JP2008234938A - Method of rapidly intensifying magnetic field of electromagnet, and pulse electromagnet system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of rapidly intensifying a magnetic field of an electromagnet capable of remarkably shortening a rise time until a required strong magnetic field is formed, and expanding the variation width of a magnetic force by turning on/off an excitation current; and a pulse electromagnet system. <P>SOLUTION: This pulse electromagnet 20 is provided with: a magnetic block 21 having a space generating a magnetic field; excitation conductors 23 and 24 arranged along the space of the magnetic block 21; and a high-voltage pulse generator and a pulse transmission line applying a pulse-like excitation currents to the excitation conductors 23 and 24. The magnetic block 21 is excited by setting the current value of the pulse-like excitation current in an irreversible region in the vicinity of a saturation point of the magnetic block 21. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a high-speed strong magnetic field-enhancing method and a pulse electromagnet system that make a magnetic material a strong magnetic field at high speed and extinguish the magnetic field.

  Currently, high energy particle beam accelerators are being used in fields such as elementary particle experiments, nuclear experiments, nuclear medicine (radiotherapy, etc.). Some conventional high energy particle beam accelerators use a pulse electromagnet for orbital deflection in order to deflect the orbit of high energy charged particles (see, for example, Patent Document 1).

FIG. 8 is a diagram illustrating a configuration example of a conventional pulse electromagnet.
A yoke 1 in which silicon steel plates are laminated is arranged on the inner periphery of the iron core frame 11, and a single coil, that is, a septum coil 3 and a return coil 4 are wound around an opening 2 of a C-shaped yoke 1 in which silicon steel plates are laminated. It has been configured. In addition, in the vicinity of the septum coil 3 in the opening 2, conductive plates 6 are provided independently without contacting the septum coil 3. The beam is extracted at the deflecting portion of the beam duct 5 by the magnetic field generated in the opening 2. Reference numeral 9 in the beam duct 5 indicates an exit trajectory, and reference numeral 10 indicates a bump trajectory. Further, a cooling pipe 12 is provided outside the iron core frame 11 in order to remove heat generated by the current flowing through the septum coil 3.

  By the way, when high-energy charged particles accelerated by a small particle accelerator are taken out and used, a high-intensity magnetic field is required. The intensity of the generated magnetic field is inversely proportional to the size of the opening 2 of the pulse electromagnet and proportional to the current flowing through the septum coil. On the other hand, since the size of the opening 2 is determined by the beam size of the charged particles, there is a limit to reducing the size of the opening 2. Therefore, in order to increase the generated magnetic field strength, the current flowing through the septum coil 3 must be increased.

  In order to perform the trajectory deflection of the charged particles as described above, first, the trajectory of the charged particles must be instantaneously deflected from the bump trajectory 10 of the septum electromagnet to the opening 2 of the septum electromagnet. This role is played by the kicker magnet system that can deflect the highest speed among pulsed electromagnets. Since the kicker electromagnet system exists on the orbit, the output should not be output in most of the time zones other than the orbital deflection, because if there is an output, the orbit will be hindered. Therefore, the kicker electromagnet system needs to clearly turn on / off the magnetic field.

  Even in the case of a magnetic material of a soft magnetic material used for the yoke 1 or the like, when the excitation current is increased and a large external magnetic field (irreversible region) exceeding the saturation point is applied, magnetization is performed even after the excitation current is turned off. The state as it was done will be maintained. For this reason, in the conventional magnetization method, when the magnetic material approaches the saturation point, the change width of the magnetic force due to on / off of the excitation current cannot be secured sufficiently.

Therefore, in the conventional method of applying a magnetic field to an electromagnet, a reversible region that is sufficiently far from the saturation point of the magnetic material and has a large gradient of the magnetic force curve is provided as an operation region that can ensure a large change width compared to the vicinity of the saturation point of the magnetic material. I used it.
JP-A-8-288126

  However, in the conventional method of applying a magnetic field to an electromagnet, since the reversible region that is sufficiently away from the saturation point of the magnetic material and has a large gradient of the magnetic force curve is used as the operation region, the magnitude of the excitation current is limited. It has been difficult to further shorten the time (rise time) required for supplying a current to obtain a desired strong magnetic field.

  In addition, in the conventional method of applying a magnetic field to an electromagnet, since only a part of the reversible region where the gradient of the magnetic force curve is large is used, it is difficult to increase the change width of the magnetic force further.

