Third harmonic cavity design and RF measurements for the FrascatiDAΦNEcollider

David Alesini,Fabio Marcellini,Luigi Palumbo,Mikhail Zobov,Roberto Boni,Mauro Migliorati,Alessandro Gallo

doi:10.1103/physrevstab.7.092001

David Alesini, Fabio Marcellini + Show 5 more

Open Access

https://doi.org/10.1103/physrevstab.7.092001

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Abstract

Third harmonic passive RF cavities have been proposed for installation in both rings of the $\mathrm{D}\mathrm{A}\ensuremath{\Phi}\mathrm{N}\mathrm{E}$ factory collider to improve the Touschek lifetime and to increase the Landau damping. This paper illustrates the design of the harmonic cavities. The main requirements were to obtain a relatively low $R/Q$ factor and a quality factor $Q$ as high as possible to satisfy beam dynamics requirements and to damp all the higher order mode (HOM) to a harmless level in order to avoid multibunch instabilities. A spherical shape of the cavity central body has been chosen as an optimum compromise between a high $Q$ resonator and a low $R/Q$ factor. HOM suppression has been provided by a ferrite ring damper designed for the superconducting cavities of the high energy ring of the KEK-B factory. The design and electromagnetic properties of the resonant modes have been studied with MAFIA and HFSS codes. Cavities have been made of aluminum and the RF measurements have been performed to characterize them. The measurements are in a good agreement with numerical simulations results, demonstrating a satisfactory HOM damping.

Highlights

The Frascati factory DANE [1] is a double ring, high luminosity collider working at the energy of the -meson resonance (1.02 GeV in the center of mass)
In this paper we describe the design of the third harmonic cavity aimed at the damping of all higher order modes (HOM) and we discuss the results of numerical simulations
In this paper we have described the design of the DANE passive third harmonic cavity

Summary

INTRODUCTION

The Frascati factory DANE [1] is a double ring, high luminosity collider working at the energy of the -meson resonance (1.02 GeV in the center of mass). In order to minimize the coherent effects [3], it is worth tuning the cavity at 3h n 1=2frev (frev is the revolution frequency) with the integer n as high as the tuning system allows This is the socalled ‘‘parking option’’ that can be used to recover approximately the usual operating conditions established before the harmonic cavity installation.

HARMONIC CAVITY DESIGN

MEASUREMENT RESULTS

Parked cavity

CONCLUSIONS