Author: Mitchell, C.E.
Paper Title Page
MOXB02 First Results of the IOTA Ring Research at Fermilab 19
 
  • A. Valishev, D.R. Broemmelsiek, A.V. Burov, K. Carlson, B.L. Cathey, S. Chattopadhyay, N. Eddy, D.R. Edstrom, J.D. Jarvis, V.A. Lebedev, S. Nagaitsev, H. Piekarz, A.L. Romanov, J. Ruan, J.K. Santucci, V.D. Shiltsev, G. Stancari
    Fermilab, Batavia, Illinois, USA
  • A. Arodzero, A.Y. Murokh, M. Ruelas
    RadiaBeam, Santa Monica, California, USA
  • D.L. Bruhwiler, J.P. Edelen, C.C. Hall
    RadiaSoft LLC, Boulder, Colorado, USA
  • S. Chattopadhyay, S. Szustkowski
    Northern Illinois University, DeKalb, Illinois, USA
  • A. Halavanau, Z. Huang, V. Yakimenko
    SLAC, Menlo Park, California, USA
  • M. Hofer
    TU Vienna, Wien, Austria
  • M. Hofer, R. Tomás García
    CERN, Geneva, Switzerland
  • K. Hwang, C.E. Mitchell, R.D. Ryne
    LBNL, Berkeley, California, USA
  • K.-J. Kim
    ANL, Lemont, Illinois, USA
  • K.-J. Kim, Y.K. Kim, N. Kuklev, I. Lobach
    University of Chicago, Chicago, Illinois, USA
  • T.V. Shaftan
    BNL, Upton, New York, USA
 
  Funding: Fermilab is operated by Fermi Research Alliance, LLC under Contract No. DE-AC02-07CH11359 with the United States Department of Energy.
The IOTA ring at Fermilab is a unique machine exclusively dedicated to accelerator beam physics R&D. The research conducted at IOTA includes topics such as nonlinear integrable optics, suppression of coherent beam instabilities, optical stochastic cooling and quantum science experiments. In this talk we report on the first results of experiments with implementations of nonlinear integrable beam optics. The first of its kind practical realization of a two-dimensional integrable system in a strongly-focusing storage ring was demonstrated allowing among other things for stable beam circulation near or at the integer resonance. Also presented will be the highlights of the world’s first demonstration of optical stochastic beam cooling and other selected results of IOTA’s broad experimental program.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOXB02  
About • paper received ※ 20 May 2021       paper accepted ※ 02 July 2021       issue date ※ 23 August 2021  
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MOPAB234 Analysis of the Chromatic Vertical Focusing Effect of Dipole Fringe Fields 760
 
  • K. Hwang, C.E. Mitchell, R.D. Ryne
    LBNL, Berkeley, USA
 
  Funding: U.S. Department of Energy under Contract No. DE-AC02-05CH11231
There have been questions regarding the impact of the dipole fringe-field models (used by accelerator codes including ELEGANT and MADX) on vertical chromaticity. Here, we analyze the cause of the disagreement among codes and suggest a correction.
 
poster icon Poster MOPAB234 [0.486 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB234  
About • paper received ※ 20 May 2021       paper accepted ※ 01 June 2021       issue date ※ 23 August 2021  
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MOPAB235 Transverse 2d Phase-Space Tomography Using Beam Position Monitor Data of Kicked Beams 763
 
  • K. Hwang, C.E. Mitchell, R.D. Ryne
    LBNL, Berkeley, USA
 
  Funding: U.S. Department of Energy under Contract No. DE-AC02-05CH11231
The time-series Beam Position Monitor (BPM) data of kicked beam is a function of lattice parameters and beam parameters including phase-space density. The decoherence model using the first-order detuning parameter has an exact solution when the beam is Gaussian. We parameterize the beam phase-space density by multiple Gaussian kernels of different weights, means, and sizes to formulate the inverse problem for 2D phase-space tomography. Numerical optimization and Bayesian inference are used to infer the beam density.
 
poster icon Poster MOPAB235 [1.253 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB235  
About • paper received ※ 20 May 2021       paper accepted ※ 02 June 2021       issue date ※ 01 September 2021  
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TUXA02
Beam Dynamics Optimization in High-Brightness Electron Injectors  
 
  • C.E. Mitchell
    LBNL, Berkeley, California, USA
 
  Funding: The work was supported by the U.S. Department of Energy Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-05CH11231.
The next generation of X-ray free electron lasers requires beams with increasingly high peak current and low emittances at ~MHz repetition rates, placing increased demands on the performance of high-brightness electron photoinjector sources. To explore the high- dimensional parameter space associated with photoinjector design, global multiobjective optimization methods based on genetic algorithms or similar tools play a critical role. We review our experience applying these tools both to understand and to optimize simulated injector beam performance for projects such as LCLS-II (at SLAC), the Advanced Photoinjector EXperiment (at LBNL), APEX2, and potential future high-brightness FEL electron sources.
 
