PPPL, Princeton, New Jersey, USA
A recently developed novel perturbative Hamiltonian transformation method which allows the determination of approximate matched kinetic quasi-equilibrium solutions for an intense charged particle beam propagating through a periodic focusing quadrupole lattice is presented.* Using this method we have identified numerically the class of self-consistent periodic kinetic 'equilibria' for intense beam propagation in alternating-gradient focusing systems, and extended the nonlinear perturbative particle simulation method to intense beam propagation in such systems. The new method has been implemented in the nonlinear perturbative particle-in-cell code BEST which is used to study properties of the newly constructed beam 'equilibria'. The results of these studies are presented and analyzed in detail.
* E.A. Startsev, R.C. Davidson and M. Dorf, Phys. Rev. ST Accel. Beams 13, 064402 (2010).
JLAB, Newport News, Virginia, USA
SLAC, Menlo Park, California, USA
Universität Bonn, Helmholtz-Institut für Strahlen- und Kernphysik, Bonn, Germany
GOO Zaryad, Novosibirsk, Russia
University of Michigan, Spin Physics Center, Ann Arbor, MI, USA
IUCF, Bloomington, Indiana, USA
Spin dynamics of polarized deuteron beams near depolarization resonances, including a new polarization preservation concept based on specially-designed multiple resonance crossings, has been tested in a series of experiments in the COSY synchrotron. Intricate spin dynamics with sophisticated pre-programmed patterns as well as effects of multiple crossings of a resonance were studied both theoretically and experimentally with excellent agreement. Possible applications of these results to preserve, manipulate and spin-flip polarized beams in synchrotrons and storage rings are discussed.
LANL, Los Alamos, New Mexico, USA
UMD, College Park, Maryland, USA
LBNL, Berkeley, California, USA
Using correlations at the cathode to tailor the beam’s eigen-emittances is a recent concept made useful by the symplectic nature of Hamiltonian systems. While introducing correlations does not change the overall 6-dimensional phase space volume, it can change the partitioning of this volume into the longitudinal and two transverse emittances, which become the eigen-emittances if the initial correlations are removed. In principle, this technique can be used to generate beams with highly asymmetric emittances, such as those needed for the next generation of very hard X-ray free-electron lasers. Based on linear correlations, the applicability of this approach is limited by the magnitude of nonlinear effects in photoinjectors. We review the eigen-emittance concept and present a linear eigen-emittance design leading to a highly partitioned, and transversely ultra-bright, electron beam. We also present numerical tools to examine the evolution of the eigen-emittances in realistic accelerator structures and results indicating how much partitioning is practical.
Fermilab, Batavia, USA
Northern Illinois University, DeKalb, Illinois, USA
Our recent experimental demonstration of a photoinjector electron bunch train with sub-picosecond structures is reported in this paper. The experiment is accomplished by converting an initially horizontal beam intensity modulation into a longitudinal phase space modulation, via a beamline capable of exchanging phase-space coordinates between the horizontal and longitudinal degrees of freedom. The initial transverse modulation is produced by intercepting the beam with a multislit mask prior to the exchange. We also compare our experimental results with numerical simulations.
UNAL, Bogota D.C, Colombia
Action and phase orbit correction method is implemented to detect magnetic errors in LHC orbits of late 2009 run. The last achievements in the theory of action and phase jump analysis have been included to reduce action and phase plots noise and to increase precision on the calculation of linear errors. The validation of the implementation is performed by MAD-X simulations of the LHC lattice V6.5, where dipole and quadrupole errors are included and recovered within 0.02%. Then, the implementation is applied to experimental orbits, taken from the 2009 run during November and December, where several interaction regions are analyzed.
