In recent years,heavy ion accelerator technology has been rapidly developing worldwide and widely applied in the fields of space radiation simulation and particle therapy.Usually,a very high uniformity in the irradiat...In recent years,heavy ion accelerator technology has been rapidly developing worldwide and widely applied in the fields of space radiation simulation and particle therapy.Usually,a very high uniformity in the irradiation area is required for the extracted ion beams,which is crucial because it directly affects the experimental precision and therapeutic effect.Specifically,ultra-large-area and high-uniformity scanning are crucial requirements for spacecraft radiation effects assessment and serve as core specification for beamline terminal design.In the 300 MeV proton and heavy ion accelerator complex at the Space Environment Simulation and Research Infrastructure(SESRI),proton and heavy ion beams will be accelerated and ultimately delivered to three irradiation terminals.In order to achieve the required large irradiation area of 320 mm×320 mm,horizontal and vertical scanning magnets are used in the extraction beam line.However,considering the various requirements for beam species and energies,the tracking accuracy of power supplies(PSs),the eddy current effect of scanning magnets,and the fluctuation of ion bunch structure will reduce the irradiation uniformity.To mitigate these effects,a beam uniformity optimization method based on the measured beam distribution was proposed and applied in the accelerator complex at SESRI.In the experiment,the uniformity is successfully optimized from 75%to over 90%after five iterations of adjustment to the PS waveforms.In this paper,the method and experimental results were introduced.展开更多
The E-field of pulse line ion accelerator （PLIA） is unique with high frequency （~MHz）, large magni- tude （~MV/m）, and limited measuring space （~cm）. The integrated optical E-field sensor （IOES） has remarkabl...The E-field of pulse line ion accelerator （PLIA） is unique with high frequency （~MHz）, large magni- tude （~MV/m）, and limited measuring space （~cm）. The integrated optical E-field sensor （IOES） has remarkable advantages and has been used for PLIA E-field measurement. Firstly, the transfer function of the IOES has been calibrated to ensure measurement accuracy. The time-domain response illustrates that the sensor has a fast dynamic performance to effectively follow a 4 ns rising edge. Then, the E-field distribution along the axis and near the insula- tor surface of the PLIA was measured, showing that propagation of the E-field is almost lossless and the E-field near the insulation surface is about 1.1 times larger than that along the axis, which is in accordance with the simulation result.展开更多
Purpose HIRFL-CSR(Heavy Ion Research Facility in Lanzhou,Cooler Storage Ring)is a heavy-ion accelerator facility at IMP(Institute of Modern Physics,Chinese Academy of Sciences).Due to the diverse physics research requ...Purpose HIRFL-CSR(Heavy Ion Research Facility in Lanzhou,Cooler Storage Ring)is a heavy-ion accelerator facility at IMP(Institute of Modern Physics,Chinese Academy of Sciences).Due to the diverse physics research requirements,including higher beam intensity and quality,in recent years,a new high-level accelerator control system,PACS(Physics-oriented Accelerator Control System),was designed and deployed in the HIRFL-CSR facility.However,as more and more complex beam commissioning needs the cooperation of multiple beam dynamics modules,which are developed independently by different accelerator physicists,it is necessary to design a framework to integrate any new beam dynamics modules and guarantee cooperation between new and existing beam dynamics modules.Method The integrated beam dynamics framework consists of the unified dynamics interface,the general dynamics scheduler and the multi-user queue.The unified dynamics interface ensures the independence of each beam dynamics module and isolates data from each beam dynamics module.The general dynamics scheduler forms beam dynamics chains from different beam dynamics modules,simplifying beam commissioning.The multi-user queue ensures that all users can access all beam dynamics modules simultaneously.Results Various beam dynamics modules are embedded in the framework,and these modules can collaborate with each other.This significantly improves the accuracy of beam commissioning and the efficiency of software development for accelerator physicists.Conclusion With the integrated beam dynamics framework,the efficiency of beam commissioning and the performance of HIRFL-CSR are significantly improved,which shows the framework is quite powerful for developing controls of complicated beam dynamics.HIAF(High Intensity heavy-ion Accelerator Facility)and EicC(Electron-Ion Collider in China)will employ many new beam dynamics schemes and innovative technologies to reach higher intensity or higher luminosity.The framework will play a vital role in building integrated,smart control systems and pushing performance boundaries of these next-generation facilities.展开更多
Automatic phase-setting is essential for modern linacs which have increasingly stringent time demands for beam tune-up and fault compensation.A key challenge in automatic phase-setting is obtaining an accurate knowled...Automatic phase-setting is essential for modern linacs which have increasingly stringent time demands for beam tune-up and fault compensation.A key challenge in automatic phase-setting is obtaining an accurate knowledge of the position and phase offsets of all cavities.This study proposes a beam-based method that employs time-of-flight experiments for simultaneous alignment and phase calibration of a superconducting hadron linac.The proposed method is verified using the CAFE2 accelerator at the Institute of Modern Physics,where offset measurements enable rapid tune-up via automatic phase-setting,and the output beam energies closely match the predicted values.The proposed method is able to address longitudinal position shifts within cryomodules due to cool-down,readily applicable to superconducting hadron linacs,and expected to be employed in the upcoming commissioning of CiADS and HIAF.展开更多
A radio frequency (r.f.) ion source used in the electrostatic accelerator was designed and built for the study on the ion beam bioengineering. The extracting characteristics were determined by experiments, from whic...A radio frequency (r.f.) ion source used in the electrostatic accelerator was designed and built for the study on the ion beam bioengineering. The extracting characteristics were determined by experiments, from which the results showed that a maximal beam current is obtained under the condition of the extracting voltage 1700V and the gas pressure in the range of (4~ 8)× 10-4 Pa. And the diameter of the ion beam was measured as well.展开更多
