Using high energy accelerators for energy production by nuclear fission goes back to the 1950's with plans for“breeder accelerators”as well as with early ideas on subcritical reactors,which are currently pursued...Using high energy accelerators for energy production by nuclear fission goes back to the 1950's with plans for“breeder accelerators”as well as with early ideas on subcritical reactors,which are currently pursued in China and other countries.Also,fusion came in,when the idea emerged in the mid 1970's to use accelerators and their highly time and space compressed beams in order to generate the extremely high density and temperatures required for inertial fusion energy production.Due to the higher repetition rates and efficiencies of accelerators,this was seen as a promising alternative to using high power lasers.After an introduction to nuclear fission applications of accelerators,this review summarizes some of the scientific developments directed towards this challenging application e with focus on the European HIDIF-study-and outlines parameters of future high energy density experiments after construction of the FAIR/Germany and HIAF/China heavy ion accelerator projects.展开更多
Direct laser acceleration(DLA)of electrons in a plasma of near-critical electron density(NCD)and the associated synchrotron-like radiation are discussed for moderate relativistic laser intensity(normalized laser ampli...Direct laser acceleration(DLA)of electrons in a plasma of near-critical electron density(NCD)and the associated synchrotron-like radiation are discussed for moderate relativistic laser intensity(normalized laser amplitude a0≤4.3)and ps length pulse.This regime is typical of kJ PW-class laser facilities designed for high-energy-density(HED)research.In experiments at the PHELIX facility,it has been demonstrated that interaction of a 1019 W/cm2 sub-ps laser pulse with a sub-mm length NCD plasma results in the generation of high-current well-directed superponderomotive electrons with an effective temperature ten times higher than the ponderomotive potential[Rosmej et al.,Plasma Phys.Controlled Fusion 62,115024(2020)].Three-dimensional particle-in-cell simulations provide good agreement with the measured electron energy distribution and are used in the current work to study synchrotron radiation from the DLA-accelerated electrons.The resulting x-ray spectrum with a critical energy of 5 keV reveals an ultrahigh photon number of 731011 in the 1–30 keV photon energy range at the focused laser energy of 20 J.Numerical simulations of betatron x-ray phase contrast imaging based on the DLA process for the parameters of a PHELIX laser are presented.The results are of interest for applications in HED experiments,which require a ps x-ray pulse and a high photon flux.展开更多
High-field experiments are very sensitive to the exact value of the peak intensity of an optical pulse due to the nonlinearity of the underlying processes.Therefore,precise knowledge of the pulse intensity,which is ma...High-field experiments are very sensitive to the exact value of the peak intensity of an optical pulse due to the nonlinearity of the underlying processes.Therefore,precise knowledge of the pulse intensity,which is mainly limited by the accuracy of the temporal characterization,is a key prerequisite for the correct interpretation of experimental data.While the detection of energy and spatial profile is well established,the unambiguous temporal characterization of intense optical pulses,another important parameter required for intensity evaluation,remains a challenge,especially at relativistic intensities and a few-cycle pulse duration.Here,we report on the progress in the temporal characterization of intense laser pulses and present the relativistic surface second harmonic generation dispersion scan(RSSHG-D-scan)—a new approach allowing direct on-target temporal characterization of high-energy,few-cycle optical pulses at relativistic intensity.展开更多
We propose and demonstrate the use of random phase plates(RPPs)for high-energy sub-picosecond lasers.Contrarily to previous work related to nanosecond lasers,an RPP poses technical challenges with ultrashort-pulse las...We propose and demonstrate the use of random phase plates(RPPs)for high-energy sub-picosecond lasers.Contrarily to previous work related to nanosecond lasers,an RPP poses technical challenges with ultrashort-pulse lasers.Here,we implement the RPP near the beginning of the amplifier and image-relay it throughout the laser amplifier.With this,we obtain a uniform intensity distribution in the focus over an area 1600 times the diffraction limit.This method shows no significant drawbacks for the laser and it has been implemented at the PHELIX laser facility where it is now available for users.展开更多
We present a study of laser-driven ion acceleration with micrometre and sub-micrometre thick targets,which focuses on the enhancement of the maximum proton energy and the total number of accelerated particles at the P...We present a study of laser-driven ion acceleration with micrometre and sub-micrometre thick targets,which focuses on the enhancement of the maximum proton energy and the total number of accelerated particles at the PHELIX facility.Using laser pulses with a nanosecond temporal contrast of up to 10^-12 and an intensity of the order of 1020 W/cm^2,proton energies up to 93 MeV are achieved.Additionally,the conversion efficiency at 45°incidence angle was increased when changing the laser polarization to p,enabling similar proton energies and particle numbers as in the case of normal incidence and s-polarization,but reducing the debris on the last focusing optic.展开更多
文摘Using high energy accelerators for energy production by nuclear fission goes back to the 1950's with plans for“breeder accelerators”as well as with early ideas on subcritical reactors,which are currently pursued in China and other countries.Also,fusion came in,when the idea emerged in the mid 1970's to use accelerators and their highly time and space compressed beams in order to generate the extremely high density and temperatures required for inertial fusion energy production.Due to the higher repetition rates and efficiencies of accelerators,this was seen as a promising alternative to using high power lasers.After an introduction to nuclear fission applications of accelerators,this review summarizes some of the scientific developments directed towards this challenging application e with focus on the European HIDIF-study-and outlines parameters of future high energy density experiments after construction of the FAIR/Germany and HIAF/China heavy ion accelerator projects.
