E. G. Bessonov, A. A. Mikhailichenko, A. V. Poseryaev
Physics of enhanced optical cooling of particle beams in storage rings, nonlinear features of cooling and requirements to ring lattices, optical and laser systems are discussed
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The problem of enhanced optical cooling (EOC) of particle beams in storage rings beyond the Robinson's damping criterion is discussed.
Numerical Modeling of a Proof-of-Principle Experiment on Optical Stochastic Cooling at the IOTA Electron Storage Ring
本文在ELEGANT程序中实现了光学随机冷却的数值模型，并用IOTA实验数据验证，为未来OSC配置及自场束流操控模拟提供了工具。
We are proposing to test experimentally the new idea of Enhanced Optical Cooling (EOC) in an electron storage ring. This experiment will confirm new fundamental processes in beam physics and will demonstrate new unique possibilities with this cooling technique. It will open important applications of EOC in nuclear physics, elementary particle physics and in Light Sources (LS) based on high brightness electron and ion beams.
In preparation for a demonstration of optical stochastic cooling in the Cornell Electron Storage Ring (CESR) we have developed a particle tracking simulation to study the relevant beam dynamics. Optical radiation emitted in the pickup undulator gives a momentum kick to that same particle in the kicker undulator. The optics of the electron bypass from pickup to kicker couples betatron amplitude and momentum offset to path length so that the momentum kick reduces emittance and momentum spread. Nearby electrons contribute an incoherent noise. Layout of the bypass line is presented that accommodat…
A new scheme for the two-dimensional cooling of ion beams in storage rings is suggested in which ions interact with a counterpropagating broad-band laser beam. The interaction region in the direction of the ion movement is much less then the wavelength of the ion betatron oscillations. The laser beam in the orbit plane has sharp flat edge directed to the ion beam and the width of the laser beam of the order of the ion beam width. Laser beam radial position is being displaced with some velocity at first from inside and then from outside to the ion beam and decreases both betatron and synchrotro…
Application of electron cooling at ion energies above a few GeV has been limited due to reduction of electron cooling efficiency with energy and difficulty in producing and accelerating a high-current high-quality electron beam. A high-current storage-ring electron cooler offers a solution to both of these problems by maintaining high cooling beam quality through naturally-occurring synchrotron radiation damping of the electron beam. However, the range of ion energies where storage-ring electron cooling can be used has been limited by low electron beam damping rates at low ion energies and hig…
Methods of particle beam cooling are reviewed.
Cooling methods are discussed in reference to the electron-positron, ion and muon beams.
Laser cooling of nuclear beams in storage rings is discussed. The main properties of nuclei with isomeric levels in the range E<50 keV are presented.
This paper presents a conceptual approach to phase modulation of the cavity field in storage ring RF systems. An implementation of the concept on Dimtel low-level RF controllers is also presented. The method is illustrated with the test results from a cavity simulator, as well as an electron storage ring KARA.
A previous publication has shown that the in-plane polarization (IPP) component of a polarized 0.97-GeV/c deuteron beam in the COSY storage ring may acquire a polarization half-life in excess of 1000 s through a combination of beam bunching, electron cooling (prior to any spin manipulation), sextupole field adjustment, and a limitation of the beam intensity. This paper documents further tests pointing to additional gains in the IPP lifetime if cooling is active throughout the beam store.
This report summaries the workshop on accelerator R&D for ultimate storage ring, held in Huairou, Beijing, Oct. 30 to Nov. 1, 2012.
In this paper we propose an improved empirical equation for the bunch lengthening in electron storage rings. The comparisons are made between the analytical and experimental results, and the agreements are quite well. This improved equation can be equally applied to the case where a storage ring is very resistive (such as the improved SLC damping rings) instead of inductive as usual.
Limits of applicability of the Robinson's damping criterion and the problem of enhanced cooling of particle beams in storage rings beyond the criterion are discussed.
Methods of enhanced laser cooling of particle beams in storage rings and Robinson's damping criterion are discussed. The dynamics of amplitudes of betatron oscillations and instantaneous orbits of electrons interacting with laser beams being displaced in the radial direction is investigated.
Currently there is significant interest in the use of storage rings to search for an electric dipole moment (EDM) in hadrons. This requires utilizing the storage ring as a precision measuring device. Part of understanding the detailed behavior of storage rings comes from careful analysis of fringe fields, but the various tracking codes available differ in their ability to model such behavior. It is the purpose of this paper to investigate these differences.
