Pub Date : 2024-03-19DOI: 10.1103/physrevaccelbeams.27.030401
Shu-Chao Duan, Ge-Guang He, Shao-Tong Zhou, Ming-Xian Kan, Gang-Hua Wang
A recently emerging approach adopts a directionally time-varying (rotating) magnetic field to drive a pinch load, aiming to mitigate the inherent magneto-Rayleigh-Taylor instability in dynamic <math display="inline" xmlns="http://www.w3.org/1998/Math/MathML"><mrow><mi>Z</mi></mrow></math> pinches. A helical return current post (RCP) serves as a functional structural element capable of generating the requisite driving magnetic field for this purpose in the load region. This paper first calculates the current azimuthally induced on the outer surface of a magnetically pinched load within this type of RCP using a zero-dimensional lumped-parameter circuit model. The results show that the induced current deviates significantly from the presumed “perfect” induced current (100% amplitude) as reported in the literature [S. A. Sorokin, <span>Plasma Phys. Rep.</span> <b>39</b>, 139 (2013); P. F. Schmit <i>et al.</i>, <span>Phys. Rev. Lett.</span> <b>117</b>, 205001 (2016); G. A. Shipley <i>et al.</i>, <span>Phys. Plasmas</span> <b>26</b>, 102702 (2019); and P. C. Campbell <i>et al.</i>, <span>Phys. Rev. Lett.</span> <b>125</b>, 035001 (2020)], with an effective coefficient of current induction considerably less than 1. However, even when the load is fully compressed to the axis, the effective coefficient does not approach zero but rather converges to a finite value that solely depends on the aspect ratio of the RCP. This is quite favorable for the suppression of magneto-Rayleigh-Taylor instability in the <math display="inline" xmlns="http://www.w3.org/1998/Math/MathML"><mrow><mi>Z</mi></mrow></math> pinch. As for the pointlike <math display="inline" xmlns="http://www.w3.org/1998/Math/MathML"><mrow><mi>X</mi></mrow></math> pinch, the axial magnetic field does not tend to zero but a finite value, though the effective coefficient tends to zero, and this result may be used to suppress the instability in <math display="inline" xmlns="http://www.w3.org/1998/Math/MathML"><mrow><mi>X</mi></mrow></math> pinch and improve the time stability and spatiotemporal unity of hot spots. In addition, the anode and cathode plates have the potential to enhance the current induced in the load. This paper then analyzes the axial distribution and time behavior of the induced current adopting an approximate analytical method and numerical integration and finds an approximate invariance that can be well characterized by <math display="inline" xmlns="http://www.w3.org/1998/Math/MathML"><mrow><mi>δ</mi><mi>t</mi></mrow></math>, the product of the normalized skin depth and time. Similar values of <math display="inline" xmlns="http://www.w3.org/1998/Math/MathML"><mrow><mi>δ</mi><mi>t</mi></mrow></math> indicate similar axial distribution characteristics. When <math display="inline" xmlns="http://www.w3.org/1998/Math/MathML"><mrow><mi>δ</mi><mi>t</mi></mrow></math> is lower than, at, or higher than the critical region (<math display="inline" xmlns="http://www.w3.org/1998/Math/MathML"><mr
最近出现的一种方法采用定向时变（旋转）磁场来驱动夹紧负载，旨在缓解动态 Z 形夹紧中固有的磁-雷利-泰勒不稳定性。螺旋回流柱 (RCP) 是一种功能性结构元件，能够在负载区产生必要的驱动磁场。本文首先使用零维整块参数电路模型计算了在这种 RCP 内的磁挤压负载外表面的方位感应电流。结果表明，感应电流明显偏离了文献 [S. A., J., J., J., J., J., J., J., J., J., J.] 中假定的 "完美 "感应电流（100% 幅值）。A.Sorokin, Plasma Phys. Rep. 39, 139 (2013); P. F.Schmit 等人，Phys.117, 205001 (2016); G. A.Shipley 等人，Phys. Plasmas 26, 102702 (2019)；以及 P. C.Campbell 等人，Phys.然而，即使负载完全压缩到轴上，有效系数也不会趋近于零，而是收敛到仅取决于 RCP 长宽比的有限值。这对抑制 Z 夹角中的磁-雷利-泰勒不稳定性非常有利。至于点状 X 陷波，虽然有效系数趋于零，但轴向磁场并不趋于零，而是趋于有限值，这一结果可用于抑制 X 陷波中的不稳定性，改善热点的时间稳定性和时空统一性。此外，阳极板和阴极板还有可能增强负载中的感应电流。本文采用近似解析法和数值积分法分析了感应电流的轴向分布和时间行为，发现了一个近似不变性，可以用归一化表皮深度与时间的乘积 δt 很好地表征。相似的 δt 值表示相似的轴向分布特征。当 δt 低于、等于或高于临界区域（0.1-0.3）时，轴向分布分别呈现哑铃形、近似扁平形和拱形。利用这些分布式感应电流可分别实现准球形、近扁平和哑铃形的内爆。
