Details

Autor(en) / Beteiligte

• Lumpkin, A. H.
• Thurman-Keup, R.
• Edstrom, D.
• Ruan, J.
• Eddy, N.
• Prieto, P.
• Napoly, O.
• Carlsten, B. E.
• Bishofberger, K.

Titel

Submacropulse electron-beam dynamics correlated with higher-order modes in Tesla-type superconducting rf cavities

Ist Teil von

• Physical review. Accelerators and beams, 2018-06, Vol.21 (6), p.064401, Article 064401

Ort / Verlag

College Park: American Physical Society

Erscheinungsjahr

2018

Quelle

Alma/SFX Local Collection

Beschreibungen/Notizen

• We report the direct observations of submacropulse beam centroid oscillations correlated with higher order modes (HOMs) which were generated by off-axis electron beam steering in TESLA-type superconducting rf cavities. The experiments were performed at the Fermilab Accelerator Science and Technology (FAST) facility using its unique configuration of a photocathode rf gun injecting beam into two separated nine-cell cavities in series with corrector magnets and beam position monitors (BPMs) located before, between, and after them. Oscillations of∼100kHzin the vertical plane and∼380kHzin the horizontal plane with up to600−μmamplitudes were observed in a 3-MHz micropulse repetition rate beam with charges of 100, 300, 500, and1000pC/b. However, the effects were much reduced at100pC/b. The measurements were based on HOM detector circuitry targeting the first and second dipole passbands, rf BPM bunch-by-bunch array data, imaging cameras, and a framing camera. Calculations reproduced the oscillation frequencies of the phenomena in the vertical case. In principle, these fundamental results may be scaled to cryomodule configurations of major accelerator facilities.