  The present invention can greatly shorten the rise time until a required strong magnetic field is obtained, can increase the range of change in magnetic force by turning on / off the excitation current, and can achieve a large size at high speed. An object of the present invention is to provide a magnetic field increasing method and a pulse electromagnet system.

  The method for increasing the speed of a strong magnetic field of an electromagnet according to the present invention is such that a pulsed excitation current is passed through an exciting conductor disposed along a magnetic material to instantly generate and extinguish the magnetic field in the magnetic material. In this method, the current value of the excitation current is set in a reversible region near the saturation point of the magnetic material to excite the magnetic material.

  According to the high-magnetization method of the electromagnet of the present invention, since the reversible region near the saturation point of the magnetic material is used as the operation region, the rise time until a required strong magnetic field can be obtained can be greatly shortened. The range of change in magnetic force due to on / off of the excitation current can be expanded, and the size can be greatly reduced.

  The pulse electromagnet system of the present invention applies a magnetic excitation block disposed along a gap of the magnetic block, a magnetic block having a gap where a magnetic field is generated, and a pulsed excitation current to the excitation conductor. High-voltage pulse generating means, and the magnetic material block is excited by setting the current value of the excitation current in a reversible region near the saturation point of the magnetic material.

  In the above-described method for increasing the magnetic field at high speed and the pulsed electromagnet system, the reversible region near the saturation point of the magnetic material includes a magnetic material saturation start point at which the rate of increase in magnetic force starts to decrease with increasing excitation current, and an excitation current. A region between the permanent magnetization start point at which the disappearance of the magnetic field is not recognized even when turned off is desirable. Further, the period of the pulsed excitation current is preferably less than 1 KHz so that the high frequency loss of the magnetic material does not become significant.

  According to the present invention, the rise time until a required strong magnetic field can be obtained can be greatly shortened, the change range of the magnetic force due to the on / off of the excitation current can be expanded, and the size can be greatly reduced. .

If the period of the excitation current for generating a magnetic field in the magnetic material is less than 1 KHz, the inventor outputs 0 when the excitation current is turned off even if the current value of the excitation current is increased to near the saturation point of the magnetic material. Or it discovered that it returned to 0 vicinity. In other words, the area that was previously considered unusable as the operating area can increase the current value of the excitation current to near the saturation point of the magnetic material depending on the excitation period of the magnetic material, and accordingly the startup time is fast. It has been found that a high magnetic field and a high magnetic field are possible.
Hereinafter, an embodiment of the present invention will be specifically described with reference to the drawings.
The operation region of the pulse electromagnet used in the high-speed magnetic field method according to the present embodiment will be described with reference to FIG.

  FIG. 1 is a diagram showing a relationship between an exciting current and a generated magnetic force in a pulse electromagnet. As shown in the figure, the generated magnetic force increases linearly in proportion to the magnitude of the excitation current up to the magnetic material saturation start point P1 where the magnetic force increase rate starts to decrease with increasing excitation current. A region from the magnetic material saturation start point P1 to the permanent magnetization start point P2 where the disappearance of the magnetic field is not recognized even when the excitation current is turned off (referred to as “OCEM region (Over-Current Excitation Method)” in this specification). In this case, the gradient of the magnetic force curve becomes gentle, and the generated magnetic force hardly changes even when the excitation current is increased after the permanent magnetization start point P2. That is, until the magnetic material saturation start point P1, the magnetic force of the magnetic material is lost if the excitation current is turned off even in the conventional magnetic field method. From the magnetic material saturation start point P1 to the permanent magnetization start point P2, the conventional magnetic field method is used. Even if the exciting current is turned off, the magnetic material remains in the magnetic material, but it is a reversible region where reversibility is recognized. Further, the permanent magnetization starting point P2 and thereafter is an irreversible region in which the magnetic material does not output the original magnetic force even if the magnetic material is converted into a permanent magnet and the excitation current is turned off. In the conventional method, even in the reversible region, an operation region (A) where the gradient of the magnetic field lines is large and the excitation current is less than 5 KA is used. In the following description, the operation area (A) is referred to as a conventional area.

  In the present embodiment, it is assumed that the OCEM region (B) in which the excitation current from the magnetic material saturation start point P1 to the permanent magnetization start point P2 is large and the gradient of the magnetic field lines is small is used. In the OCEM region (B), the exciting current is as large as 9 KA to 20 KA, and the generated magnetic force is several times larger than that in the conventional region (A).