This work demonstrates experimentally the close relation between return currents from relativistic laser-driven target polarization and the quality of the relativistic laser–plasma interaction for laser-driven second...This work demonstrates experimentally the close relation between return currents from relativistic laser-driven target polarization and the quality of the relativistic laser–plasma interaction for laser-driven secondary sources,taking as an example ion acceleration by target normal sheath acceleration.The Pearson linear correlation of maximum return current amplitude and proton spectrum cutoff energy is found to be in the range from~0.70 to 0.94.kA-scale return currents rise in all interaction schemes where targets of any kind are charged by escaping laser-accelerated relativistic electrons.Their precise measurement is demonstrated using an inductive scheme that allows operation at high repetition rates.Thus,return currents can be used as a metrological online tool for the optimization of many laser-driven secondary sources and for diagnosing their stability.In particular,in two parametric studies of laser-driven ion acceleration,we carry out a noninvasive online measurement of return currents in a tape target system irradiated by the 1 PW VEGA-3 laser at Centro de Láseres Pulsados:first the size of the irradiated area is varied at best compression of the laser pulse;second,the pulse duration is varied by means of induced group delay dispersion at best focus.This work paves the way to the development of feedback systems that operate at the high repetition rates of PW-class lasers.展开更多
The article contains an error regarding the electron spectra displayed in Figs.4 and 5 and the data extracted from these spectra.The measurements were made with the SESAME magnetic spectrometer,the working principle o...The article contains an error regarding the electron spectra displayed in Figs.4 and 5 and the data extracted from these spectra.The measurements were made with the SESAME magnetic spectrometer,the working principle of which is recalled in Fig.1.Specifically,a magnetic dipole is used to separate charged particles(electrons in the case of this experiment)depending on their energy,charge and mass.The deflected particles then hit an imaging plate(IP)and deposit energy in its sensitive layer.The kinetic energy of the particles can be evaluated from their impact position on the IP and their number can be inferred from the local energy deposition.展开更多
Laser-driven ion acceleration,as produced by interaction of a high-intensity laser with a target,is a growing field of interest.One of the current challenges is to enhance the acceleration process,i.e.,to increase the...Laser-driven ion acceleration,as produced by interaction of a high-intensity laser with a target,is a growing field of interest.One of the current challenges is to enhance the acceleration process,i.e.,to increase the produced ion energy and the ion number and to shape the energy distribution for future applications.In this paper,we investigate the effect of helical coil(HC)targets on the laser-matter interaction process using a 150 TW laser.We demonstrate that HC targets significantly enhance proton acceleration,improving energy bunching and beam focusing and increasing the cutoff energy.For the first time,we extend this analysis to carbon ions,revealing a marked reduction in the number of low-energy carbon ions and the potential for energy bunching and post-acceleration through an optimized HC design.Simulations using the particle-in-cell code SOPHIE confirm the experimental results,providing insights into the current propagation and ion synchronization mechanisms in HCs.Our findings suggest that HC targets can be optimized for multispecies ion acceleration.展开更多
A particle-in-cell simulation is conducted to investigate the plasma acceleration process in a micro-cathode vacuum arc thruster.A coaxial electrode structure thruster with an applied magnetic field configuration is u...A particle-in-cell simulation is conducted to investigate the plasma acceleration process in a micro-cathode vacuum arc thruster.A coaxial electrode structure thruster with an applied magnetic field configuration is used to investigate the effects of the distribution of the magnetic field on the acceleration process and the mechanism of electrons and ions.The modeling results show that due to the small Larmor radius of electrons,they are magnetized and bound by the magnetic field lines to form a narrow electron channel.Heavy ions with a large Larmor radius take a long time to keep up with the electron movement.The presence of a magnetic field strengthens the charge separation phenomenon.The electric field caused by the charge separation is mainly responsible for the ion acceleration downstream of the computation.The impact of variations in the distribution of the magnetic field on the acceleration of the plasma is also investigated in this study,and it is found that the position of the magnetic coil relative to the thruster exit has an important impact on the acceleration of ions.In order to increase the axial velocity of heavy ions,the design should be considered to reduce the confinement of the magnetic field on the electrons in the downstream divergent part of the applied magnetic field.展开更多
In contrast to ion beams produced by conventional accelerators,ion beams accelerated by ultrashort intense laser pulses have advantages of ultrashort bunch duration and ultrahigh density,which are achieved in compact ...In contrast to ion beams produced by conventional accelerators,ion beams accelerated by ultrashort intense laser pulses have advantages of ultrashort bunch duration and ultrahigh density,which are achieved in compact size.However,it is still challenging to simultaneously enhance their quality and yield for practical applications such as fast ion ignition of inertial confinement fusion.Compared with other mechanisms of laser-driven ion acceleration,the hole-boring radiation pressure acceleration has a special advantage in generating high-fluence ion beams suitable for the creation of high energy density state of matters.In this paper,we present a review on some theoretical and numerical studies of the hole-boring radiation pressure acceleration.First we discuss the typical field structure associated with this mechanism,its intrinsic feature of oscillations,and the underling physics.Then we will review some recently proposed schemes to enhance the beam quality and the efficiency in the hole-boring radiation pressure acceleration,such as matching laser intensity profile with target density profile,and using two-ion-species targets.Based on this,we propose an integrated scheme for efficient high-quality hole-boring radiation pressure acceleration,in which the longitudinal density profile of a composite target as well as the laser transverse intensity profile are tailored according to the matching condition.展开更多
