Undulator

Patent metadata

Field	Value
Publication number	US-10624200-B2
Application number	US-201515527447-A
Country	US
Kind code	B2
Filing date	Nov 13, 2015
Priority date	Nov 17, 2014
Publication date	Apr 14, 2020
Grant date	Apr 14, 2020

Abstract

An undulator comprises at least M permanent magnet periods arranged sequentially in a transmission direction of electron beams, each of the permanent magnet periods comprises four rows of permanent magnet structures, in which each row comprises N rows of permanent magnet groups, and each row of the permanent magnet groups comprises K permanent magnet units, wherein M, N and K are natural numbers greater than or equal to 1; the four rows of the permanent magnet structures are pairwise matched, then relatively disposed on both sides of the transmission direction of electron beams, and are capable of forming at least one composite magnetic fields by relative displacement, such that elliptically polarized light, circularly polarized light, or linearly polarized light with an arbitrary polarization angle of 0°˜360° is generated when electron beams pass through the composite magnetic fields, and such that velocity directions of electrons are deviated from an axis direction of the undulator.

First claim

What is claimed is:

1. An undulator at least comprising: M permanent magnet periods arranged sequentially in a transmission direction of electron beams, each of the permanent magnet period(s) comprises four permanent magnet structures, each permanent magnet structures comprises two permanent magnet groups, and each permanent magnet groups comprises a row of K permanent magnet(s), wherein M and K are natural numbers greater than or equal to 1;
the four permanent magnet structures are pairwise matched, and are relatively disposed on both sides of the transmission direction of electron beams, and are capable of forming at least one kind of composite magnetic fields by relative displacement, such that elliptically polarized light, circularly polarized light, or linearly polarized light with an arbitrary polarization angle is generated when the electron beams pass through the composite magnetic fields, and velocity directions of electrons are deviated from an axis direction of the undulator;
the groups in inner side of the permanent magnet structures constitute a first assembly, and the groups in the outer side of the permanent magnet structures constitute a second assembly;
wherein the first assembly generates a main magnetic field, the second assembly generates an auxiliary magnetic field;
the permanent magnets included in the permanent magnet groups corresponding to the auxiliary magnetic field have a magnetization direction perpendicular to a gap direction of the undulator, and a magnetic field period of the auxiliary magnetic field is adapted to be adjusted by setting a vacant region in its corresponding permanent magnet groups.

2. The undulator according to claim 1 , wherein the main magnetic field and the auxiliary magnetic field have different magnetic field periods.

3. The undulator according to claim 2 , wherein the main magnetic field and the auxiliary magnetic field are adapted to be adjusted according to an energy of fundamental photon, an energy of electron beam and a length of the undulator as needed, such that an angle between a velocity direction of electrons and an axis direction of the undulator is greater than half of an acceptance angle of the fundamental wave photon as needed, thereby obtaining a maximum light intensity under a condition of a smaller thermal load.

4. The undulator according to claim 3 , wherein the energy of the electron beam is 3.5 GeV, the length of the undulator is 4.5 m, the energy of the fundamental photon as needed is 7 eV, the acceptance angle of fundamental photons is 0.6 mrad, wherein a ratio of the magnetic field intensity between the main magnetic field and the auxiliary magnetic field formed by the permanent magnet groups is 7:3.

5. The undulator according to claim 1 , wherein a ratio of the magnetic field periods of the main magnetic field to and the auxiliary magnetic field is 2:3.

6. The undulator according to claim 1 , wherein the permanent magnet are made of neodymium iron boron material, and saturation magnetic field intensity of the permanent magnet units are larger than or equal to 1.25 T.

7. The undulator according to claim 1 , wherein the undulator further comprises: two stationary magnet brackets and two moving magnet brackets, the two permanent magnet structures are fixed on the stationary magnet brackets respectively to form two fixed permanent magnet structures, the other two permanent magnet structures are fixed on the moving magnet brackets respectively to form two moving permanent magnet structures; driven by the moving magnet brackets, the moving permanent magnet structures are adapted to move different displacements relative to the fixed permanent magnet structures to generate different composite magnetic fields, thereby generating polarized light having different polarizations.

8. An undulator, at least comprising: M permanent magnet period(s) arranged sequentially in a transmission direction of electron beams, each of the permanent magnet periods comprises four permanent magnet structures, and each permanent magnet structure comprises K permanent magnet(s), wherein M and K are natural numbers greater than or equal to 1;
the magnetic directions of K permanent magnets have different angles relative to the upward direction;
the four permanent magnet structures are pairwise matched, and are relatively disposed on both sides of the transmission direction of electron beams, and are capable of forming at least one kind of composite magnetic fields by relative displacement, such that elliptically polarized light, circularly polarized light, or linearly polarized light with an arbitrary polarization angle is generated when the electron beams pass through the composite magnetic fields, and velocity directions of electrons are deviated from an axis direction of the undulator.

9. The undulator according to claim 8 , wherein the magnetic field generated by four magnetic structures is decomposed into the main magnetic field and the auxiliary magnetic field according to different magnetic directions, the intensity ratio of main and auxiliary magnetic field is adjusted by changing magnetic direction of the permanent magnets.

10. The undulator according to claim 8 , wherein the energy of the electron beam is 3.5 GeV, the length of the undulator is 4.5 m, the energy of the fundamental photon as needed is 7 eV, the acceptance angle of fundamental photons is 0.6 mrad, wherein a ratio of the magnetic field intensity between the main magnetic field and the auxiliary magnetic field formed by the permanent magnet structures is 7:3; wherein the permanent magnet structures comprise 24 permanent magnets; a clockwise direction is regarded to be positive, a upward direction is regarded as a zero degree angle, and the angles of magnetic direction of the 24 permanent magnets are 0°, −23°, 67°, 67°, 157°, 157°, −113°, −113°, −23°, 0°, 90°, 90°, 180°, −157°, −67°, −67°, 23°, 23°, 113°, 113°, −157°, 180°, −90°, −90°.

Assignees

• Shanghai Inst Microsystem & Information Tech Cas

Inventors

• Qiao Shan
• Chang Rui
• Ji Fuhao
• Ye Mao

Classifications

• H05H2007/041

  for beam bunching, e.g. undulators · CPC title

• H01F7/0278

  for generating uniform fields, focusing, deflecting electrically charged particles (for magnetic separation by Lorentz force B03C1/023; specially adapted for NMR applications G01R33/383) · CPC title

• H01F7/02

  Permanent magnets {[PM]} · CPC title

• H05H7/04 Primary

  Magnet systems {, e.g. undulators, wigglers (free-electron laser H01S3/0903)}; Energisation thereof · CPC title

• H05H13/04

  Synchrotrons · CPC title