JP2007035495A - Magnetic circuit device and synchrotron device using it - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a magnetic circuit device efficiently accumulating electron beams by easily removing a fringe magnetic field without disturbing a controlled field distribution area even in a limited space. <P>SOLUTION: In this compact synchrotron device, a coil 2 inside a yoke 1, and a coil (a schematic drawing) inside a pole piece 3 make up a bipolar electromagnet as well as a magnetic circuit device for removing a fringe magnetic field generated by a controlled magnetic field in the vicinity of the controlled magnetic field distribution area E<SB>B</SB>satisfying conditions of a stable revolution trajectory for accumulating electron beams. A magnetic field generator (generating a magnetic field for removing the fringe magnetic field) is arranged, which is made by combining and arranging magnet blocks (made by combining the given number of permanent magnets with different magnifying directions) 6 to 12 along a magnetic flux line of the controlled magnetic field distribution area E<SB>B</SB>in a circular shape so as to be extended in the vicinity of incident and irradiating routes of electron beams along the stable revolution trajectory. Gaps to be light paths for accepting and irradiating the electron beams are provided at the magnetic block 6, 11. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention is mainly disposed in a small synchrotron apparatus that accumulates a high-energy electron beam, and an unnecessary magnetic field in an electron beam transmission path in order to improve the electron beam accumulation efficiency and increase the X-ray conversion efficiency. The present invention relates to a magnetic circuit device having a function of removing the light and a synchrotron device using the same.

  2. Description of the Related Art Conventionally, as a synchrotron device for accumulating and circulating an electron beam from an accelerator, a large-sized type in which a large number of deflecting electromagnets are generally arranged in an annular shape is known. In the case of this large type synchrotron device, it is necessary to secure a wide installation location, and although there is a leakage magnetic field from each electromagnet, the area is limited to the vicinity of the installation location of each electromagnet, An electromagnet for correcting the leakage magnetic field, or a magnetic circuit device for removing the leakage magnetic field can be easily installed (a sufficient space can be secured for this). There is no need to do it.

  However, in the case of this large type synchrotron device, it is necessary to arrange a plurality of deflecting quadrupole magnets in an annular shape. There is a drawback that it is necessary and the price becomes high.

  Therefore, in recent years, in addition to the fact that it is desired that high-intensity X-rays with a small electron ring can be installed at the factory size, by introducing a new electron beam injection mechanism called resonance injection method, A compact synchrotron device using a single dipole electromagnet that has been compacted to a minimum has been developed.

  FIG. 3 shows a configuration of a main part of a conventional small synchrotron device (although it has been researched and developed but is not an invention related to a patent document). FIG. 3 (a) relates to a side view partially in section. FIG. 2B is a plan view partially seen from the top surface direction. However, as is apparent from the comparison between FIGS. 3A and 3B, the schematic structure is simply shown here to include a portion where the detailed structure including the scale does not match, and FIG. The radial lines shown in () indicate the connection opening portions of various pipes connected to keep the inside of the small synchrotron device in a vacuum.

The main part of this small synchrotron device has a structure in which the coil 2 is arranged on the upper side in the yoke 1 and a coil (not shown) is housed in the pole piece 3 on the lower side to form a single bipolar electromagnet. A control magnetic field distribution region E _B that satisfies the conditions of the stable orbital region for accumulating the electron beam is formed inside, but it is indicated by an arrow in the vicinity of the entrance / exit path of the internal electron beam (in the vicinity including the steering coil 4). A fringing magnetic field _BF due to a control magnetic field is generated in an internal region where the incident beam B _IN is incident and an internal region where the outgoing beam B _OUT indicated by an arrow is emitted.

  That is, in the case of this small synchrotron device, when a magnetic field is applied from the vertical direction to the traveling charged particles in an accelerator (not shown) such as a microtron as a previous step, the traveling direction of the charged particles and the magnetic field perpendicular to the traveling direction. Since the force is applied in a direction perpendicular to both of the application directions, the electron beam rotates on the circumference with a constant radius in a region where a magnetic field in a certain direction is applied, and the electron beam is rotated using this rotational motion. Accelerated emission is performed.

Therefore, an accelerated electron beam is incident on the inside of the small synchrotron device as an incident beam _{BIN, and then,} as shown by an arrow due to the influence of a magnetic field, a stable orbit for accumulating the electron beam. reaches the control magnetic field distribution area E _B controls the magnetic field distribution regions with slightly diverted so as to be attracted to E _B satisfying, while rotational movement in the range of thousands to several tens of thousands times in the control field distribution region E _B When the beam amount is stored and a predetermined beam amount is stored, the beam is emitted from the emission unit as an outgoing beam B _OUT . Here, when the accumulation of the electron beam, it is necessary to appropriate stable orbit region accurately control the magnetic field distribution area E _B is formed.

