JPH10302999A - Flat hybrid undulator with circular, elliptical or variable polarization - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a circular or elliptical polarizing undulator which has a simple construction and is easy to manufacture, and a hybrid undurator in which polarization is variable. SOLUTION: A magnetic pole 14 and a permanent magnet magnetized in a direction of the arrow are arranged so that they are slanted in opposite directions in an upper part and lower part. Thereby, a horizontal component is generated, and furthermore, by recessing appropriately the recessed magnetic pole 14 to equalize a horizontal and vertical components, circular polarization is generated. In addition, since the polarization is made variable between a circle and an ellipse, the magnetic pole 14 are divided into three sections along an upper and lower direction, so that each of them can be moved up and down.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flat hybrid undulator which generates circular or elliptically polarized light or has variable polarization.

[0002]

2. Description of the Related Art A conventional plate-type circularly polarized undulator is described in a paper by S. Sasaki et al., "Design of a new type of plan."
ar undulator for generating variably polarized rad
iation ”(1993, NUCLEAR INSTRUMNETS & METHOD
As shown in S IN PHYSICS RESERCH), it was made by combining only permanent magnets.

[0003] In the case of a flat plate type linearly polarized undulator, if a permanent magnet alone is a hybrid type combining a magnetic pole and a permanent magnet, a stronger magnetic field can be generated.
S "(February 1983, JOURNALDE PHYSIQUE).

A conventional plate-type circularly polarized undulator has a complicated magnetic circuit structure. Specifically, the above S.Sa
Disclosed in the paper of Saki et al. is a pair of magnet rows in which the magnet rows are arranged in parallel on the upper and lower sides along the direction of the magnet rows in which the permanent magnets are arranged. And a total of four magnet rows were used. Also,
In another conventional form, a pair of magnet rows are provided on the left and right outside a pair of upper and lower magnet rows along the direction of the magnet row in which the permanent magnets are arranged to generate circularly polarized light, , 4
The two magnet rows had to be arranged in a rectangular cross section. Note that there is a similar problem in the case of elliptically polarized light.

[0005] Furthermore, in the hybrid type having the advantage that a stronger magnetic field can be generated, there has not been a flat plate undulator capable of generating circularly or elliptically polarized light or changing the polarization.

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to provide a flat circular or elliptically polarized light hybrid undulator which has a simple structure and is easy to manufacture.

Another object of the present invention is to provide a plate-type hybrid undulator whose polarization is variable.

[0008]

In order to solve the above-mentioned problem, a flat circular or elliptically polarized light hybrid undulator according to the present invention comprises an upper and lower one in which a plurality of magnetic poles and permanent magnets are periodically combined. A pair of magnet rows are provided facing each other, and the pair of magnet rows facing each other are arranged such that the magnetic poles included in each magnet row face each other and the permanent magnets also face each other. The included magnetic poles are:
It has a concave shape and is arranged so that the concave portions face each other,
The permanent magnets included in each magnet row are alternately magnetized in a periodically combined direction, and the magnetization directions of the upper and lower opposing permanent magnets are magnetized in opposite directions to each other. And permanent magnets are arranged obliquely in opposite directions on the upper and lower sides of the pair of magnet rows.

In order to solve the above-mentioned another problem, a flat-type variable polarization hybrid undulator according to the present invention comprises an upper and lower one in which a plurality of magnetic poles and permanent magnets are periodically combined.
A pair of magnet rows are provided facing each other, and the pair of magnet rows facing each other are arranged such that the magnetic poles included in each magnet row face each other and the permanent magnets also face each other. The included permanent magnets are alternately magnetized in a periodically combined direction, and the magnetization directions of the upper and lower opposing permanent magnets are magnetized in opposite directions, and the magnetic poles and the permanent magnets are The magnetic poles are arranged obliquely in opposite directions on the upper side and the lower side of the pair of magnet rows, and the magnetic poles are arranged at least 3 along the vertical direction in which the pair of magnet rows face each other.
And at least three magnetic pole members each of which is vertically movable.