Central frequency is a key parameter of storage rings. This paper presents the measurement of central frequency of the HLS-II storage ring using the sextupole modulation method. Firstly, the basis of central frequency measurement of the electron storage ring is briefly introduced. Then, the error sources and the optimized measurement method for the HLS-II storage ring are discussed. The workflow of the self-compiled Matlab script used in central frequency measurement is also described. In the end, the results achieved by using two methods to cross-check each other are shown. The measured value…
We studied the coupled beam motion in a storage ring between the transverse and longitudinal directions introduced by crab cavities. Analytic form of the linear decoupling transformation is derived. The equilibrium bunch distribution in an electron storage ring with a crab cavity is given, including contribution to the eigen-emittance induced by the crab cavity. Application to the short pulse generation scheme using crab cavities is considered.
We propose to optimize the nonlinear beam dynamics of existing and future storage rings with direct online optimization techniques. This approach may have crucial importance for the implementation of diffraction limited storage rings. In this paper considerations and algorithms for the online optimization approach are discussed. We have applied this approach to experimentally improve the dynamic aperture of the SPEAR3 storage ring with the robust conjugate direction search method and the particle swarm optimization method. The dynamic aperture was improved by more than 5 mm within a short peri…
A new, hybrid design is proposed to eliminate the main systematic errors in the frozen spin, storage ring measurement of the proton electric dipole moment. In this design, electric bending plates steer the particles, and magnetic focusing replaces electric. The magnetic focusing should permit simultaneous clock-wise and counter-clock-wise storage to cancel systematic errors related to the out-of-plane dipole electric field. Errors related to the quadrupole electric fields can be eliminated by successive runs of magnetic focusing with different strengths.
The lattice of laser-electron storage ring with controlled momentum compaction factor dedicated to generation of intense X-rays under Compton scattering is described. In such storage ring one can achieve the large energy acceptance and keep the long-term stable motion of electron beam with large energy spread. The intensity of X-rays may be very stable due to using of electron beam with steady-state parameters for Compton scattering. Parameters of the storage ring, electron beam and X-rays obtained by electron beam dynamics simulation involving Compton scattering are presented.
A new 150 MeV electron storage ring is being built at Fermilab. The construction of a new machine pursues two goals: A test of highly non-linear integrable optics and a test of optical stochastic cooling. This paper discusses details of OSC arrangements, choice of major parameters of the cooling scheme and incoming experimental tests of the optical amplifier prototype which uses highly doped Ti-sapphire crystal as amplification medium.
Injection performance of storage ring is one of the important factors for the light efficiency and quality of Synchrotron Radiation Facility when it is in top-up mode. To evaluate the injection performance of storage ring at SSRF, we build a bunch-by-bunch position measuring system based on oscilloscope IOC. Accurate assessment of energy mismatching, distribution of residual oscillation and angle error of injection kickers can be achieved by this system.
In present work we investigate the potential of a longitudinally focusing device to compress bunches passing an undulator for a synchrotron storage ring. If integrated into a storage ring similar to PETRAIII such device could potentially produce continuous $\sim$1ps pulses of photons in the $nm$ range with peak pulse powers of tens of GW. Even without operating in FEL saturation mode the longitudinal focusing can provide means to increase the brightness and shorten the photon pulse length.
The upgrade project of Hefei Light Source storage ring is under way. In this paper, the wake fields of new designed vacuum chambers have been simulated by CST code, and then broadband impedances were obtained by FFT. Together with resistive wall wake fields, broadband impedance model for storage ring was established. Using theoretical formula, longitudinal and transverse single bunch instabilities were discussed. With carefully-designed vacuum chamber, the threshold of beam instabilities was higher than beam current goal.
A muon storage ring neutrino source uses an induction linac for muon capture, a 200 MHz copper cavity system for cooling, and 200 and 400 MHz superconducting rf systems for acceleration to a final energy of up to 50 GeV. These systems and their requirements are discussed in this paper.
Enhanced radiative cooling of ion beams in storage rings and Robinson's damping criterion are discussed.
