The Design And Performance Of CW And Pulsed Power Couplers: A Review

SERA 06The design of input power couplers represents one of the most important challenges of accelerators that use super-conducting RF technology. These devices must fulfil several functions while being subject to mechanical, electromagnetic, vacuum and cryogenic constraints. The rapidly increasing number of projects, planned or under construction, which propose to use super-conducting cavities has prompted developments in power couplers for both CW and pulsed applications. Amongst the projects for which couplers have, or are being, developed one finds VUV and X-ray free electron lasers (based on self-amplified spontaneous emission), spallation neutron sources (SNS), energy recovery linacs, and high energy colliders. We will review the design requirements and performances obtained for several of these couplers. Particular attention will be paid to the couplers which have been used on the TESLA Test Facility at DESY, the variations of this coupler which are under consideration for future synchrotron light sources and the coupler chosen for use on the SNS

A laser triggered electron source for pulsed radiolysis

We present the design of a photo-injector based accelerator for pulsed radiolysis applications. This machine is destined to meet the needs of the physical chemistry community at the Universite de Paris XI. A 4 MeV Energy electron pulse of a few picoseconds duration and with a charge in the range of 1 to 10 nC is produced from a Cs/sub 2 /Te photocathode. The photocathode is placed in the half energy spread cell of a 1-1/2 cell, 3 GHz RF gun, whose design is based on the gun used for the drive beam of the CERN CLIC Test facility. A 4 cell "booster" cavity is then used to accelerate the beam to an energy of 9 MeV. The transport system consists of a quadrupole triplet downsteam of the booster, two rectangular, 30 degree bend, dipoles with a pair of quadrupoles between them and a second triplet downstream of the second dipole. Energy dependent path length effects in the two dipoles allow the possibility of magnetic bunch compression depending on the phase-energy correlation of the bunch exiting the booster cavity. The beam envelope and the bunch length have been calculated through the transport line using TRACE-3d and PARMELA. These codes allow us to verify the required beam parameters at the experimental areas. We discuss the adjustment of the optics, aimed at producing the minimum electron bunch length at the experimental targets. (4 refs)

CTF3 Design Report: Preliminary Phase

The design of CLIC is based on a two-beam scheme, where the short pulses of high power 30 GHz RF are extracted from a drive beam running parallel to the main beam. The 3rd generation CLIC Test Facility (CTF3) will demonstrate the generation of the drive beam with the appropriate time structure, the extraction of 30 GHz RF power from this beam, as well as acceleration of a probe beam with 30 GHz RF cavities. The project makes maximum use of existing equipment and infrastructure of the LPI complex, which became available after the closure of LEP. In the first stage of the project, the "Preliminary Phase", the existing LIL linac and the EPA ring, both modified to suit the new requirements, are used to investigate the technique of frequency multiplication by means of interleaving bunches from subsequent trains. This report describes the design of this phase