[0010]

FIG. 1 schematically shows the structure of a flat circularly polarized hybrid undulator according to a preferred embodiment of the present invention. Referring to FIG. 1, a plate-type circularly polarized hybrid undulator includes a pair of magnet rows, that is, an upper magnet row 1.
It has a magnetic circuit consisting of zeros and a lower magnet row 12. Each magnet row 10, 12 has a magnetic pole 14 and a permanent magnet 16 alternately arranged in a periodic combination. The upper and lower magnet rows 10, 12 are arranged such that the magnetic poles 14 included therein face each other, and the permanent magnets 16 also face each other. The magnetic poles 14 included in the upper and lower magnet rows 10 and 12 have a concave cross-sectional shape, and are arranged such that the concave portions of the upper magnetic pole 14 and the lower magnetic poles 14 face each other. Upper and lower magnet rows 1
As shown by arrows in FIG. 1, the permanent magnets 16 included in 0 and 12 are magnetized in the arranged direction and alternately in opposite directions. Also, upper magnet row 1
The permanent magnet 16 of 0 and the permanent magnet 16 of the lower magnet row 12 opposed thereto are magnetized so that the directions of magnetization are opposite. Further, the magnetic poles 14 and the permanent magnets 16 of the upper magnet row 10
The magnetic poles 14 and the permanent magnets 16 of the lower magnet row 12 are arranged obliquely at the same angle in the opposite directions on the upper and lower sides.

When the magnetic poles and the permanent magnets are arranged perpendicular to the direction in which the magnetic poles and the permanent magnets are arranged as in the prior art, the magnetic field generates only a vertical component. However, if the magnetic circuit is structured as described above, the magnetic field becomes 90%. A horizontal component is created with a degree of phase shift resulting in the generation of an elliptically polarized undulator magnetic field. Further, by adjusting the concave shape of the magnetic pole 14 so that the horizontal component and the vertical component are equal, a circularly polarized undulator magnetic field is generated.

FIGS. 2 and 3 show an example of specific dimensions of the plan view circularly polarized light hybrid undulator shown in FIG. FIG. 2 is a side view of the plate-type circularly polarized hybrid undulator shown in FIG. 1 as viewed from the direction of arrows AA in FIG. FIG. 2 shows only the four magnetic poles 14 and three permanent magnets 16 from the left in each of the upper magnet row 10 and the lower magnet row 12 shown in FIG. 1, and the remaining magnetic poles 14 and permanent magnets 16 Not shown. FIG. 3 is a plan view of the lower magnet row 12 of the flat circularly polarized hybrid undulator shown in FIG. 1, showing only four magnetic poles 14 and three permanent magnets 16 from the left side of the lower magnet row 12, and It is shown without the remaining poles 14 and permanent magnets 16.

FIG. 4 shows the result of calculating the magnetic field distribution on the central axis of the flat circularly polarized undulator adapted to generate circularly polarized light with the structure shown in FIG. The values of the magnetic field in FIG. 4 are on the central axis shown in FIGS. The calculation specifications are as follows.

