Over-compression, a method to shape the longitudinal bunch distribution for a reduced energy spread

Conference · Fri Jul 01 04:00:00 EDT 1994

OSTI ID:10109373

Decker, F J; Holtzapple, R; Raubenheimer, T

In the Stanford Linear Collider the energy spread of the bunches at the end of the linac is dominated by longitudinal wakefields. A short, high current bunch with a Gaussian shape will produce a double-horned energy distribution. It can be shown that certain charge distributions with a sharp rise time (about rectangular or half-Gaussian) will give no additional energy spread due to the linac, since the generated wakefield and the rf-curvature cancel each other exactly. In this paper different methods are presented on how to achieve such distributions by using non-linear dependences in the RTL (Ring-To-Linac) compression region. A simple and effective method to achieve such a distribution is by over-compression. When not fully compressing the bunch, there are two settings of the compressor voltage, under and over-compression, which give the same core bunch length in the linac. By switching from the under to the over-compressed setting, the tails are reduced from more than Gaussian to less than Gaussian beam tails. This results in a roughly rectangular shape which will give the wakefield-rf cancellation. Simulations, measurements and their implications are discussed.

• Research Organization: Stanford Linear Accelerator Center, Menlo Park, CA (United States)
• Sponsoring Organization: USDOE, Washington, DC (United States)
• DOE Contract Number: AC03-76SF00515
• OSTI ID: 10109373
• Report Number(s): SLAC-PUB--6604; CONF-9408125--46; ON: DE95006052
• Country of Publication: United States
• Language: English

Related Subjects

43 PARTICLE ACCELERATORS
430200
BEAM BUNCHING
BEAM DYNAMICS, FIELD CALCULATIONS, AND ION OPTICS
ELECTRON BEAMS
ENERGY SPECTRA
STANFORD LINEAR COLLIDER