检索结果-内蒙古大学图书馆

Gain Switching of the Microbunching Instability to Produce Giant Bursts of Terahertz Coherent Synchrotron Radiation

Physical Review Letters 2024年第14期133卷 145001页

作者： C. Evain E. Roussel S. Bielawski M.-A. Tordeux F. Ribeiro M. Labat N. Hubert J.-B. Brubach P. Roy C. Szwaj CNRS UMR 8523—PhLAM—Physique des Lasers Atomes et Molécules F-59000 Lille France L’Orme des Merisiers Départementale 128 91190 Saint-Aubin France

relativistic electron bunches used to produce synchrotron radiation are systematically subjected to spontaneous appearance of microstructures, when a high number of electrons are used. In storage rings, this usually leads to an intense coherent emission in the terahetz range, with powers that are orders of magnitude higher than standard incoherent emission. However this emission generally displays an erratic behavior, which has strongly limited its domain of application so far. In this Letter—inspired by the process of gain switching in lasers—we present a new method for controlling the electron bunch dynamics during this instability. We show that it is possible to trigger the formation of the microstructures in the bunch, and also to considerably enhance the peak power of the coherent terahertz bursts. The experimental demonstration of this scheme—based on the modulation of a rf-cavity signal—is performed at the SOLEIL facility.

关键词： Accelerator/storage ring control systems Beam control Beam instabilities High intensity beam dynamics Nonlinear beam dynamics Pattern formation relativistic multiple-particle dynamics Spatiotemporal chaos Storage rings Fokker-Planck & Vlasov model Terahertz sources

来源：评论

学校读者我要写书评

暂无评论

Dense Polarized Positrons from Beam-Solid Interaction

引用

Physical Review Letters 2024年第23期132卷 235001-235001页

作者： Xing-Long Zhu Wei-Yuan Liu Tong-Pu Yu Min Chen Su-Ming Weng Wei-Min Wang Zheng-Ming Sheng Institute for Fusion Theory and Simulation School of Physics Tsung-Dao Lee Institute Key Laboratory for Laser Plasmas (MOE) School of Physics and Astronomy Collaborative Innovation Center of IFSA Department of Physics Department of Physics and Beijing Key Laboratory of Opto-electronic Functional Materials and Micro-nano Devices

relativistic positron sources with high spin polarization have important applications in nuclear and particle physics and many frontier fields. However, it is challenging to produce dense polarized positrons. Here we present a simple and effective method to achieve such a positron source by directly impinging a relativistic high-density electron beam on the surface of a solid target. During the interaction, a strong return current of plasma electrons is induced and subsequently asymmetric quasistatic magnetic fields as high as megatesla are generated along the target surface. This gives rise to strong radiative spin flips and multiphoton processes, thus leading to efficient generation of copious polarized positrons. With three-dimensional particle-in-cell simulations, we demonstrate the production of a dense highly polarized multi-GeV positron beam with an average spin polarization above 40% and nC-scale charge per shot. This offers a novel route for the studies of laserless strong-field quantum electrodynamics physics and for the development of high-energy polarized positron sources.

关键词： Beam polarization High intensity beam dynamics Plasma-beam interactions Radiation & particle generation in plasmas relativistic multiple-particle dynamics Positrons relativistic plasmas particle-in-cell methods

来源：评论

学校读者我要写书评

暂无评论

Radiative polarization dynamics of relativistic electrons in an intense electromagnetic field

引用

Physical Review A 2021年第4期103卷 042807-042807页

作者： Yuhui Tang Zheng Gong Jinqing Yu Yinren Shou Xueqing Yan State Key Laboratory of Nuclear Physics and Technology and Key Laboratory of HEDP of the Ministry of Education CAPT School of Physics Peking University Beijing 100871 China School of Physics and Electronics Hunan University Changsha 410082 China Beijing Laser Acceleration Innovation Center Huairou Beijing 101400 China CICEO Shanxi University Taiyuan Shanxi 030006 China Institute of Guangdong Laser Plasma Technology Baiyun Guangzhou 510540 China

