JPH097800A - Magnetic circuit for inserting light source device - Google Patents

Abstract

PURPOSE: To obtain a magnetic circuit for inserting light source device which can regulate the magnetic field intensity while fixing the interval of magnet lines. CONSTITUTION: While magnet lines 50A and 50B composed by arranging plural permanent magnets 51 and 52, and plural magnet poles 53 and 54 alternatively are provided opposing each other by placing a specific interval, variable magnet lines 60A and 60B composed by arranging plural permanent magnets 61 and 62, and plural spacers 63 and 64 alternatively are provided opposing each other, holding the magnet line couple 50A and 50B. The magnet lines 50A and 50B are composed by arranging permanent magnets 51A and 51B magnetized to the -side in the longitudinal direction, and permanent magnets 52A and 52B magnetized in the reverse side, alternatively holding magnetic poles 53 and 54, while the magnet lines 60A and 60B are composed by arranging permanent magnets 61A and 61B magnetized to the -side vertical to the longitudinal direction, and permanent magnets 62A and 62B magnetized in the reverse side, alternatively holding spacers 63 and 64. The movable magnet lines 60A and 60B are set movable in the longitudinal direction.

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 radiated light by meandering 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 varying the gap width of the magnetic circuit, has a simple pedestal structure, is easy to manufacture, and is optimal for applications such as photo-CVD and X-ray exposure of LSI.

[0002]

2. Description of the Related Art It is known that high-speed electrons traveling in an accelerator to which a periodic magnetic field is applied make a meandering motion by the periodic magnetic field, and radiate light from each meandering point (see FIG. 4). Halbach, Nuclear Instr
ments and Method, 187 (198)
1), 109). An insertion light source device is a device that obtains emitted light by utilizing this principle.

The insertion light source device has a linear portion (gap) of an electron accelerator or an electron storage ring having a magnetic circuit constructed by arranging a magnet array in which a plurality of permanent magnets are arranged so as to form a tubular space. It is inserted so as to sandwich the vacuum chamber, and a sine-shaped periodic magnetic field is generated in the gap of the magnetic circuit (see FIG. 4). This insertion light source device includes a hull back type that is composed only of permanent magnets, and a hybrid type that is composed of a combination of permanent magnets and magnetic poles (pole pieces) made of iron, iron-cobalt alloy, or the like.

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

FIG. 7 shows a hybrid type magnetic circuit constructed by combining permanent magnets and magnetic poles. Also in this device, as in the Hullback type, the magnet arrays 30A and 30B are used.
Are arranged in parallel in the vertical direction with a gap G in between, and in each magnet row, permanent magnets and magnetic pole members are alternately arranged. 1
Looking at the period, in the magnet array 30A, permanent magnets 31A and 32A whose magnetization directions are −z and + z, respectively, are arranged alternately with two magnetic pole members 33A to form one cycle, and in the magnet array 30B. , One permanent magnet 31 </ b> B and 32 </ b> B whose magnetization directions are + z and −z are alternately arranged together with two magnetic pole members 33 </ b> B to form one cycle. Other configurations and operations are similar to those of the Hullback type.

[0006] The magnetic circuit is provided with a variable air gap mechanism for varying the air gap width of the opposing magnet rows in order to adjust the magnetic field strength. That is, the magnetic field strength is adjusted by expanding or narrowing the gap G. FIG. 8 shows an example of the relationship between the width of the gap G and the magnetic field strength in a hybrid magnetic circuit, for example. The magnetic field in the gap G rapidly increases in magnetic field strength as the gap G narrows. On the other hand, when the gap G is widened, the magnetic field strength decreases, but even if it is widened beyond a certain level, the change in the magnetic field strength becomes gradual, 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 big difference. However, in general, the weight of the magnet used in the hybrid type is often smaller. In addition, since the angle and characteristics of the permanent magnets were large at the initial stage of the development of the insertion light source, the magnetic field strength was easier to arrange in the hybrid type than in the hullback type. However, recently, the variation of permanent magnets is small and the characteristics are uniform, and since the method of recombination of magnet pairs has been introduced and improved, both methods can obtain the same magnetic field distribution. . Although the electron orbit may shift when the magnetic field is adjusted by changing the gap G, the electron shift is small in the Halbach type because almost linearity is established, but the hybrid type is non-linear because the hybrid type is non-linear. Misalignment of electron trajectories is likely to occur.

