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Proceedings of the 1999 Particle Accelerator Conference (Cat. No.99CH36366)最新文献

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Planar waveguide hybrids for very high power RF 用于非常高功率射频的平面波导混合
Pub Date : 1999-05-10 DOI: 10.1109/PAC.1999.795572
C. Nantista, W. R. Fowkes, N. Kroll, Sami G. Tantawi
Two basic designs have been developed for waveguide hybrids, or 3-dB couplers, capable of handling hundreds of megawatts at X-band. Coupling is provided by one or two connecting waveguides with h-plane junctions and matching elements. In the former case, the connecting waveguide supports two modes. Small apertures and field-enhancing e-bends are avoided to reduce the risk of RF breakdown. The h-plane symmetry also allows the use of over-moded rectangular waveguide in which the height has been increased to reduce field amplitudes without affecting the scattering matrix. The theory and designs are presented, along with the results of prototype tests of functionality and power-handling capability. Such a device is integral to the RF pulse compression or power distribution system of the Next Linear Collider (NLC) for combining, splitting, and directing power. This work was motivated by the observation of RF breakdown at power levels above 200 MW in conventional and modified magic-T's.
两种基本设计已经被开发出来,用于波导混合,或3db耦合器,能够在x波段处理数百兆瓦的功率。耦合是由一个或两个带h面结和匹配元件的连接波导提供的。在前一种情况下,连接波导支持两种模式。避免了小孔径和场增强e弯曲,以降低射频击穿的风险。h面对称也允许使用过度模矩形波导,其中的高度已经增加,以减少场振幅,而不影响散射矩阵。介绍了该系统的原理和设计,并给出了样机的功能和功率处理性能测试结果。这种装置是下一代线性对撞机(NLC)射频脉冲压缩或功率分配系统的组成部分,用于组合、分裂和定向功率。这项工作的动机是在常规和改进的magic-T中观察到200 MW以上功率水平的射频击穿。
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引用次数: 22
Tune-shift with amplitude due to nonlinear kinematic effect 非线性运动效应引起的振幅调谐
Pub Date : 1999-05-10 DOI: 10.1109/PAC.1999.795714
W. Wan
Tracking studies of the Muon Collider 50 on 50 GeV collider ring show that the on-momentum dynamic aperture is limited to around 10/spl sigma/ even with the chromaticity sextupoles turned off. Numerical results from the normal form algorithm show that the tune-shift with amplitude is surprisingly large. Both analytical and numerical results are presented to show that nonlinear kinematic effect originated from the large angles of particles in the interaction region is responsible for the large tune-shift which in turn limits the dynamic aperture. A comparative study of the LHC collider ring is also presented to demonstrate the difference between the two machines.
在50 GeV对撞机环上对μ子对撞机50的跟踪研究表明,即使关闭色度六极,非动量动态孔径也被限制在10/spl sigma左右。范式算法的数值结果表明,随振幅变化的频移非常大。分析和数值结果表明,由于粒子在相互作用区域的大角度引起的非线性运动效应导致了大的调谐位移,从而限制了动态孔径。本文还对大型强子对撞机环进行了比较研究,以说明这两种机器之间的差异。
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引用次数: 1
Experimental demonstration of high power millimeter wave gyro-amplifiers 大功率毫米波陀螺放大器的实验论证
Pub Date : 1999-05-07 DOI: 10.1109/PAC.1999.795433
M. Blank, J. Calame, B. Danly, B. Levush, J. Choi, M. Garven, K. Nguyen, D. Pershing
The Naval Research Laboratory is currently investigating gyro-amplifiers as high power, broadband sources for millimeter wave radars. A three-cavity Ka-band gyroklystron achieved 225 kW peak output power with 0.82% bandwidth. At W-band, several multi-cavity gyro-amplifiers have been experimentally demonstrated. A four-cavity gyroklystron amplifier has achieved 84 kW peak output power at 34% efficiency with 370 MHz bandwidth. A five-cavity gyroklystron demonstrated 72 kW peak output power with 410 MHz bandwidth and 50 dB saturated gain. For applications requiring greater bandwidth, gyrotwystron amplifiers are also under study. A four section W-band gyrotwystron demonstrated 50 kW peak output power at 925 MHz bandwidth.