orblancog@bt.unal.edu.co, Universidad Nacional de Colombia
jfcardona@unal.edu.co, Professor, Universidad Nacional de Colombia
ELSA, Bonn, Germany
Since more than four decades, the University of Bonn supports research at the in-house electron accelerator ELSA. Presently, the polarized electrons gained from an inverted source are accumulated in a stretcher ring and accelerated within a fraction of a second up to 3.2 GeV. During the fast ramping various depolarizing resonances are crossed. By taking several expedient measures (closed orbit correction, tune jumping, etc.) a high polarization degree of up to 65% is reached. One important part of these measures is the harmonic correction of integer resonances. Those resonances are compensated by applying additional horizontal fields, distributed sinusoidally along an one-turn orbit length. In case of an appropriate setting of amplitude and phase, all resonance driving effects should be neutralized completely. First studies have shown that vertical displacements and resulting horizontal fields in the quadrupole magnets, caused by the resonance correction, have to be taken into account as well. With regard to a new correction scheme, the first experimental results confirmed by simulative and theoretical studies will be presented.
KIT, Karlsruhe, Germany
CLASSE, Ithaca, New York, USA
University of Delhi, Delhi, India
Fermilab, Batavia, USA
University of Delhi, Delhi, India
Fermilab, Batavia, USA
ESS-Bilbao, Zamudio, Spain
ESS Bilbao, Bilbao, Spain
STFC/RAL/ISIS, Chilton, Didcot, Oxon, United Kingdom
Bilbao, Faculty of Science and Technology, Bilbao, Spain
University of the Basque Country, Faculty of Science and Technology, Bilbao, Spain
The ESS-Bilbao linac will accelerate H+ and H− beams up to 50 MeV, which need to be transported to three laboratories, where different types of experiments will be conducted. This paper reports on the preliminary design of the transfer line, which is mainly performed based on beam dynamics simulations.
ESS Bilbao, Bilbao, Spain
Bilbao, Faculty of Science and Technology, Bilbao, Spain
University of the Basque Country, Faculty of Science and Technology, Bilbao, Spain
ESS-Bilbao, Zamudio, Spain
In this work we present a future upgrade of the ESS-Bilbao multi-source Low Energy Transport System (LEBT). It consists of a set of solenoids and steering dipoles used to match the characteristics of both ion source beams i.e., the Electron Cyclotron Resonance (ECR) H+/D+ source and the H− Penning source, to the input specifications of the RFQ. Different configurations of the geometry and magnetic fields are studied in order to minimize the emittance growth along the LEBT, while providing the beam specifications required by the RFQ.
ANL, Argonne, USA
BNL, Upton, Long Island, New York, USA
An Electron Beam Ion Source (EBIS) being developed at the Argonne National Laboratory (ANL) will be used to charge breed rare isotopes from a 1 Ci 252Cf source, the Californium Rare Isotope Breeder Upgrade (CARIBU). Simulations have been performed using commercially available software, TriComp, to ensure the electron collector is properly designed to dissipate the electron beam power and provide adequate acceptance for the injected ion beam.
BNL, Upton, Long Island, New York, USA
To increase luminosity in the Relativistic Heavy Ion Collider’s (RHIC’s) polarized proton 250 GeV operations, we are considering reducing beta* to 0.65 m at the interaction points (IPs), and increasing bunch intensity. The new working point near the 2/3 integer will used on the ramp to preserve polarization. In addition, we plan to adjust the betatron-phase advances between IP6 and IP8 to (k+1/2)*PI so to lower the dynamic beta-beat from the beam-beam interaction. The effects of all these changes will impact the dynamic aperture, and hence, it must be evaluated carefully. In this article, we present the results of tracking the dynamic aperture with the proposed lattices.
BNL, Upton, Long Island, New York, USA
The NSLS-II magnet multipole specifications were determined based on analysis of nonlinear beam dynamics. The required field quality does not exceed what was specified for the existing third-generation light sources. While the prototype magnets have met these specifications, the magnets from mass production could potentially have bigger errors which exceed certain tolerances. In this paper we discuss the results of recent calculations to provide further insight into the acceptable range of the magnet multipoles based on the physics requirements.