The mode of the insertion light source device is classified into a wiggler mode and an undulator mode depending on the degree of meandering of the electron beam. In the Wiggler mode, the emitted light generated from each meandering point of the electron beam is superimposed, and the emitted light having a power 10 to 1000 times higher than that of the emitted light from the deflecting electromagnet is obtained. On the other hand, in the undulator mode, the radiated light generated by each meandering motion interferes with each other, and the fundamental wave and the higher-order light of the wiggle light further include 10
Light that is about 1000 times stronger can be obtained.

Whether the mode is the wiggler mode or the undulator mode can be classified by a parameter called K value. When the K value is around 1 or less, it becomes undulator mode, and when it is more than K value, it becomes a wiggler.

The K value is proportional to the air gap magnetic field strength,
The gap width is changed to obtain a magnetic field strength suitable for obtaining the required light. Further, when using the undulator mode having a low K value, it is necessary to make the magnetic field variable to a region having a magnetic field strength as low as possible.

[0011]

As described above, the conventional insertion light source device is provided with the air gap changing mechanism for changing the air gap width of the magnet rows facing each other in order to adjust the magnetic field strength. High-speed electrons passing through the periodic magnetic field generated by the insertion light source device are very sensitive to the disturbance of the periodic magnetic field, and the electron trajectories easily change. Therefore, it is necessary to ensure the parallelism, relative positional accuracy, and air gap accuracy between opposing magnet rows so that the magnetic field distribution is not disturbed before and after changing the air gap width. Due to the above reasons, strict accuracy is required for the dimensional accuracy and the 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 device can be installed without removing the vacuum chamber of the electron accelerator or the storage ring. Often. However, in the cantilever structure, since the gap is smoothly moved while maintaining parallelism and the like against the attractive force of the magnet array, it is difficult and complicated to design the strength of the pedestal.

Further, in the insertion light source device, the attraction force acts between the magnet rows facing each other, and the attraction force increases as the gap width becomes narrower. Since the attractive force depends on the peak magnetic field strength, the number of cycles, the total length, etc., it is often on the order of 1 ton, although it depends on the device. Therefore, it is necessary to design the structural strength of the base plate that holds and fixes the permanent magnet and the gantry structure that holds the base plate in accordance with the attraction force in the shortest gap width.

A step motor or an AC servomotor is used as a drive 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 an insertion light source device having a long total length, and a plurality of relatively short insertion light source devices may be arranged side by side to form a set of devices. In this case, it is necessary to change the gap widths of the plurality of insertion light source devices in synchronization with each other with high accuracy, and there is a possibility that errors associated with driving may be superimposed in addition to processing and assembly errors and installation errors.

In order to make the magnetic field strength variable with the air gap width fixed, a large number of electromagnets may be arranged to form an insertion light source. However, if the insertion light source device is constructed of electromagnets, the volume of the coil winding portion becomes large. However, the cycle length cannot be made shorter than that of the insertion light source device using the permanent magnet. Further, since the electromagnet generates heat, dimensional accuracy and magnetic field strength change, which may adversely affect the electron orbit.

As described above, in the conventional magnetic circuit for the insertion light source device, the magnetic field intensity is adjusted by changing the gap width between the magnet rows, but the gap width is made variable. As a result, the above-mentioned various problems have arisen. Therefore, 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 Therefore, an object of the present invention is to provide a magnetic circuit for an insertion light source device which can adjust the magnetic field strength while keeping the distance between the magnet rows fixed.

[0019]