美国海军研究实验室目前正在研究将陀螺放大器作为毫米波雷达的高功率宽带源。三腔ka波段回旋速调管的峰值输出功率为225 kW,带宽为0.82%。在w波段,实验证明了几种多腔陀螺放大器。一种四腔回旋速调管放大器以34%的效率和370 MHz的带宽实现了84 kW的峰值输出功率。五腔回旋速调管的峰值输出功率为72 kW,带宽为410 MHz,饱和增益为50 dB。对于需要更大带宽的应用,回旋调强放大器也在研究之中。四段w波段回旋回旋管在925 MHz带宽下显示了50 kW的峰值输出功率。
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引用次数: 3
Beam motions near separatrix 光束在分离矩阵附近运动
Pub Date : 1999-05-04 DOI: 10.1109/PAC.1999.794169
M. Ball, B. Brabson, J. Budnick, C. Chu, D. Caussyn, J. Collins, V. Derenchuk, G. East, M. Ellison, D. Friesel, K. Fung, B. Hamilton, W. Hsi, H. Huang, W. Jones, S. Lee, D. Li, K. Ng, X. Pei, A. Riabko, T. Slaon
Experimental data on particle motion near the separatrix of the one dimensional (1-D) fourth-integer islands are analyzed. When the beam bunch is initially kicked to the separatrix orbit, we observed a strong decoherence in the coherent betatron motion. We find that, through intensive particle tracking simulation analysis, the decoherence has resulted from the beam being split into beamlets in the betatron phase space. However, we also observe an unexpected recoherence of coherence signal, which may result form a modulated closed orbit or the homoclinic structure near the separatrix.
分析了一维(1-D)四整数岛分离矩阵附近粒子运动的实验数据。当束束最初被踢到分离矩阵轨道时,我们观察到相干电子加速器运动中有很强的退相干。通过深入的粒子跟踪模拟分析,我们发现,退相干是由于束流在电子加速器相空间中分裂成小束流造成的。然而,我们也观察到相干信号的意想不到的重相干,这可能是由于调制的闭合轨道或在分离矩阵附近的同宿结构造成的。
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引用次数: 2
Diffusion mechanism of particle beams in the presence of phase modulation in double RF systems 双射频系统中存在相位调制时粒子束的扩散机制
Pub Date : 1999-05-04 DOI: 10.1109/PAC.1999.794162
M. Ball, J. Budnick, C. Chu, K. Fung, B. Hamilton, D. Jeon, X. Kang, L. L. Kiang, S. Lee, A. Pei, T. Sloan, K. Ng
The particle diffusion mechanism due to phase modulation on one of the RF cavities in a double RF system is studied. We find that the Einstein relation is satisfied if there is a global chaos in the phase space. On the other hand, the existence of dominant parametric resonances forces the particles streaming along the separatrix, which may result in an anomalous diffusion process. The particle tracking simulations based on the Hamiltonian for the double RF system is employed to reveal the essential diffusion mechanism. Also for the first time, a coherent octupole mode has been observed in the bunch beam excitation. The phase space evolution of the octupole mode is displayed.
研究了双射频系统中粒子在其中一个射频腔内的相位调制扩散机理。我们发现,当相空间中存在全局混沌时,满足爱因斯坦关系。另一方面,主导参数共振的存在迫使粒子沿分离矩阵流动,这可能导致反常的扩散过程。采用基于哈密顿量的粒子跟踪模拟,揭示了双射频系统的基本扩散机制。同时也首次在束束激发中观察到相干八极子模式。显示了八极子模式的相空间演化。
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引用次数: 0
Beam test of a superconducting cavity for the Fermilab high-brightness electron photo-injector 费米实验室高亮度电子光注入器超导腔的光束测试
Pub Date : 1999-05-04 DOI: 10.1109/PAC.1999.795425
W. Hartung, J. Carneiro, M. Champion, H. Edwards, J. Fuerst, K. Koepke, M. Kuchnir
An electron photo-injector facility has been constructed at Fermilab for the purpose of providing a 14-18 MeV electron beam with high charge per bunch (8 nC), short bunch length (1 mm RMS), and small transverse emittance. The facility was used to commission a second-generation photo-cathode RF gun for the TESLA Test Facility (TTF) Linac at DESY; in the future, the Fermilab electron beam will be used for R and D in bunch length compression, beam diagnostics, and new acceleration techniques. Acceleration beyond 4 MeV is provided by a 9-cell superconducting cavity. The cavity also provides a longitudinal position-momentum correlation for subsequent bunch length compression. We report on the RF tests and a first beam test of this cavity.
