31 July 2016 to 5 August 2016
Gaylord Hotel and Conference Center
US/Eastern timezone

Understanding perturbations to the nonlinear integrable optics in IOTA

3 Aug 2016, 11:00
Woodrow Wilson B (Gaylord Hotel)

Woodrow Wilson B

Gaylord Hotel

Oral Working Group 7 WG7


Dr. Nathan Cook (RadiaSoft LLC)


We present simulation results of 2.5 MeV proton beams in the IOTA ring [1] with significant space charge tune shift. We consider issues of nonlinearities in the underlying lattice, including dispersion and chromaticity, as well as the impact of incoherent tune shifts on integrable motion.


Tune spread with amplitude suppresses intensity-driven parametric instabilities such as beam halo. Conventional approaches to achieving high tune spreads, such as the use of octupoles, reduce dynamic aperture. The nonlinear integrable optics [2] promise to introduce large tune spreads with amplitude without introducing resonances that limit the dynamic aperture [3]. The Integrable Optics Test Accelerator (IOTA) is a small ring, currently under construction at Fermilab, which will explore these concepts with low-energy proton beams with at high intensity. The stability of these invariants is particularly sensitive to collective effects such as space charge induced tune shift, as well as intrinsic nonlinearities in the single particle motion, such as dispersion and chromaticity [4].

We present results from simulations of IOTA using the accelerator simulation package Synergia and the particle-in-cell framework Warp exploring the behavior of proton beams in the IOTA lattice. In the high current regime, we examine potential lattice variations that correct for tune depression and beam mismatch while minimizing deviations from integrability. For operation at low intensity, we consider the nonlinear response due to finite phase advance across the nonlinear magnet as well as nonlinear dispersive and chromatic effects. We present evidence for these effects, and illustrate the sensitivity of the dynamics to sextupole fields, showing that their proper pairing can preserve integrability and reduce beam loss.

[1] Nagaitsev et al., “Design and Simulation of IOTA – a Novel Concept of Integrable Optics Test Accelerator” (2013) https://arxiv.org/abs/1301.7032
[2] V. Danilov and S. Nagaitsev, Phys. Rev. ST-AB 13, 84002 (2010).
[3] S. Webb et al., “Effects of Nonlinear Decoherence on Halo Formation” (2013) http://arxiv.org/abs/1205.7083
[4] S. Webb et al., “Chromatic and Dispersive Effects in Nonlinear Integrable Optics” (2015), submitted to PRSTAB; http://arxiv.org/abs/1504.05981

This material is based upon work supported by the U.S. Department of Energy, Office of Science, Office of High Energy Physics under Award Number DE-SC0011340.

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Primary author

Dr. Nathan Cook (RadiaSoft LLC)


Dr. Alexander Romanov (Fermilab) Dr. Alexander Valishev (Fermilab) Dr. Christopher Hall (RadiaSoft, LLC) Dr. David Bruhwiler (RadiaSoft LLC) Prof. Rami Kishek (University of Maryland) Stephen Webb (RadiaSoft, LLC)

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