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arXiv · 1811.06618

Quasi-integrable optics for a small electron recirculator

K. Ruisard·H. B. Komkov·B. Beaudoin·I. Haber·D. Matthew·T. Koeth
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Abstract

This paper describes the design and simulation of a proof-of-concept quasi-integrable octupole lattice at the University of Maryland Electron Ring (UMER). This experiment tests the feasibility of nonlinear integrable optics, a novel technique that is expected to mitigate resonant beam loss and enable low-loss high-intensity beam transport in rings. Integrable lattices with large amplitude-dependent tune spreads, created by nonlinear focusing elements, are proposed to damp beam response to resonant driving perturbations while maintaining large dynamic aperture [Danilov and Nagaitsev PRSTAB 2010]. At UMER, a lattice with a single octupole insert is designed to test the predictions of this theory. The planned experiment employs a low-current high-emittance beam with low space charge tune shift (~0.005) to probe the dynamics of a lattice with large externally-induced tune spread. Design studies show that a lattice composed of a 25-cm octupole insert and existing UMER optics can induce a tune spread of \sim 0.13. Stable transport is observed in PIC simulation for many turns at space charge tune spread 0.008. A maximum spread of dnu = 0.11 (RMS 0.015) is observed for modest octupole strength (peak 50 T/m^3). A simplified model of the system explores beam sensitivity to steering and focusing errors. Results suggest that control of orbit distortion to <0.2 mm within the insert region is essential. However, we see only weak dependence on deviations of lattice phase advance (<=0.1 rad.) from the invariant-conserving condition.

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K. Ruisard, H. B. Komkov, B. Beaudoin, I. Haber, D. Matthew, T. Koeth. 2018-11-15. Quasi-integrable optics for a small electron recirculator. https://doi.org/10.1103/physrevaccelbeams.22.041601

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