Beam Dynamics in Independent Phased Cavities

TL;DR

This paper develops an analytical Hamiltonian-based model for beam dynamics in independent phased cavity linacs, providing insights beyond numerical simulations and applying the theory to a real accelerator system.

Contribution

It introduces a full theoretical framework for particle acceleration in independent phased cavities, which was previously analyzed mainly through simulations.

Findings

Analytical description of beam dynamics in independent phased cavities.

Matched beam conditions derived for such linacs.

Application of theory to 805 MHz Coupled Cavity Linac at LANSCE.

Abstract

Linear accelerators containing the sequence of independently phased cavities with constant geometrical velocity along each structure are widely used in practice. The chain of cavities with identical cell lengths is utilized within a certain beam velocity range, with subsequent transformation to the next chain with higher cavity velocity. Design and analysis of beam dynamics in this type of accelerator are usually performed using numerical simulations. A full theoretical description of particle acceleration in an array of independent phased cavities has not been developed. In the present paper, we provide an analytical treatment of beam dynamics in such linacs employing Hamiltonian formalism. We begin our analysis with an examination of beam dynamics in an equivalent traveling wave of a single cavity, propagating within accelerating section with constant phase velocity. We then consider beam dynamics in arrays of cavities, utilizing an effective traveling wave propagating along with the whole accelerator with the velocity of synchronous (reference) particle. The analysis concluded with the determination of the matched beam conditions. Finally, we present a beam dynamics study in 805 MHz Coupled Cavity Linac of the LANSCE accelerator facility.