We propose a self-consistent model which utilizes the polarization vector to theoretically describe the evolution of spin polarization of relativistic electrons in an intense electromagnetic field. The variation of radiative polarization due to instantaneous no photon emission is introduced into our model, which extends the applicability of the polarization vector model derived from the nonlinear Compton scattering under local constant crossed-field approximation to the complex electromagnetic environment in laser plasma interaction. According to this model, we develop a Monte Carlo method to simulate the electron spin under the influence of radiation and precession simultaneously. Our model is consistent with the quantum physical picture that spin can only be described by a probability distribution before measurement, and it contains the entire information on the spin. The correctness of our model is confirmed by the successful reproduction of the Sokolov-Ternov effect and the comparison of the simulation results with other models in the literature. The results show the superiority in accuracy, applicability, and computational efficiency of our model, and we believe that our model is a better choice to deal with the electron spin in particle-in-cell simulation for laser plasma interaction.

关键词： Beam code development & simulation techniques Quantum electrodynamics relativistic multiple-particle dynamics Spin polarization Strong electromagnetic field effects Spin

来源：评论

学校读者我要写书评

暂无评论

Instantaneous and Retarded Interactions in Coherent Radiation

引用

Physical Review Letters 2024年第16期133卷 165001页

作者： Zhuoyuan Liu Xiujie Deng Tong Li Lixin Yan Department of Engineering Physics Institute for Advanced Study

In coherent radiation of an ensemble of electrons, the radiation field from electrons resonantly drives the other electrons inside to produce stimulated emission. The radiation reaction force on the electrons accounting for this stimulated radiation loss is classically described by the Liénard-Wiechert potential. Despite its being the foundation of beam physics for decades, we show that using the “acceleration field” in Liénard-Wiechert potential to describe radiative interactions leads to divergences due to its implicit dependence on instantaneous interactions. Here, we propose an alternative theory for electromagnetic radiation by decomposing the interactions into an instantaneous part and retarded part. It is shown that only the retarded part contributes to the irreversible radiation loss and the instantaneous part describes the space charge related effects. We further apply this theory to study the coherent synchrotron radiation energy loss, which hopefully will reshape our understanding of coherent radiation and collective interactions.

关键词： Beam instabilities Electromagnetic field calculations High intensity beam dynamics relativistic multiple-particle dynamics Classical electromagnetism Methods in electromagnetism

来源：评论

学校读者我要写书评

暂无评论

Two-bunch seeding of soft x-ray free electron lasers

引用

Physical Review Accelerators and Beams 2024年第11期27卷 110703-110703页

作者： E. Schneidmiller Deutsches Elektronen-Synchrotron DESY Notkestr. 85 22607 Hamburg Germany

Seeded free electron lasers (FELs) demonstrate a good performance and are successfully used in different user experiments in extreme ultraviolet and soft x-ray regimes. In this paper, a simple modification of the seeding scenario is proposed relying on the generation of two closely spaced bunches with very different properties: a low-current seeding bunch and a high-current bunch that amplifies coherent radiation, produced by the seeding bunch. This approach eliminates different limitations and mitigates some harmful effects in the standard scenario. In particular, one can generate very high harmonic numbers with a moderate laser power in a simple high-gain harmonic generation (HGHG) scheme. Alternatively, in case of moderate harmonic numbers, one can strongly reduce the required laser power thus simplifying the design of high repetition rate seeded FELs. An influence of beam dynamics effects (like nonlinearities of the longitudinal phase space of electron beams, coherent synchrotron radiation, longitudinal space charge, geometrical wakefields, and microbunching instabilities) on properties of the output radiation (spectrum broadening, pedestals, and stability) can be to a large extent reduced in the proposed scheme. In this paper, we illustrate the operation of the two-bunch seeding scheme in HGHG configuration with realistic start-to-end simulations for the soft x-ray user facility free electron laser in Hamburg. We show that nearly Fourier-limited multigigawatt pulses can be generated at 4 nm using the present compact design of the undulator system. With several thousand pulses per second, this can be a unique source for photon science.

