Electromagnetic Design of \beta_g= 0.9, 650 MHz Superconducting Radiofrequency Cavity

TL;DR

This paper details the electromagnetic design and optimization of a 650 MHz superconducting RF cavity with 9=0.9 for particle acceleration, including mode analysis and stability considerations.

Contribution

It introduces a systematic design procedure for optimizing a superconducting RF cavity geometry for maximum gradient and stability.

Findings

Optimized cavity geometry achieves high acceleration gradient.

Higher order mode analysis identifies potential beam stability issues.

Stiffener placement reduces Lorentz force detuning.

Abstract

We present the electromagnetic design study of a multi cell, \beta_g= 0.9, 650 MHz elliptic superconducting radiofrequency cavity, which can be used for accelerating H- particles in the linear accelerator part of a Spallation Neutron source. The design has been optimized for maximum achievable acceleration gradient by varying the geometry parameters of the cavity, for which a simple and general procedure is evolved that we describe in the paper. For the optimized geometry, we have studied the higher order modes supported by the cavity, and the threshold current for the excitation of the regenerative beam break up instability due to dipole modes has been estimated. Lorentz force detuning studies have also been performed for the optimized design and the calculations are presented to find the optimum location of the stiffener ring to compensate for the Lorentz force detuning.