A method of enhanced optical cooling (EOC) based on nonlinear selective interaction between particles and theirs amplified undulator radiation wavelets (URW) in storage rings is discussed. It leads to non-exponential fast damping. The selectivity is arranged by a moving screen located on the image plane of the optical system projecting URW there.
Here, and in a sequel, we invoke the invariant spin field to provide an in--depth study of spin motion at and near low order orbital resonances in a simple model for the effects of vertical betatron motion in a storage ring with Siberian Snakes. This leads to a clear understanding, within the model, of the behaviour of the beam polarisation at and near so--called snake resonances in proton storage rings.
No Abstract of this Colloquium
Beam Optics Ramping in Under-Constrained Lattice Design: Application to Electron-Ion Collider Hadron Storage Ring Cooling Section
本文针对电子-离子对撞机强子储存环冷却段中可调旋钮多于束流光学约束导致的注入与顶能光学解不连通问题，提出了中点惩罚方案和自上而下自适应加权方法，确保渐变路径连续并满足所有约束，为欠约束系统提供了通用渐变策略。
A method for reversing the laser modulation in a Storage ring
针对储存环激光调制会降低电子束品质且受结构限制难以实现调制解调的问题，提出无需特殊储存环结构的可逆激光调制方法，模拟显示可大幅恢复束流品质，助力高重频相干储存环光源实现。
In the trial \cite{BNL} of measuring the proton electric moment, storage rings with electrostatic lattice have been considered. Here an overview is given about the main parameters regarding such a kind of focusing. Beyond confirming all the issues regarding this subject, a non-null element $M_{31}$ is introduced in all the $3\times 3$ matrices which deal with the vector $(x,x',Δp/p)$ and its role is discussed.
Fast ion instability has been observed in the early commissioning and operation of the Shanghai Synchrotron Radiation Facility (SSRF) storage ring. In this paper, a weak-strong code is used to simulate the fast ion instability in SSRF storage ring. Various fill patterns and gas pressures are investigated. The results show that the mini-train fill patterns are very effective to suppress the growth of the fast ion instability.
HLS (Hefei Light Source) is a second generation synchrotron radiation source. After injected into the storage ring at energy of 200MeV, the electrons will be ramped to 800MeV. During ramping, the magnetic fields of the bend, quadruple and sextuple magnets are ramped up synchronously to keep the working point of the storage ring unchanged. This process is carefully controlled by HLS control system, which is built under EPICS. Several measures are taken to insure the synchronization and linearity of the ramping.
Conceptual Design of a Low-Energy Ion Beam Storage Ring and a Recoil Separator to Study Radiative Neutron Capture by Radioactive Ions
本文提出了一种低能离子存储环及回收分离器的概念设计，用于通过离子光学计算和粒子跟踪模拟研究放射性离子的辐射中子捕获反应。
I describe a new scheme for selectively isolating high density low longitudinal emittance beam particles in a storage ring from the rest of the beam without emittance dilution. I discuss the general principle of the method, called longitudinal momentum mining, beam dynamics simulations and results of beam experiments. Multi-particle beam dynamics simulations applied to the Fermilab 8 GeV Recycler (a storage ring) convincingly validate the concepts and feasibility of the method, which I have demonstrated with beam experiments in the Recycler. The method presented here is the first of its kind.
We calculate equilibrium emittances and damping times due to the emission of synchrotron radiation for coupled storage ring lattices by evaluating the projections of the commonly used synchrotron radiation integrals onto the normal modes of the coupled motion. Orbit distortion is included by calculating off-axis contributions to the radiation integrals. We provide explicit formulae for fast forward calculation, which have been implemented into the interactive lattice design code OPA.
We explore the possibility of operating a SASE FEL with a Storage Ring. We use a semi-analytical model to obtain the evolution inside the undulator by taking into account the interplay on the laser dynamics due to the induced energy spread and to the radiation damping. We obtain the Renieri's limit for the stationary output power and discuss the possibility of including in our model the effect of the beam instabilities.