In short, in the case of such a small synchrotron device, in order to generate high-intensity X-rays at a practical level, the electron beam circulates and accumulates on a stable orbit according to the synchrotron principle to enhance the beam intensity. It defines a controlled magnetic field distribution area E _B in a region defined in the radial direction of the synchrotron device to ensure the track.

However, in the case of this small synchrotron device, in the entrance / exit path where the electron beam enters and exits, it is avoided that it is affected by an unnecessary magnetic field of the fringing magnetic field _BF by a single bipolar electromagnet (control magnetic field). However, the influence of this is so great that it causes the electron beam to diverge or extinguish. Therefore, it is necessary to provide means for correcting the magnetic field as a countermeasure. In other words, in such a small synchrotron device, when an electron beam generated by an accelerator such as a microtron is incident on a single dipole electromagnet, the internal magnetic field is controlled by the control magnetic field of the dipole electromagnet before being guided to a stable orbit. The magnetic field correction means using a permanent magnet or the like for removing the fringing magnetic field _BF is used to adversely affect the convergence and stability of the electron beam by passing through the strong fringing magnetic field _BF generated in the magnetic field. There is a need to do.

As such a magnetic field correction means, a pair of opposed permanent magnets having a simple structure is provided inside (bipolar) for the purpose of removing an unnecessary magnetic field in the vicinity of the entrance / exit path of the electron beam influenced by the fringing magnetic field _BF. In the electromagnet), it is installed so as to cover the entire circumference of the stable orbit, and the reverse magnetic field generated by the influence of the fringing magnetic field _BF of each of these permanent magnets affects the control magnetic field distribution region E _B satisfying the stable orbit. In other words, a magnetic circuit device is used in which another pair of opposing permanent magnets is provided separately for removing the reverse magnetic field. Incidentally, also in this incident and exit paths around, the provision of control magnetic field distribution area E _B for stable orbit intended to be strictly applied, the leakage magnetic field by the permanent magnet to be installed as a magnetic circuit device generates a small synchro disturbing the control magnetic field distribution area E _B by two quadrupole magnets in Tron device has a those that are not to adversely affect the X-ray generation.

  In the case of the small synchrotron apparatus provided with the magnetic circuit device by two sets of a total of four permanent magnets as the magnetic field correction means shown in FIGS. 3 (a) and 3 (b) described above, the use conditions in a narrow space As a result, a very strong magnetic field can be generated with two single permanent magnets facing each other, which is very effective. On the other hand, if the spacing between the magnetic poles in the space to be opposed is wide, the magnetic field strength cannot be obtained. In addition, there is a problem that the reverse magnetic field due to the fringing magnetic field also increases locally, and it is necessary to install another permanent magnet to cancel the newly generated reverse magnetic field in the other region, and the control magnetic field distribution region In addition to the problem that the work for installing each permanent magnet without disturbing the magnetic field is not easy, the energy of the electron beam is high on the structure, and the magnetic field intensity that needs to be corrected is also high. In this case, it is impossible to avoid the inconvenience in handling that it is difficult to take measures to improve the generation efficiency of the magnetic field strength. There is a problem that it is difficult to apply, and as a result, it is difficult to remove the fringing magnetic field easily without disturbing the control magnetic field distribution region and to accumulate the electron beam with high accuracy and efficiency.

  The present invention has been made to solve such problems, and its technical problem is to easily remove the fringing magnetic field without disturbing the control magnetic field distribution region even in a limited space, thereby increasing the electron beam. An object of the present invention is to provide a magnetic circuit device having a structure capable of accumulating with accuracy and efficiency and a small synchrotron device using the magnetic circuit device.

  According to the present invention, in a magnetic circuit device disposed in a small synchrotron device that generates high-intensity X-rays by bremsstrahlung when an electron beam from an accelerator is accumulated and collides with a minute target, the small synchrotron It is arranged in the vicinity of a controlled magnetic field distribution region satisfying a stable orbit for accumulating an electron beam in the apparatus, and for canceling the influence of a fringing magnetic field generated near the entrance / exit path of the electron beam by the controlled magnetic field A magnetic circuit device having a magnetic field generator for generating a magnetic field is obtained.