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TUPAB223 Design of Double- and Multi-Bend Achromat Lattices with Large Dynamic Aperture and Approximate Invariants 1945
 
  • Y. Li, R.S. Rainer, V.V. Smaluk
    BNL, Upton, New York, USA
  • K. Hwang, C.E. Mitchell, R.D. Ryne
    LBNL, Berkeley, California, USA
 
  Funding: Funded by U.S. Department of Energy (DOE) under Contract No. DE-SC0012704 (BNL) and DE-AC02-05CH11231 (LBNL), U.S. DOE Early Career Research Program under the Office of High Energy Physics.
A numerical method to design nonlinear double- and multi-bend achromat (DBA and MBA) lattices with approximate invariants of motion is described. The search for such nonlinear lattices is motivated by Fermilab’s Integrable Optics Test Accelerator (IOTA), whose design is based on an integrable Hamiltonian system with two invariants of motion. While it may not be possible to design an achromatic lattice for a dedicated synchrotron light source storage ring with one or more exact invariants of motion, it is possible to tune the sextupoles and octupoles in existing DBA and MBA lattices to produce approximate invariants. In our procedure, the lattice is tuned while minimizing the turn-by-turn fluctuations of the Courant-Snyder actions Jx and Jy at several distinct amplitudes, while simultaneously minimizing diffusion of the on-energy betatron tunes. The resulting lattices share some important features with integrable ones, such as a large dynamic aperture, trajectories confined to invariant tori, robustness to resonances and errors, and a large amplitude-dependent tune-spread.
 
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DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB223  
About • paper received ※ 10 May 2021       paper accepted ※ 15 June 2021       issue date ※ 20 August 2021  
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WEPAB248 Kurth Vlasov-Poisson Solution for a Beam in the Presence of Time-Dependent Isotropic Focusing 3213
 
  • C.E. Mitchell, K. Hwang, R.D. Ryne
    LBNL, Berkeley, USA
 
  Funding: This work was supported by the Director, Office of Science of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231.
The well-known K-V distribution provides an exact solution of the self-consistent Vlasov-Poisson system describing an unbunched charged particle beam with nonzero temperature in the presence of time-dependent linear transverse focusing. We describe a lesser-known exact solution of the Vlasov-Poisson system that is based on the work of Kurth in stellar dynamics. Unlike the K-V distribution, the Kurth distribution is a true function of the phase space variables, and the solution may be constructed on either the 4D or 6D phase space, for the special case of isotropic linear focusing. Numerical studies are performed for benchmarking simulation codes, and the stability properties of a 4D Kurth distribution are compared with those of a K-V distribution.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB248  
About • paper received ※ 19 May 2021       paper accepted ※ 14 July 2021       issue date ※ 02 September 2021  
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WEPAB249 Model of Curvature Effects Associated with Space Charge for Long Beams in Dipoles 3217
 
  • C.E. Mitchell, K. Hwang, R.D. Ryne
    LBNL, Berkeley, USA
 
  Funding: This work was supported by the Director, Office of Science of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231.
For modeling the dynamics within a dipole of a bunch whose length is much larger than the vacuum pipe radius, it is typical to use a 2D (or 2.5D) Poisson solver, with arc length taken as the independent variable. However, sampled at a fixed time, the beam is curved, space charge is not truly 2D, and the usual cancellation between E and B contributions to the Lorentz force need not exactly hold. The size of these effects is estimated using an idealized model of a uniform torus of charge rotating inside a toroidal conducting pipe. Simple expressions are provided for the correction of the electric and magnetic fields to first order in the reciprocal of the curvature radius.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB249  
About • paper received ※ 19 May 2021       paper accepted ※ 02 July 2021       issue date ※ 02 September 2021  
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