A multi-objective genetic algorithm is developed for optimizing nonlinearities in diffraction limited storage rings. This algorithm determines sextupole and octupole strengths for chromaticity correction that deliver optimized dynamic aperture and beam lifetime. The algorithm makes use of dominance constraints to breed desirable properties into the early generations. The momentum aperture is optimized indirectly by constraining the chromatic tune footprint and optimizing the off-energy dynamic aperture. The result is an effective and computationally efficient technique for correcting chromatic…
We propose a method to simultaneously correct linear optics errors and linear coupling for storage rings using turn-by-turn (TbT) beam position monitor (BPM) data. The independent component analysis (ICA) method is used to isolate the betatron normal modes from the measured TbT BPM data. The betatron amplitudes and phase advances of the projections of the normal modes on the horizontal and vertical planes are then extracted, which, combined with dispersion measurement, are used to fit the lattice model. The fitting results are used for lattice correction. The method has been successfully demon…
I extend and update earlier work, summarised in [1], whereby the invariant polarisation-tensor field (ITF) for deuterons in storage rings was introduced to complement the invariant spin field (ISF). Taken together, the ITF and the ISF provide a definition of the equilibrium spin density-matrix field which, in turn, offers a clean framework for describing equilibrium spin-1 ensembles in storage rings. I show how to construct the ITF by stroboscopic averaging, I give examples, I discuss adiabatic invariance and I introduce a formalism for describing the effect of noise and damping.
We improve the algorithm to noninvasively update the response matrix using information from the orbit-feedback system, described in [1]. The new version is capable of adapting to slow changes of the lattice, albeit at the expense of limiting the accuracy.
Estimated AC power consumption ranges from ~280 MW (1) to 416 MW (2) for a 350 GeV E_cm 80 km circumference colliding beam storage ring complex with parameters given in (1). The difference between the two estimates is from differing assumptions concerning heat removal, cryo-plant efficiency, klystron operation etc. The purpose of this note is to list and explain these. (1) Mike Koratzinos, et al, IPAC13 (2) Marc Ross, Higgs Quo Vadis Workshop, March 2013.
In the SSRF Phase-II beamline project, a Superconducting Wiggler (SW) will be installed in the electron storage ring. It may greatly impact on the beam dynamics due to the very high magnetic field. The emittance growth becomes a main problem, even after a well correction of the beam optics. A local achromatic lattice is studied, in order to combat the emittance growth and keep the good performance of the SSRF storage ring, as well as possible. Other effects of the SW are simulated and optimized as well, including the beta beating, the tune shift, the dynamic aperture, and the field error effec…
Turkish Accelerator Center) project is aimed to build an accelerator center in Turkey. The first step of the project is to construct IR-FEL facility. The second stage is to build a synchrotron radiation facility named TURKAY, which is the third generation synchrotron radiation light source that aimed to achieve high brilliance photon beam from low emittance electron beam at 3 GeV. The electron beam parameters highly depend on the magnetic lattice of the storage ring. In this paper a low emittance storage ring for TURKAY is proposed and beam dynamic properties of the magnetic lattice are invest…
Stochastic cooling, as the different cooling mechanism from electron cooling, is designed and constructed on CSRe (experimental Cooling Storage Ring) in HIRFL (Heavy Ion Research Facility in Lanzhou) at present. The beam extracted from CSRm (main Cooling Storage Ring) is injected into the CSRe, and then the secondary beam with large momentum spread and large emittance is produced at the internal target area. This paper is designed to optimize the lattice of CSRe in order to satisfy the requirement of stochastic cooling system. Particle Tracking Method is used and both transverse and longitudin…
The general theoretical description of the influence of oscillating horizontal magnetic and quasimagnetic fields on the spin evolution in storage rings is presented. Previous results are generalized to the case when both of the horizontal components of the oscillating field are nonzero and the vector of this field circumscribes an ellipse. General equations describing a behavior of all components of the polarization vector are derived and the case of an arbitrary initial polarization is considered. The derivation is fulfilled in the case when the oscillation frequency is nonresonant. The gener…
The Storage Ring at the Advanced Light Source is capable of being filled in selectable buckets. Typically, 276 consecutive buckets out of 328 possible are selected. It has been found that the amount of charge injected is not uniform bucket-to-bucket, sometimes varying by 100% or more. This variability causes problems with beam stability, and it may shorten the beam lifetime. We have devised a feedback system that allows for beam filling in an orderly manner, yielding bunch heights uniform to within 17%. At fill time, multiple bunches are injected into the Storage ring first, then, using feedba…
Synchrotron radiation emitted by electrons passing through an undulator placed in a storage ring is decomposed in coherent modes. The case of ultimate storage rings where the electron emittance is comparable to the emittance of the photon fan is analyzed by means of the cross spectral density and the coherent mode spectrum. The proposed method permits naturally the statistical analysis and propagation of the cross spectral density along the beamline optics. The coherence properties of the X-ray beam at any point of the beamline are completely given in terms of the eigenvalues and coherent mode…
The injection control system of Hefei Light Source (HLS) storage ring is a subsystem of the upgraded HLS control system, which is based upon EPICS. Three programmable logic controllers (PLCs) are used as device controllers, which control one septum modulator and four kicker modulators of HLS storage ring. An Industrial PC is used as Input/Output Controller (IOC) and it connects the PLCs with serial communication (RS232 mode) over fibre. A PC with Linux is used as operator interface (OPI), operator application are running on it. The control system was completed in July 2000. The commissioning s…
The six species heavy ion beam was accumulated with the help of electron cooling in the main ring of Cooler Storage Ring of Heavy Ion Research Facility in Lanzhou(HIRFL-CSR), the ion beam accumulation dependence on the parameters of cooler was investigated experimentally. The 400MeV/u 12C6+ and 200MeV/u 129Xe54+ was stored and cooled in the experimental ring CSRe, the cooling force was measured in different condition.