{"title":"Analytical analysis of the generation of a rotating driving magnetic field on the outer surface of a magnetic pinch load with a helical return current post","authors":"Shu-Chao Duan, Ge-Guang He, Shao-Tong Zhou, Ming-Xian Kan, Gang-Hua Wang","doi":"10.1103/physrevaccelbeams.27.030401","DOIUrl":"https://doi.org/10.1103/physrevaccelbeams.27.030401","url":null,"abstract":"A recently emerging approach adopts a directionally time-varying (rotating) magnetic field to drive a pinch load, aiming to mitigate the inherent magneto-Rayleigh-Taylor instability in dynamic <math display=\"inline\" xmlns=\"http://www.w3.org/1998/Math/MathML\"><mrow><mi>Z</mi></mrow></math> pinches. A helical return current post (RCP) serves as a functional structural element capable of generating the requisite driving magnetic field for this purpose in the load region. This paper first calculates the current azimuthally induced on the outer surface of a magnetically pinched load within this type of RCP using a zero-dimensional lumped-parameter circuit model. The results show that the induced current deviates significantly from the presumed “perfect” induced current (100% amplitude) as reported in the literature [S. A. Sorokin, <span>Plasma Phys. Rep.</span> <b>39</b>, 139 (2013); P. F. Schmit <i>et al.</i>, <span>Phys. Rev. Lett.</span> <b>117</b>, 205001 (2016); G. A. Shipley <i>et al.</i>, <span>Phys. Plasmas</span> <b>26</b>, 102702 (2019); and P. C. Campbell <i>et al.</i>, <span>Phys. Rev. Lett.</span> <b>125</b>, 035001 (2020)], with an effective coefficient of current induction considerably less than 1. However, even when the load is fully compressed to the axis, the effective coefficient does not approach zero but rather converges to a finite value that solely depends on the aspect ratio of the RCP. This is quite favorable for the suppression of magneto-Rayleigh-Taylor instability in the <math display=\"inline\" xmlns=\"http://www.w3.org/1998/Math/MathML\"><mrow><mi>Z</mi></mrow></math> pinch. As for the pointlike <math display=\"inline\" xmlns=\"http://www.w3.org/1998/Math/MathML\"><mrow><mi>X</mi></mrow></math> pinch, the axial magnetic field does not tend to zero but a finite value, though the effective coefficient tends to zero, and this result may be used to suppress the instability in <math display=\"inline\" xmlns=\"http://www.w3.org/1998/Math/MathML\"><mrow><mi>X</mi></mrow></math> pinch and improve the time stability and spatiotemporal unity of hot spots. In addition, the anode and cathode plates have the potential to enhance the current induced in the load. This paper then analyzes the axial distribution and time behavior of the induced current adopting an approximate analytical method and numerical integration and finds an approximate invariance that can be well characterized by <math display=\"inline\" xmlns=\"http://www.w3.org/1998/Math/MathML\"><mrow><mi>δ</mi><mi>t</mi></mrow></math>, the product of the normalized skin depth and time. Similar values of <math display=\"inline\" xmlns=\"http://www.w3.org/1998/Math/MathML\"><mrow><mi>δ</mi><mi>t</mi></mrow></math> indicate similar axial distribution characteristics. When <math display=\"inline\" xmlns=\"http://www.w3.org/1998/Math/MathML\"><mrow><mi>δ</mi><mi>t</mi></mrow></math> is lower than, at, or higher than the critical region (<math display=\"inline\" xmlns=\"http://www.w3.org/1998/Math/MathML\"><mr","PeriodicalId":54297,"journal":{"name":"Physical Review Accelerators and Beams","volume":"51 1","pages":""},"PeriodicalIF":1.7,"publicationDate":"2024-03-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140168253","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-03-18DOI: 10.1103/physrevaccelbeams.27.031601
Wencan Xu, Z. A. Conway, E. Daly, J. Guo, K. Hernandez, D. Holmes, R. A. Rimmer, F. Severino, K. Smith, D. Weiss, A. Zaltsman
The next high-current Electron-Ion Collider (EIC) is a new accelerator to be built at Brookhaven National Laboratory in collaboration with Thomas Jefferson National Accelerator Facility. In the EIC Electron Storage Ring (ESR), there will be beam currents of up to 2.5 A, which will excite massive higher-order-mode (HOM) power in the 17 single-cell 591 MHz superconducting radio-frequency (SRF) cavities. Damping the HOM power in the ESR SRF cavities is a challenge. A room temperature cylindrical shell shape silicon carbide (SiC) beamline HOM absorber (BLA) was chosen as the baseline design, due to its broadband and high-power capability, and previous demonstrations at other accelerator facilities, albeit at much lower power. Because the EIC BLA HOM power dissipation is significantly greater than the previous applications, it is imperative to carry out high-power testing to determine the maximum device performance levels achievable for thermal transport, rf breakdown, and mechanical stress, prior to finalizing the design. A SiC HOM absorber with a state-of-the-art geometry size was prototyped to verify the shrink-fit technique, test outgassing rate, and high-power handling capability. This paper presents the HOM damper’s prototyping and test results.
