1 上海师范大学物理系,上海 200234
2 中国科学院上海光学精密机械研究所强场激光物理国家重点实验室,上海 201800
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。
激光光学 激光尾波场 电子加速 能量啁啾 betatron辐射 逆康普顿散射 自由电子激光
Author Affiliations
Abstract
1 SANKEN (Institute of Scientific and Industrial Research), Osaka University, Ibaraki, Osaka, Japan
2 Kansai Institute for Photon Science (KPSI), National Institutes for Quantum Science and Technology (QST), Kizugawa-city, Kyoto, Japan
3 RIKEN SPring-8 Center, Sayo, Hyogo, Japan
Supersonic gas jets generated via a conical nozzle are widely applied in the laser wakefield acceleration of electrons. The stability of the gas jet is critical to the electron injection and the reproducibility of the wakefield acceleration. Here we discussed the role of the stilling chamber in a modified converging–diverging nozzle to dissipate the turbulence and to stabilize the gas jets. By the fluid dynamics simulations and the Mach–Zehnder interferometer measurements, the instability originating from the nonlinear turbulence is studied and the mechanism to suppress the instability is proposed. Both the numerical and experimental results prove that the carefully designed nozzle with a stilling chamber is able to reduce the perturbation by more than 10% compared with a simple-conical nozzle.
shock injection hydrodynamic stability laser wakefield acceleration laser–plasma interaction High Power Laser Science and Engineering
2023, 11(6): 06000e91
Author Affiliations
Abstract
1 Department of Physics, National University of Defense Technology, Changsha, China
2 Department of Nuclear Science and Technology, National University of Defense Technology, Changsha, China
3 Key Laboratory for Laser Plasmas (MOE) and School of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai, China
4 Collaborative Innovation Center of IFSA, Shanghai Jiao Tong University, Shanghai, China
5 Tsung-Dao Lee Institute, Shanghai Jiao Tong University, Shanghai, China
Relativistic few-cycle mid-infrared (mid-IR) pulses are unique tools for strong-field physics and ultrafast science, but are difficult to generate with traditional nonlinear optical methods. Here, we propose a scheme to generate such pulses with high efficiency via plasma-based frequency modulation with a negatively chirped laser pulse (NCLP). The NCLP is rapidly compressed longitudinally due to dispersion and plasma etching, and its central frequency is downshifted via photon deceleration due to the enhanced laser intensity and plasma density modulations. Simulation results show that few-cycle mid-IR pulses with the maximum center wavelength of $7.9\;\unicode{x3bc} \mathrm{m}$ and pulse intensity of ${a}_{\mathrm{MIR}}=2.9$ can be generated under a proper chirp parameter. Further, the maximum energy conversion efficiency can approach 5.0%. Such a relativistic mid-IR source is promising for a wide range of applications.
chirp laser pulses laser wakefield photon deceleration relativistic mid-infrared generation High Power Laser Science and Engineering
2023, 11(5): 05000e57
Author Affiliations
Abstract
1 State Key Laboratory of High Field Laser Physics and CAS Center for Excellence in Ultra-intense Laser Science, Shanghai Institute of Optics and Fine Mechanics (SIOM), Chinese Academy of Sciences (CAS), Shanghai, China
2 School of Physical Science and Technology, ShanghaiTech University, Shanghai, China
A single-shot measurement of electron emittance was experimentally accomplished using a focused transfer line with a dipole. The betatron phase of electrons based on laser wakefield acceleration (LWFA) is energy dependent owing to the coupling of the longitudinal acceleration field and the transverse focusing (defocusing) field in the bubble. The phase space presents slice information after phase compensation relative to the center energy. Fitting the transverse size of the electron beam at different energy slices in the energy spectrum measured 0.27 mm mrad in the experiment. The diagnosis of slice emittance facilitates local electron quality manipulation, which is important for the development of LWFA-based free electron lasers. The quasi-3D particle-in-cell simulations matched the experimental results and analysis well.
beam diagnostic emittance laser wakefield acceleration High Power Laser Science and Engineering
2023, 11(3): 03000e36
Author Affiliations
Abstract
1 Key Laboratory of Laser Plasma (MoE), School of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai, China
2 IFSA Collaborative Innovation Center, Shanghai Jiao Tong University, Shanghai, China
3 Shanghai Advanced Research Institute, Chinese Academy of Sciences, Shanghai, China
4 Key Laboratory of Nuclear Physics and Ion-beam Application (MoE), Institute of Modern Physics, Fudan University, Shanghai, China
A pulsed fast neutron source is critical for applications of fast neutron resonance radiography and fast neutron absorption spectroscopy. However, due to the large transversal source size (of the order of mm) and long pulse duration (of the order of ns) of traditional pulsed fast neutron sources, it is difficult to realize high-contrast neutron imaging with high spatial resolution and a fine absorption spectrum. Here, we experimentally present a micro-size ultra-short pulsed neutron source by a table-top laser–plasma wakefield electron accelerator driving a photofission reaction in a thin metal converter. A fast neutron source with source size of approximately 500 μm and duration of approximately 36 ps has been driven by a tens of MeV, collimated, micro-size electron beam via a hundred TW laser facility. This micro-size ultra-short pulsed neutron source has the potential to improve the energy resolution of a fast neutron absorption spectrum dozens of times to, for example, approximately 100 eV at 1.65 MeV, which could be of benefit for high-quality fast neutron imaging and deep understanding of the theoretical model of neutron physics.