Proton generation,transport and interaction with hollow cone targets are investigated by means of two-dimensional PIC simulations.A scaled-down hollow cone with gold walls,a carbon tip and a curved hydrogen foil insid...Proton generation,transport and interaction with hollow cone targets are investigated by means of two-dimensional PIC simulations.A scaled-down hollow cone with gold walls,a carbon tip and a curved hydrogen foil inside the cone has been considered.Proton acceleration is driven by a 10^(20) W·cm^(-2) and 1 ps laser pulse focused on the hydrogen foil.Simulations show an important surface current at the cone walls which generates a magnetic field.This magnetic field is dragged by the quasi-neutral plasma formed by fast protons and co-moving electrons when they propagate towards the cone tip.As a result,a tens of kT B z field is set up at the cone tip,which is strong enough to deflect the protons and increase the beam divergence substantially.We propose using heavy materials at the cone tip and increasing the laser intensity in order to mitigate magnetic field generation and proton beam divergence.展开更多
MoS_(2)targets were irradiated by infra-red(IR)pulsed laser in a high vacuum to determine hot plasma parameters,atomic,molecular and ion emission,and angular and charge state distributions.In this way,pulsed laser dep...MoS_(2)targets were irradiated by infra-red(IR)pulsed laser in a high vacuum to determine hot plasma parameters,atomic,molecular and ion emission,and angular and charge state distributions.In this way,pulsed laser deposition(PLD)of thin films on graphene oxide substrates was also realized.An Nd:YAG laser,operating at the 1064 nm wavelength with a 5 ns pulse duration and up to a 1 J pulse energy,in a single pulse or at a 10 Hz repetition rate,was employed.Ablation yield was measured as a function of the laser fluence.Plasma was characterized using different analysis techniques,such as time-of-flight measurements,quadrupole mass spectrometry and fast CCD visible imaging.The so-produced films were characterized by composition,thickness,roughness,wetting ability,and morphology.When compared to the MoS_(2)targets,they show a slight decrease of S with respect to Mo,due to higher ablation yield,low fusion temperature and high sublimation in vacuum.The pulsed IR laser deposited Mo Sx(with 1<x<2)films are uniform,with a thickness of about 130 nm,a roughness of about 50 nm and a higher wettability than the MoS_(2)targets.Some potential applications of the pulsed IR laser-deposited Mo Sx films are also presented and discussed.展开更多
The interaction of high energy lepton jets composed of electrons and positrons with background electron–proton plasma is investigated numerically based upon particle-in-cell simulation,focusing on the acceleration pr...The interaction of high energy lepton jets composed of electrons and positrons with background electron–proton plasma is investigated numerically based upon particle-in-cell simulation,focusing on the acceleration processes of background protons due to the development of electromagnetic turbulence.Such interaction may be found in the universe when energetic lepton jets propagate in the interstellar media.When such a jet is injected into the background plasma,theWeibel instability is excited quickly,which leads to the development of plasma turbulence into the nonlinear stage.The turbulent electric and magnetic fields accelerate plasma particles via the Fermi II type acceleration,where the maximum energy of both electrons and protons can be accelerated to much higher than that of the incident jet particles.Because of background plasma acceleration,a collisionless electrostatic shock wave is formed,where some pre-accelerated protons are further accelerated when passing through the shock wave front.Dependence of proton acceleration on the beam-plasma density ratio and beam energy is investigated.For a given background plasma density,the maximum proton energy generally increases both with the density and kinetic energy of the injected jet.Moreover,for a homogeneous background plasma,the proton acceleration via both turbulent fields and collisionless shocks is found to be significant.In the case of an inhomogeneous plasma,the proton acceleration in the plasma turbulence is dominant.Our studies illustrate a scenario where protons from background plasma can be accelerated successively by the turbulent fields and collisionless shocks.展开更多
Laser-driven ion accelerators have the advantages of compact size,high density,and short bunch duration over conventional accelerators.Nevertheless,it is still challenging to generate ion beams with quasi-monoenergeti...Laser-driven ion accelerators have the advantages of compact size,high density,and short bunch duration over conventional accelerators.Nevertheless,it is still challenging to generate ion beams with quasi-monoenergetic peak and low divergence in experiments with the current ultrahigh intensity laser and thin target technologies.Here we propose a scheme that a Laguerre–Gaussian laser irradiates a near-critical-density(NCD)plasma to generate a quasi-monoenergetic and low-divergence proton beam.The Laguerre–Gaussian laser pulse in an NCD plasma excites a moving longitudinal electrostatic field with a large amplitude,and it maintains the inward bowl-shape for dozens of laser durations.This special distribution of the longitudinal electrostatic field can simultaneously accelerate and converge the protons.Our particle-in-cell(PIC)simulation shows that the efficient proton acceleration can be realized with the Laguerre–Gaussian laser intensity ranging from 3.9×10^(21)W·cm^(-2)–1.6×10^(22)W·cm^(-2)available in the near future,e.g.,a quasi-monoenergetic proton beam with peak energy~115 MeV and divergence angles less than 5°can be generated by a 5.3×10^(21)W·cm^(-2)pulse.This work could provide a reference for the high-quality ion beam generation with PWclass laser systems available recently.展开更多
Laser-accelerated ion beams(LIBs) have been increasingly applied in the field of material irradiation in recent years due to the unique properties of ultra-short beam duration, extremely high beam current, etc. Here w...Laser-accelerated ion beams(LIBs) have been increasingly applied in the field of material irradiation in recent years due to the unique properties of ultra-short beam duration, extremely high beam current, etc. Here we explore an application of using laser-accelerated ion beams to prepare graphene. The pulsed LIBs produced a great instantaneous beam current and thermal effect on the SiC samples with a shooting frequency of 1 Hz. In the experiment, we controlled the deposition dose by adjusting the number of shootings and the irradiating current by adjusting the distance between the sample and the ion source. During annealing at 1100℃, we found that the 190 shots ion beams allowed more carbon atoms to self-assemble into graphene than the 10 shots case. By comparing with the controlled experiment based on ion beams from a traditional ion accelerator, we found that the laser-accelerated ion beams could cause greater damage in a very short time. Significant thermal effect was induced when the irradiation distance was reduced to less than 1 cm, which could make partial SiC self-annealing to prepare graphene dots directly. The special effects of LIBs indicate their vital role to change the structure of the irradiation sample.展开更多