下一个大电流电子-离子对撞机（EIC）是布鲁克海文国家实验室与托马斯-杰斐逊国家加速器合作建造的新型加速器。在 EIC 电子存储环（ESR）中，束流将高达 2.5 A，这将在 17 个单细胞 591 MHz 超导射频（SRF）空腔中激发出巨大的高阶模（HOM）功率。在 ESR SRF 腔中阻尼 HOM 功率是一项挑战。由于碳化硅（SiC）光束线 HOM 吸收器（BLA）具有宽带和高功率能力，而且之前在其他加速器设施中进行过演示（尽管功率要低得多），因此被选为基准设计。由于 EIC BLA HOM 功率耗散远远大于之前的应用，因此在最终确定设计之前，必须进行大功率测试，以确定在热传输、射频击穿和机械应力方面可达到的最大器件性能水平。我们制作了具有最先进几何尺寸的 SiC HOM 吸波器原型，以验证收缩贴合技术、测试排气率和大功率处理能力。本文介绍了 HOM 减震器的原型设计和测试结果。
{"title":"High-power test results for a cylindrical-shell silicon carbide higher-order-mode damper","authors":"Wencan Xu, Z. A. Conway, E. Daly, J. Guo, K. Hernandez, D. Holmes, R. A. Rimmer, F. Severino, K. Smith, D. Weiss, A. Zaltsman","doi":"10.1103/physrevaccelbeams.27.031601","DOIUrl":"https://doi.org/10.1103/physrevaccelbeams.27.031601","url":null,"abstract":"The next high-current Electron-Ion Collider (EIC) is a new accelerator to be built at Brookhaven National Laboratory in collaboration with Thomas Jefferson National Accelerator Facility. In the EIC Electron Storage Ring (ESR), there will be beam currents of up to 2.5 A, which will excite massive higher-order-mode (HOM) power in the 17 single-cell 591 MHz superconducting radio-frequency (SRF) cavities. Damping the HOM power in the ESR SRF cavities is a challenge. A room temperature cylindrical shell shape silicon carbide (SiC) beamline HOM absorber (BLA) was chosen as the baseline design, due to its broadband and high-power capability, and previous demonstrations at other accelerator facilities, albeit at much lower power. Because the EIC BLA HOM power dissipation is significantly greater than the previous applications, it is imperative to carry out high-power testing to determine the maximum device performance levels achievable for thermal transport, rf breakdown, and mechanical stress, prior to finalizing the design. A SiC HOM absorber with a state-of-the-art geometry size was prototyped to verify the shrink-fit technique, test outgassing rate, and high-power handling capability. This paper presents the HOM damper’s prototyping and test results.","PeriodicalId":54297,"journal":{"name":"Physical Review Accelerators and Beams","volume":"108 1","pages":""},"PeriodicalIF":1.7,"publicationDate":"2024-03-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140149695","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-03-12DOI: 10.1103/physrevaccelbeams.27.034701
Hans G. Rinderknecht, G. Bruhaug, V. Muşat, G. Gregori, H. Poole, D. Bishel, D. A. Chin, J. R. Rygg, G. W. Collins
The physics basis for an electron-beam-based Compton scattering x-ray source is investigated for single-shot experiments at the major high-energy-density facilities, such as the Omega Laser Facility, National Ignition Facility, and pulsed power facility. A source of monoenergetic () 10- to 50-keV x rays can be produced by scattering of a short-pulse optical laser by a 23- to 53-MeV electron beam and collimating the scattered photons. The number and spectrum of scattered photons are calculated as a function of electron packet charge, electron and laser pulse duration, laser intensity, and collision geometry. A source delivering greater than photons in a 1-mm-radius spot and 100-ps time resolution is plausible with the available electron gun and laser technology. Applications of this source for x-ray diffraction, x-ray imaging, x-ray absorption fine structure, and x-ray absorption spectroscopy in high-energy-density physics experiments are described, demonstrating significant advancements compared to the present state of the art.
