# US 10,485,089 B2 · Helical permanent magnet structure and undulator using the same

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- Number: US 10,485,089 B2
- Document ID: US10485089B2
- Status: Granted
- Kind: B2
- Application number: 15/697,481
- Filed: 2017-09-07
- Published: 2019-03-07
- Granted: 2019-11-19
- Earliest claimed: 2017-09-07
- Assignees: National Synchrotron Radiation Research Center
- Applicants: National Synchrotron Radiation Research Center
- Inventors: Cheng-Ying Kuo; Cheng-Hsing Chang; Cheng-Hsiang Chang
- Web page: https://patentgrep.com/patent/US10485089B2

## CPC

- H05H 7/04: Magnet systems {, e.g. undulators, wigglers (free-electron laser H01S3/0903)}; Energisation thereof
- H01F 7/0278: {for generating uniform fields, focusing, deflecting electrically charged particles (for magnetic separation by Lorentz force B03C1/023; specially adapted for NMR applications G01R33/383)}
- H05H 13/04: Synchrotrons
- H01S 3/0903: {Free-electron laser}
- H05H 2007/041: {for beam bunching, e.g. undulators}
- 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
- H01F: MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
- H01S: DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL

## Abstract

A helical permanent magnet structure includes at least one magnet assembly. The magnet assembly includes a plurality of permanent magnets and poles. The permanent magnets are with a magnetization direction, and formed as helical shape and arranged as a helical surface, the center of the helical surface has a longitudinal passage for being passed through by a charged particle. The poles are with the same amount of the permanent magnets, wherein the poles are magnetized by the permanent magnets and absorb on one side of the permanent magnets.

## Claims

### Claim 1

A helical permanent magnet structure, comprising:
at least one magnet assembly, comprising:
a plurality of permanent magnets with a magnetization direction, the permanent magnets being formed as helical shape and arranged as a helical surface, and the center of the helical surface having a longitudinal passage for being passed through by a charged particle; and
a plurality of poles with the same amount of the permanent magnets, wherein the poles are magnetized by the permanent magnets and absorb on one side of the permanent magnets; and
an inner frame surrounding outside and limiting the magnet assembly,
wherein the magnet assembly further comprises a plurality of positioning members, and the permanent magnets and the poles are positioned in the inner frame.

### Claim 2 (depends on 1)

The helical permanent magnet structure of claim 1, wherein the helical permanent magnet structure comprises a plurality of the magnet assemblies, and the magnet assemblies are combined in series to extend the longitudinal passage.

### Claim 3 (depends on 1)

The helical permanent magnet structure of claim 1, wherein the helical permanent magnet structure comprises a plurality of the magnet assemblies, and the magnet assemblies are interlaced with each other in a double helix.

### Claim 4 (depends on 3)

The helical permanent magnet structure of claim 3, wherein two of the magnetization directions of the magnet assemblies are reverse.

### Claim 5 (depends on 1)

The helical permanent magnet structure of claim 1, further comprising:
a plurality of guiding members fixedly disposed and matched with the shape of the inner frame for allowing the longitudinal movement thereon.

### Claim 6 (depends on 1)

The helical permanent magnet structure of claim 1, wherein the permanent magnets comprise a neodymium-iron-boron alloy.

### Claim 7 (depends on 1)

The helical permanent magnet structure of claim 1, wherein the poles comprise vanadium steel, iron, cobalt or alloys thereof.

### Claim 8 (depends on 1)

The helical permanent magnet structure of claim 1, wherein the cross section of the longitudinal passage is circular or elliptical.

### Claim 9 (depends on 1)

The helical permanent magnet structure of claim 1, wherein the number of the permanent magnets is four.

### Claim 10 (depends on 1)

An undulator, comprising:
the helical permanent magnet structure of claim 1.

### Claim 11 (depends on 10)

The undulator of claim 10, wherein the undulator is a free electron laser or a synchrotron radiation accelerator.

### Claim 12 (depends on 10)

The undulator of claim 10, wherein the helical permanent magnet structure comprises a plurality of the magnet assemblies, and the magnet assemblies are combined in series to extend the longitudinal passage.

### Claim 13 (depends on 10)

The undulator of claim 10, wherein the helical permanent magnet structure comprises a plurality of the magnet assemblies, and the magnet assemblies are interlaced with each other in a double helix.

### Claim 14 (depends on 13)

The undulator of claim 13, wherein two of the magnetization directions of the magnet assemblies are reverse.