The mechanical dimensions and arrangement are as shown in FIGS. The main points are described below. FIG.
As shown in FIG. 3, the magnetic poles 14 and the permanent magnets 16 of the lower magnet row 12 are positioned 45 ° to the right from a plane perpendicular to the central axis.
Although not shown, the magnetic poles 14 and the permanent magnets 16 of the upper magnet row 10 are arranged at an angle of 45 degrees to the left from a plane perpendicular to the central axis. The repetition pitch of the magnetic pole 14 and the repetition pitch of the permanent magnet 16 along the central axis are both 30 mm.
That is, the magnetic field period is set to be 60 mm, and the thickness of the magnetic pole 14 and the permanent magnet 16 is the same and 10.6 m
m. As shown in FIG. 2, the upper and lower permanent magnets 16
Is 15 mm. The depth of the concave portion of the magnetic pole 14 is 5 m.
m. The top surface of the magnetic pole 14 on the central axis side protrudes 2.5 mm from the top surface of the permanent magnet 16 on the central axis side. The angle a of the magnetic pole 14 shown in FIG. 3 is shifted from the central axis by 15 mm, and the angle b of the concave portion of the magnetic pole 14 shown in FIG. 3 is also at a position 15 mm away from the central axis. The magnetic pole 14 has a height of 3
0 mm, width: 53.03 mm, width of the recess is 31.
82 mm. The permanent magnet 16 has a height of 40 mm and a width of 74.25 mm.

The material of the permanent magnet 16 is an Nd-Fe-B permanent magnet called N36H "manufactured by Shin-Etsu Chemical Co., Ltd. The material of the magnetic pole 14 is a magnetic material called permender.

From the relationship between the changes in the magnetic field strength in the horizontal direction (black squares) and in the vertical direction (circles) in FIG. It can be seen that it has occurred. The position of 0.05 m in the position of the horizontal axis of the graph shown in FIG. 4 corresponds to the leftmost corner (the position of point P in FIG. 1) shown in FIG.

FIG. 5 schematically shows the structure of a flat type variable polarization hybrid undulator according to a preferred embodiment of the present invention. 5, the same or similar elements as those in FIG. 1 are denoted by the same reference numerals, and description thereof will not be repeated. The embodiment shown in FIG. 5 differs from the embodiment shown in FIG. 1 in that, as shown in FIG.
The magnetic pole members 140, 142 and 144 are divided into three parts along the vertical direction where 0 and 12 are opposed to each other, and each of them is configured to be movable in the vertical direction. That is, the magnetic pole 14 is divided into outer magnetic pole members 142 and 144 and an inner magnetic pole member 140, and is movable in the vertical direction, respectively, and the height between the upper surfaces of the magnetic pole members 142 and 144 and the upper surface of the permanent magnet 16 is set. (Position) difference a, the upper surfaces of the magnetic pole members 142 and 144 and the magnetic pole member 1
The degree of polarization b can be changed from circularly polarized light to elliptically polarized light, and vice versa, by changing the magnitude of the difference b in height (position) from the upper surface of 40.

FIG. 6 shows the result of calculating the magnetic field distribution on the central axis in order to show that the degree of polarization changes by changing the differences a and b. In this calculation example, the difference a is 2.5 m
m, and only the difference b is changed. The other mechanical dimensions and positions of the arrangement and the materials of the magnetic poles 14 and the permanent magnets 16 are the same as those in FIG. FIG. 6A shows that b = 0
, Ie, the three pole members 140, 142 and 144
FIG. 6B shows the case where b = −9.0 mm, that is, the magnetic pole member 14.
0 is 9 mm from the upper surfaces of the magnetic pole members 142 and 144.
The case where the magnetic pole 14 is lowered (therefore, the sectional shape of the magnetic pole 14 becomes concave) is shown. It can be seen from the horizontal and vertical magnetic field strength amplitudes and phase relationships shown in FIG. 6A that circularly polarized light is generated. Further, it can be seen from the relationship between the amplitude and the phase of the magnetic field strength in the horizontal direction and the vertical direction shown in FIG. 6B that elliptically polarized light is generated. In addition, the position of 0.0 m at the position of the horizontal axis of both graphs (A) and (B) shown in FIG. 6 is the leftmost corner (FIG. 5) shown in FIG.
(The position of the point P in FIG. 3).

In the above calculation example, the difference a is fixed, but it is obvious to those skilled in the art from the knowledge of the art that the degree of polarization changes even if the difference a is changed. Also, the magnetic pole members 140, 142
As means for moving the undulator 144 in the vertical direction, any known moving mechanism can be appropriately used depending on the purpose of use of the undulator.