研究了基于电子束的康普顿散射X射线源的物理基础，以便在主要的高能量密度设施（如欧米茄激光设施、国家点火设施和Z脉冲功率设施）上进行单发实验。通过23-53MeV电子束对短脉冲光学激光的散射，并对散射光子进行准直，可以产生10-50keV的单能量（δε/ε<5%）X射线源。散射光子的数量和光谱是根据电子包电荷、电子和激光脉冲持续时间、激光强度以及碰撞几何形状的函数计算得出的。利用现有的电子枪和激光技术，可以在半径为 1 毫米的光斑中产生超过 1010 个光子，时间分辨率为 100ps。介绍了这种光源在高能量密度物理实验中的 X 射线衍射、X 射线成像、X 射线吸收精细结构和 X 射线吸收光谱等方面的应用，展示了与目前技术水平相比的显著进步。
{"title":"Electron-beam-based Compton scattering x-ray source for probing high-energy-density physics","authors":"Hans G. Rinderknecht, G. Bruhaug, V. Muşat, G. Gregori, H. Poole, D. Bishel, D. A. Chin, J. R. Rygg, G. W. Collins","doi":"10.1103/physrevaccelbeams.27.034701","DOIUrl":"https://doi.org/10.1103/physrevaccelbeams.27.034701","url":null,"abstract":"The physics basis for an electron-beam-based Compton scattering x-ray source is investigated for single-shot experiments at the major high-energy-density facilities, such as the Omega Laser Facility, National Ignition Facility, and <math display=\"inline\" xmlns=\"http://www.w3.org/1998/Math/MathML\"><mrow><mi>Z</mi></mrow></math> pulsed power facility. A source of monoenergetic (<math display=\"inline\" xmlns=\"http://www.w3.org/1998/Math/MathML\"><mrow><mi>δ</mi><mi>ε</mi><mo>/</mo><mi>ε</mi><mo><</mo><mn>5</mn><mo>%</mo></mrow></math>) 10- to 50-keV x rays can be produced by scattering of a short-pulse optical laser by a 23- to 53-MeV electron beam and collimating the scattered photons. The number and spectrum of scattered photons are calculated as a function of electron packet charge, electron and laser pulse duration, laser intensity, and collision geometry. A source delivering greater than <math display=\"inline\" xmlns=\"http://www.w3.org/1998/Math/MathML\"><mrow><msup><mrow><mn>10</mn></mrow><mrow><mn>10</mn></mrow></msup></mrow></math> photons in a 1-mm-radius spot and 100-ps time resolution is plausible with the available electron gun and laser technology. Applications of this source for x-ray diffraction, x-ray imaging, x-ray absorption fine structure, and x-ray absorption spectroscopy in high-energy-density physics experiments are described, demonstrating significant advancements compared to the present state of the art.","PeriodicalId":54297,"journal":{"name":"Physical Review Accelerators and Beams","volume":"17 1","pages":""},"PeriodicalIF":1.7,"publicationDate":"2024-03-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140149601","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-03-08DOI: 10.1103/physrevaccelbeams.27.032802
Andrei Trebushinin, Gianluca Geloni, Svitozar Serkez, Ruslan Khubbutdinov, Evgeny Saldin
In this work, we propose to use a pinhole camera at high photon energies, specifically 200–300 keV, to measure ultra-small electron beam size by means of bending magnet radiation. We show that there is a sufficient photon flux at the detector position. Our theoretical analysis includes an examination of the applicability of the van Cittert-Zernike theorem for the bending magnet radiation generated by an ultralow emittance electron beam and a detailed analysis of the imaging properties of rectangular pinhole cameras. This led us to practical, universal formulas. We identify the optimal aperture size and resolution of the camera in the given geometry. The theoretical findings are further substantiated by wavefront propagation numerical simulations of partially coherent radiation. This study serves both as a practical guide for optical engineering and an educational resource for explaining the imaging properties of pinhole cameras.
{"title":"Pinhole camera for electron beam size diagnostic at storage ring with an ultralow emittance","authors":"Andrei Trebushinin, Gianluca Geloni, Svitozar Serkez, Ruslan Khubbutdinov, Evgeny Saldin","doi":"10.1103/physrevaccelbeams.27.032802","DOIUrl":"https://doi.org/10.1103/physrevaccelbeams.27.032802","url":null,"abstract":"In this work, we propose to use a pinhole camera at high photon energies, specifically 200–300 keV, to measure ultra-small electron beam size by means of bending magnet radiation. We show that there is a sufficient photon flux at the detector position. Our theoretical analysis includes an examination of the applicability of the van Cittert-Zernike theorem for the bending magnet radiation generated by an ultralow emittance electron beam and a detailed analysis of the imaging properties of rectangular pinhole cameras. This led us to practical, universal formulas. We identify the optimal aperture size and resolution of the camera in the given geometry. The theoretical findings are further substantiated by wavefront propagation numerical simulations of partially coherent radiation. This study serves both as a practical guide for optical engineering and an educational resource for explaining the imaging properties of pinhole cameras.","PeriodicalId":54297,"journal":{"name":"Physical Review Accelerators and Beams","volume":"10 1","pages":""},"PeriodicalIF":1.7,"publicationDate":"2024-03-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140071118","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-03-08DOI: 10.1103/physrevaccelbeams.27.032801
P. González Caminalet al.
Longitudinal electron-beam diagnostics play a critical role in the operation and control of x-ray free-electron lasers, which rely on parameters such as the current profile, the longitudinal phase space, or the slice emittance of the particle distribution. On the one hand, the femtosecond-scale electron bunches produced at these facilities impose stringent requirements on the resolution achievable with the diagnostics. On the other, research and development of novel accelerator technologies such as beam-driven plasma-wakefield accelerators (PWFA) demand unprecedented capabilities to resolve the centroid offsets in the full transverse plane along the longitudinal bunch coordinate. We present the beam-based commissioning of an advanced -band transverse-deflection rf structure (TDS) system with the new feature of providing variable polarization of the deflecting force: the PolariX-TDS. By means of a comprehensive campaign of measurements conducted with the prototype, key parameters of the rf performance of the system are validated and a phase-space characterization of an electron bunch is accomplished with a time resolution of 3.3 fs. Furthermore, an analysis of second-order effects induced on the bunch from its passage through the PolariX-TDS is presented.