fast neutrons high-power laser laser wakefield acceleration photofission reaction High Power Laser Science and Engineering
2022, 10(5): 05000e33
Author Affiliations
Abstract
1 Intense Laser Irradiation Laboratory, INO-CNR, Pisa, Italy
2 ELI-NP, Magurele, Ilfov, Romania
3 Maison de la Simulation, CEA, USR 3441, Gif-sur-Yvette, France
4 INFN, Sect. of Pisa, Pisa, Italy
After the introduction of the ionization-injection scheme in laser wake field acceleration and of related high-quality electron beam generation methods, such as two-color and resonant multi-pulse ionization injection (ReMPI), the theory of thermal emittance has been used to predict the beam normalized emittance obtainable with those schemes. We recast and extend such a theory, including both higher order terms in the polynomial laser field expansion and non-polynomial corrections due to the onset of saturation effects on a single cycle. Also, a very accurate model for predicting the cycle-averaged distribution of the extracted electrons, including saturation and multi-process events, is proposed and tested. We show that our theory is very accurate for the selected processes of ${\mathrm{Kr}}^{8^{+}\to {10}^{+}}$ and ${\mathrm{Ar}}^{8^{+}\to {10}^{+}}$ , resulting in a maximum error below 1%, even in a deep-saturation regime. The accurate prediction of the beam phase-space can be implemented, for example, in laser-envelope or hybrid particle-in-cell (PIC)/fluid codes, to correctly mimic the cycle-averaged momentum distribution without the need for resolving the intra-cycle dynamics. We introduce further spatial averaging, obtaining expressions for the whole-beam emittance fitting with simulations in a saturated regime, too. Finally, a PIC simulation for a laser wakefield acceleration injector in the ReMPI configuration is discussed.
field theory ionization high-quality electron beams ionization injection laser wakefield acceleration laser–plasma acceleration resonant multi-pulse ionization injection tunnel ionization two-color ionization ultraintense laser pulses High Power Laser Science and Engineering
2022, 10(2): 02000e15
强激光与粒子束
2021, 33(7): 074001
强激光与粒子束
2020, 32(9): 092001
中国工程物理研究院 激光聚变研究中心, 四川 绵阳 621900
在激光尾场加速中, 光学注入是一种有效的可控电子注入机制。然而, 低电量、大发散度的电子束特性无法满足实际应用的需要。为获得大电量、高品质电子束提出采用紧聚焦的超高斯激光作为注入脉冲的新型注入方案。研究发现, 相比于普通高斯激光, 紧聚焦的超高斯激光不仅能够将电子束发散度降低近一个数量级, 而且能够保持电子束电荷量不变。通过哈密顿理论模型证实, 离轴电子是发散度的主要来源, 而紧聚焦的超高斯激光极大地限制了离轴电子的注入, 因此有效地降低了电子束的发散度。
激光尾场加速 光学注入 电子束发散度 离轴电子 紧聚焦超高斯激光 laser wakefield accelerations optical injection emittance of electron beam off-axis injected electrons tightly focused super-Gaussian laser 强激光与粒子束
2018, 30(11): 111003
Author Affiliations
Abstract
1 Science and Technology on Plasma Physics Laboratory
,
Laser Fusion Research Center
,
China Academy of Engineering Physics
,
Mianyang 621900
,
China
2 IFSA Collaborative Innovation Center
,
Shanghai Jiao Tong University
,
Shanghai 200240
,
China
Muons produced by the Bethe–Heitler process from laser wakefield accelerated electrons interacting with high
materials have velocities close to the laser wakefield. It is possible to accelerate those muons with laser wakefield directly. Therefore for the first time we propose an all-optical ‘Generator and Booster’ scheme to accelerate the produced muons by another laser wakefield to supply a prompt, compact, low cost and controllable muon source in laser laboratories. The trapping and acceleration of muons are analyzed by one-dimensional analytic model and verified by two-dimensional particle-in-cell (PIC) simulation. It is shown that muons can be trapped in a broad energy range and accelerated to higher energy than that of electrons for longer dephasing length. We further extrapolate the dependence of the maximum acceleration energy of muons with the laser wakefield relativistic factor
and the relevant initial energy
. It is shown that a maximum energy up to 15.2 GeV is promising with
and
on the existing short pulse laser facilities.
laser wakefield acceleration muon source High Power Laser Science and Engineering
2018, 6(4): 04000e63