A document has recently been posted on the arXiv [1], describing analytical formulas and results of particle tracking simulations, for precision tests of numerical integration algorithms for an EDM (electric dipole moment) storage ring. In the context of an all-electric storage ring, the authors cite theoretical formulas by Orlov [2]. However, the reference to Orlov is to a talk at a workshop in 2012, and is unpublished and difficult for independent researchers to access and validate. This note rederives and generalizes some of Orlov's principal results, using a Hamiltonian formalism, and also…
The Jacobi-Anger identity is employed to quantify the findings of Morse, Orlov and Semertzidis [1]. The secular term in the longitudinal spin component is proportional to a Bessel function. A suggestion for values of machine parameters to optimize the secular term is presented.
Using Longitudinal Strong Focusing Principle to Lower Particle Beam Energy Spread Locally in a Storage Ring
本文提出利用纵向强聚焦原理在存储环中局部降低粒子束能量展宽，并通过可逆Echo SSMB在高功率EUV辐射生成中的应用示例展示了该方法的核心思想和主要贡献。
An intense circularely polarised photon beam interacts with a cooled antiproton beam in a storage ring. Due to spin dependent absorption cross sections for the reaction gamma+antiproton > pi- + antineutron a built-up of polarisation of the stored antiprotons takes place. Figures-of-merit around 0.1 can be reached in principle over a wide range of antiproton energies. In this process antineutrons with Polarisation > 70% emerge. The method is presented for the case of 300 MeV/c cooled antiproton beam.
Energy recovery linacs have been studied and developed over a number of decades. In the standard arrangement there is a separate particle source and particle beam dump. In this paper, a new arrangement is explored where the energy recovery linac is used as an energy source in a storage ring which has multiple beam energies. Several interesting topologies for the multiple beam energies are shown schematically. Possible energy equilibria with and without radiation damping are discussed. This idea may have applications to the problem of electron cooling.
In order to improve the quality and stability of synchrotron light, Hefei Light Source has a major upgrade. Higher accuracy is necessary for installation and alignment of the storage ring magnets. It is not necessarily essential that the magnets are positioned exactly. In fact, the aim is to adjust neighboring magnets with a high accuracy to one another; in other words, these neighboring magnets are positioned on a smoothing curve. The paper presents an attempt to develop a reliable smoothing method based on curve fitting of least squares and iteration according to the structure characteristic…
Contribution of Wiggler to Radiation Integral in an Electron Storage Ring
本文针对电子储存环中wiggler对电子束发射度的量子激发贡献，提出了比文献近似公式更精确的评估结果，对未来光源发展具有重要价值。
Louisiana State University Center for Advanced Microstructures and Devices (CAMD) began a control system upgrade project in early 1997. At the time, the storage ring was controlled by a VAX/VMS system, primarily using CAMAC for I/O. The injector Linac was controlled by a separate VME/OS/9 system using custom I/O components. The storage ring control system has been replaced with a PC/Linux based system, utilizing the existing CAMAC subsystem [1]. In an effort to both migrate channels away from CAMAC, and integrate the Linac controls with the storage ring controls, a design for upgrades utilizin…
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