纵向电子束诊断在 X 射线自由电子激光器的运行和控制中起着至关重要的作用，这些激光器依赖于电流曲线、纵向相空间或粒子分布的切片发射率等参数。一方面，这些设施产生的飞秒尺度的电子束对诊断所能达到的分辨率提出了严格的要求。另一方面，新型加速器技术（如束流驱动等离子辐照加速器（PWFA））的研发需要前所未有的能力来分辨沿纵向束坐标全横向平面的中心偏移。我们介绍了基于波束的先进 X 波段横向偏转射频结构（TDS）系统的调试情况，该系统具有提供可变偏转力极化的新功能：PolariX-TDS。通过对原型进行全面测量，验证了系统射频性能的关键参数，并以 3.3 fs 的时间分辨率完成了电子束的相空间特性分析。此外，还分析了电子束通过 PolariX-TDS 时产生的二阶效应。
{"title":"Beam-based commissioning of a novelX-band transverse deflection structure with variable polarization","authors":"P. González Caminalet al.","doi":"10.1103/physrevaccelbeams.27.032801","DOIUrl":"https://doi.org/10.1103/physrevaccelbeams.27.032801","url":null,"abstract":"Longitudinal electron-beam diagnostics play a critical role in the operation and control of x-ray free-electron lasers, which rely on parameters such as the current profile, the longitudinal phase space, or the slice emittance of the particle distribution. On the one hand, the femtosecond-scale electron bunches produced at these facilities impose stringent requirements on the resolution achievable with the diagnostics. On the other, research and development of novel accelerator technologies such as beam-driven plasma-wakefield accelerators (PWFA) demand unprecedented capabilities to resolve the centroid offsets in the full transverse plane along the longitudinal bunch coordinate. We present the beam-based commissioning of an advanced <math display=\"inline\" xmlns=\"http://www.w3.org/1998/Math/MathML\"><mi>X</mi></math>-band transverse-deflection rf structure (TDS) system with the new feature of providing variable polarization of the deflecting force: the PolariX-TDS. By means of a comprehensive campaign of measurements conducted with the prototype, key parameters of the rf performance of the system are validated and a phase-space characterization of an electron bunch is accomplished with a time resolution of 3.3 fs. Furthermore, an analysis of second-order effects induced on the bunch from its passage through the PolariX-TDS is presented.","PeriodicalId":54297,"journal":{"name":"Physical Review Accelerators and Beams","volume":"23 1","pages":""},"PeriodicalIF":1.7,"publicationDate":"2024-03-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140071252","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-03-07DOI: 10.1103/physrevaccelbeams.27.033501
He Zhao, Lijun Mao, Meitang Tang, Fu Ma, Xiaodong Yang, Jiancheng Yang
In electron cooling, the transverse cooling rate is usually smaller than the longitudinal rate, especially at high energies. By introducing dispersive cooling, it is possible to redistribute the cooling rate between longitudinal and transverse planes. Theoretically, achieving dispersive electron cooling requires an ion dispersion and a transverse gradient of longitudinal friction force. The latter depends on many factors such as the relative momentum offset, transverse displacement, e-beam density distribution, and space charge effect. Therefore, several methods can be employed to achieve dispersive electron cooling based on these factors. Based on the dc electron beam, these factors and their respective impacts on the cooling rate are discussed and analyzed. For the first time, we propose a new mechanism to achieve dispersive cooling for a uniform electron beam by placing part of the ion beam outside of the electron beam. Based on a linear friction force model, we propose a simple formula to numerically estimate the cooling rate redistribution effect of these methods. The analytical results are in good agreement with Monte Carlo calculation and numerical simulation.