基金the DFG(Project No.PU 213/9),EPSRC Grant No.EP/P026796/1the 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Direct laser acceleration(DLA)of electrons in a plasma of near-critical electron density(NCD)and the associated synchrotron-like radiation are discussed for moderate relativistic laser intensity(normalized laser amplitude a0≤4.3)and ps length pulse.This regime is typical of kJ PW-class laser facilities designed for high-energy-density(HED)research.In experiments at the PHELIX facility,it has been demonstrated that interaction of a 1019 W/cm2 sub-ps laser pulse with a sub-mm length NCD plasma results in the generation of high-current well-directed superponderomotive electrons with an effective temperature ten times higher than the ponderomotive potential[Rosmej et al.,Plasma Phys.Controlled Fusion 62,115024(2020)].Three-dimensional particle-in-cell simulations provide good agreement with the measured electron energy distribution and are used in the current work to study synchrotron radiation from the DLA-accelerated electrons.The resulting x-ray spectrum with a critical energy of 5 keV reveals an ultrahigh photon number of 731011 in the 1–30 keV photon energy range at the focused laser energy of 20 J.Numerical simulations of betatron x-ray phase contrast imaging based on the DLA process for the parameters of a PHELIX laser are presented.The results are of interest for applications in HED experiments,which require a ps x-ray pulse and a high photon flux.
基金supported by DFG through the Cluster of Excellence“Munich Center for Advanced Photonics”(MAP)(EXC 158)and TR-18 funding schemesthe Euratom research and training program 2014-2018 under Grant agreement No.633053 within the framework of the EUROfusion Consortium“International Max-Planck Research School of Advanced Photon Science”(IMPRS-APS),and the Max-Planck Society.
文摘High-field experiments are very sensitive to the exact value of the peak intensity of an optical pulse due to the nonlinearity of the underlying processes.Therefore,precise knowledge of the pulse intensity,which is mainly limited by the accuracy of the temporal characterization,is a key prerequisite for the correct interpretation of experimental data.While the detection of energy and spatial profile is well established,the unambiguous temporal characterization of intense optical pulses,another important parameter required for intensity evaluation,remains a challenge,especially at relativistic intensities and a few-cycle pulse duration.Here,we report on the progress in the temporal characterization of intense laser pulses and present the relativistic surface second harmonic generation dispersion scan(RSSHG-D-scan)—a new approach allowing direct on-target temporal characterization of high-energy,few-cycle optical pulses at relativistic intensity.
基金European Union’s Horizon 2020 research and innovation program under grant agreement number 633053。
文摘We propose and demonstrate the use of random phase plates(RPPs)for high-energy sub-picosecond lasers.Contrarily to previous work related to nanosecond lasers,an RPP poses technical challenges with ultrashort-pulse lasers.Here,we implement the RPP near the beginning of the amplifier and image-relay it throughout the laser amplifier.With this,we obtain a uniform intensity distribution in the focus over an area 1600 times the diffraction limit.This method shows no significant drawbacks for the laser and it has been implemented at the PHELIX laser facility where it is now available for users.
基金This work has been carried out within the framework of the EUROfusion Consortium and has received funding from the Euratom research and training programme 2014–2018 and 2019–2020 under grant agreement No.633053.
文摘We present a study of laser-driven ion acceleration with micrometre and sub-micrometre thick targets,which focuses on the enhancement of the maximum proton energy and the total number of accelerated particles at the PHELIX facility.Using laser pulses with a nanosecond temporal contrast of up to 10^-12 and an intensity of the order of 1020 W/cm^2,proton energies up to 93 MeV are achieved.Additionally,the conversion efficiency at 45°incidence angle was increased when changing the laser polarization to p,enabling similar proton energies and particle numbers as in the case of normal incidence and s-polarization,but reducing the debris on the last focusing optic.