Author: Nagaitsev, S.
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TUA3IO01
 Possible Road Maps for High-Energy Collider Based on Advanced Acceleration Techniques  
 
  • S. Nagaitsev
    Fermilab, Batavia, Illinois, USA
  
  In February 2016, DOE organize a closed workshop to discuss possible roadmaps toward future high-energy linear colliders. Three accelerations techniques were discussed. The purpose of this paper is to summarize the outcome of this workshop.  
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WEA1CO06
 Analytical theory for McMillan map  
 
  • T. Zolkin, S. Nagaitsev
    Fermilab, Batavia, Illinois, USA
  
  McMillan map is an important discrete time model of 1D transverse nonlinear accelerator lattice. We provide a full analytical theory based on parametrization of individual canonical biquadratic curves*. Using the normal forms provided in* we were able to generalize this result to entire phase-plane of finite trajectories and calculate mechanical action-angle coordinates. The bifurcation map for canonical McMillan map including stability of fixed points is provided. In addition, we discuss the connection of these results with possible 2D generalizations - axially symetric and 2D-magnetostatic McMillan lenses.
Iatrou, A., & Roberts, J. A. (2002). Integrable mappings of the plane preserving biquadratic invariant curves II. Nonlinearity, 15(2), 459. 		 
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WEA2IO02
 Proposed Experimental Validation of Hamiltonian Perturbation Theory in IOTA  
 
  • D.L. Bruhwiler, N.M. Cook, C.C. Hall, R.A. Kishek, S.D. Webb
    RadiaSoft LLC, Boulder, Colorado, USA
  • S. Nagaitsev, A.L. Romanov, A. Valishev
    Fermilab, Batavia, Illinois, USA
  
  The Integrable Optics Test Accelerator (IOTA) is a small ring under construction to explore advanced concepts in beam dynamics, initially with electron pencil beams to emulate single-particle dynamics and later with low-energy proton beams including significant space charge tune depression. Hamiltonian perturbation theory and simulations with Synergia, Warp and other codes are being used to develop an experimental program for beam dynamics, including the highly nonlinear 'elliptic' magnet originally proposed by Danilov and Nagaitsev. The results suggest a number of experiments that could be performed at IOTA. For example, small changes in the linear tune and the strength of the elliptic magnet can be used to control dynamic aperture. Both electron and proton beams can be used to measure the tune spread as a function of the elliptic magnet strength, for comparison with theory. Space charge driven halo formation due to envelope oscillations can be measured over a range of elliptic magnet strengths. Theoretical and computational results will be presented to guide future decisions regarding experimental diagnostics for IOTA.  
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THPOA48 Model of Electron Cloud Instability in Fermilab Recycler 1197
 
  • S. A. Antipov
    University of Chicago, Chicago, Illinois, USA
  • A.V. Burov, S. Nagaitsev
    Fermilab, Batavia, Illinois, USA
  
  An electron cloud instability might limit the intensity in the Fermilab Recycler after the PIP-II upgrade. A multibunch instability typically develops in the horizontal plane within a hundred turns and, in certain conditions, leads to beam loss. Recent studies have indicated that the instability is caused by an electron cloud, trapped in the Recycler index dipole magnets. We developed an analytical model of an electron cloud driven instability with the electrons trapped in combined function dipoles. The resulting instability growth rate of about 30 revolutions is consistent with experimental observations and qualitatively agrees with the simulation in the PEI code. The model allows an estimation of the instability rate for the future in-tensity upgrades.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2016-THPOA48  
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THPOA49 Electron Cloud Trapping in Recycler Combined Function Dipole Magnets 1200
SUPO06   use link to see paper's listing under its alternate paper code  
 
  • S. A. Antipov
    University of Chicago, Chicago, Illinois, USA
  • S. Nagaitsev
    Fermilab, Batavia, Illinois, USA
  
  Electron cloud can lead to a fast instability in intense proton and positron beams in circular accelerators. In the Fermilab Recycler the electron cloud is confined within its combined function magnets. We show that combined function magnets trap the electron cloud with their magnetic field, present the results of analytical estimates of trapping, and compare them to numerical simulations of electron cloud formation. The electron cloud in a combined function magnet is located at the beam center and up to 1% of the particles can be trapped by its magnetic field. Since the process of electron cloud build-up is exponential, once trapped this amount of electrons significantly increases the density of the cloud on the next revolution. In a Recycler combined function dipole this multi-turn accumulations allows the electron cloud reaching final intensities orders of magnitude greater than in a pure dipole. The multi-turn build-up can be stopped by injection of a single clearing bunch of 1*1010 p at any position in the ring.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2016-THPOA49  
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