Summary of working group on collective instabilities

Conference · Sun May 01 04:00:00 EDT 1988

OSTI ID:6861033

Zisman, M S

In this paper we summarize the efforts of the Working Group on Collective Instabilities at the Workshop on the RHIC Performance. Impedance estimates have been made for some of the main hardware in RHIC, including bellows, pickup electrodes, abort kicker, and transverse damper. In general, these impedances are not expected to limit the beam intensity for Au ions, but might limit the proton intensity. We have also calculated the higher-order modes of the standard 26.7-MHz rf cavity for use in estimating coupled-bunch instability growth rates. Predictions of intrabeam scattering confirm the results in the RHIC Conceptual Design Report. For the standard assumptions, there is a threefold growth in transverse emittance. Varying the initial transverse emittance by a factor of two changes the final emittance value (after 10 hours) by less than 20%. If a 214-MHz rf system is considered, the growth is more severe---about a factor of five---and a beam lifetime of 10 hours requires an rf voltage in excess of 32 MV. Coupled-bunch calculations show that the transverse instabilities are dominated by the resistive-wall impedance for either rf choice. A modest damping system should be adequate to deal with this. Longitudinal growth times of about 20 ms are expected for the low-frequency rf case; growth times for the high-frequency rf system are a factor of 10 longer and the instability is predicted to be Landau damped. Copper plating of the dipole vacuum chambers has been found to have no deleterious effects, provided the coating is uniform and not overly thick. 14 refs., 3 tabs.

• Research Organization: Lawrence Berkeley Lab., CA (USA)
• DOE Contract Number: AC03-76SF00098
• OSTI ID: 6861033
• Report Number(s): LBL-25334; CONF-880335-8; ON: DE88014868
• Country of Publication: United States
• Language: English

Related Subjects

43 PARTICLE ACCELERATORS
430200* -- Particle Accelerators-- Beam Dynamics
Field Calculations
& Ion Optics
ACCELERATORS
BEAM BUNCHING
BEAM DYNAMICS
BEAM EMITTANCE
BEAM MONITORS
BEAMS
BROOKHAVEN RHIC
DAMPING
HEAVY ION ACCELERATORS
INSTABILITY GROWTH RATES
ION BEAMS
LANDAU DAMPING
MEASURING INSTRUMENTS
MONITORS
PERFORMANCE
RF SYSTEMS
SCATTERING
STORAGE RINGS