JP3128476B2 - Magnetic circuit for insertion light source device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic circuit used in an insertion light source device for generating radiation light by meandering of an electron beam of an electron accelerator. More specifically, the present invention relates to a magnetic circuit for an insertion light source device, which does not require a mechanism for changing the gap width of the magnetic circuit, has a simple gantry structure, is easy to manufacture, and is most suitable for applications such as photo-CVD and LSI X-ray exposure.

[0002]

2. Description of the Related Art It is known that high-speed electrons orbiting in an accelerator to which a periodic magnetic field is applied make a meandering motion by the periodic magnetic field and emit light from each meandering point as shown in FIG. Halbach, Nuclear Instrument
ments and Method, 187 (198
1), 109). A device that obtains emitted light using this principle is an insertion light source device.

[0003] An insertion light source device is provided in an electron accelerator or a linear portion (gap) of an electron accumulator ring having a magnetic circuit configured by arranging a plurality of permanent magnets so that a tubular gap is formed. It is inserted so as to sandwich the vacuum chamber, and generates a sinusoidal periodic magnetic field in the gap of the magnetic circuit (see FIG. 4). This insertion light source device includes a hull-back type constituted by only a permanent magnet, and a hybrid type constituted by combining a permanent magnet with a magnetic pole (pole piece) made of iron, an iron-cobalt alloy or the like.

FIGS. 5 and 6 show a Halbach-type magnetic circuit composed of only permanent magnets. In this device, the magnet rows 10A and 10B are vertically arranged in parallel with a gap G therebetween. In each magnet row, a plurality of rectangular permanent magnets having different magnetization directions are arranged. For example, looking at one cycle composed of four permanent magnets, as shown in FIG. 6, in the magnet row 10A, the magnetization directions are -y and-.
z, + y, + z permanent magnets 11A, 12A, 13
A and 14A are arranged adjacent to each other in the axial direction of the air gap G to form one cycle, and in the magnet row 10B, the permanent magnets 11 whose magnetization directions are -y, + z, + y, and -z, respectively.
B, 12B, 13B, and 14B are arranged adjacent to each other in the axial direction of the gap G to form one cycle. Such an array is repeatedly arranged N times (N is an integer of 2 or more) to form a magnetic circuit. In the magnetic circuit having the above configuration, a magnetic flux flows as shown by a closed arrow,
A periodic magnetic field is generated in the gap G.

FIG. 7 shows a hybrid type magnetic circuit formed by combining permanent magnets and magnetic poles. Also in this device, the magnet arrays 30A and 30B
Are vertically arranged in parallel with a gap G therebetween. In each magnet row, permanent magnets and magnetic pole materials are alternately arranged. 1
Looking at the period, in the magnet row 30A, permanent magnets 31A and 32A whose magnetization directions are -z and + z, respectively, are alternately arranged together with the two magnetic pole materials 33A to constitute one cycle, and in the magnet row 30B. , The permanent magnets 31B and 32B whose magnetization directions are + z and −z are alternately arranged together with the two magnetic pole materials 33B to constitute one cycle. Other configurations and operations are the same as those of the Halbach type.

[0006] The magnetic circuit is provided with a gap varying mechanism for varying the gap width of the opposing magnet row in order to adjust the magnetic field strength. That is, the magnetic field strength is adjusted by increasing or decreasing the gap G. FIG. 8 shows an example of the relationship between the width of the air gap G and the magnetic field strength in a hybrid type magnetic circuit, for example. The magnetic field in the gap G sharply increases in magnetic field strength as the gap G becomes smaller. On the other hand, when the gap G is widened, the magnetic field strength decreases. However, when the gap G is widened by a certain amount or more, the change in the magnetic field strength becomes gentle and the magnetic field does not easily approach zero. Since the residual magnetic field when the gap G is widened affects the electron orbit, it is better to be as small as possible.