在费米实验室建立了一个电子光注入装置,目的是提供14-18 MeV的电子束,每束高电荷(8nc),束长短(1 mm RMS),横向发射度小。该设施用于为DESY的特斯拉测试设施(TTF)直线加速器调试第二代光电阴极射频枪;在未来,费米实验室电子束将用于束长压缩、束诊断和新的加速技术的研发。超过4兆电子伏的加速度由一个9单元超导腔提供。该空腔还为随后的束长压缩提供了纵向位置-动量关联。我们报告了该腔的射频测试和第一束测试。
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引用次数: 5
Neutrino induced radiation at muon colliders 介子对撞机的中微子诱导辐射
Pub Date : 1999-05-03 DOI: 10.1109/PAC.1999.792184
N. Mokhov, A. van Ginneken
Intense highly collimated neutrino beams are created from muon decays at high-energy muon colliders causing significant radiation problems even at very large distances from the collider ring. A newly developed weighted neutrino interaction generator permits detailed Monte Carlo simulations of the interactions of neutrinos (and of their progeny) to be performed using the MARS code. Dose distributions in a human tissue-equivalent phantom (TEP) are calculated when irradiated with neutrino beams (100 MeV-10 TeV). Results are obtained for a bare TEP, one embedded in several shielding materials and for a TEP located at various distances behind a shield. The distance from the collider ring (up to 60 km) at which recommended annual dose limits can be met is calculated for 0.5, 1, 2, 3 and 4 TeV muon colliders. The possibility to mitigate the problem via beam wobbling is investigated.
强烈的高度准直的中微子束是由高能介子对撞机的介子衰变产生的,即使在距离对撞机环很远的地方也会产生严重的辐射问题。新开发的加权中微子相互作用发生器允许使用MARS代码对中微子(及其后代)的相互作用进行详细的蒙特卡罗模拟。用中微子束(100 MeV-10 TeV)照射人体组织等效幻体(TEP)时,计算了剂量分布。得到了裸TEP、嵌入多种屏蔽材料的TEP和位于屏蔽后不同距离的TEP的结果。计算了0.5、1、2、3和4 TeV介子对撞机与对撞机环(最多60公里)之间可达到建议年剂量限值的距离。研究了通过光束摆动来缓解这一问题的可能性。
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引用次数: 10
A low-cost, NIST-traceable, high performance dielectric resonator master oscillator [for CEBAF] 一种低成本、nist可追溯、高性能介电谐振主振荡器[用于CEBAF]
Pub Date : 1999-05-01 DOI: 10.1109/PAC.1999.795349
L. Doolittle, C. Hovater, L. Merminga, J. Musson, M. Wissmann
The current CEBAF Master Oscillator (MO) uses a quartz-based 10 MHz reference to synthesize 70 MHz and 499 MHz, which are then distributed to each of the klystron galleries on site. Due to the specialised nature of CEBAF's MO requirements, it has been determined that an in-house design and fabrication would provide a cost-effective alternative to purchasing or modifying vendor equipment. A Global Positioning System (GPS) disciplined, Direct Digital Synthesis (DDS) based MO is proposed which incorporates low-cost consumer RF components, designed for cellular communications. A 499 MHz Dielectric Resonant Oscillator (DRO) Voltage Controlled Oscillator (VCO) is phase-locked to a GPS-disciplined 10 MHz reference, and micro-tuned via a DDS, in an effort to achieve the lowest phase noise possible.