{"title":"Theoretical and simulation study of dispersive electron cooling","authors":"He Zhao, Lijun Mao, Meitang Tang, Fu Ma, Xiaodong Yang, Jiancheng Yang","doi":"10.1103/physrevaccelbeams.27.033501","DOIUrl":"https://doi.org/10.1103/physrevaccelbeams.27.033501","url":null,"abstract":"In electron cooling, the transverse cooling rate is usually smaller than the longitudinal rate, especially at high energies. By introducing dispersive cooling, it is possible to redistribute the cooling rate between longitudinal and transverse planes. Theoretically, achieving dispersive electron cooling requires an ion dispersion and a transverse gradient of longitudinal friction force. The latter depends on many factors such as the relative momentum offset, transverse displacement, e-beam density distribution, and space charge effect. Therefore, several methods can be employed to achieve dispersive electron cooling based on these factors. Based on the dc electron beam, these factors and their respective impacts on the cooling rate are discussed and analyzed. For the first time, we propose a new mechanism to achieve dispersive cooling for a uniform electron beam by placing part of the ion beam outside of the electron beam. Based on a linear friction force model, we propose a simple formula to numerically estimate the cooling rate redistribution effect of these methods. The analytical results are in good agreement with Monte Carlo calculation and numerical simulation.","PeriodicalId":54297,"journal":{"name":"Physical Review Accelerators and Beams","volume":"23 1","pages":""},"PeriodicalIF":1.7,"publicationDate":"2024-03-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140071117","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-03-06DOI: 10.1103/physrevaccelbeams.27.034401
Weiwei Li, Tianlong He, Zhenghe Bai
Nonevaporable getter (NEG) coating is widely required in the new generation of light sources and circular colliders for small vacuum pipes to improve the vacuum level, which, however, also enhances the high-frequency resistive-wall impedance and often generates a resonator-like peak in the terahertz frequency region. In this paper, we will use the parameters of the planned Hefei Advanced Light Facility storage ring to study the impact of NEG-coating resistive-wall impedance on the longitudinal microwave instability via particle tracking simulation. Using different NEG-coating parameters (resistivity and thickness) as examples, we find that the impedance with a narrow and strong peak in the terahertz frequency region can cause terahertz scale microbunching instability, which has a low instability threshold current and contributes to a large energy spread widening above the threshold. In order to obtain a convergent simulation of the beam dynamics, one must properly resolve such a peak. The coating with a lower resistivity has a less sharp peak in its impedance spectrum, and there is a regime that it is helpful to suppress the terahertz scale microbunching instability and in return contributes to a higher instability threshold current.
{"title":"Terahertz scale microbunching instability driven by high resistivity nonevaporable getter coating resistive-wall impedance","authors":"Weiwei Li, Tianlong He, Zhenghe Bai","doi":"10.1103/physrevaccelbeams.27.034401","DOIUrl":"https://doi.org/10.1103/physrevaccelbeams.27.034401","url":null,"abstract":"Nonevaporable getter (NEG) coating is widely required in the new generation of light sources and circular <math display=\"inline\" xmlns=\"http://www.w3.org/1998/Math/MathML\"><msup><mi>e</mi><mo>+</mo></msup><msup><mi>e</mi><mo>−</mo></msup></math> colliders for small vacuum pipes to improve the vacuum level, which, however, also enhances the high-frequency resistive-wall impedance and often generates a resonator-like peak in the terahertz frequency region. In this paper, we will use the parameters of the planned Hefei Advanced Light Facility storage ring to study the impact of NEG-coating resistive-wall impedance on the longitudinal microwave instability via particle tracking simulation. Using different NEG-coating parameters (resistivity and thickness) as examples, we find that the impedance with a narrow and strong peak in the terahertz frequency region can cause terahertz scale microbunching instability, which has a low instability threshold current and contributes to a large energy spread widening above the threshold. In order to obtain a convergent simulation of the beam dynamics, one must properly resolve such a peak. The coating with a lower resistivity has a less sharp peak in its impedance spectrum, and there is a regime that it is helpful to suppress the terahertz scale microbunching instability and in return contributes to a higher instability threshold current.","PeriodicalId":54297,"journal":{"name":"Physical Review Accelerators and Beams","volume":"30 1","pages":""},"PeriodicalIF":1.7,"publicationDate":"2024-03-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140055891","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-03-05DOI: 10.1103/physrevaccelbeams.27.034801
Gevy J. Cao, Carl A. Lindstrøm, Erik Adli, Sébastien Corde, Spencer Gessner
Plasma acceleration has emerged as a promising technology for future particle accelerators, particularly linear colliders. Significant progress has been made in recent decades toward high-efficiency and high-quality acceleration of electrons in plasmas. However, this progress does not generalize to the acceleration of positrons, as plasmas are inherently charge asymmetric. Here, we present a comprehensive review of historical and current efforts to accelerate positrons using plasma wakefields. Proposed schemes that aim to increase energy efficiency and beam quality are summarized and quantitatively compared. A dimensionless metric that scales with the luminosity-per-beam power is introduced, indicating that positron-acceleration schemes are currently below the ultimate requirement for colliders. The primary issue is electron motion; the high mobility of plasma electrons compared to plasma ions, which leads to nonuniform accelerating and focusing fields that degrade the beam quality of the positron bunch, particularly for high efficiency acceleration. Finally, we discuss possible mitigation strategies and directions for future research.