A general solution of the electrostatic potential that determines the maximum light-ion energy is derived for the test-particle acceleration model by taking into account the influence of the substrate-ion density grad...A general solution of the electrostatic potential that determines the maximum light-ion energy is derived for the test-particle acceleration model by taking into account the influence of the substrate-ion density gradient. It is shown that the substrate-ion density structure is also dependent on laser pulse duration. In the picosecond or sub-picosecond regime, the decreasing density gradient of the substrate-ions leads to an evident reduction in the acceleration efficiency of the light-ions. However, this kind of influence is negligible in the ultrashort regime.展开更多
A scheme of generating energetic ions by the interaction of an ultrahigh-intensity laser pulse and a thin solid foil is studied. The combination of the effects of radiation pressure and Coulomb explosion makes the ion...A scheme of generating energetic ions by the interaction of an ultrahigh-intensity laser pulse and a thin solid foil is studied. The combination of the effects of radiation pressure and Coulomb explosion makes the ion acceleration more effective. The maximum ion velocity variation with time is predicted theoretically while the temporal evolution of the electrostatic field due to the Coulomb explosion is taken into consideration. Two-dimensional particle-in-cell simulations are done to verify the theory.展开更多
Recently, perpendicular shocks have been generated in laboratory experiments by the interaction between a laser-produced supersonic plasma flow and a magnetized ambient plasma. Here, we explore the ion dynamics and th...Recently, perpendicular shocks have been generated in laboratory experiments by the interaction between a laser-produced supersonic plasma flow and a magnetized ambient plasma. Here, we explore the ion dynamics and the formation of such kinds of shock with a one-dimensional(1D)particle-in-cell simulation model using achievable parameters for laser experiments. A small part of the ambient ions is first reflected by the laser-driven piston. These piston-reflected ions interact with the upstream plasma and form a shock then. By analyzing the contribution of the electric force and the Lorentz force during the reflection, shock-reflected ions are found to be accelerated by two different mechanisms: shock drift acceleration and shock surfing acceleration,where shock drift acceleration is the dominant one. Very few ions are reflected twice by the shock and accelerated to a large velocity, implying that a more energetic population of ions can be observed in future experiments.展开更多
Acceleration of protons by the radiation pressure of a circularly polarized laser pulse with the intensity up to 1021 W/cm^2 from a double-layer or multi-ion-mixed thin foil is investigated by two-dimensional particle...Acceleration of protons by the radiation pressure of a circularly polarized laser pulse with the intensity up to 1021 W/cm^2 from a double-layer or multi-ion-mixed thin foil is investigated by two-dimensional particle-in-cell simulations. The double-layer foil is composed of a heavy ion layer and a proton layer. It is found that the radiation pressure acceleration can be classified into three regimes according to the laser intensity due to the different critical intensities for laser transparency with different ion species. When the laser intensity is moderately high, the laser pushes the electrons neither so slowly nor so quickly that the protons can catch up with the electrons, while the heavy ions cannot. Therefore, the protons can be accelerated efficiently. The proton beam generated from the double-layer foil is of better quality and higher energy than that from a pure proton foil with the same areal electron density. When the laser intensity is relatively low, both the protons and heavy ions are accelerated together, which is not favorable to the proton acceleration. When the laser intensity is relatively high, neither the heavy ions nor the protons can be accelerated efficiently due to the laser transparency through the target.展开更多
The shock wave acceleration of ions driven by laser-heated thermal pressure is studied through one-dimensional particle-in-cell simulation and analysis. The generation of high-energy mono-energetic protons in recent e...The shock wave acceleration of ions driven by laser-heated thermal pressure is studied through one-dimensional particle-in-cell simulation and analysis. The generation of high-energy mono-energetic protons in recent experiments （D. Haberberger et al., 2012 Nat. Phys. 8 95） is attributed to the use of exponentially decaying density profile of the plasma target. It does not only keep the shock velocity stable but also suppresses the normal target normal sheath acceleration. The effects of target composition are also examined, where a similar collective velocity of all ion species is demonstrated. The results also give some reference to future experiments of producing energetic heavy ions.展开更多
基金Supported by National Key R&D Program of China(2019YFA0405400)。
文摘In recent years,heavy ion accelerator technology has been rapidly developing worldwide and widely applied in the fields of space radiation simulation and particle therapy.Usually,a very high uniformity in the irradiation area is required for the extracted ion beams,which is crucial because it directly affects the experimental precision and therapeutic effect.Specifically,ultra-large-area and high-uniformity scanning are crucial requirements for spacecraft radiation effects assessment and serve as core specification for beamline terminal design.In the 300 MeV proton and heavy ion accelerator complex at the Space Environment Simulation and Research Infrastructure(SESRI),proton and heavy ion beams will be accelerated and ultimately delivered to three irradiation terminals.In order to achieve the required large irradiation area of 320 mm×320 mm,horizontal and vertical scanning magnets are used in the extraction beam line.However,considering the various requirements for beam species and energies,the tracking accuracy of power supplies(PSs),the eddy current effect of scanning magnets,and the fluctuation of ion bunch structure will reduce the irradiation uniformity.To mitigate these effects,a beam uniformity optimization method based on the measured beam distribution was proposed and applied in the accelerator complex at SESRI.In the experiment,the uniformity is successfully optimized from 75%to over 90%after five iterations of adjustment to the PS waveforms.In this paper,the method and experimental results were introduced.