BNL, Upton, Long Island, New York, USA
A large distortion of the vertical beta function became evident in the Brookhaven AGS during the 2010 polarized proton run. This paper describes the beam measurements and model calculations made to verify the distortion of the optics, to infer possible sources and to explore correcting strategies. The optics distortion is only apparent when operating with a betatron tune very near the integer (as required for polarization preservation during acceleration in the AGS) and with the lattice chromaticity sextupoles powered. The measurements indicate a small (on the order of millimeters) unexpected systematic horizontal closed orbit displacement in the sextupoles that is not evident in beam position monitor measurements. Motivated especially by these observations a complete survey of the AGS was performed during the 2010 shutdown period.&nb sp; The results of that survey and their impact on the observed optical errors in the AGS are included.
CUNY, Bayside, New York, USA
UMD, College Park, Maryland, USA
CLASSE, Ithaca, New York, USA
We report on the status of emittance tuning techniques at the CESR Test Accelerator CesrTA. The CesrTA experimental program requires the capability to operate in a variety of machine lattices with the smallest possible emittance. We have attempted to minimize the turn-around time of our low emittance tuning procedure. We utilize high bandwidth BPM electronics for fast, precision measurements of orbit, betatron phase, transverse coupling, and dispersion. Turn by turn data is used to measure BPM button electrode gains to a under a percent. Gain-corrected coupling data is utilized to determine BPM tilts to 10mrad, allowing for measurement of vertical dispersion at the level of 10mm. Measurement and analysis of the data for characterizing BPM response takes 5 minutes. Beam based measurement of machine functions, data analysis, and implementing corrections in the machine takes another 5 minutes. An x-ray beam size monitor provides a real time check on the effectiveness of the procedure. A typical correction results in an emittance less than 20pm at 2.1GeV in 1-2 iterations. Sub 15pm has been achieved with adjustment of closed coupling/vertical dispersion bumps and betatron tunes.
Fermilab, Batavia, USA
Fermilab, Batavia, USA
LBNL, Berkeley, California, USA
LLNL, Livermore, California, USA
To attain the highest accelerating gradient in the compact dielectric wall (DWA) accelerator, the accelerating voltage pulses should have the shortest possible duration. To do so, the DWA will be operated in the “virtual” traveling mode*. Since only a short section of HGI wall would be excited, the accelerating field’s axial profile could be non-uniform and time dependent, especially near the entrance and exit of the DWA, which could lead to dispersion in beam acceleration and transport, and eventually emittance growth. The dispersive transverse kick on a short proton bunch at the DWA entrance and its impact on acceptable input proton bunch length will be discussed. Without using any external lenses, the dispersive transverse kicks on the beam can be mitigated. Implementing the mitigations into the transport strategy, we have established a baseline transport case. Results of simulations using 3-D, EM PIC code, LSP** indicate that the DWA transport performance meets the medical specifications for intensity modulation proton treatment. Sensitivity of the transport performance to the switch timing will be presented.
* G. J. Caporaso, Y-J Chen and S. E. Sampayan, "The Dielectric Wall Accelerator", Rev. of Accelerator Science and Technology, vol. 2, p. 253 (2009).
** Alliant Techsystems Inc., http://www.lspsuite.com/.
LANL, Los Alamos, New Mexico, USA
An Emittance EXchanger (EEX), like a chicane, can be used for bunch compression. However, it offers a unique characteristic: the R56 term in an EEX vanishes, which decouples the final longitudinal position from the particles’ energies, thereby suppressing the microbunch instability. Also, it can provide simultaneous compression in both the longitudinal and one transverse dimensions, where, for example, the final longitudinal size is smaller than the initial horizontal size and the final horizontal size is smaller than the initial longitudinal size. In this scheme, there is no dependence on an energy slew needed for compressing the beam, simplifying the rf requirements. A bunch-compression scheme using two EEXs is presented, including CSR calculations.