关键词： Beam processes Classical electromagnetism Lasers Optics & lasers relativistic multiple-particle dynamics X-ray beams & optics

来源：评论

学校读者我要写书评

暂无评论

Three-dimensional theory of superradiant free-electron lasers

引用

Physical Review Research 2024年第3期6卷 033158-033158页

作者： River R. Robles Luca Giannessi Agostino Marinelli Menlo Park California 94025 USA Department of Applied Physics Stanford PULSE Institute 34149 Basovizza Trieste Italy 00044 Frascati (Roma) Italy

The solitonlike superradiant regime of free-electron lasers (FEL) offers a promising path towards ultrashort pulses, beyond the natural limit dictated by the bandwidth of the high-gain FEL instability. In this work we present a three-dimensional theory of the superradiant regime, including the effects of beam emittance and energy spread. Our work takes advantage of recent developments in nonlinear FEL theory to provide a fully analytical description of solitonlike superradiance. Our theory proves the existence of a diffraction-dominated steady-state regime in which the superradiant peak power grows indefinitely while leaving the pulse duration and on-axis intensity almost unchanged. These results are in excellent agreement with three-dimensional simulations and are supported by recent experimental results at the Linac Coherent Light Source. This work advances nonlinear FEL theory and provides a theoretical framework for the next generation of attosecond x-ray FELs.

关键词： Beam dynamics Collective dynamics Methods in electromagnetism relativistic multiple-particle dynamics Free-electron lasers particle accelerators Solitons Phase space dynamics

来源：评论

学校读者我要写书评

暂无评论

Mitigation of the microbunching instability through transverse Landau damping

引用

Physical Review Accelerators and Beams 2024年第7期27卷 074402-074402页

作者： A. D. Brynes G. Perosa C.-Y. Tsai E. Allaria L. Badano G. De Ninno E. Ferrari D. Garzella L. Giannessi G. Penco P. Rebernik Ribič E. Roussel S. Spampinati C. Spezzani M. Trovò M. Veronese S. Di Mitri 34149 Basovizza Trieste Italy Department of Physics Department of Electrotechnical Theory and Advanced Electromagnetic Technology 5000 Nova Gorica Slovenia Notkestr. 85 22607 Hamburg Germany Laboratori Nazionali di Frascati 00044 Frascati Rome Italy CNRS UMR 8523 -

The microbunching instability has been a long-standing issue for high-brightness free-electron lasers (FELs) and is a significant showstopper to achieve full longitudinal coherence in the x-ray regime. This paper reports the first experimental demonstration of microbunching instability mitigation through transverse Landau damping, based on linear optics control in a dispersive region. Analytical predictions for the microbunching content are supported by numerical calculations of the instability gain. The effect is confirmed through the experimental characterization of the spectral brightness of the FERMI FEL under different transverse optics configurations of the transfer line between the linear accelerator and the FEL.

关键词： Beam instabilities Beam optics relativistic multiple-particle dynamics

来源：评论

学校读者我要写书评

暂无评论

Current status and desired precision of the isotopic production cross sections relevant to astrophysics of cosmic rays. II. Fluorine to silicon and updated results for Li, Be, and B

引用

Physical Review C 2024年第6期109卷 064914-064914页

作者： Yoann Génolini David Maurin Igor V. Moskalenko Michael Unger LAPTh Université Savoie Mont Blanc CNRS Cedex Annecy 74941 France LPSC Université Grenoble-Alpes CNRS/IN2P3 Grenoble 38026 France W. W. Hansen Experimental Physics Laboratory Kavli Institute for Particle Astrophysics and Cosmology Stanford University Stanford 94305 CA United States Institute for Astroparticle Physics (IAP) Karlsruhe Institute of Technology (KIT) Karlsruhe Germany Institutt for Fysikk Norwegian University of Science and Technology (NTNU) Trondheim Norway