基金Supported by Fund of National Priority Basic Research of China (2011CB209403)National Natural Science Foundation of China(51107063)
文摘The E-field of pulse line ion accelerator （PLIA） is unique with high frequency （~MHz）, large magni- tude （~MV/m）, and limited measuring space （~cm）. The integrated optical E-field sensor （IOES） has remarkable advantages and has been used for PLIA E-field measurement. Firstly, the transfer function of the IOES has been calibrated to ensure measurement accuracy. The time-domain response illustrates that the sensor has a fast dynamic performance to effectively follow a 4 ns rising edge. Then, the E-field distribution along the axis and near the insula- tor surface of the PLIA was measured, showing that propagation of the E-field is almost lossless and the E-field near the insulation surface is about 1.1 times larger than that along the axis, which is in accordance with the simulation result.
基金support from the National Key R&D Program of China(Grant No.2019YFA0405400)the support from Young Elite Scientists Sponsorship Program by CAST(Grant No.2023QNRC001)the support from the National Natural Science Foundation of China(Grant No.12105332).
文摘Purpose HIRFL-CSR(Heavy Ion Research Facility in Lanzhou,Cooler Storage Ring)is a heavy-ion accelerator facility at IMP(Institute of Modern Physics,Chinese Academy of Sciences).Due to the diverse physics research requirements,including higher beam intensity and quality,in recent years,a new high-level accelerator control system,PACS(Physics-oriented Accelerator Control System),was designed and deployed in the HIRFL-CSR facility.However,as more and more complex beam commissioning needs the cooperation of multiple beam dynamics modules,which are developed independently by different accelerator physicists,it is necessary to design a framework to integrate any new beam dynamics modules and guarantee cooperation between new and existing beam dynamics modules.Method The integrated beam dynamics framework consists of the unified dynamics interface,the general dynamics scheduler and the multi-user queue.The unified dynamics interface ensures the independence of each beam dynamics module and isolates data from each beam dynamics module.The general dynamics scheduler forms beam dynamics chains from different beam dynamics modules,simplifying beam commissioning.The multi-user queue ensures that all users can access all beam dynamics modules simultaneously.Results Various beam dynamics modules are embedded in the framework,and these modules can collaborate with each other.This significantly improves the accuracy of beam commissioning and the efficiency of software development for accelerator physicists.Conclusion With the integrated beam dynamics framework,the efficiency of beam commissioning and the performance of HIRFL-CSR are significantly improved,which shows the framework is quite powerful for developing controls of complicated beam dynamics.HIAF(High Intensity heavy-ion Accelerator Facility)and EicC(Electron-Ion Collider in China)will employ many new beam dynamics schemes and innovative technologies to reach higher intensity or higher luminosity.The framework will play a vital role in building integrated,smart control systems and pushing performance boundaries of these next-generation facilities.
基金supported by the National Natural Science Foundation of China(U22A20261)the Large Research Infrastructures China initiative Accelerator Driven System(2017-000052-75-01-000590).
文摘Automatic phase-setting is essential for modern linacs which have increasingly stringent time demands for beam tune-up and fault compensation.A key challenge in automatic phase-setting is obtaining an accurate knowledge of the position and phase offsets of all cavities.This study proposes a beam-based method that employs time-of-flight experiments for simultaneous alignment and phase calibration of a superconducting hadron linac.The proposed method is verified using the CAFE2 accelerator at the Institute of Modern Physics,where offset measurements enable rapid tune-up via automatic phase-setting,and the output beam energies closely match the predicted values.The proposed method is able to address longitudinal position shifts within cryomodules due to cool-down,readily applicable to superconducting hadron linacs,and expected to be employed in the upcoming commissioning of CiADS and HIAF.
文摘A radio frequency (r.f.) ion source used in the electrostatic accelerator was designed and built for the study on the ion beam bioengineering. The extracting characteristics were determined by experiments, from which the results showed that a maximal beam current is obtained under the condition of the extracting voltage 1700V and the gas pressure in the range of (4~ 8)× 10-4 Pa. And the diameter of the ion beam was measured as well.