Both the hullback type and the hybrid type show almost the same magnetic field strength and distribution, and there is no significant difference. However, in general, the hybrid type often uses less magnet weight. Also, in the early stage of the development of the insertion light source, since the angle and characteristics of the permanent magnet varied greatly, the hybrid type was easier to align the magnetic field strength than the Halbach type. However, recently, the dispersion of permanent magnets is small, the characteristics are uniform, and the method of rearrangement of magnet pairs has been introduced and improved, so that the same magnetic field distribution can be obtained with either method. . When the magnetic field is adjusted by changing the air gap G, the electron orbit may be shifted, but in the Halbach type, almost linearity is established, and the electron orbit is small. The electron orbit is likely to shift.

[0008] The mode of the insertion light source device is classified into a wiggler mode and an undulator mode according to the degree of meandering of the electron beam. In the wiggler mode, radiated light generated from each meandering point of the electron beam is superimposed, and radiated light having a power 10 to 1000 times higher than the radiated light from the bending electromagnet is obtained. On the other hand, in the undulator mode, the radiated light generated from each meandering motion interferes with each other, and the fundamental wave and its higher-order light have more than 10 to 10 parts of the wiggler light.
Light that is about 1000 times stronger is obtained.

Whether the mode is the wiggler mode or the undulator mode can be classified by a parameter called a K value. The undulator mode is set when the K value is around 1 or less, and the wiggler is set when the K value is larger than 1.

The K value is proportional to the air gap magnetic field strength,
The gap width is changed to a magnetic field strength suitable for obtaining the required light. When the undulator mode having a low K value is used, it is necessary to change the magnetic field to a region where the magnetic field intensity is as low as possible.

[0011]

As described above, the conventional insertion light source device is provided with an air gap changing mechanism for changing the air gap width of the opposing magnet rows in order to adjust the magnetic field strength. High-speed electrons passing through the periodic magnetic field by the insertion light source device are very sensitive to the disturbance of the periodic magnetic field, and the electron orbit changes easily. Therefore, it is necessary to ensure the parallelism between the opposing magnet rows, the relative positional accuracy, the air gap accuracy, and the like so that the magnetic field distribution does not become disordered before and after the gap width is changed. For the above reasons, strict accuracy is required for the dimensional accuracy and positioning accuracy of the insertion light source device.

Further, the conventional apparatus employs a so-called cantilever structure in which one side of the magnet row is not supported so that the insertion light source apparatus can be installed without removing the vacuum chamber of the electron accelerator or the storage ring. Often. However, in the cantilever structure, the gap is smoothly moved while maintaining the parallelism or the like against the attractive force of the magnet row, so that the strength design of the gantry is difficult and complicated.

In addition, in the insertion light source device, an attractive force acts between the opposing magnet rows, and the attractive force increases as the gap width decreases. The attraction force depends on the peak magnetic field strength, the number of cycles, the total length, and the like, and thus varies depending on the apparatus, but is often on the order of 1 ton. Therefore, it is necessary to design the structural strength of the base plate for holding and fixing the permanent magnet and the gantry structure for holding the base plate in accordance with the attractive force at the shortest gap width.

Further, a stepping motor or an AC servomotor is used as a driving source for varying the gap width.
A large-capacity motor is required to drive against the suction force.

Further, it may be difficult to integrally manufacture a long insertion light source device having a long overall length, and a plurality of relatively short insertion light source devices may be connected to form a single device. In this case, the gap widths of the plurality of insertion light source devices must be accurately and synchronously changed, and errors due to driving may be superimposed in addition to machining and assembly errors and installation errors.

In order to make the magnetic field strength variable while keeping the gap width fixed, it is sufficient to arrange a number of electromagnets as an insertion light source. However, if the insertion light source device is constituted by electromagnets, the volume of the coil winding becomes large. However, the period cannot be as short as the insertion light source device using the permanent magnet. In addition, since the electromagnet generates heat, dimensional accuracy and magnetic field strength change, which may adversely affect the electron trajectory.

As described above, in the conventional magnetic circuit for the insertion light source device, the magnetic field strength is adjusted by changing the gap width between the magnet rows, but the gap width is made variable. As a result, various problems described above have arisen, and a magnetic circuit capable of adjusting the magnetic field strength without changing the gap width between the magnet rows is desired.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a magnetic circuit for an insertion light source device capable of adjusting the magnetic field intensity while keeping the distance between the magnet rows fixed.

