# US 2014/0191654 A1 · Distributed Coupling High Efficiency Linear Accelerator

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- Number: US 2014/0191654 A1
- Document ID: US20140191654A1
- Status: Published application
- Kind: A1
- Application number: 14/207,376
- Filed: 2014-03-12
- Published: 2014-07-10
- Earliest claimed: 2012-07-20
- Assignees: The Board of Trustees of the Leland Stanford Junior University
- Applicants: The Board of Trustees of the Leland Stanford Junior University
- Inventors: Sami G. Tantawi; Jeffrey Neilson
- Web page: https://patentgrep.com/patent/US20140191654A1

## CPC

- H05H 9/04: Standing-wave linear accelerators
- H05H 7/02: Circuits or systems for supplying or feeding radio-frequency energy
- H05H 7/18: Cavities; Resonators {(travelling-wave tubes H01J23/18; hyperfrequency cavities in general H01P7/04, H01P7/06)}
- H05H 9/044: {Coupling cavity LINACS, e.g. side coupled}
- H05H: PLASMA TECHNIQUE (apparatus or processes specially adapted for producing X-rays H05G2/00); PRODUCTION OF ACCELERATED ELECTRICALLY-CHARGED PARTICLES OR OF NEUTRONS; PRODUCTION OR ACCELERATION OF NEUTRAL MOLECULAR OR ATOMIC BEAMS

## Abstract

A microwave circuit for a linear accelerator includes multiple monolithic metallic cell plates stacked upon each other so that the beam axis passes vertically through a central acceleration cavity of each plate. Each plate has a directional coupler with coupling arms. A first coupling slot couples the directional coupler to an adjacent directional coupler of an adjacent cell plate, and a second coupling slot couples the directional coupler to the central acceleration cavity. Each directional coupler also has an iris protrusion spaced from corners joining the arms, a convex rounded corner at a first corner joining the arms, and a corner protrusion at a second corner joining the arms.

## Claims

### Claim 1

A microwave circuit for a linear accelerator, the microwave circuit comprising multiple monolithic metallic cell plates stacked upon each other;
wherein each of the cell plates has a central acceleration cavity aligned with a vertical beam axis of the linear accelerator;
wherein each of the cell plates has a directional coupler having coupling arms with in-plane widths less than an operational wavelength of the linear accelerator;
wherein each of the cell plates has a first coupling slot coupling the directional coupler to an adjacent directional coupler of an adjacent cell plate;
wherein each of the cell plates has a second coupling slot coupling the directional coupler to the central acceleration cavity;
wherein each directional coupler has an iris protrusion spaced from corners joining the arms;
wherein each directional coupler has a convex rounded corner at a first corner joining the arms;
wherein each directional coupler has a corner protrusion at a second corner joining the arms.

### Claim 2 (depends on 1)

The microwave circuit of claim 1 wherein each directional coupler has four arms arranged to form a cross, and four corners joining the arms.

### Claim 3 (depends on 2)

The microwave circuit of claim 2 wherein two of the four arms are side arms, wherein the side arms have elbow coupling regions defined by irises in the arms, wherein the elbow coupling regions couple adjacent cells of the microwave circuit.

### Claim 4 (depends on 2)

The microwave circuit of claim 2 wherein each arm has an iris protrusion spaced from one of the four corners joining the arms, wherein two of the four corners joining the arms have a convex rounded shape and are positioned diagonally relative to each other, wherein another two of the four corners joining the arms have corner protrusions and are positioned diagonally relative to each other.

### Claim 5

A microwave circuit for a linear accelerator, the microwave circuit comprising multiple monolithic metallic cell plates, a distribution waveguide, and a sequence of feed arms;
wherein the cell plates are stacked upon each other and grouped to form a sequence of cell sections;
wherein each of the feed arms has two slots coupled symmetrically on opposite sides of the distribution waveguide, wherein the two slots are coupled to adjacent cell sections.

### Claim 6 (depends on 5)

The microwave circuit of claim 5 wherein each of the feed arms is designed to provide equal power and appropriately correlated phases to the adjacent cell sections.

### Claim 7 (depends on 5)

The microwave circuit of claim 5 wherein each of the feed arms has a short circuit length equal to a quarter of a waveguide wavelength.

### Claim 8 (depends on 5)

The microwave circuit of claim 5 wherein each of the cell sections has four cells.