Karl Bane
This is an initial study of the longitudinal, single-bunch stability in the proposed FACET-II e+ damping ring. It is preliminary because many vacuum chamber objects of the ring have not yet been designed.
机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。
继续探索
The E-203 collaboration is testing a device on FACET at SLAC to measure the longitudinal profile of electron bunches using Smith-Purcell radiation. At FACET the electron bunches have an energy of 20~GeV and a duration of a few hundred femtoseconds. Smith-Purcell radiation is emitted when a charged particle passes close to the surface of a metallic grating. We have studied the stability of the measurement from pulse to pulse and the resolution of the measure depending on the number of gratings used.
In DAΦNE, the Frascati e+/e- collider, the crab waist collision scheme has been successfully implemented in 2008 and 2009. During the collision operations for Siddharta experiment, an unusual synchrotron damping effect has been observed. Indeed, with the longitudinal feedback switched off, the positron beam becomes unstable with beam currents in the order of 200-300 mA. The longitudinal instability is damped by bringing the positron beam in collision with a high current electron beam (~2A). Besides, we have observed a shift of \approx 600Hz in the residual synchrotron sidebands. Precise measur…
We examine the stability of intense flat bunches in barrier buckets used in the Recycler. We consider some common stationary distributions and show that they would be unstable against rigid dipole oscillations. We then discuss an analytical model for the line density that best describes measured bunch profiles. We include space charge in this model to predict the bunch intensity at which Landau damping would be lost. The dependence of this threshold on the bunch length is studied and related to the results of an experimental study with shorter bunch lengths. The threshold for the microwave ins…
Landau damping mechanism plays a crucial role in providing single-bunch stability in LHC, High-Luminosity LHC, other existing as well as previous and future (like FCC) circular hadron accelerators. In this paper, the thresholds for the loss of Landau damping (LLD) in the longitudinal plane are derived analytically using the Lebedev matrix equation (1968) and the concept of the emerged van Kampen modes (1983). We have found that for the commonly-used particle distribution functions from a binomial family, the LLD threshold vanishes in the presence of the constant inductive impedance Im$Z/k$ abo…
Radiation Damping and Quantum Excitation for Longitudinal Charged Particle Dynamics in the Thermal Wave Model
在最近提出的粒子束的\it热波模型（TWM）的基础上，考虑辐射阻尼和量子激发（随机效应），给出了在射频势阱存在下，圆形加速机器中纵向带电粒子动力学的描述。纵向动力学是由一个复杂的波函数的平方模量给出了纵向聚束密度分布的1-D薛定谔方程。在此框架中，适当的{ \it r.m.s.自然地恢复了由于阻尼效应引起的发射度标度律，并找到了由于量子激发（QE）和辐射阻尼（RD）之间的竞争引起的束团长度的渐近平衡条件，这一结果为将已经在质子中验证过的TWM应用于电子中提供了可能，因为QE和RD对电子是非常重要的。
A pulsed electron lens produces a betatron tune shift along a hadron bunch as a function of the longitudinal coordinates, which is a longitudinal detuning. An example of transverse detuning are the tune shifts due to octupole magnets. This paper considers a pulsed electron lens as a measure to mitigate the head-tail instabilities. Using a detailed analytical description within a Vlasov formalism, the coherent properties of the longitudinal and transverse detuning are presented. The analytical predictions are compared with the results of the particle tracking simulations. A pulsed electron lens…
Simulation of longitudinal Landau damping in bunches with space charge
本文通过粒子跟踪模拟研究空间电荷作用下强子束团纵向偶极模的朗道阻尼损失，发现分支点和阻尼不依赖于远低于实际值的截断参数，并验证了网格与无网格求解器结果。
In DAFNE, the Frascati $e^+e^-$ collider operating since 1998, an innovative collision scheme, the crab waist, has been successfully implemented during the years 2008-09. During operations for the Siddharta experiment an unusual synchrotron oscillation damping effect induced by beam-beam collisions has been observed. Indeed, when the longitudinal feedback is off, the positron beam becomes unstable with currents above 200-300 mA due to coupled bunch instability. The longitudinal instability is damped by colliding the positron beam with a high current electron beam (of the order of 2 A). A shift…