One of the features of the magnetic circuit of the hybrid undulator according to the present invention is that not only the vertical component but also the horizontal component is generated with a phase shift of 90 degrees. It may be arranged diagonally in the opposite direction on the lower side. Therefore, the present invention is not limited to the above-described embodiment, and the angle of the slant is not limited to 45 degrees, but may be another angle.

In the embodiment shown in FIG. 5 in order to make the polarization variable, the magnetic pole 14 is divided into three parts. However, the present invention is not limited to this. You may make it do.

[0022]

Since the present invention is constructed as described above, a horizontal component is generated in addition to the vertical component of the magnetic field. Therefore, the magnetic field of the circularly polarized light or the elliptically polarized light is generated by the upper and lower two rows of magnets. Can be generated, the structure of the magnetic circuit of the undulator is simplified, and the manufacture is also facilitated.

Further, by dividing the magnetic poles so as to be movable in the vertical direction, it is possible to easily realize a plate-type variable polarization hybrid undulator capable of freely changing the degree of polarization between circularly polarized light and elliptically polarized light. Can be.

[Brief description of the drawings]

FIG. 1 schematically shows the structure of a flat circularly polarized hybrid undulator according to a preferred embodiment of the present invention.

FIG. 2 is a partial side view showing one example of specific dimensions of the plan view circularly polarized light hybrid undulator shown in FIG. 1;

FIG. 3 is a partial plan view of the lower magnet row 12 showing an example of specific dimensions of the circularly polarized hybrid undulator shown in FIG. 1;

FIG. 4 shows a result of calculating a magnetic field distribution on a central axis of a plate-type circularly polarized undulator adapted to generate circularly polarized light with the structure shown in FIG.

FIG. 5 schematically illustrates the structure of a flat circularly polarized hybrid undulator according to a preferred embodiment of the present invention.

FIG. 6 shows a calculation result of a magnetic field distribution on a central axis in order to show that the degree of polarization can be changed by making each of three magnetic pole members constituting a magnetic pole movable.

[Explanation of symbols]

 10: Upper magnet row 12: Lower magnet row 14: Magnetic pole 16: Permanent magnet 140, 142, 144: Magnetic pole member

Claims (2)

[Claims] 1. A flat circular or elliptically polarized light hybrid undulator provided with a pair of upper and lower magnet rows that periodically combine a plurality of magnetic poles and permanent magnets. The pair of magnet rows are arranged such that the magnetic poles included in each magnet row face each other and the permanent magnets also face each other, and the magnetic poles included in each magnet row have a concave shape and the concave portions face each other. The permanent magnets included in each magnet row are alternately magnetized in a periodically combined direction, and the magnetization directions of the upper and lower opposing permanent magnets are magnetized in opposite directions. A flat circular or elliptically polarized hybrid undulator, wherein the magnetic poles and the permanent magnets are arranged obliquely in opposite directions on the upper and lower sides of the pair of magnet rows. 2. A variable-polarization hybrid undulator according to claim 1, wherein a pair of upper and lower magnet rows, each of which periodically combines a plurality of magnetic poles and permanent magnets, are provided to face each other. The magnet rows are arranged such that the magnetic poles included in each magnet row face each other and the permanent magnets also face each other, and the permanent magnets included in each magnet row are alternately magnetized in a periodically combined direction, Further, the directions of magnetization of the upper and lower opposed permanent magnets are magnetized in opposite directions, and the magnetic poles and the permanent magnets are arranged obliquely in opposite directions on the upper and lower sides of the pair of magnet rows. The magnetic pole is formed of at least three magnetic pole members each of which is divided into at least three along the vertical direction in which the pair of magnet rows face each other, and each of the magnetic pole members comprises at least three magnetic pole members movable in the vertical direction. Type variable polarization hybrid undulator.