搜索到3026篇“ WAKEFIELD“的相关文章
等离子体密度对尾场加速中最优束流负载的影响
2024年
探讨了当束团参数固定时,通过改变束团电荷量来改变束流的负载状态以达到最优束流负载条件,以及改变等离子体密度对束流负载特性的影响;通过实验发现,等离子体的入口和出口处均存在逐渐增加或降低的等离子体密度坡,并探究了该密度坡对束团相对能散的影响.利用QuickPIC对粒子的行为及其在等离子体中的演化状态进行了模拟;利用理论分析法对束团状态和相对能散的变化进行了综合分析和论证.结果表明:1)在传播方向上局部微调等离子体密度可降低尾随束团的相对能散;2)密度坡的存在会降低相对能散;3)改变等离子体密度,可实现欠负载、过负载,以及最优束流负载之间的切换,最终能散相较最优束流负载状态下的能散更低.
黄开国安维明
激光尾波场电子加速及新型辐射源(特邀)被引量:1
2024年
受益于超短超强激光技术的持续迅猛发展,飞秒强激光为人类提供了全新的实验手段与极端的物理条件,使激光物质相互作用进入到一个极端非线性的强场超快新范畴,催生了大量新原理、新现象,推动了技术变革。飞秒强激光驱动的等离子体尾波场加速原理是一种具有超高加速梯度的粒子加速新原理,该技术的加速梯度可达100 GV/m,相比于传统射频加速器提高了3个数量级以上,可在厘米量级的加速长度内获得GeV量级的高品质高能电子束,极大地降低了加速器的成本,为发展新一代粒子加速技术和新型超快辐射源提供了新机遇和新途径。从飞秒强激光驱动等离子体尾波场中的电子注入、能量啁啾控制和高品质电子束产生以及基于高品质电子束的betatron X射线辐射、高能伽马射线和小型化自由电子激光这几个方面介绍了激光等离子体尾波场电子加速的若干主要研究进展,并对未来进行了展望。
余昌海秦志勇张志钧刘建胜
关键词:激光光学电子加速逆康普顿散射自由电子激光
Tunable energy spectrum betatron x-ray sources in a plasma wakefield
2024年
X-ray sources with tunable energy spectra have a wide range of applications in different scenarios due to their different penetration depths.However,existing x-ray sources face difficulties in terms of energy regulation.In this paper,we present a scheme for tuning the energy spectrum of a betatron x-ray generated from a relativistic electron bunch oscillating in a plasma wakefield.The center energy of the x-ray source can be tuned from several keV to several hundred keV by changing the plasma density,thereby extending the control range by an order of magnitude.At different central energies,the brightness of the betatron radiation is in the range of 3.7×10^(22)to 5.5×10^(22)photons/(0.1%BW·s·mm^(2)·mrad^(2))and the photon divergence angle is about 2 mrad.This high-brightness,energy-controlled betatron source could pave the way to a wide range of applications requiring photons of specific energy,such as phase-contrast imaging in medicine,non-destructive testing and material analysis in industry,and imaging in nuclear physics.
奚传易寿寅任韩立琦阿卜杜伍普尔·阿布力米提刘晓丹赵研英余金清
关键词:X-RAY
Electro-optic 3D snapshot of a laser wakefield accelerated kilo-ampere electron bunch被引量:1
2024年
Laser wakefield acceleration,as an advanced accelerator concept,has attracted great attentions for its ultrahigh acceleration gradient and the capability to produce high brightness electron bunches.The three-dimensional(3D)density serves as an evaluation metric for the particle bunch quality and is intrinsically related to the applications of an accelerator.Despite its significance,this parameter has not been experimentally measured in the investigation of laser wakefield acceleration.We report on an electro-optic 3D snapshot of a laser wakefield electron bunch at a position outside the plasma.The 3D shape of the electron bunch was detected by simultaneously performing optical transition radiation imaging and electro-optic sampling.Detailed 3D structures to a few micrometer levels were reconstructed using a genetic algorithm.The electron bunch possessed a transverse size of less than 30 micrometers.The current profile shows a multi-peak structure.The main peak had a duration of<10 fs and a peak current>1 kA.The maximum electron 3D number density was~9×10^(21)m^(-3).This research demonstrates a feasible way of 3D density monitoring on femtosecond kilo-ampere electron bunches,at any position of a beam transport line for relevant applications.
