Title :
Transverse collective instability in the PSR
Author :
Colton, E.P. ; Neuffer, D. ; Swain, G. ; Thiessen, H.A. ; Lombardi, A. ; Wang, T.S.
Author_Institution :
Los Alamos Nat. Lab., NM, USA
Abstract :
An instability in the Proton Storage Ring (PSR) is observed as fast loss of beam during accumulation and storage when the injected beam current exceeds a threshold value. Instabilities are observed during both coasting-beam and bunched-beam operation. Large coherent transverse oscillations occur prior to and during the beam loss. The growth times are rapid, typically in the range 10-100 μs. The instability threshold is observed to depend strongly upon RF voltage, beam size, injected momentum spread, and nonlinear fields. Weaker dependences upon betratron tune, vacuum pressure, and stripping-foil bias voltage have also been observed. A possible e-p oscillation component of the unbunched beam instability is suggested. Growth times suggest a significant Re(Z⊥) of ~0.2-0.5 MΩ/m; the source of this is not yet precisely identified
Keywords :
particle beam diagnostics; proton accelerators; storage rings; 10 to 100 mus; PSR; Proton Storage Ring; RF voltage; accumulation; beam size; betratron tune; bunched-beam operation; coasting-beam; coherent transverse oscillations; e-p oscillation component; fast loss of beam; growth times; injected beam current; injected momentum spread; instability threshold; nonlinear fields; stripping-foil bias voltage; transverse collective instability; unbunched beam instability; vacuum pressure; Damping; Frequency; Impedance; Laboratories; Particle beam injection; Particle beam measurements; Particle beams; Protons; Storage rings; Threshold voltage;
Conference_Titel :
Particle Accelerator Conference, 1989. Accelerator Science and Technology., Proceedings of the 1989 IEEE
Conference_Location :
Chicago, IL
DOI :
10.1109/PAC.1989.73395
