paper discusses a possible energy transformation that leads to the acceleration of fast ions and electrons.In plasma-focus discharges that occur during deuteriumfilling,which have amaximumcurrent of about 1MA,the ...The paper discusses a possible energy transformation that leads to the acceleration of fast ions and electrons.In plasma-focus discharges that occur during deuteriumfilling,which have amaximumcurrent of about 1MA,the accelerated deuterons produce fast fusion neutrons and fast electrons hard X-ray emissions.Their total energy,which is of the order of several kilojoules,can be delivered by the discharge through a magnetic dynamo and selforganization to the ordered plasma structures that are formed in a pinch during the several hundreds of nanoseconds of the pinch implosion,stagnation,and evolution of instabilities.This energy is finally released during the decay of the ordered plasma structures in the volume between the anode face and the umbrella front of the plasma and current sheath in the form of induced electric fields that accelerate fast electrons and ions.展开更多
The laser system PALS,as a driver of a broad-beam ion source,delivered deuterons which generated neutrons with energies higher than 14 Me V through the 7Li(d,n)8 Be reaction.Deuterons with sub-Me V energy were acceler...The laser system PALS,as a driver of a broad-beam ion source,delivered deuterons which generated neutrons with energies higher than 14 Me V through the 7Li(d,n)8 Be reaction.Deuterons with sub-Me V energy were accelerated from the front surface of a massive CD2 target in the backward direction with respect to the laser beam vector.Simultaneously,neutrons were emitted from the primary CD2 target and a secondary Li F catcher.The total maximum measured neutron yield from 2D(d,n)3He,7Li(d,n)8Be,12C(d,n)13N reactions was ～3.5(±0.5) × 108 neutrons/shot.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The authors are grateful toA.Yu.Labetsky and B.J.Sobocinski for their help with the experiments on GIT-12 and HAWK,respectively.This research has been supported by the Grant Agency of the Czech Republic(Grant No.19-02545S)the Czech Ministry of Education(Grant Nos.LTT17015,LTAUSA17084,and CZ.02.1.01/0.0/0.0/16_019/0000778)+1 种基金the Czech Technical University in Prague(Grant No.SGS19/167/OHK3/3T/13)the Naval Research Laboratory Base Program,and a TPU Competitiveness Enhancement Program grant.
文摘Z-pinch experiments with a hybrid configuration of a deuterium gas puff have been carried out on theHAWK(NRL,Washington,DC)and GIT-12(IHCE,Tomsk)pulsed power generators at 0.7 MA and 3MA currents,respectively.On GIT-12,neutron yields reached an average value of 231012 neutrons,and deuterons were accelerated up to an energy of 30 MeV.This was 50 times the ion energy provided by the generator driving voltage of 0.6 MV and the highest energy observed in z-pinches and dense plasma foci.To confirm these unique results independently on another device,we performed several experimental campaigns on theHAWKgenerator.Comparison of the experiments onGIT-12 andHAWKhelped us to understand which parameters are essential for optimized neutron production.Since theHAWKgenerator is of a similar pulsed power architecture as GIT-12,the experiments on GIT-12 and HAWK are important for the study of how charged-particle acceleration scales with the current.
基金supported in part by research programs funded by Grant Nos.MSMT LTT17015,LTAUSA17084,CZ.02.1.01/0.0/0.0/16_019/0000778,GACR 19-02545S,PPN/BIL/2018/00133/U/00001,IAEA CRP 23071,CRP 23225,and SGS 19/167/OHK3/3T/13by the Polish Ministry of Science and Higher Education using the financial resources allocated in 2019 for international cofinanced projects.
文摘The paper discusses a possible energy transformation that leads to the acceleration of fast ions and electrons.In plasma-focus discharges that occur during deuteriumfilling,which have amaximumcurrent of about 1MA,the accelerated deuterons produce fast fusion neutrons and fast electrons hard X-ray emissions.Their total energy,which is of the order of several kilojoules,can be delivered by the discharge through a magnetic dynamo and selforganization to the ordered plasma structures that are formed in a pinch during the several hundreds of nanoseconds of the pinch implosion,stagnation,and evolution of instabilities.This energy is finally released during the decay of the ordered plasma structures in the volume between the anode face and the umbrella front of the plasma and current sheath in the form of induced electric fields that accelerate fast electrons and ions.
基金funding from the Czech Science Foundation (Grant No.P205/12/0454)the Czech Republic’s Ministry of Education,Youth and Sports (Project No.LM2010014)+2 种基金LASERLAB-EUROPE (grant agreement no 284464,EC’s Seventh Framework Programme)the European Social Fundstate budget of the Czech Republic (Project No.CZ.1.07/2.3.00/20.0279)
文摘The laser system PALS,as a driver of a broad-beam ion source,delivered deuterons which generated neutrons with energies higher than 14 Me V through the 7Li(d,n)8 Be reaction.Deuterons with sub-Me V energy were accelerated from the front surface of a massive CD2 target in the backward direction with respect to the laser beam vector.Simultaneously,neutrons were emitted from the primary CD2 target and a secondary Li F catcher.The total maximum measured neutron yield from 2D(d,n)3He,7Li(d,n)8Be,12C(d,n)13N reactions was ～3.5(±0.5) × 108 neutrons/shot.
