## Abstract

It is well known that each resonant mode in the RF

spectrum of multi-cell accelerating cavities will split into

a passband containing a number of modes, and that the

coupling of these modes to the beam is dependent on the

velocity of the accelerated particles. If these modes are

found to degrade the quality of the beam, it is possible to

take various measures to damp them, and thus keep their

effect below some critical threshold. In the case of the parasitic modes within the same passband as the fundamental

accelerating mode, their frequency is typically too close to

that of the fundamental to allow their power to be safely

extracted, and so cavity designers must rely on the natural

damping of the cavity itself. This note contains a theoretical discussion of the coupling of the beam to these passband modes for a large class of accelerating cavities, and

provides a mathematical model for use during the design

and optimisation of linacs.

spectrum of multi-cell accelerating cavities will split into

a passband containing a number of modes, and that the

coupling of these modes to the beam is dependent on the

velocity of the accelerated particles. If these modes are

found to degrade the quality of the beam, it is possible to

take various measures to damp them, and thus keep their

effect below some critical threshold. In the case of the parasitic modes within the same passband as the fundamental

accelerating mode, their frequency is typically too close to

that of the fundamental to allow their power to be safely

extracted, and so cavity designers must rely on the natural

damping of the cavity itself. This note contains a theoretical discussion of the coupling of the beam to these passband modes for a large class of accelerating cavities, and

provides a mathematical model for use during the design

and optimisation of linacs.

Original language | English |
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Publication status | Published - 2012 |

Event | LINAC12 - Tel Aviv, Israel Duration: 9 Sept 2012 → 14 Sept 2012 |

### Conference

Conference | LINAC12 |
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Country/Territory | Israel |

City | Tel Aviv |

Period | 9/09/12 → 14/09/12 |