KR970009413B1 - Helical undulator - Google Patents

Abstract

The invention provides a helical undulator of a permanent magnet capable of minutely adjusting a magnetic field. In this invention, four permanent magnets are arrayed for their magnetism directions to be changed by 90 degrees on a cylinder of non-magnetic metal having a number of holes. By adjusting the height of the magnets of which magnetisms are in the direction of an undulator axis, the magnetic field can be minutely adjusted.

Description

Permanent magnet helical undulator with precise magnetic field adjustment

1 is a schematic diagram of a permanent magnet helical undulator with magnetic field precision adjustment.

Where Lw represents one period of the magnetic field.

2 is a principle diagram of fine-tuning the magnetic field by adjusting the height of the magnets whose magnetization direction is parallel to the undurator axis.

* Explanation of symbols for main parts of the drawings

1,12: Non-magnetic metal cylinder for magnet fixing with string grooves

2: Permanent magnet block in which the magnetization direction is perpendicular to the central axis of the undurater

3: Permanent magnet block in which the magnetization direction is parallel to the central axis of the undurater

4: Cylinder with screw holes to fix permanent magnets to the magnet fixing cylinder or to adjust the height of the magnets

5: Head screw for fixing permanent magnet or adjusting permanent magnet height

6: direction of force received by permanent magnets

The present invention relates to a permanent magnet helical undurator capable of fine adjustment of magnetic field, and more particularly, to a helical unduretane of a new structure capable of fine adjustment of a magnetic field at each position while using a permanent magnet. In general, the undurator is a key component of free-election laser and synchroton radiation, where the meandering electron beam of relativistic speed is obtained to obtain laser beam or synchroton radiation.

The undulator is divided into a planar undulator and a helical undulator according to the distribution of the magnetic field, and the generated light has linear polarization and circular polarization, respectively. The first developed undulators have obtained the required magnetic field distribution using electromagnets, but their use is avoided due to the disadvantages of requiring large current supplies for high magnetic fields and large auxiliary equipment such as cooling devices for continuous operation. Recently, rare earth-based or Nd-Fe-B permanent magnets have been used to develop an undulator, which has a much stronger magnetic field than the electronic shelf, but has a simple structure and size, and can be used permanently. However, due to structural problems, most of the permanent magnet undurators developed were frayer unduters, and permanent magnet helical unduters are being proposed at the basic structure possible.

The present invention invented a permanent magnet helical undulator having a high performance, simple and feasible structure as shown in FIG. In a non-magnetic metal cylinder (1), such as a twelve-row grooved magnet fixing aluminum, four magnets (2) (3) whose magnetization direction changes by 90 degrees along the cylindrical axis of each row are arranged periodically with one cycle Each line is configured to form a bifilar magnetic field with a slightly different starting point.

In such a structure, the magnetic field distribution at both ends of the endurita is uniform, and the four magnets generally cancel each other's magnetic field error, so that the total magnetic field and error are reduced, and the magnetic field lines are concentrated in the center of the cylinder.

According to the method of the present invention, the magnetic field strength of the actual undulator was measured at 1.44 kG. The standard deviation of the magnetic field error was 1.8%. The small size and compact structure allow a strong magnetic field to be obtained, and have a relatively low magnetic field error without repositioning or adjusting the magnets.

And, as shown in FIG. 2, since magnets having a magnetization direction parallel to the cylinder side are pushed out of the cylinder, the distance from the center of the cylinder can be simply changed by varying the degree of pressing using a screw. . As the magnets move away from the center of the cylinder, the strength of the magnetic field at the center of the cylinder becomes weaker, and closer to the center of the cylinder, the magnetic field strength becomes stronger. Since the degree of change is minute, the intensity of the magnetic field at each position of the undurator can be finely adjusted to further reduce the error of the entire magnetic field.

As described above, the present invention relates to a helical undulator of a new structure that has a strong magnetic field and low magnetic field error in a small and simple structure using a permanent magnet and enables fine adjustment of the magnetic field in a simple manner. Compared with the existing permanent magnet frayer unduter, the structure of the whole system is simple and the volume is very small.

There is an easy advantage.

Claims (2)

A permanent magnet helical undulator capable of finely adjusting magnetic field, characterized by periodically arranging four permanent magnets in which the magnetization direction is changed by 90 degrees in a non-magnetic metal cylinder having a plurality of grooves. The permanent magnet helical undulator, which is capable of precise magnetic field adjustment, characterized in that the magnetization direction of the magnets in the axial direction adjusts the magnetic field by adjusting the height.