A second harmonic (6-16 MHZ) rf system with feedback-reduced gap impedance for accelerating flat-topped bunches in the CERN PS booster

Conference · Mon Aug 01 04:00:00 EDT 1983 · IEEE Trans. Nucl. Sci.; (United States)

OSTI ID:5354859

Baillod, J M; Magnani, L; Nassibian, G; Pedersen, F; Weissflog, W

Since all experimental and theoretical evidence indicates that the beam intensity in the PSB is at present limited by the Laslett Q shift after trapping, a second harmonic accelerating system is being added with the aim of producing flat-topped bunches. Calculations indicate that the resulting improvement in bunching factor should permit an intensity increase of 25 to 40%. Additionally, the bucket area is increased by 25 to 45% depending on intensity. A general description of the new cavities, which operate over a frequency range of 6-16 MHz with a maximum gap voltage of 8 kV, is given together with a description of associated power amplifiers and low level electronics. A notable feature is the use of a fast feedback system to reduce the gap impedance seen by the beam by an order of magnitude, incorporating a 130 W wide-band transistor amplifier with a total delay of about 5 ns. Initial performance with beam of the first system installed confirms theoretical expectations in terms of bunching factor and increased intensity limit. An expected improvement in beam stabilization by Landau damping from the strongly non-linear accelerating wave shape did not occur; on the contrary, Landau damping is lost even at low intensities, and harmful longitudinal bunched-beam modes of orders as high as sextupole (m = 3) and decapole (m = 5) have been observed and partly cured.

• Research Organization: CERN, 1211 Geneva 23
• OSTI ID: 5354859
• Report Number(s): CONF-830311-
• Conference Information: Journal Name: IEEE Trans. Nucl. Sci.; (United States) Journal Volume: NS-30:4
• Country of Publication: United States
• Language: English

Related Subjects

43 PARTICLE ACCELERATORS
430303* -- Particle Accelerators-- Experimental Facilities & Equipment
ACCELERATORS
AMPLIFIERS
BEAM BUNCHING
BEAM DYNAMICS
CAVITY RESONATORS
CERN PS SYNCHROTRON
CYCLIC ACCELERATORS
DAMPING
ELECTRONIC EQUIPMENT
EQUIPMENT
FEEDBACK
FLUX DENSITY
FREQUENCY RANGE
HARMONICS
IMPEDANCE
LANDAU DAMPING
MAGNETIC FLUX
MHZ RANGE
MHZ RANGE 01-100
OSCILLATIONS
PARTICLE BOOSTERS
PHASE SHIFT
POWER AMPLIFIERS
RESONATORS
RF SYSTEMS
SYNCHROTRONS
TRANSISTOR AMPLIFIERS