{"title":"Positron acceleration in plasma wakefields","authors":"Gevy J. Cao, Carl A. Lindstrøm, Erik Adli, Sébastien Corde, Spencer Gessner","doi":"10.1103/physrevaccelbeams.27.034801","DOIUrl":"https://doi.org/10.1103/physrevaccelbeams.27.034801","url":null,"abstract":"Plasma acceleration has emerged as a promising technology for future particle accelerators, particularly linear colliders. Significant progress has been made in recent decades toward high-efficiency and high-quality acceleration of electrons in plasmas. However, this progress does not generalize to the acceleration of positrons, as plasmas are inherently charge asymmetric. Here, we present a comprehensive review of historical and current efforts to accelerate positrons using plasma wakefields. Proposed schemes that aim to increase energy efficiency and beam quality are summarized and quantitatively compared. A dimensionless metric that scales with the luminosity-per-beam power is introduced, indicating that positron-acceleration schemes are currently below the ultimate requirement for colliders. The primary issue is <i>electron motion</i>; the high mobility of plasma electrons compared to plasma ions, which leads to nonuniform accelerating and focusing fields that degrade the beam quality of the positron bunch, particularly for high efficiency acceleration. Finally, we discuss possible mitigation strategies and directions for future research.","PeriodicalId":54297,"journal":{"name":"Physical Review Accelerators and Beams","volume":"95 1","pages":""},"PeriodicalIF":1.7,"publicationDate":"2024-03-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140047906","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-03-05DOI: 10.1103/physrevaccelbeams.27.030702
Rachel A. Margraf, James P. MacArthur, Gabriel Marcus, Heinz-Dieter Nuhn, Alberto Lutman, Aliaksei Halavanau, Zhen Zhang, Zhirong Huang
Electrons in an x-ray free electron laser (XFEL) develop periodic density fluctuations, known as microbunches, which enable the exponential gain of x-ray power in an XFEL. When an electron beam microbunched at a hard x-ray wavelength is kicked, microbunches are often washed out due to the dispersion and of the bend. An achromatic (dispersion-free) bend with a small , however, can preserve microbunches, which rotate to follow the new trajectory of the electron bunch. Rotated microbunches can subsequently interact in a repointed undulator to produce a new beam of off-axis x rays. In this work, we demonstrate hard x-ray multiplexing in the Linac Coherent Light Source hard x-ray undulator line using microbunch rotation through a first-order-achromatic bend created by transversely offsetting quadrupole magnets in the FODO lattice. Quadrupole offsets are determined analytically from beam-matrix theory. We also discuss the application of microbunch rotation to out-coupling a cavity-based XFEL.
X 射线自由电子激光器（XFEL）中的电子会产生周期性的密度波动，即所谓的微束，这使得 XFEL 中的 X 射线功率呈指数增长。当以硬 X 射线波长为微束的电子束被踢出时，由于弯曲的色散和 R56，微束通常会被冲掉。然而，R56 较小的消色散（无色散）弯管可以保留微束，微束会跟随电子束的新轨迹旋转。旋转的微束随后可以在重新定点的起伏器中相互作用，产生新的离轴 X 射线束。在这项工作中，我们利用微束旋转通过由 FODO 晶格中横向偏移的四极磁铁产生的 10 μrad 一阶半色弯曲，演示了在里纳克相干光源硬 X 射线起爆线中的硬 X 射线多路复用。四极偏移是通过波束矩阵理论分析确定的。我们还讨论了微束旋转在腔基 XFEL 外耦合中的应用。
{"title":"Microbunch rotation in an x-ray free-electron laser using a first-order achromatic bend","authors":"Rachel A. Margraf, James P. MacArthur, Gabriel Marcus, Heinz-Dieter Nuhn, Alberto Lutman, Aliaksei Halavanau, Zhen Zhang, Zhirong Huang","doi":"10.1103/physrevaccelbeams.27.030702","DOIUrl":"https://doi.org/10.1103/physrevaccelbeams.27.030702","url":null,"abstract":"Electrons in an x-ray free electron laser (XFEL) develop periodic density fluctuations, known as microbunches, which enable the exponential gain of x-ray power in an XFEL. When an electron beam microbunched at a hard x-ray wavelength is kicked, microbunches are often washed out due to the dispersion and <math display=\"inline\" xmlns=\"http://www.w3.org/1998/Math/MathML\"><msub><mi>R</mi><mn>56</mn></msub></math> of the bend. An achromatic (dispersion-free) bend with a small <math display=\"inline\" xmlns=\"http://www.w3.org/1998/Math/MathML\"><msub><mi>R</mi><mn>56</mn></msub></math>, however, can preserve microbunches, which rotate to follow the new trajectory of the electron bunch. Rotated microbunches can subsequently interact in a repointed undulator to produce a new beam of off-axis x rays. In this work, we demonstrate hard x-ray multiplexing in the Linac Coherent Light Source hard x-ray undulator line using microbunch rotation through a <math display=\"inline\" xmlns=\"http://www.w3.org/1998/Math/MathML\"><mrow><mn>10</mn><mtext> </mtext><mtext> </mtext><mi mathvariant=\"normal\">μ</mi><mi>rad</mi></mrow></math> first-order-achromatic bend created by transversely offsetting quadrupole magnets in the FODO lattice. Quadrupole offsets are determined analytically from beam-matrix theory. We also discuss the application of microbunch rotation to out-coupling a cavity-based XFEL.","PeriodicalId":54297,"journal":{"name":"Physical Review Accelerators and Beams","volume":"6 1","pages":""},"PeriodicalIF":1.7,"publicationDate":"2024-03-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140071123","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-03-01DOI: 10.1103/physrevaccelbeams.27.030701