According to a first aspect of the present invention, two magnet rows each having a plurality of permanent magnets and magnetic poles alternately arranged are provided so as to face each other at a predetermined interval. A first magnet row pair, and a second magnet row in which a plurality of permanent magnets and spacers are alternately arranged so as to face each other with the first magnet row pair interposed therebetween. A pair of magnet rows, each magnet row of the first pair of magnet rows includes a permanent magnet magnetized in one longitudinal direction of the magnet row;
The permanent magnets and the permanent magnets magnetized in the opposite direction are alternately arranged with the magnetic poles sandwiched therebetween, and the permanent magnets in one magnet row and the other magnet rows magnetized in the opposite direction to the permanent magnets. Are arranged so that the magnetic poles of one magnet row and the magnetic poles of another magnet row face each other, and each magnet row of the second magnet row pair is The permanent magnets magnetized in one direction perpendicular to the longitudinal direction and the permanent magnets magnetized in the opposite direction to the permanent magnets are alternately arranged with the spacer interposed therebetween, and the permanent magnets in one magnet row are arranged. And a permanent magnet of another magnet row magnetized in the same direction as the permanent magnet face each other, and a spacer of one magnet row and a spacer of another magnet row face each other. The first and second magnet row pairs are provided such that their mutual positions are relatively movable 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 the first
2. The pair of magnet rows of No. 1 is fixed, and the second pair of magnet rows is provided so as to be movable in the longitudinal direction.
A magnetic circuit for the insertion light source device described is provided.

The invention according to claim 3 of the present invention is the second invention.
3. The magnet for an insertion light source device according to claim 1 or 2, wherein each magnet row of the magnet row pair is provided with an iron base plate on a side opposite to the first magnet row pair side. Provide the circuit.

[0022]

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

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 this embodiment includes magnet arrays 50A and 50B facing the gap G and facing each other, and movable magnet arrays 60A and 60B arranged outside each of the magnet arrays.

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

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

The movable magnet array 60A (60B) includes 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 period is, for example, a permanent magnet 61A (61B) magnetized in the direction of -y, a spacer 63A (6).
3B), a permanent magnet 62A (62) magnetized in the + y direction.
B), spacers 64A (64B) are 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 array. The length of one cycle (cycle length) and the number of cycles of the movable magnet rows 60A and 60B are set to be 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 array, and the permanent magnets 61A (61B) and 62A (62B) are magnetized in opposite directions. In addition, the movable magnet arrays 60A and 60
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 so as to face each other. And 61A and 61B
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, by a drive source (not shown), both magnet rows are provided so as to move in synchronization with each other in the longitudinal direction. That is, the two magnet arrays move while maintaining the phase of the mutual cycle. A motor or hydraulic mechanism can be used as a drive source. Both magnet rows may be driven by one drive source, but each magnet row may be driven by a separate drive source as long as the phases of both magnet rows are maintained.

Since the magnetic flux of the permanent magnet is concentrated on the magnetic pole, a material having a high saturation magnetization is preferable. For example, pure iron or Fe-Co alloy is preferable. A non-magnetic material is used for the spacer.

Next, the operation of varying the magnetic field strength in the magnetic circuit of this embodiment will be described. First, in order to obtain the maximum magnetic field strength, the movable magnet rows 60A and 6
OB is set to the phase arrangement as shown in FIG. That is, for example, the magnetic poles 53A (53) of the magnet array 50A (50B).
B) and the permanent magnet 61A of the movable magnet array 60A (60B)
(61B) is set to face.

In such a phase arrangement, the magnet array 50A
Adjacent permanent magnets 51A and 52 with the magnetic pole 53A of
The magnetic flux emitted from A concentrates on the magnetic pole 53A. In addition, the magnetic flux from the permanent magnet 61A of the movable magnet array 60A that closely faces and opposes the magnetic pole 53A also concentrates on the magnetic pole 53A. Magnetic pole 53
The magnetic flux concentrated in A passes through the air gap G and the magnet array 5 on the opposite side.
It is absorbed by the magnetic pole 53B of 0B, and is further divided into the permanent magnets 51B and 52B adjacent to each other with the magnetic pole 53B sandwiched therebetween.

On the other hand, the magnetic flux emitted from the permanent magnets 51B and 52B adjacent to each other with the magnetic pole 54B of the magnet array 50B interposed therebetween is concentrated on the magnetic pole 54B. Further, the magnetic flux from the permanent magnets 62B of the movable magnet array 60B, which closely faces and opposes the magnetic pole 54B, is also concentrated on the magnetic pole 54B. The magnetic flux concentrated on the magnetic pole 54B is
It is sucked into the magnetic pole 54A of the magnet array 50A on the opposite side via the gap G, and is further divided into the adjacent permanent magnets 51A and 52A with the magnetic pole 54A sandwiched therebetween.