  According to the present invention, in the magnetic circuit device, the magnetic field generator generates a new reverse magnetic field without affecting the control magnetic field distribution region, and a new magnetic field for correcting the reverse magnetic field. A magnetic circuit device comprising a set of permanent magnets that does not require a magnetic circuit is obtained.

  Furthermore, according to the present invention, in the above magnetic circuit device, the magnetic field generator is configured to input and output the electron beam along a stable orbit through a plurality of magnet blocks having magnetization directions along the magnetic flux lines in the controlled magnetic field distribution region. In addition to an annular coupling structure that is annularly coupled so as to extend in the vicinity of the path, a predetermined one of the plurality of magnet blocks is provided with a gap serving as an optical path for entering and exiting an electron beam. A magnetic circuit device is obtained.

  In addition, according to the present invention, in the above magnetic circuit device, the plurality of magnet blocks include a predetermined number of permanent magnets having different types of magnetization directions, each of which is opened at a portion close to the stable orbit, and a leakage magnetic field is generated. Thus, a magnetic circuit device that is combined so as to be suppressed can be obtained.

  On the other hand, according to the present invention, a synchrotron device including any one of the above magnetic circuit devices can be obtained.

  In the case of the magnetic circuit device of the present invention, a magnetic field generator is disposed in the vicinity of a controlled magnetic field distribution region that satisfies a stable orbit for accumulating an electron beam in a small synchrotron device, and the vicinity of the entrance / exit path of the electron beam by the controlled magnetic field. The structure that generates a magnetic field to counteract the influence of the fringing magnetic field generated in the case of the electron beam, the influence of the fringing magnetic field immediately before the electron beam incident in the small synchrotron device moves to the stable orbit, and the stable orbit It is possible to accurately remove the influence of the fringing magnetic field during emission when the electron beam is emitted from the orbit to the emission part, and easily remove the fringing magnetic field without disturbing the control magnetic field distribution region even in a limited space. Electron beams can be accumulated with high accuracy and efficiency, and high-energy electron beams can be emitted stably. In it a structure that is to improve the X-ray conversion efficiency, the basic performance of the compact synchrotron apparatus provided with a magnetic circuit device according resulting so be dramatically increases.

  A magnetic circuit device according to the best mode of the present invention is disposed in a small synchrotron device that generates high-intensity X-rays by bremsstrahlung when an electron beam from an accelerator is accumulated and collides with a minute target. In the small synchrotron device, it is placed near the controlled magnetic field distribution area that satisfies the stable orbit for accumulating the electron beam, and the influence of the fringing magnetic field generated near the entrance / exit path of the electron beam by the controlled magnetic field is It is based on having a magnetic field generator that generates a magnetic field for canceling.

  However, this magnetic field generator is composed of a set of permanent magnets that do not affect the control magnetic field distribution region, do not generate a new reverse magnetic field, and do not require a new magnetic circuit for correcting the reverse magnetic field. Or an annular coupling structure in which a plurality of magnet blocks having magnetization directions along the magnetic flux lines in the controlled magnetic field distribution region are arranged so as to extend in the vicinity of the entrance / exit path of the electron beam along a stable orbit. In addition, a predetermined one in each magnet block is provided with a gap as an optical path for entering and exiting the electron beam. Further, in the case of the structure of the latter magnetic field generator, each magnet block has a predetermined number of permanent magnets having different types of magnetization directions, each of which is opened at a portion close to the stable orbit, so that generation of a leakage magnetic field can be suppressed. It is preferable that they are combined.

  Particularly in the magnetic circuit device having the latter structure, as a highly efficient magnetic circuit configuration for increasing the magnetic field strength, a plurality of magnet blocks having magnetization directions along the magnetic flux lines are connected in an annular shape, and each magnet block is respectively The magnetic field strength can be increased by using an annular coupling structure in which a predetermined number of permanent magnets having different types of magnetization directions are combined, and when a conventional magnetic circuit device using opposed permanent magnets is used. In comparison, under the same magnetic field strength conditions, the size of the magnet can be made smaller, and the total amount of magnets used can be suppressed. In addition, the magnetic circuit device is such that when installed in a small synchrotron device, the leakage magnetic field does not affect the control magnetic field distribution region by a single bipolar electromagnet, and the magnetic flux line of each permanent magnet in each magnet block. By adjusting the size of the coupling part and the angle of coupling and adjusting the distribution of the leakage magnetic field after setting the direction of the magnetization direction along the axis to be different, the generation of the leakage magnetic field can be minimized There is no need to separately provide magnetic field correction means (magnetic circuit device using a new permanent magnet or the like) for removing the leakage magnetic field. Furthermore, the magnetic circuit device has a structure in which a predetermined gap of each magnet block (indicating a magnet block alone) is provided with a gap serving as an entrance / exit path for the electron beam so that the incident / exited electron beam can pass therethrough. Even in the vicinity of the controlled magnetic field distribution area in the TRON device and in the limited installation conditions near the entrance / exit path, we devised to avoid the influence of the fringing magnetic field as much as possible when entering and exiting the electron beam. is doing.