基金funding from the European Union’s Horizon 2020 research and innovation program through the European IMPULSE project under Grant Agreement No.871161from LASERLAB-EUROPE V under Grant Agreement No.871124+6 种基金from the Grant Agency of the Czech Republic(Grant No.GM23-05027M)Grant No.PDC2021120933-I00 funded by MCIN/AEI/10.13039/501100011033by the European Union Next Generation EU/PRTRsupported by funding from the Ministerio de Ciencia,Innovación y Universidades in Spain through ICTS Equipment Grant No.EQC2018-005230-Pfrom Grant No.PID2021-125389O A-I00 funded by MCIN/AEI/10.13039/501100011033/FEDER,UEby“ERDF A Way of Making Europe”by the European Unionfrom grants of the Junta de Castilla y León with Grant Nos.CLP263P20 and CLP087U16。
文摘This work demonstrates experimentally the close relation between return currents from relativistic laser-driven target polarization and the quality of the relativistic laser–plasma interaction for laser-driven secondary sources,taking as an example ion acceleration by target normal sheath acceleration.The Pearson linear correlation of maximum return current amplitude and proton spectrum cutoff energy is found to be in the range from~0.70 to 0.94.kA-scale return currents rise in all interaction schemes where targets of any kind are charged by escaping laser-accelerated relativistic electrons.Their precise measurement is demonstrated using an inductive scheme that allows operation at high repetition rates.Thus,return currents can be used as a metrological online tool for the optimization of many laser-driven secondary sources and for diagnosing their stability.In particular,in two parametric studies of laser-driven ion acceleration,we carry out a noninvasive online measurement of return currents in a tape target system irradiated by the 1 PW VEGA-3 laser at Centro de Láseres Pulsados:first the size of the irradiated area is varied at best compression of the laser pulse;second,the pulse duration is varied by means of induced group delay dispersion at best focus.This work paves the way to the development of feedback systems that operate at the high repetition rates of PW-class lasers.
文摘The article contains an error regarding the electron spectra displayed in Figs.4 and 5 and the data extracted from these spectra.The measurements were made with the SESAME magnetic spectrometer,the working principle of which is recalled in Fig.1.Specifically,a magnetic dipole is used to separate charged particles(electrons in the case of this experiment)depending on their energy,charge and mass.The deflected particles then hit an imaging plate(IP)and deposit energy in its sensitive layer.The kinetic energy of the particles can be evaluated from their impact position on the IP and their number can be inferred from the local energy deposition.
基金supported by the CEA/DAM Laser Plasma Experiments Validation Project and the CEA/DAM Basic Technical and Scientific Studies Projectsupported by the National Sciences and Engineering Research Council of Canada(NSERC)(Grant Nos.RGPIN-2023-05459 and ALLRP 556340-20)+3 种基金the Digital Research Alliance of Canada(Job pve-323-ac)the Canada Foundation for Innovation(CFI)the Ministère de l’Économie,de l’Innovation et de l’Énergie(MEIE)from QuébecThis study was granted access to the HPC resources of IRENE under allocation Grant No.A0170512899 made by GENCI.We acknowledge the financial support of the IdEx University of Bordeaux/Grand Research Program“GPR LIGHT”and of the Graduate Program on Light Sciences and Technologies of the University of Bordeaux.
文摘Laser-driven ion acceleration,as produced by interaction of a high-intensity laser with a target,is a growing field of interest.One of the current challenges is to enhance the acceleration process,i.e.,to increase the produced ion energy and the ion number and to shape the energy distribution for future applications.In this paper,we investigate the effect of helical coil(HC)targets on the laser-matter interaction process using a 150 TW laser.We demonstrate that HC targets significantly enhance proton acceleration,improving energy bunching and beam focusing and increasing the cutoff energy.For the first time,we extend this analysis to carbon ions,revealing a marked reduction in the number of low-energy carbon ions and the potential for energy bunching and post-acceleration through an optimized HC design.Simulations using the particle-in-cell code SOPHIE confirm the experimental results,providing insights into the current propagation and ion synchronization mechanisms in HCs.Our findings suggest that HC targets can be optimized for multispecies ion acceleration.
基金supported by National Natural Science Foundation of China(Nos.11735004,11575019,and 11702021)National Postdoctoral Program for Innovative Talents(BX20180029)Defense Industrial Technology Development Program(JCKY2018203B029)。
文摘A particle-in-cell simulation is conducted to investigate the plasma acceleration process in a micro-cathode vacuum arc thruster.A coaxial electrode structure thruster with an applied magnetic field configuration is used to investigate the effects of the distribution of the magnetic field on the acceleration process and the mechanism of electrons and ions.The modeling results show that due to the small Larmor radius of electrons,they are magnetized and bound by the magnetic field lines to form a narrow electron channel.Heavy ions with a large Larmor radius take a long time to keep up with the electron movement.The presence of a magnetic field strengthens the charge separation phenomenon.The electric field caused by the charge separation is mainly responsible for the ion acceleration downstream of the computation.The impact of variations in the distribution of the magnetic field on the acceleration of the plasma is also investigated in this study,and it is found that the position of the magnetic coil relative to the thruster exit has an important impact on the acceleration of ions.In order to increase the axial velocity of heavy ions,the design should be considered to reduce the confinement of the magnetic field on the electrons in the downstream divergent part of the applied magnetic field.
基金This work was supported in part by the National Basic Research Program of China(Grant No.2013CBA01504)the National Natural Science Foundation of China(Grant Nos.11675108,11421064,11405108 and 11374210).
文摘In contrast to ion beams produced by conventional accelerators,ion beams accelerated by ultrashort intense laser pulses have advantages of ultrashort bunch duration and ultrahigh density,which are achieved in compact size.However,it is still challenging to simultaneously enhance their quality and yield for practical applications such as fast ion ignition of inertial confinement fusion.Compared with other mechanisms of laser-driven ion acceleration,the hole-boring radiation pressure acceleration has a special advantage in generating high-fluence ion beams suitable for the creation of high energy density state of matters.In this paper,we present a review on some theoretical and numerical studies of the hole-boring radiation pressure acceleration.First we discuss the typical field structure associated with this mechanism,its intrinsic feature of oscillations,and the underling physics.Then we will review some recently proposed schemes to enhance the beam quality and the efficiency in the hole-boring radiation pressure acceleration,such as matching laser intensity profile with target density profile,and using two-ion-species targets.Based on this,we propose an integrated scheme for efficient high-quality hole-boring radiation pressure acceleration,in which the longitudinal density profile of a composite target as well as the laser transverse intensity profile are tailored according to the matching condition.