[0019]

According to the first aspect of the present invention, two magnet rows in which a plurality of permanent magnets and magnetic poles are alternately arranged are provided so as to face each other at a predetermined interval. A second magnet row in which a plurality of first magnet row pairs and permanent magnets and spacers are alternately arranged in plural numbers are provided so as to face each other with the first magnet row pair interposed therebetween. A pair of magnet rows, wherein each magnet row of the first magnet row pair includes a permanent magnet magnetized in one longitudinal direction of the magnet row;
The permanent magnets and permanent magnets magnetized in the opposite direction are arranged alternately with the magnetic poles interposed therebetween, and the permanent magnets of one magnet array and another magnet array magnetized in the opposite direction to the permanent magnets Are arranged so that the permanent magnets of the magnet rows face each other, and the magnetic poles of one magnet row face the magnetic poles of the other magnet row. Permanent magnets magnetized in one direction perpendicular to the longitudinal direction, and permanent magnets magnetized in the opposite direction to the permanent magnets are alternately arranged with the spacer interposed therebetween. And permanent magnets of another magnet row magnetized in the same direction as the permanent magnet face each other, and the spacers of one magnet row and the spacers of the other magnet row are arranged so as to face each other. The first and second magnet row pairs are provided so that their mutual positions can be relatively moved in the longitudinal direction. To provide a magnetic circuit for inserting the light source apparatus according to claim.

The invention according to claim 2 of the present invention is characterized in that the first
The pair of magnet rows is fixed, and the second pair of magnet rows is provided movably in the longitudinal direction.
A magnetic circuit for an insertion light source device as described above is provided.

According to a third aspect of the present invention, the second aspect
3. The magnet for an insertion light source device according to claim 1, wherein each magnet row of the pair of magnet rows has an iron base plate provided on a side opposite to the first magnet row pair. 4. Provide a circuit.

[0022]

Next, the present invention will be described in more detail with reference to examples.

FIGS. 1 and 2 are partial side sectional views showing an embodiment of a magnetic circuit for an insertion light source device according to the present invention. The magnetic circuit of the present embodiment includes a pair of magnet arrays 50A and 50B facing each other facing the gap G, and movable magnet arrays 60A and 60B arranged outside each of these magnet arrays.

The magnet array 50A (50B) has a permanent magnet 51
A (51B) and 52A (52B) are magnetic poles 53A (53
B) and 54A (54B), and one cycle is, for example, the magnetic poles 53A (53B), -z (+
two permanent magnets, which are arranged in the order of a permanent magnet 51A (51B) magnetized in the direction of z), a magnetic pole 54A (54B), and a permanent magnet 52A (52B) magnetized in the direction of + z (-z); It is composed of two magnetic poles, and these are arranged in N cycles (N represents an integer) in the longitudinal direction of the magnet row.
The length of one cycle (cycle length) and the number of cycles of the magnet arrays 50A and 50B are set to be equal.

Each of the permanent magnets of the magnet arrays 50A and 50B is magnetized in a direction parallel to the longitudinal direction of the magnet arrays,
A (51B) and 52A (52B) are magnetized in opposite directions. Further, the magnet rows 50A and 50B are arranged such that the magnetic poles and the permanent magnets face each other, and in particular, the permanent magnets are arranged such that 51A and 51B face each other and 52A and 52B face each other. Then, 51A and 51B are magnetized in opposite directions, and 52A and 52B are magnetized in opposite directions.

The movable magnet array 60A (60B) is composed of a permanent magnet 61A (61B) or 62A (62B) and a spacer 6
3A (63B) or 64A (64B) are alternately arranged in the axial direction, and one cycle is, for example, a permanent magnet 61A (61B) magnetized in the -y direction and a spacer 63A (6).
3B), the permanent magnet 62A (62
B), spacers 64A (64B) arranged in this order,
It is composed of two magnetic poles and two permanent magnets, and these are arranged in N cycles (N represents an integer) in the axial direction of the magnet row. The length of one cycle (cycle length) and the number of cycles of the movable magnet rows 60A and 60B are set equal to the cycle length of the magnet rows 50A and 50B.