当前的CEBAF主振荡器(MO)使用基于石英的10 MHz参考来合成70 MHz和499 MHz,然后将其分配到现场的每个速调管画廊。由于CEBAF MO要求的专业性,已经确定内部设计和制造将为购买或修改供应商设备提供具有成本效益的替代方案。提出了一种基于直接数字合成(DDS)的全球定位系统(GPS),它包含了低成本的消费射频组件,专为蜂窝通信而设计。499mhz介电谐振振荡器(DRO)压控振荡器(VCO)锁相到gps规范的10mhz参考,并通过DDS进行微调谐,以尽可能实现最低的相位噪声。
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引用次数: 1
Radiation environment resulting from Main Injector beam extraction to the NuMi beam line 主注入器光束提取到NuMi光束线的辐射环境
Pub Date : 1999-04-29 DOI: 10.1109/PAC.1999.792880
A. Drozhdin, P. Lucas, N. Mokhov, C. Moore, S. Striganov
A 120 GeV Main Injector proton beam will be delivered to the NuMI beam line at Fermilab at the rate of 3.7/spl times/10/sup 20/ per year. Realistic Monte Carlo simulations have been performed to examine the radiation environment in the beam extraction system and NuMI beam line elements. A complete 3-D model of the 160 meter extraction region has been implemented utilizing the computer code MARS. The model includes a description of the field of the electrostatic septa and POISSON calculated field maps of the Lambertson magnets and the other lattice components in the area. The beam element alignment and the source term have been simulated using the code STRUCT. Results on beam losses in the system, energy deposition in the core elements and residual dose rates on the components are presented.
一个120 GeV的主注入器质子束将以每年3.7/spl次/10/sup / 20/的速度输送到费米实验室的NuMI束流线。采用蒙特卡罗仿真方法对光束提取系统的辐射环境和NuMI光束线元进行了仿真研究。利用计算机代码MARS实现了160米提取区域的完整三维模型。该模型包括静电区场的描述和泊松计算的兰伯森磁体和区域内其他晶格分量的场图。利用STRUCT程序对波束单元对准和源项进行了模拟。给出了系统中的光束损耗、核心元件中的能量沉积和元件上的残余剂量率的计算结果。
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引用次数: 1
Theory and measurement of the electron cloud effect 电子云效应的理论与测量
Pub Date : 1999-04-29 DOI: 10.1109/PAC.1999.795641
K. Harkay
Photoelectrons produced through the interaction of synchrotron radiation and the vacuum chamber walls can be accelerated by a charged particle beam, acquiring sufficient energy to produce secondary electrons (SEs) in collisions with the walls. If the secondary-electron yield (SEY) coefficient of the wall material is greater than one, a runaway condition can develop. In addition to the SEY, the degree of amplification depends on the beam intensity and temporal distribution. As the electron cloud builds up along a train of stored bunches, a transverse perturbation of the head bunch can be communicated to trailing bunches in a wakefield-like interaction with the cloud. The electron cloud effect is especially of concern for the high-intensity PEP-II (SLAC) and KEK B-factories and at the Large Hadron Collider (LHC) at CERN. An initiative was undertaken at the Advanced Photon Source (APS) storage ring to characterize the electron cloud in order to provide realistic limits on critical input parameters in the models and improve their predictive capabilities. An intensive research program was undertaken at CERN to address key issues relating to the LHC. After giving an overview, the recent theoretical and experimental results from the APS and the other laboratories are discussed.
通过同步辐射和真空室壁的相互作用产生的光电子可以被带电粒子束加速,获得足够的能量在与壁的碰撞中产生二次电子(SEs)。如果壁材的二次电子产率系数大于1,就会出现失控的情况。除了SEY,放大的程度还取决于光束强度和时间分布。当电子云沿着存储束的序列积聚时,头部束的横向扰动可以在与云的尾流场类似的相互作用中传递给尾部束。电子云效应对于高强度PEP-II (SLAC)和KEK b工厂以及欧洲核子研究中心的大型强子对撞机(LHC)来说尤其值得关注。在先进光子源(APS)存储环上进行了一项倡议,以表征电子云,以便为模型中的关键输入参数提供现实限制,并提高其预测能力。欧洲核子研究中心开展了一项深入的研究计划,以解决与大型强子对撞机有关的关键问题。在给出概述之后,讨论了APS和其他实验室最近的理论和实验结果。
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引用次数: 12
期刊
Proceedings of the 1999 Particle Accelerator Conference (Cat. No.99CH36366)
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