Eduard Prat, Christoph Kittel, Marco Calvi, Paolo Craievich, Philipp Dijkstal, Sven Reiche, Thomas Schietinger, Guanglei Wang
The intrinsic energy spread of electron beams needs to be measured to characterize and optimize high-brightness electron beam sources such as those driving x-ray free-electron lasers (FELs). We demonstrate the use of the optical klystron effect as a precise and high-resolution method to measure the electron beam energy spread. The optical klystron setup consists of undulator modules and magnetic chicanes placed between them. The energy spread is found by measuring the radiation power produced in the undulators as a function of the chicanes’ strengths. High resolution and simplicity are the advantages of this approach, in contrast to the standard method, which measures the longitudinal phase space of the electron beam with a transverse deflector. The demonstration was performed at Athos, the soft x-ray FEL beamline of SwissFEL, for which we measured energy spreads below 1 MeV at a central beam energy of 3.4 GeV. We have verified the consistency of the method for different parameters (radiation wavelengths, undulator polarization configurations, and electron bunch durations) and we have benchmarked it against the standard measurement approach using a transverse deflector. Our results confirm the optical klystron as a valid approach to measure the electron beam energy spread. The method can be especially useful to reconstruct low energy spread values, where the conventional approach may be resolution limited, such as in ultra high-brightness radiofrequency photoinjectors or plasma sources, or when transverse deflectors are not available.
需要测量电子束的内在能量分布，以确定高亮度电子束源（如驱动X射线自由电子激光器（FEL）的电子束源）的特性并对其进行优化。我们展示了如何利用光速斯特龙效应来精确、高分辨率地测量电子束能量扩散。光学卡氏管装置由起伏模块和放置在它们之间的磁性卡氏管组成。能量扩散是通过测量起伏器中产生的辐射功率与磁卡槽强度的函数关系来实现的。与使用横向偏转器测量电子束纵向相位空间的标准方法相比，这种方法具有分辨率高和操作简单的优点。演示是在 SwissFEL 的软 X 射线 FEL 光束线 Athos 上进行的，我们测量了中心束能量为 3.4 GeV 时低于 1 MeV 的能散。我们验证了该方法在不同参数（辐射波长、减压器偏振配置和电子束持续时间）下的一致性，并将其与使用横向偏转器的标准测量方法进行了比较。我们的结果证实了光学速调管是测量电子束能量扩散的有效方法。这种方法对于重建低能量扩散值特别有用，因为传统方法的分辨率可能会受到限制，例如在超高亮度射频光射器或等离子体源中，或者在没有横向偏转器的情况下。
{"title":"Experimental characterization of the optical klystron effect to measure the intrinsic energy spread of high-brightness electron beams","authors":"Eduard Prat, Christoph Kittel, Marco Calvi, Paolo Craievich, Philipp Dijkstal, Sven Reiche, Thomas Schietinger, Guanglei Wang","doi":"10.1103/physrevaccelbeams.27.030701","DOIUrl":"https://doi.org/10.1103/physrevaccelbeams.27.030701","url":null,"abstract":"The intrinsic energy spread of electron beams needs to be measured to characterize and optimize high-brightness electron beam sources such as those driving x-ray free-electron lasers (FELs). We demonstrate the use of the optical klystron effect as a precise and high-resolution method to measure the electron beam energy spread. The optical klystron setup consists of undulator modules and magnetic chicanes placed between them. The energy spread is found by measuring the radiation power produced in the undulators as a function of the chicanes’ strengths. High resolution and simplicity are the advantages of this approach, in contrast to the standard method, which measures the longitudinal phase space of the electron beam with a transverse deflector. The demonstration was performed at Athos, the soft x-ray FEL beamline of SwissFEL, for which we measured energy spreads below 1 MeV at a central beam energy of 3.4 GeV. We have verified the consistency of the method for different parameters (radiation wavelengths, undulator polarization configurations, and electron bunch durations) and we have benchmarked it against the standard measurement approach using a transverse deflector. Our results confirm the optical klystron as a valid approach to measure the electron beam energy spread. The method can be especially useful to reconstruct low energy spread values, where the conventional approach may be resolution limited, such as in ultra high-brightness radiofrequency photoinjectors or plasma sources, or when transverse deflectors are not available.","PeriodicalId":54297,"journal":{"name":"Physical Review Accelerators and Beams","volume":"22 1","pages":""},"PeriodicalIF":1.7,"publicationDate":"2024-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140019607","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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