The permanent magnets of the movable magnet arrays 60A and 60B are magnetized in a direction perpendicular to the longitudinal direction of the magnet arrays, and the permanent magnets 61A (61B) and 62A (62B) are magnetized in opposite directions. The movable magnet arrays 60A and 60A
B means that the spacers and the permanent magnets face each other, and in particular, the permanent magnets 61A and 61B face each other, and 62A and 62B
Are arranged to face each other. And 61A and 61B
And 62A and 62B are magnetized in the same direction.

The movable magnet arrays 60A and 60B are installed on iron base plates 65A and 65B, respectively. Then, both magnet rows are provided so as to move synchronously in the longitudinal direction by a drive source (not shown). That is, the magnet rows move while maintaining the phase of the mutual cycle. A motor or a hydraulic mechanism can be used as a drive source. Although both magnet arrays may be driven by one drive source, each magnet array may be driven by a separate drive source as long as the phases of both magnet arrays are maintained.

Since the magnetic pole concentrates the magnetic flux of the permanent magnet, a material having a saturation magnetization as high as possible is preferable. For example, pure iron or an Fe—Co alloy is preferable. Further, a non-magnetic material is used for the spacer.

Next, the operation of the magnetic circuit of this embodiment for varying the magnetic field strength will be described. First, to obtain the state where the magnetic field intensity is the highest, the movable magnet arrays 60A and 60A
0B is set to a phase arrangement as shown in FIG. That is, for example, the magnetic pole 53A (53) of the magnet row 50A (50B)
B) and the permanent magnet 61A of the movable magnet array 60A (60B)
(61B) are set to face each other.

In such a phase arrangement, the magnet array 50A
Permanent magnets 51A and 52 adjacent to each other with the magnetic pole 53A therebetween.
The magnetic flux from A concentrates on the magnetic pole 53A. Further, the magnetic flux from the permanent magnets 61A of the movable magnet array 60A that is close to and opposed to the magnetic pole 53A also concentrates on the magnetic pole 53A. Magnetic pole 53
The magnetic flux concentrated on A is transmitted through the gap G to the magnet row 5 on the opposite side.
The magnetic pole 53B is sucked into the magnetic pole 53B, and further divided into permanent magnets 51B and 52B adjacent to each other with the magnetic pole 53B interposed therebetween.

On the other hand, magnetic fluxes emitted from the permanent magnets 51B and 52B adjacent to each other across the magnetic pole 54B of the magnet row 50B concentrate on the magnetic pole 54B. Further, the magnetic flux from the permanent magnets 62B of the movable magnet row 60B opposed to the magnetic pole 54B is also concentrated on the magnetic pole 54B. The magnetic flux concentrated on the magnetic pole 54B is
The air is sucked into the magnetic pole 54A of the magnet row 50A on the opposite side via the air gap G, and further divided into the permanent magnets 51A and 52A adjacent to each other across the magnetic pole 54A.

In this manner, a magnetic field as shown by a broken arrow in FIG. 1 is obtained. In this phase arrangement, the maximum magnetic field strength is obtained in the gap G.

Next, in order to set the magnetic field strength to the minimum, the movable magnet arrays 60A and 60B are moved by a half cycle to set the phase arrangement as shown in FIG. That is,
For example, the magnetic pole 53A (53B) of the magnet row 50A (50B)
And the permanent magnets 62A (62) of the movable magnet row 60A (60B).
B) are set to face each other.

In such a phase arrangement, as in the case of FIG. 1, the magnetic fluxes emitted from the permanent magnets 51A and 52A adjacent to each other across the magnetic pole 53A of the magnet row 50A concentrate on the magnetic pole 53A. However, since the magnetization direction of the permanent magnet 62A of the movable magnet row 60A that is opposed to the magnetic pole 53A is opposite to that of the permanent magnet 61A in the case of FIG. 1, the magnetic flux concentrated on the magnetic pole 53A passes through the permanent magnet 62A. Base iron plate 65
It flows to A side. This is because the magnetic resistance is smaller when the magnetic flux flows to the base iron plate 65A side than when the magnetic flux flows to the gap side G. Similarly, the magnetic flux concentrated on the magnetic pole 54A of the magnet row 50B flows toward the base iron plate 65B via the permanent magnet 61B of the movable magnet row 60B.