High-precision cosmic-ray (CR) data from ongoing and recent past experiments (Voyager, ACE-CRIS, PAMELA, ATIC, CREAM, NUCLEON, AMS-02, CALET, DAMPE) are being released in the tens of the MeV/n to multi-TeV/n energy range. Astrophysical and dark matter interpretations of these data are limited by the precision of nuclear production cross sections. In Paper I [Phys. Rev. C 98, 034611 (2018)], we set up a procedure to rank nuclear reactions whose desired measurements will enable us to fully exploit currently available data on CR Li to N (Z=3–7) species. Here we extend these rankings to O up to Si nuclei (Z=8–14), also updating our results on the LiBeB species. We also highlight how comprehensive new high-precision nuclear data that could, e.g., be obtained at the Super Proton Synchrotron at CERN would be a game changer for the determination of key astrophysical quantities (diffusion coefficient, halo size of the Galaxy) and indirect searches for dark matter signatures.

关键词： Cosmic ray & astroparticle detectors Cosmic rays & astroparticles Dark matter Nuclear fragmentation Nucleon-nucleon interactions particle dark matter relativistic multiple-particle dynamics High-energy accelerators & colliders particle accelerators Proton & ion sources

来源：评论

学校读者我要写书评

暂无评论

Numerical modeling of a proof-of-principle experiment on optical stochastic cooling at an electron storage ring

引用

Physical Review Accelerators and Beams 2024年第1期27卷 012801-012801页

作者： A. J. Dick M. Borland J. Jarvis V. Lebedev P. Piot A. Romanov M. Wallbank Northern Illinois Center for Accelerator & Detector Development and Department of Physics Northern Illinois University DeKalb Illinois 60115 USA Argonne National Laboratory Lemont Illinois 60439 USA Fermi National Accelerator Laboratory Batavia Illinois 60510 USA

Cooling of beams circulating in storage rings is critical for many applications including particle colliders and synchrotron light sources. A method enabling unprecedented beam-cooling rates, optical stochastic cooling (OSC), was recently demonstrated in the Integrable Optics Test Accelerator (IOTA) electron storage ring at Fermilab [J. Jarvis et al., Nature (London) 608, 287 (2022)]. This paper describes the numerical implementation of the OSC process in the particle-tracking program elegant and discusses the validation of the developed model with available experimental data. The model is also employed to highlight some features associated with different modes of operation of OSC. The developed simulation tool should be valuable in guiding future configurations of optical stochastic cooling and, more broadly, modeling self-field-based beam manipulations.

关键词： Beam code development & simulation techniques Beam cooling Beam optics relativistic multiple-particle dynamics Single-particle dynamics Advanced accelerator test facilities Storage rings Undulators & wigglers

来源：评论

学校读者我要写书评

暂无评论

Multiturn simulation of radiative Bhabha scattering in the equivalent photon approximation

引用

Physical Review Accelerators and Beams 2024年第9期27卷 091001页

作者： Peter Kicsiny Xavier Buffat Daniel Schulte Helmut Burkhardt Tatiana Pieloni Mike Seidel CH 1211 Geneva 23 Switzerland Route Cantonale 1015 Lausanne Switzerland

In this paper, we present a Monte Carlo event generator for radiative Bhabha scattering, based on the method of equivalent photons, and optimized for multiturn tracking simulations in the xsuite framework. We demonstrate the accuracy of the event generator with successful benchmarks of the luminosity and event cross section against currently existing alternative tools. Consequently, we use it to investigate existing estimates of the radiative Bhabha scattering beam lifetime at the FCC-ee, as well as the impact of radiative Bhabha scattering on the beam dynamics, using full nonlinear tracking models.

关键词： Beam code development & simulation techniques Beam loss Beam processes relativistic multiple-particle dynamics

来源：评论

学校读者我要写书评

暂无评论

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案：

请选择收藏分类：

通借通还

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：