Experiments on the fast beam-ion instability at the ALS

Conference · Wed Oct 01 04:00:00 EDT 1997

OSTI ID:666061

Zimmermann, F; Chao, A; Heifets, S; Minty, M; Seeman, J; Stupakov, G ^[1]; Byrd, J; Thomson, J ^[2]; Raubenheimer, T ^[3]

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1. Stanford Univ., CA (US). Stanford Linear Accelerator Center
2. Lawrence Berkeley National Lab., CA (US)
3. CERN, Geneva (Switzerland)

The authors report on the first observation of the fast beam-ion instability (FBII), at the Advanced Light Source (ALS). The FBII is a novel single-pass instability, which is similar to the classical beam break up instability in a linac. Unlike the classical trapped-ion instability, the FBII cannot be cured by a clearing gap in the bunch train, and it is predicted to be a potential limitation for many multi-bunch small-emittance storage rings and linacs. In order to induce the FBII in the ALS, they added helium gas to the vacuum system so as to increase the vacuum pressure by two orders of magnitude above its normal value. At an elevated pressure of about 50--100 nTorr, the authors observed a variety of effects, including an increase of the vertical beam size by a factor 2--4, self-excited betatron sidebands, and a growth of the betatron motion along the bunch train. The onset of the vertical beam-size increase (as a function of bunch number) occurred close to the theoretically predict ed instability threshold.

• Research Organization: Stanford Univ., Stanford Linear Accelerator Center, CA (US); Lawrence Berkeley National Lab., CA (US)
• Sponsoring Organization: USDOE Office of Energy Research, Washington, DC (US)
• DOE Contract Number: AC03-76SF00515; AC03-76SF00098
• OSTI ID: 666061
• Report Number(s): SLAC-PUB--7617; CONF-970792--; ON: DE98059120
• Country of Publication: United States
• Language: English

Related Subjects

43 PARTICLE ACCELERATORS
ACCELERATORS
ADVANCED LIGHT SOURCE
BETATRONS
ELECTRONS
HELIUM
INSTABILITY
LINEAR ACCELERATORS
POSITRONS
STORAGE RINGS
VACUUM SYSTEMS