As a result, the magnetic flux leaking into the gap G becomes extremely small, and the magnetic field intensity in the gap G is greatly reduced. If the dimensions and the like of the magnetic poles are appropriately designed, the magnetic field strength of the gap G can be reduced to almost zero.

Next, the movable magnet arrays 60A and 60B are shown in FIG.
2 and a part of the magnetic flux concentrated on the permanent magnet 53A or 54B flows to the base iron plate 65A or 65B side, and a part flows to the magnetic pole 53B or 54A with the gap G interposed therebetween. Therefore, the magnetic field strength of the gap G also takes an intermediate value.

As described above, the movable magnet arrays 60A and 60B
Is moved in the longitudinal direction, it is possible to make the magnetic field strength in the gap G variable while keeping the width of the gap G fixed.

The movable magnet arrays 60A and 60B are shown in FIG.
2 from the state of FIG. 2 to the state of FIG.
At 0A or 60B, at first, a repulsive force acts in a direction perpendicular to the moving direction with the magnet row 50A or 50B, but finally, it changes to an attractive force. Therefore, the movable magnet arrays 60A and 60B as a whole receive an attractive force or a repulsive force. However, the moving directions of the movable magnet rows 60A and 60B are
The direction is perpendicular to the direction in which the repulsive force acts, and the driving force required for movement is reduced to a value obtained by multiplying the suction repulsive force by the friction coefficient. Therefore, the required driving force is much smaller than in the conventional case where the gap width of the opposing magnet rows is made variable. Further, the moving distance of the movable magnet array may be a half cycle, and the moving distance may be shorter than when the gap width is changed.

Although the iron base plates 65A and 65B are not necessarily essential in the present invention, when an iron base plate is used, it is necessary to effectively reduce the magnetic flux leaking to the gap G during the phase arrangement in FIG. Can be.

FIG. 3 shows an example in which the magnetic circuit of the present invention is fixed. Both ends of the magnet rows 50A and 50B are fixed to the columns 67 via fixing members 66, respectively. The movable magnet rows 60A and 60B are fixed to a fixed base plate 68, respectively, and provided so as to be movable in the longitudinal direction together with the fixed base plate 68. These are integrated by a column 67 and further fixed to a base plate 69. However, the base plate 69 can be replaced with a fixed base plate 68.

As described above, in the present invention, it is not necessary to change the gap width between the opposing magnet rows, so that the gantry structure may be simple. Further, since the relative position accuracy and the assembling accuracy of the opposing magnet rows are improved, the magnetic field distribution can be precisely controlled. In order to incorporate the mount into the electron accelerator, it is desirable that the mount has a cantilever structure. However, it is easier to maintain the strength of the mount than a mount having a variable gap.

[0043]

As described above, according to the present invention, the provision of a new movable magnet array makes it possible to make the magnetic field intensity variable while keeping the gap width fixed. Strength and magnetic field accuracy can be realized.

[Brief description of the drawings]

FIG. 1 is a partial side sectional view showing one embodiment of a magnetic circuit for an insertion light source device of the present invention.

FIG. 2 is a partial side sectional view showing one embodiment of a magnetic circuit for an insertion light source device according to the present invention.

FIG. 3 is a partial side sectional view showing another embodiment of the magnetic circuit for the insertion light source device of the present invention.

FIG. 4 is a diagram for explaining the movement of an electron beam in a periodic magnetic field and the action of generating emitted light.

FIG. 5 is a partial perspective view showing one embodiment of a conventional magnetic circuit for a hull-back type insertion light source device.

FIG. 6 is a partial sectional view showing one embodiment of a conventional magnetic circuit for a hull-back type insertion light source device.

FIG. 7 is a partial cross-sectional view showing one embodiment of a conventional magnetic circuit for a hybrid insertion light source device.

FIG. 8 is a diagram showing the relationship between the width of a gap G and the magnetic field strength in a hybrid type magnetic circuit.