基金This work has been partially supported by the grant numberENE2014-54960-R of the Spanish Ministry of Economy andCompetitivenessthe COST Action MP1208 and the Co-ordinated Research Project of IAEA F13016.
文摘Proton generation,transport and interaction with hollow cone targets are investigated by means of two-dimensional PIC simulations.A scaled-down hollow cone with gold walls,a carbon tip and a curved hydrogen foil inside the cone has been considered.Proton acceleration is driven by a 10^(20) W·cm^(-2) and 1 ps laser pulse focused on the hydrogen foil.Simulations show an important surface current at the cone walls which generates a magnetic field.This magnetic field is dragged by the quasi-neutral plasma formed by fast protons and co-moving electrons when they propagate towards the cone tip.As a result,a tens of kT B z field is set up at the cone tip,which is strong enough to deflect the protons and increase the beam divergence substantially.We propose using heavy materials at the cone tip and increasing the laser intensity in order to mitigate magnetic field generation and proton beam divergence.
基金supported by OP RDE,MEYS,Czech Republic under the project CANAM OP(No.CZ.02.1.01/0.0/0.0/16_013/0001812)by the Czech Science Foundation GACR(No.23-06702S)。
文摘MoS_(2)targets were irradiated by infra-red(IR)pulsed laser in a high vacuum to determine hot plasma parameters,atomic,molecular and ion emission,and angular and charge state distributions.In this way,pulsed laser deposition(PLD)of thin films on graphene oxide substrates was also realized.An Nd:YAG laser,operating at the 1064 nm wavelength with a 5 ns pulse duration and up to a 1 J pulse energy,in a single pulse or at a 10 Hz repetition rate,was employed.Ablation yield was measured as a function of the laser fluence.Plasma was characterized using different analysis techniques,such as time-of-flight measurements,quadrupole mass spectrometry and fast CCD visible imaging.The so-produced films were characterized by composition,thickness,roughness,wetting ability,and morphology.When compared to the MoS_(2)targets,they show a slight decrease of S with respect to Mo,due to higher ablation yield,low fusion temperature and high sublimation in vacuum.The pulsed IR laser deposited Mo Sx(with 1<x<2)films are uniform,with a thickness of about 130 nm,a roughness of about 50 nm and a higher wettability than the MoS_(2)targets.Some potential applications of the pulsed IR laser-deposited Mo Sx films are also presented and discussed.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.12135009,11991074,11975154,and 12005287).
文摘The interaction of high energy lepton jets composed of electrons and positrons with background electron–proton plasma is investigated numerically based upon particle-in-cell simulation,focusing on the acceleration processes of background protons due to the development of electromagnetic turbulence.Such interaction may be found in the universe when energetic lepton jets propagate in the interstellar media.When such a jet is injected into the background plasma,theWeibel instability is excited quickly,which leads to the development of plasma turbulence into the nonlinear stage.The turbulent electric and magnetic fields accelerate plasma particles via the Fermi II type acceleration,where the maximum energy of both electrons and protons can be accelerated to much higher than that of the incident jet particles.Because of background plasma acceleration,a collisionless electrostatic shock wave is formed,where some pre-accelerated protons are further accelerated when passing through the shock wave front.Dependence of proton acceleration on the beam-plasma density ratio and beam energy is investigated.For a given background plasma density,the maximum proton energy generally increases both with the density and kinetic energy of the injected jet.Moreover,for a homogeneous background plasma,the proton acceleration via both turbulent fields and collisionless shocks is found to be significant.In the case of an inhomogeneous plasma,the proton acceleration in the plasma turbulence is dominant.Our studies illustrate a scenario where protons from background plasma can be accelerated successively by the turbulent fields and collisionless shocks.
基金Project supported by the Strategic Priority Research Program of the Chinese Academy of Sciences(Grant No.XDA25050300)the National Natural Science Foundation of China(Grant No.12205366)+2 种基金the National Key Research and Development Program of China(Grant No.2018YFA0404801)the Fundamental Research Funds for the Central Universities(Grant No.2020MS138)the Research Funds of Renmin University of China(Grant No.20XNLG01)。
文摘Laser-driven ion accelerators have the advantages of compact size,high density,and short bunch duration over conventional accelerators.Nevertheless,it is still challenging to generate ion beams with quasi-monoenergetic peak and low divergence in experiments with the current ultrahigh intensity laser and thin target technologies.Here we propose a scheme that a Laguerre–Gaussian laser irradiates a near-critical-density(NCD)plasma to generate a quasi-monoenergetic and low-divergence proton beam.The Laguerre–Gaussian laser pulse in an NCD plasma excites a moving longitudinal electrostatic field with a large amplitude,and it maintains the inward bowl-shape for dozens of laser durations.This special distribution of the longitudinal electrostatic field can simultaneously accelerate and converge the protons.Our particle-in-cell(PIC)simulation shows that the efficient proton acceleration can be realized with the Laguerre–Gaussian laser intensity ranging from 3.9×10^(21)W·cm^(-2)–1.6×10^(22)W·cm^(-2)available in the near future,e.g.,a quasi-monoenergetic proton beam with peak energy~115 MeV and divergence angles less than 5°can be generated by a 5.3×10^(21)W·cm^(-2)pulse.This work could provide a reference for the high-quality ion beam generation with PWclass laser systems available recently.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11875077,11975037,and 11921006)the National Grand Instrument Project of China(Grant Nos.2019YFF01014400 and 2019YFF01014404).