  In any case, a magnetic circuit device having a magnetic field generator of the type described above can drastically improve its basic performance by being applied to a small synchrotron device.

  FIG. 1 shows the configuration of the main part of a small synchrotron device provided with a magnetic circuit device according to Embodiment 1 of the present invention. FIG. 1 (a) relates to a side view partially in section. (B) relates to a partially transparent plan view from the upper surface direction. However, as is clear from the comparison between FIGS. 1A and 1B, the schematic structure is simply shown here to include a portion where the detailed structure including the scale does not match, and FIG. The radial lines shown in (1) indicate the connection openings of various pipes connected to keep the inside of the small synchrotron device in a vacuum.

Referring to FIG. 1 (a), the main part of this small synchrotron device is also arranged with a coil 2 on the upper side in the yoke 1 and a coil (not shown) in the pole piece 3 on the lower side. The control magnetic field distribution region E _B that satisfies the conditions of the stable orbital region for accumulating the electron beam is formed inside, but here separately shown in FIG. as shown, there is forming a magnetic circuit device for canceling the effects of fringing magnetic field generated by the control magnetic field in the vicinity in incident and exit path of the electron beam control magnetic field distribution area E _B, controls the magnetic field distribution region E A plurality (seven in this case) of magnet blocks 6 to 12 having a magnetization direction along the magnetic flux line _B are circularly 105 degrees so as to extend in the vicinity of the entrance / exit path for the electron beam along a stable orbit. Range of A magnetic field generator (generating a magnetic field for canceling the influence of the fringing magnetic field) having an annular coupling structure that is coupled and arranged across the magnet blocks 6 and 11 is disposed, and an optical path for entering and exiting the electron beam is provided in the magnet blocks 6 and 11. A gap is provided. However, the magnet blocks 6 to 12 are combined in such a manner that a predetermined number of magnets having different types of magnetization directions are opened on the side of the stable orbit side and the generation of a leakage magnetic field can be suppressed, as will be described later. It is made up of.

That is, even in a small synchrotron apparatus wherein, inside the area where the incident beam B _IN indicated by an arrow in the vicinity having a near incident and exit path inside the electron beam (steering coil 4 is incident, and emission indicated by the arrows A fringing magnetic field, which is schematically illustrated by a control magnetic field, is generated in an inner region where the beam B _OUT is emitted. Here, a magnetic field generator (which forms a magnetic circuit device) that generates a magnetic field for canceling the influence of the fringing magnetic field is generated. as), seven of the magnet blocks 6-12 in a wide range of the vicinity of the internal control magnetic field distribution area E _B arranged so as to extend in the input and output path proximal with respect to the electron beam incidence and emission path unnecessary magnetic field In order to reduce the influence of the reverse magnetic field generated at the end of the magnet by allowing the electron beam to enter and exit from the gap between the magnet blocks 6 and 11. Due to the structure, reaches the incident beam B _IN is controlled magnetic field distribution area slightly while diverted to through the incident optical path is drawn to control the magnetic field distribution region E _B of the gap E _B magnet block 6 from the incident portion, the control field distribution region E _B stored beam amount while rotating motion in a range of thousands to tens of thousands times, emitted from the emission unit through an exit optical path of the gap of the magnet blocks 11 After accumulated a predetermined beam weight When emitted as the beam B _OUT , the influence of the fringing magnetic field immediately before the electron beam incident in the small synchrotron device moves to the stable orbit and the emission from which the electron beam is emitted from the stable orbit to the emission unit The influence of the fringing magnetic field at the time can be accurately removed.

Therefore, in this case the small synchrotron devices, can be easily removed fringing magnetic field without disturbing the limited control field distribution region in space E _B efficiently accumulate electron beam with high precision, and stably high in An energy electron beam can be emitted and the X-ray conversion efficiency can be improved.

  FIG. 2 shows a detailed structure of the magnetic circuit device. FIG. 2A is a side sectional view of the magnet block 10 in the direction of the line AA ′ in FIG. b) relates to an enlarged view showing a combination pattern of a predetermined number of permanent magnets 101 to 105 which is a part of FIG.