[Explanation of symbols]

 50A, 50B Fixed magnet row 51A, 51B, 52A, 52B Permanent magnet 53A, 53B, 54A, 54B Magnetic pole 60A, 60B Movable magnet row 61A, 61B, 62A, 62B Permanent magnet 63A, 63B, 64A, 64B Spacer 65A, 65B Iron Base plate 66 Fixing member 67 Column 68 Fixed base plate 69 Base plate G Gap

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H05H 13/04

Claims (6)

(57) [Claims] A first magnet row pair in which two magnet rows in which a plurality of permanent magnets and magnetic poles are alternately arranged are provided so as to face each other at a predetermined interval; and a permanent magnet and a spacer. And a second magnet row pair in which two magnet rows in which a plurality of magnet rows are alternately arranged are provided so as to face each other across the first magnet row pair. Each magnet row includes a permanent magnet magnetized in one direction in the longitudinal direction of the magnet row, and a permanent magnet magnetized in the opposite direction to the permanent magnet.
The permanent magnets of one magnet row are arranged alternately with the magnetic poles interposed therebetween, and the permanent magnets of another magnet row magnetized in the opposite direction to the permanent magnets face each other, and the magnetic poles of one magnet row are arranged. And the magnetic poles of another magnet row are arranged so as to face each other, and each magnet row of the second magnet row pair includes a permanent magnet magnetized in one direction perpendicular to the longitudinal direction of the magnet row. The permanent magnets and permanent magnets magnetized in the opposite direction are alternately arranged with the spacer interposed therebetween, and the permanent magnets of one magnet row and another magnet row magnetized in the same direction as the permanent magnets And the spacers of one magnet row and the spacers of the other magnet row are arranged so as to face each other, and the first and second magnet row pairs have a mutual position in the longitudinal direction. A magnetic circuit for an insertion light source device, which is provided so as to be relatively movable. 2. The magnetic circuit for an insertion light source device according to claim 1, wherein the first magnet row pair is fixed, and the second magnet row pair is provided so as to be movable in a longitudinal direction. . 3. The magnet row of the second magnet row pair, wherein an iron base plate is provided on the side opposite to the first magnet row pair side. 3. The magnetic circuit for an insertion light source device according to 2. 4. A first magnet row pair, in which two magnet rows in which a plurality of permanent magnets and magnetic poles are alternately arranged are provided so as to face each other at a predetermined interval, a permanent magnet and a spacer. And a second magnet row pair in which two magnet rows in which a plurality of magnet rows are alternately arranged are provided so as to face each other across the first magnet row pair. Each magnet row includes a permanent magnet magnetized in one direction in the longitudinal direction of the magnet row, and a permanent magnet magnetized in the opposite direction to the permanent magnet.
The permanent magnets of one magnet row are arranged alternately with the magnetic poles interposed therebetween, and the permanent magnets of another magnet row magnetized in the opposite direction to the permanent magnets face each other, and the magnetic poles of one magnet row are arranged. And the magnetic poles of another magnet row are arranged so as to face each other, and each magnet row of the second magnet row pair includes a permanent magnet magnetized in one direction perpendicular to the longitudinal direction of the magnet row. The permanent magnets and permanent magnets magnetized in the opposite direction are alternately arranged with the spacer interposed therebetween, and the permanent magnets of one magnet row and another magnet row magnetized in the same direction as the permanent magnets And the spacers of one magnet row and the spacers of the other magnet row are arranged so as to face each other, and the first and second magnet row pairs have a mutual position in the longitudinal direction. It is provided so as to be relatively movable, and the magnetic field strength is maintained with the gap width fixed.
Can be varied, and sufficient magnetic field strength and magnetic field
A magnetic circuit for an insertion light source device, which is capable of realizing field accuracy and precisely controlling a magnetic field distribution . 5. The first magnet row pair is fixed, and the second magnet row pair is provided movably in a longitudinal direction ,
Variable magnetic field strength in the gap while keeping the gap width fixed
5. The magnetic circuit for an insertion light source device according to claim 1, wherein the magnetic circuit can be used. 6. Each magnet row of the second magnet row pair is provided with an iron base plate on a side opposite to the first magnet row pair side, respectively , to effectively reduce a magnetic flux leaking to a gap side. 5. The method according to claim 1, wherein the number can be reduced.
6. A magnetic circuit for an insertion light source device according to claim 5.