Phys. Rev. ST Accel. Beams 12, 054204 (2009) [5 pages]Fourth order resonance of a high intensity linear accelerator
It is discovered that, for a high intensity beam, the 4σ=360° (or 4ν=1) resonance of a linear accelerator is manifested through the octupolar term of space charge potential when the depressed phase advance per cell σ is close to and below 90° but no resonance effect is observed when σ is just above 90°. To verify that this is a resonance, a frequency analysis is performed and a study of resonance crossing from above and from below the resonance is conducted. It is observed that this fourth order resonance is dominating over the better known envelope instability and practically replacing it. The simulation study shows a clear emittance growth by this resonance and its stop band. A proposal to GSI was made to perform an experiment to measure the stop band of this resonance using the UNILAC. The experiment confirmed this resonance and will be published in a separate paper. This article is available under the terms of the Creative Commons Attribution 3.0 License. Further distribution of this work must maintain attribution to the author(s) and the published article’s title, journal citation, and DOI. © 2009 The American Physical Society URL:
http://link.aps.org/doi/10.1103/PhysRevSTAB.12.054204
DOI:
10.1103/PhysRevSTAB.12.054204
PACS:
29.27.Bd, 41.75.−i
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