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

Next, when the magnetic field strength is to be the smallest, the movable magnet arrays 60A and 60B are moved by a half period to set the phase arrangement as shown in FIG. That is,
For example, the magnetic poles 53A (53B) of the magnet array 50A (50B)
And the permanent magnets 62A (62) of the movable magnet array 60A (60B).
B) is set to face.

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

As a result, the magnetic flux leaking into the gap G is extremely small, and the magnetic field strength of the gap G is significantly reduced. By appropriately designing the dimensions of the magnetic poles, it is possible to make the magnetic field strength of the air gap G substantially zero.

Next, the movable magnet arrays 60A and 60B are shown in FIG.
2, a part of the magnetic flux concentrated in 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 across the gap G. Therefore, the magnetic field strength of the gap G also takes an intermediate value.

Thus, the movable magnet arrays 60A and 60B are
By moving in the longitudinal direction, it is possible to make the magnetic field strength in the gap G variable while the width of the gap G is fixed.

The movable magnet arrays 60A and 60B are shown in FIG.
Moving from the state of FIG. 2 to the state of FIG.
0A or 60B initially exerts a repulsive force in a direction perpendicular to the moving direction with the magnet array 50A or 50B, but finally 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 arrays 60A and 60B are
It is a direction perpendicular to the direction of the repulsive force, and the driving force required for movement is reduced to the product of the suction repulsive force and the friction coefficient. Therefore, the required driving force can be much smaller than in the conventional case where the gap width of the facing 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 that in the case where the gap width is changed.

The iron base plates 65A and 65B are not essential in the present invention, but when the iron base plate is used, the magnetic flux leaking to the air gap G side during the phase arrangement in FIG. 2 is effectively reduced. You can

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

As described above, in the present invention, since it is not necessary to change the gap width between the magnet rows facing each other, the gantry structure can be simple. In addition, since the relative position accuracy of the magnet rows facing each other and the assembling accuracy are improved, the magnetic field distribution can be precisely controlled. It should be noted that the mount is preferably a cantilever structure in order to be incorporated in the electron accelerator, but it is easier to maintain the strength of the mount as compared with a mount with a variable air gap.

[0043]

As described above, according to the present invention, by newly providing the movable magnet array, the magnetic field strength can be made variable while the gap width is fixed, and a simple mechanism can provide a sufficient magnetic field. Strength and magnetic field accuracy can be realized.

[Brief description of drawings]

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

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

FIG. 3 is a partial side sectional view showing another embodiment of the magnetic circuit for an 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 an example of a conventional magnetic circuit for a hull back type insertion light source device.

FIG. 6 is a partial cross-sectional view showing an example of a conventional magnetic circuit for a hullback type insertion light source device.

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

FIG. 8 is a diagram showing a relationship between a width of a gap G and a 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 Pillar 68 Fixed base plate 69 Base plate G Gap

Claims (3)

[Claims] 1. A first magnet row pair, which is provided so as to face two magnet rows, in which a plurality of permanent magnets and magnetic poles are alternately arranged, facing each other at a predetermined interval, a permanent magnet and a spacer. A plurality of magnet rows arranged alternately, and a second magnet row pair provided so as to face each other with the first magnet row pair sandwiched therebetween. Each magnet row has a permanent magnet magnetized in one 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 array and the permanent magnets of another magnet array magnetized in the opposite direction to the permanent magnets are arranged alternately with the magnetic poles sandwiched between them, and the magnetic poles of the one magnet array are opposite. And the magnetic poles of other magnet rows are arranged to face each other, and each magnet row of the second magnet row pair is a permanent magnet magnetized in one direction perpendicular to the longitudinal direction of the magnet row. The permanent magnets and the permanent magnets magnetized in the opposite direction are alternately arranged with the spacer interposed therebetween, and the permanent magnets in one magnet row and the other magnet rows magnetized in the same direction as the permanent magnets. Of the first magnet array and the permanent magnets of the first magnet array and the spacers of the one magnet array and the spacers of the other magnet array are opposed to each other, and the first and second magnet array pairs have mutual positions 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 pair of magnet rows is fixed, and the second pair of magnet rows is provided so as to be movable in the longitudinal direction. . 3. The iron base plate is provided on each of the magnet rows of the second magnet row pair on the side opposite to the first magnet row pair side, respectively. 2. The magnetic circuit for an insertion light source device according to 2.