Kai HuangZhan JinNobuhiko NakaniiTomonao HosokaiMasaki Kando
关键词:ACCELERATION
Compact laser wakefield acceleration toward high energy with micro-plasma parabola
2024年
Laser wakefield acceleration(LWFA)promises compact accelerators toward the high-energy frontier.However,the approach to the 100 GeV milestone faces the obstacle of the long focal length required for optimal acceleration with high-power lasers,which reaches hundreds of meters for 10-100 PW lasers.The long focal length originates from optimal laser intensity required to avoid nonlinear effects and hence large spot size and Rayleigh length.We propose a"telescope"geometry in which a micro-plasma parabola(MPP)is coupled with a short-focal-length off-axis parabola,minimizing the focal length to the meter range for LWFA under optimized conditions driven by lasers beyond 1 PW.Full-dimensional kinetic simulations demonstrate the generation of a 9 GeV electron bunch within only 1 m optical length—only one-tenth of that required with the conventional approach with the same performance.The proposed MPP provides a basis for the construction of compact LWFAs toward single-stage 100 GeV acceleration with 100 PW class lasers.
Xuesong GengTongjun XuLingang ZhangIgor KostyukovAlexander PukhovBaifei ShenLiangliang Ji
关键词:ACCELERATION
The acceleration of a high-charge electron bunch to 10 GeV in a 10-cm nanoparticle-assisted wakefield accelerator被引量:1
2024年
An intense laser pulse focused onto a plasma can excite nonlinear plasma waves.Under appropriate conditions,electrons from the background plasma are trapped in the plasma wave and accelerated to ultra-relativistic velocities.This scheme is called a laser wakefield accelerator.In this work,we present results from a laser wakefield acceleration experiment using a petawatt-class laser to excite the wakefields as well as nanoparticles to assist the injection of electrons into the accelerating phase of the wakefields.We find that a 10-cm-long,nanoparticle-assisted laser wakefield accelerator can generate 340 pC,10±1.86 GeV electron bunches with a 3.4 GeV rms convolved energy spread and a 0.9 mrad rms divergence.It can also produce bunches with lower energies in the 4–6 GeV range.
Constantin AniculaeseiThanh HaSamuel YoffeLance LabunStephen MiltonEdward McCaryMichael M.SpinksHernan J.QuevedoOu Z.LabunRitwik SainAndrea HannaschRafal ZgadzajIsabella PaganoJose A.Franco-AltamiranoMartin L.RinguetteErhart GaulScott V.LuedtkeGanesh TiwariBernhard ErsfeldEnrico BrunettiHartmut RuhlTodd DitmireSandra BruceMichael E.DonovanMichael C.DownerDino A.JaroszynskiBjorn Manuel Hegelich
关键词:ACCELERATIONNANOPARTICLECHARGE
Divergence angle consideration in energy spread measurement for high-quality relativistic electron beam in laser wakefield acceleration
2024年
The thorough exploration of the transverse quality represented by divergence angle has been lacking yet in the energy spread measurement of the relativistic electron beam for laser wakefield acceleration(LWFA). In this work, we fill this gap by numerical simulations based on the experimental data, which indicate that in a C-shape magnet, magnetic field possesses the beam focusing effect, considering that the divergence angle will result in an increase in the full width at half maxima(FWHM) of the electron density distribution in a uniformly isotropic manner, while the length-to-width ratio decreases. This indicates that the energy spread obtained from the electron deflection distance is smaller than the actual value, regardless of the divergence angle. A promising and efficient way to accurately correct the value is presented by considering the divergence angle(for instance, for an electron beam with a length-to-width ratio of 1.12, the energy spread correct from 1.2% to 1.5%), providing a reference for developing the high-quality electron beam source.
