Linear accelerator accelerating module to suppress back-acceleration of field-emitted particles

Patent metadata

Field	Value
Publication number	US-9839114-B2
Application number	US-201615260101-A
Country	US
Kind code	B2
Filing date	Sep 8, 2016
Priority date	Sep 9, 2015
Publication date	Dec 5, 2017
Grant date	Dec 5, 2017

Abstract

A method for the suppression of upstream-directed field emission in RF accelerators. The method is not restricted to a certain number of cavity cells, but requires similar operating field levels in all cavities to efficiently annihilate the once accumulated energy. Such a field balance is desirable to minimize dynamic RF losses, but not necessarily achievable in reality depending on individual cavity performance, such as early Q 0 -drop or quench field. The method enables a significant energy reduction for upstream-directed electrons within a relatively short distance. As a result of the suppression of upstream-directed field emission, electrons will impact surfaces at rather low energies leading to reduction of dark current and less issues with heating and damage of accelerator components as well as radiation levels including neutron generation and thus radio-activation.

First claim

What is claimed is:

1. A method for suppressing prevalent field emission in the upstream direction in a superconducting radio frequency (RF) accelerator, comprising:
providing an accelerator structure including a plurality of independently phased multi-cell cavities in a string;
providing an intermediate beam tube having a beam tube length between each of the multi-cell cavities wherein the beam tube length of the intermediate beam tube between the multi-cell cavities is determined according to the following equation

L
tube

=

(

N
+

1
2

)

·

L
cell

≈

(

N
+

1
2

)

·

β
⁢

⁢
λ

2

.

wherein L tube is the beam tube length between cavities, L cell is the length of the cells in each multi-cell cavity, β is the particle velocity relative to the speed of light, λ is the wavelength of the accelerating mode, and N is an integer number;
injecting a stream of electrons into said accelerator structure; and
applying an accelerating field of at least 3 MV/m to accelerate the electrons to a relativistic speed.

2. A superconducting radio frequency (RF) accelerator structure comprising:
a plurality of independently phased multi-cell cavities in a string;
an intermediate beam tube having a beam tube length between each of the multi-cell cavities;
wherein the beam tube length of the intermediate beam tube between the cavities is determined according to the following equation

L
tube

=

(

N
+

1
2

)

·

L
cell

≈

(

N
+

1
2

)

·

β
⁢

⁢
λ

2

.

wherein L tube is the beam tube length between cavities, L cell is the length of the cells in each multi-cell cavity, β is the particle velocity relative to the speed of light, λ is the wavelength of the accelerating mode, and N is an integer number.

Assignees

• Jefferson Science Ass Llc
• Asml Netherlands Bv

Inventors

• Benson Stephen V
• Marhauser Frank
• Douglas David R
• Ament Lucas J P

Classifications

• H05H9/044

  Coupling cavity LINACS, e.g. side coupled · CPC title

• H05H7/02 Primary

  Circuits or systems for supplying or feeding radio-frequency energy · CPC title

• H05H7/08 Primary

  Arrangements for injecting particles into orbits · CPC title

• H05H7/18

  Cavities; Resonators {(travelling-wave tubes H01J23/18; hyperfrequency cavities in general H01P7/04, H01P7/06)} · CPC title

• H05H9/00

  Linear accelerators · CPC title