NRL, Washington, DC, USA
UMD, College Park, Maryland, USA
SAIC, Billerica, Massachusetts, USA
Beam-Wave Research, Inc., Union City, USA
We explore periodically cusped magnetic (PCM) fields in the regime of a Ka-Band coupled-cavity travelling wave tube (beam current = 3.5A, voltage = 19.5kV, 10:1 beam aspect ratio). We use finite-element beam optics code MICHELLE to simulate the 3-dimensional beam optics for the beam transport within a PCM field. Realistic 3-dimensional magnetic fields have been considered to determine the practicality of these designs. We present the methodology used to focus and transport a thermal beam from a shielded-cathode, high aspect-ratio electron gun.
Northern Illinois University, DeKalb, Illinois, USA
Fermilab, Batavia, USA
Fermilab is currently building a superconducting RF (SCRF) linear-accelerator test facility. In addition to testing ILC-spec SCRF accelerating modules for ILC and Project-X, the facility will be capable of supporting a variety of advanced accelerator R&D experiments. The accelerator facility includes a 40-MeV photoinjector capable of producing bunches with variable parameters. In this paper, we present start-to-end simulations of the accelerator beamline.
ORNL RAD, Oak Ridge, Tennessee, USA
ORNL, Oak Ridge, Tennessee, USA
ORNL, Oak Ridge, Tennessee, USA
SLAC, Menlo Park, California, USA
FACET, the Facility for Advanced Accelerator and Experimental Tests, is a new facility being constructed in sector 20 of the SLAC linac primarily to study beam driven plasma wakefield acceleration. The FACET beamline consists of a chicane and final focus system to compress the 23 GeV, 3 nC electron bunches to ~20μm long and ~10μm wide. Simulations of the FACET beamline indicate the short-duration and large, 1.5% rms energy spread beams may suffer a factor of four emittance growth from a combination of chromaticity, incoherent synchrotron radiation (ISR), and coherent synchrotron radiation (CSR). Emittance growth is directly correlated to head erosion in plasma wakefield acceleration and is a limiting factor in single stage performance. Studies of the geometric, CSR, and ISR components are presented. Numerical calculation of the rms emittance can be overwhelmed by long tails in the simulated phase space distributions; more useful definitions of emittance are given. A complete simulation of the beamline is presented as well, which agrees with design specifications.
SLAC, Menlo Park, California, USA
Alternative chicane-type beamlines are proposed for exact emittance exchange between horizontal phase space (x,x') and longitudinal phase space (z, delta). Methods to achieve exact phase space exchanges, i.e. mapping x to z, x' to delta, z to x and delta to x' are suggested. Some applications of the phase space exchanger and the feasibility of an emittance exchange experiment with the proposed beamline at SLAC are discussed.
The University of Texas at Austin, Austin, Texas, USA
Fermilab, Batavia, USA
University of Connecticut, Storrs, Connecticut, USA
JLAB, Newport News, Virginia, USA
UMD, College Park, Maryland, USA
The University of Maryland Electron Ring (UMER) is a research accelerator designed to operate with extreme space charge. The existence of high-precision experimental measurements of tune, dispersion, chromaticity, response matrix elements, and other parameters*, **, *** has prompted a revision of the models used to describe the machine. Due to the low energy (10 keV) of the electrons, the dipole and quadrupole magnets used are air-core printed-circuit coils whose fields we calculate using a Biot-Savart solver. Different levels of approximations for the magnetic fields have been developed. We present simulation results from the particle-in-cell code WARP, and from the accelerator code, ELEGANT. These are compared both against simpler models as well as experimental results. The improved modeling has significantly reduced the discrepancies between simulation and experiment.
* D.F. Sutter, et al., Proc. PAC 2009
** C. Wu, et al., Proc. PAC 2009
*** S. Bernal, et al., Proc. AAC 2010