卢光伟李曜均胡曦辰陈思宇徐豪祝铭阳闫文超陈黎明
Ultrahigh-brightness 50 MeV electron beam generation from laser wakefield acceleration in a weakly nonlinear regime
2024年
We propose an efficient scheme to produce ultrahigh-brightness tens of MeV electron beams by designing a density-tailored plasma to induce a wakefield in the weakly nonlinear regime with a moderate laser energy of 120 mJ.In this scheme,the second bucket of the wakefield can have a much lower phase velocity at the steep plasma density down-ramp than the first bucket and can be exploited to implement longitudinal electron injection at a lower laser intensity,leading to the generation of bright electron beams with ultralow emittance together with low energy spread.Three-dimensional particle-in-cell simulations are carried out and demonstrate that high-quality electron beams with a peak energy of 50 MeV,ultralow emittance of28 nm rad,energy spread of 1%,charge of 4.4 pC,and short duration less than 5 fs can be obtained within a 1-mm-long tailored plasma density,resulting in an ultrahigh six-dimensional brightness B6D,n of2×1017 A/m2/0.1%.By changing the density parameters,tunable bright electron beams with peak energies ranging from 5 to 70 MeV,a small emittance of B0.1 mm mrad,and a low energy spread at a few-percent level can be obtained.These bright MeV-class electron beams have a variety of potential applications,for example,as ultrafast electron probes for diffraction and imaging,in laboratory astrophysics,in coherent radiation source generation,and as injectors for GeV particle accelerators.
Zhongtao XiangChanghai YuZhiyong QinXuhui JiaoJiahui ChengQiaoxuan ZhouGatie AxiJianghua JieYa HuangJintan CaiJiansheng Liu
关键词:WEAKLYACCELERATION
Effect of sharp vacuum-plasma boundary on the electron injection and acceleration in a few-cycle laser driven wakefield
2023年
The electron injection and acceleration driven by a few-cycle laser with a sharp vacuum-plasma boundary have been investigated through three-dimensional(3D)particle-in-cell simulations.It is found that an isotropic boundary impact injection(BII)first occurs at the vacuum-plasma boundary,and then carrier-envelope-phase(CEP)shift causes the transverse oscillation of the plasma bubble,resulting in a periodic electron self-injection(SI)in the laser polarization direction.It shows that the electron charge of the BII only accounts for a small part of the total charge,and the CEP can effectively tune the quality of the injected electron beam.The dependences of laser intensity and electron density on the total charge and the ratio of BII charge to the total charge are studied.The results are beneficial to electron acceleration and its applications,such as betatron radiation source.
张国博刘松邹德滨崔野刘建鹏杨晓虎马燕云邵福球
《威克菲尔德牧师传》中查尔斯·普里姆罗斯博士的伦理解读
2023年
本文试图纠正将奥利弗·哥德史密斯针对查尔斯·普里姆罗斯博士的描述视为讽刺或戏仿牧师唯物主义的解读。相反,通过从牧师在《威克菲尔德牧师传》(1766)中显露并表现出的伦理身份来解读他性格中的矛盾。牧师的道德困境与其缺乏经验有关,根源在于他无法有效地维护自己的家长权威。一旦叙述者揭示了怪异的伯切尔先生的真实身份是威廉·桑希尔爵士,并在小说结尾将他推介为救世之神,准男爵就被提升为牧师伦理身份的逆反模式:他将为了自己的公共和私人形象,设定唯一的伦理标准,进而掌控困扰普里姆罗斯博士的伦理混乱。
桑德罗·荣格

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黄婷
作品数:8被引量:55H指数:3
供职机构:重庆交通大学
研究主题:公交服务 公共交通 雇主品牌 层次分析 服务质量