  Referring to FIG. 2 (a), the magnet block 10 showing a part of the magnetic field generator is fixed in the case 201, and the housing 202a for attaching and fixing the frame body 201 is a housing using a bolt 203. 202b can be attached and fixed. The housings 202a and 202b have a structure in which a predetermined number (here, five) of permanent magnets 101 to 105 are incorporated and joined together. However, the case 201, the frame body 201, and the housing 202a here are opened at the portion near the stable orbit, and the shapes of the combined permanent magnets 101 to 105 correspond to the permanent magnet. It is devised so that generation | occurrence | production of the leakage magnetic field from the magnets 101-105 can be suppressed.

  Referring to FIG. 2 (b), here, the magnet block 10 shows a state in which several types of permanent magnets 101 to 105 having different magnetization directions are combined and the flow of magnetic flux is aligned in one direction.

  As shown here, the magnet block 10 is composed of at least five permanent magnets 101 to 105, and the other magnet blocks 6, 7, 8, 9, and 11 have the same structure. However, the magnet block 6 is provided with a gap serving as an optical path for allowing an electron beam to enter, and the magnet block 11 is provided with a gap serving as an optical path for emitting an electron beam.

  That is, with respect to the magnet blocks 6 to 12 related to the whole magnetic circuit device (magnetic field generator) of the first embodiment, the manufacturing dimensions are limited in the traveling direction of the electron beam, so the magnet blocks 6 to 12 are divided and arranged in parallel. Although it is necessary to increase the number of types of magnetization directions related to the number of magnet blocks 6 to 12, it is possible to increase the magnetic field strength and to easily suppress the generation of a leakage magnetic field. Further, by adjusting the shape and magnetization direction of each permanent magnet in the magnet blocks 6 to 12, it is possible to adjust the strength of the magnetic field leaking according to the distance from the magnetic circuit device, and in the x direction. , Y direction magnetic field components can be adjusted.

The principal part structure of the small-sized synchrotron device provided with the magnetic circuit device which concerns on Example 1 of this invention is shown, (a) is related with the side view made into a partial cross section, (b) is from an upper surface direction. This relates to a partially transparent plan view. 1 shows a detailed structure of a magnetic circuit device according to Embodiment 1 of the present invention, in which (a) relates to a side sectional view of a magnet block in the direction of the line AA ′ in FIG. FIG. 6 relates to an enlarged view showing a combination pattern of a predetermined number of permanent magnets which are a part of (a). The principal part structure of the conventional small-sized synchrotron apparatus is shown, (a) is related with the side view made into the partial cross section, (b) is related with the top view seen through partially from the upper surface direction.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Yoke 2 Coil 3 Pole piece 4 Steering coil 6-12 Magnet block 101-105 Permanent magnet 201 Case 202a, 202b Housing 203 Bolt 204 Frame B _IN incident beam B _OUT outgoing beam B _F fusing magnetic field E _B Control magnetic field distribution area

Claims (5)

  In a magnetic circuit device disposed in a synchrotron device for accumulating and circulating a charged particle beam, the magnetic particle device is disposed in the vicinity of a controlled magnetic field distribution region satisfying a stable orbit for accumulating the electron beam in the synchrotron device. And a magnetic field generator for generating a magnetic field for removing the influence of the fringing magnetic field generated near the entrance / exit path of the electron beam by the control magnetic field.   2. The magnetic circuit device according to claim 1, wherein the magnetic field generator generates a new reverse magnetic field without affecting the control magnetic field distribution region and corrects the reverse magnetic field. A magnetic circuit device comprising a set of permanent magnets that do not require a magnet.   2. The magnetic circuit device according to claim 1, wherein the magnetic field generator includes a plurality of magnet blocks having magnetization directions along magnetic flux lines in the controlled magnetic field distribution region along the stable orbit. It is composed of an annular coupling structure that is annularly coupled so as to extend in the vicinity, and a predetermined one of the plurality of magnet blocks is provided with a gap serving as a path for entering and exiting the electron beam. A magnetic circuit device comprising:   4. The magnetic circuit device according to claim 3, wherein each of the plurality of magnet blocks has a predetermined number of permanent magnets having different types of magnetization directions, each of which is open at a portion closer to the stable orbit, and generation of a leakage magnetic field can be suppressed. A magnetic circuit device characterized by being combined as described above. A synchrotron device comprising the magnetic circuit device according to claim 1.

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