Conditions for existence, uniqueness and stability of bunch steady states are considered. For the existence uniqueness problem, simple algebraic equations are derived, showing the result both for the action and Hamiltonian domain distributions. For the stability problem, van Kampen theory is used. Emerging of discrete van Kampen modes show either loss of Landau damping, or instability. This method can be applied for an arbitrary impedance, RF shape and beam distribution function Available areas on intensity-emittance plane are shown for resistive wall wake and single harmonic, bunch shortening…
In the Brazilian synchrotron light source, we observed that modulating the phase of the accelerating fields at approximately twice the synchrotron frequency suppressed remarkably well a longitudinal coupled-bunch mode of the beam driven by a higher order mode (HOM) in one of the radiofrequency (RF) cavities. In this work, we present the results of a set of systematic measurements, in single and multibunch mode, aimed at characterizing the effects of RF phase modulation on the beam. We compare those experiments with the results of tracking simulations and of a theoretical model in which Landau …
Compton scattering provides one of the most promising scheme to obtain polarized positrons for the next generation of $e^-$ -- $e^+$ colliders. Moreover it is an attractive method to produce monochromatic high energy polarized gammas for nuclear applications and X-rays for compact light sources. In this framework a four-mirror Fabry-Pérot cavity has been installed at the Accelerator Test Facility (ATF - KEK, Tsukuba, Japan) and is used to produce an intense flux of polarized gamma rays by Compton scattering \cite{ipac-mightylaser}. For electrons at the ATF energy (1.28 GeV) Compton scattering …
Generalized threshold of longitudinal multi-bunch instability in synchrotrons
针对纵向耦合束团不稳定性与单束团朗道阻尼损失，提出数值求解稳定性问题的新方法并推导解析阈值，发现LLD会降低CBI阈值，解释了CERN SPS观测结果并适用于未来加速器设计。
Coherent Synchrotron Radiation (CSR) can play an important role by not only increasing the energy spread and emittance of a beam, but also leading to a potential instability. Previous studies of the CSR induced longitudinal instability were carried out for the CSR impedance due to dipole magnets. However, many storage rings include long wigglers where a large fraction of the synchrotron radiation is emitted. This includes high-luminosity factories such as DAPHNE, PEP-II, KEK-B, and CESR-C as well as the damping rings of future linear colliders. In this paper, the instability due to the CSR imp…
Theoretical models for longitudinal coupled-bunch instabilities driven by harmonic cavities in electron storage rings
本文提出统一理论框架分析双射频系统纵向耦合束团不稳定性，推导Lebedev方程，首次实现mode-1阈值与实验数据极好吻合，揭示PTBL不稳定性抗Landau阻尼机制，并在pycolleff中实现。
One of the main challenges of the lattice design of synchrotrons, used as light sources or damping rings (DRs), is the minimization of the emittance. The optimal lattice configurations for achieving the absolute minimum emittance are the theoretical minimum emittance (TME) cells. This paper elaborates the optimization strategy in order to further reduce the betatron emittance of a TME cell by using dipoles whose magnetic field varies longitudinally. Based on analytical results, the magnet design for the fabrication of variable bends with the optimal characteristics is discussed. In order to ha…
Van Kampen modes are eigen-modes of Jeans-Vlasov equation. Their spectrum consists of continuous and, possibly, discrete parts. Onset of a discrete van Kampen mode means emergence of a coherent mode without any Landau damping; thus, even a tiny couple-bunch wake is sufficient to drive instability. Longitudinal instabilities observed at Tevatron, RHIC and SPS can be explained as loss of Landau damping (LLD), which is shown here to happen at fairly low impedances. For repulsive wakes and single-harmonic RF, LLD is found to be extremely sensitive to steepness of the bunch distribution function at…
Threshold for loss of Landau damping in double-harmonic rf systems
本研究将朗道阻尼损失研究拓展至双谐波射频系统，推导了对应阈值的解析方程，分析了电压比、相对相位等因素的影响，并通过CERN的PS、SPS束流测量及模拟验证了理论有效性。
We propose an innovative beam cooling scheme based on laser driven plasma wakefields to address the challenge of high luminosity generation for a future linear collider. For linear colliders, beam cooling is realised by means of damping rings equipped with wiggler magnets and accelerating cavities. This scheme ensures systematic reduction of phase space volume through synchrotron radiation emission whilst compensating for longitudinal momentum loss via an accelerating cavity. In this paper, the concept of a plasma wiggler and its effective model analogous to a magnetic wiggler are introduced; …
扫码添加微信好友，提出您的宝贵建议 👇
💡 备注请填写：网站反馈
发表机构由 AI 从论文文本抽取，如发现错误，欢迎反馈修正建议。