Design of Low-Frequency Superconducting Spoke Cavities for High-Velocity Applications

Superconducting single- and multi-spoke cavities have been designed to-date for particle velocities from β~0.15 to β~0.65. Superconducting spoke cavities may also be of interest for higher-velocity, low-frequency applications, either for hadrons or electrons. We present the design of 325 and 352 MHz spoke cavities optimized for β=0.8 and β=1

Development of Spoke Cavities for High Velocity Applications

In response to recent interest in alternatives to TM-type cavities for low-frequency, high-velocity applications we have initiated a program for the development of multispoke superconducting cavities. We have completed the electromagnetic design for two-spoke cavities operating at 325, 352, 500, and 700 MHz with a design velocity of β0 = 0.82 or β0 = 1. We present the results of the optimization, higher order mode (HOM) analysis, multipacting analysis, and an initial analysis of multipole effects of the fundamental accelerating mode

Multipole Expansion of the Fields in Superconducting High-Velocity Spoke Cavities

Multi-spokes superconducting cavities in the high-beta regime are being considered for a number of applications. In order to accurately model the dynamics of the particles in such cavities, knowledge of the fields off-axis are needed. We present a study of the multipoles expansion of the fields from an EM simulation field data for two-spokes cavities operating at 325 MHz, β = 0.82, and 500 MHz, β = 1

Study of Cavity Imperfection Impact on RF-Parameters and Multipole Components in a Superconducting RF-Dipole Cavity

The ODU/SLAC superconducting rf-dipole cavity is under consideration for the crab-crossing system in the upcoming LHC luminosity upgrade. While the proposed cavity complies well within the rf-parameters and multipolar component restrictions for the LHC system, cavity imperfections arising from cavity fabrication, welding and frequency tuning may have a significant effect in these parameters. We report on an initial study of the impact of deviation from the ideal shape on the cavity’s performance in terms of rf-parameters and multipolar components

A Compact Beam Spreader Using RF Deflecting Cavities for the LCLS-II

The LCLS-II project currently under development is designed to accelerate electron bunches up to 4 GeV and transport them to one of two FEL undulators located more than 2 km downstream of the end of the LCLS-II linac. The upgrade requires a spreader system to separate the baseline electron bunches and transport them to two undulator lines or a local dump. Fast bipolar kickers (FK) or transverse electric rf deflectors (RFD) are considered as fast-switching devices (FSD). In the RFD approach described here three design options operating at 325 MHz are studied including a superconducting rf-dipole cavity, a normal conducting rf-dipole cavity, and a normal conducting 4-rod cavity. Optional compact splitting schemes involving a combination of vertical and horizontal initial deflections are addresse

Imperfection and Tolerance Analysis of HOM Couplers for ODU/SLAC 400 MHz Crabbing Cavity

In preparation for the LHC High Luminosity upgrade, a 400 MHz crab cavity has been developed jointly at ODU/SLAC, including two higher order mode couplers designed to dampen the wakefields in order to comply with the impedance budget specified for the LHC system. During fabrication, assembly, and processing of the couplers, a number of imperfections may arise that could modify the higher order mode spectrum and the associated impedance for each mode. We present here a detailed study of the imperfections of the horizontal- and vertical- HOM couplers, and the associated allowed tolerances for manufacture, assembly and processing