文摘Laser-accelerated ion beams(LIBs) have been increasingly applied in the field of material irradiation in recent years due to the unique properties of ultra-short beam duration, extremely high beam current, etc. Here we explore an application of using laser-accelerated ion beams to prepare graphene. The pulsed LIBs produced a great instantaneous beam current and thermal effect on the SiC samples with a shooting frequency of 1 Hz. In the experiment, we controlled the deposition dose by adjusting the number of shootings and the irradiating current by adjusting the distance between the sample and the ion source. During annealing at 1100℃, we found that the 190 shots ion beams allowed more carbon atoms to self-assemble into graphene than the 10 shots case. By comparing with the controlled experiment based on ion beams from a traditional ion accelerator, we found that the laser-accelerated ion beams could cause greater damage in a very short time. Significant thermal effect was induced when the irradiation distance was reduced to less than 1 cm, which could make partial SiC self-annealing to prepare graphene dots directly. The special effects of LIBs indicate their vital role to change the structure of the irradiation sample.
基金supported by the National Natural Science Foundation of China (Grant No. 10734080)the National Basic Research Program of China (Grant No. 2006CB806000)+1 种基金the Chinese Academy of Sciences,the Shanghai Commission of Science and Technology (Grant Nos. 06DZ22015 and 0652nm005)the Hunan Provincial Natural Science Foundation of China (GrantNo. 09JJ3012)
文摘A general solution of the electrostatic potential that determines the maximum light-ion energy is derived for the test-particle acceleration model by taking into account the influence of the substrate-ion density gradient. It is shown that the substrate-ion density structure is also dependent on laser pulse duration. In the picosecond or sub-picosecond regime, the decreasing density gradient of the substrate-ions leads to an evident reduction in the acceleration efficiency of the light-ions. However, this kind of influence is negligible in the ultrashort regime.
基金Project supported by National Natural Science Foundation of China (Grant Nos 10675155 and 10834008)the 973 Program (GrantNo 2006CB806004)Japan-Korea-China Cooperative Project on High Energy Density Sciences for Laser Fusion Energy
文摘A scheme of generating energetic ions by the interaction of an ultrahigh-intensity laser pulse and a thin solid foil is studied. The combination of the effects of radiation pressure and Coulomb explosion makes the ion acceleration more effective. The maximum ion velocity variation with time is predicted theoretically while the temporal evolution of the electrostatic field due to the Coulomb explosion is taken into consideration. Two-dimensional particle-in-cell simulations are done to verify the theory.
基金funded by the Strategic Priority Research Program of Chinese Academy of Sciences (No. XDB41000000)National Natural Science Foundation of China(NSFC)(Nos. 42174181 ,12205298)the Key Research Program of Frontier Sciences CAS (No. QYZDJ-SSWDQC010)。
文摘Recently, perpendicular shocks have been generated in laboratory experiments by the interaction between a laser-produced supersonic plasma flow and a magnetized ambient plasma. Here, we explore the ion dynamics and the formation of such kinds of shock with a one-dimensional(1D)particle-in-cell simulation model using achievable parameters for laser experiments. A small part of the ambient ions is first reflected by the laser-driven piston. These piston-reflected ions interact with the upstream plasma and form a shock then. By analyzing the contribution of the electric force and the Lorentz force during the reflection, shock-reflected ions are found to be accelerated by two different mechanisms: shock drift acceleration and shock surfing acceleration,where shock drift acceleration is the dominant one. Very few ions are reflected twice by the shock and accelerated to a large velocity, implying that a more energetic population of ions can be observed in future experiments.
基金supported in part by National Natural Science Foundation of China (Nos. 10734130, 10925421, 10935002, 10974250)the National High-Tech ICF Committee in China and the National Basic Research Program of China (Nos. 2007CB815100, 2009GB105002)the JSPS-CAS Core-University Program on Plasma and Nuclear Fusion, and CORE (Center for Optical Research and Education) at Utsunomiya University Japan
文摘Acceleration of protons by the radiation pressure of a circularly polarized laser pulse with the intensity up to 1021 W/cm^2 from a double-layer or multi-ion-mixed thin foil is investigated by two-dimensional particle-in-cell simulations. The double-layer foil is composed of a heavy ion layer and a proton layer. It is found that the radiation pressure acceleration can be classified into three regimes according to the laser intensity due to the different critical intensities for laser transparency with different ion species. When the laser intensity is moderately high, the laser pushes the electrons neither so slowly nor so quickly that the protons can catch up with the electrons, while the heavy ions cannot. Therefore, the protons can be accelerated efficiently. The proton beam generated from the double-layer foil is of better quality and higher energy than that from a pure proton foil with the same areal electron density. When the laser intensity is relatively low, both the protons and heavy ions are accelerated together, which is not favorable to the proton acceleration. When the laser intensity is relatively high, neither the heavy ions nor the protons can be accelerated efficiently due to the laser transparency through the target.
基金Project supported by the Shanghai Natural Special Foundation for Outstanding Young Teachers in University,China(Grant No.yyy10043)
文摘The shock wave acceleration of ions driven by laser-heated thermal pressure is studied through one-dimensional particle-in-cell simulation and analysis. The generation of high-energy mono-energetic protons in recent experiments （D. Haberberger et al., 2012 Nat. Phys. 8 95） is attributed to the use of exponentially decaying density profile of the plasma target. It does not only keep the shock velocity stable but also suppresses the normal target normal sheath acceleration. The effects of target composition are also examined, where a similar collective velocity of all ion species is demonstrated. The results also give some reference to future experiments of producing energetic heavy ions.