FIG. 2 is a cross-sectional view of the pulse electromagnet of the present embodiment.
The magnetic block 21 is made of a high electrical resistance ferrite material. The magnetic block 21 has a rectangular tubular body as a whole, and a septum coil 23 and a return coil 24 as excitation conductors are inserted through the central gap portion 22. When applied to a high energy particle beam accelerator, the center of the central gap 22 is the beam trajectory P.

  FIG. 3 is a system configuration diagram for flowing an exciting current through the exciting conductors (23, 24) of the pulse electromagnet. The high voltage pulse generator 30 has a capability of generating a pulse current of up to 20 KA with a rise time of 0.1 μsec and a time length of 1.3 μsec. The pulse current generated by the high voltage pulse generator 30 is applied to one end of the pulse electromagnet coil 23 via the pulse transmission line 31. The other end of the coil 23 is connected to one end of the return coil 24, and the other end of the return coil 24 is connected to the ground. The dimensions of the magnetic block 21 are adjusted so that the operating area of the pulse electromagnet is the OCEM area (B) in FIG. In this embodiment, a ferrite material is used as a magnetic material that can withstand the pulse current.

  Comparison results of high-speed characteristics between the conventional pulse electromagnet using the conventional region (A) and the pulse electromagnet of the present embodiment using the OCEM region (B) will be described.

  The basic structure and parameters of the conventional pulse electromagnet used for measuring the output characteristics shown in FIG. 4 and the pulse electromagnet of this embodiment are as shown in the basic design example of FIG. The actual measurement values of the dimensions are shown in FIG. The conventional pulse electromagnet used a distributed constant capable of generating the strongest magnetic field and a total reflection current utilizing type. The pulse width of the excitation current was 1.3 μsec.

  As shown in FIGS. 4 and 6, when excitation is performed using the conventional region (A) with a conventional pulse electromagnet, the time until the maximum output is obtained (rise time) is 0.969 μsec. On the other hand, when excitation is performed using the OCEM region (B), the time until the maximum output is obtained (rise time) is 0.467 μsec, and the rise time is about twice as long in this embodiment. It turns out that it is speeding up.

  Further, according to the present embodiment using the OCEM region (B), if an output equivalent to that of the conventional pulse electromagnet using the conventional region (A) is to be obtained, the size of the magnetic material is greatly reduced as shown in FIG. I understand that I can do it.

  FIG. 7 is a dimension comparison diagram in the case where the conventional pulse electromagnet and the pulse electromagnet of the present embodiment are designed under the condition that the magnetic field performance generated in the central gap portion of the magnetic block is equivalent. FIG. 2A shows a conventional pulse electromagnet, and FIG. 2B shows a pulse electromagnet of the present embodiment. As shown in the figure, the conventional pulse electromagnet requires a large metal electrode plate 41 on the outer periphery of the magnetic block 40 in order to achieve high speed performance. On the other hand, in the present embodiment, the metal electrode plate 41 is unnecessary, and at the same time, it is used in the OCEM region, and the volume of the magnetic block 21 itself can be reduced. For this reason, in this embodiment, the overall size can be greatly reduced as compared with the conventional pulse electromagnet.

  The output waveform shown in FIG. 4 is normalized by the value of the upper flat portion for comparison, but the maximum output (upper flat portion) when using the OCEM region (B) is 0.3 T, and the conventional region ( A) The maximum output during use was 0.1T. That is, by using the OCEM region (B), it is possible to realize a magnetic force that is three times stronger than when the conventional region (A) is used.

  As described above, in the present embodiment, the pulse electromagnet is changed to a high-speed magnetic field using the OCEM region (B), so that the maximum output is obtained as compared with the pulse electromagnet used in the conventional region (A). In addition, the rise time of the magnetic field can be greatly shortened, and the magnetic force change width that is the width between the maximum output when the excitation current is applied and the output when the excitation current is turned off (for example, 0) can be expanded. In addition, the magnetic block itself and the entire pulse electromagnet can be greatly reduced.

  In the above description, the pulse electromagnet suitable for bending the traveling direction of the charged particle in the high energy particle beam accelerator and the method for making the magnetic field at a high speed strong magnetic field accelerator have been described. Any application that repeats generation and disappearance of magnetic force on the order of 1 μsec) is applicable.

  The present invention can be applied to a pulsed electromagnet system that makes a magnetic material a strong magnetic field at high speed and extinguishes the magnetic field.

Characteristics diagram of generated magnetic force-excitation current shown in comparison with the OCEM region used in the present embodiment and the conventional region used conventionally. Sectional view of pulse electromagnet of this embodiment System configuration diagram for applying excitation current to the excitation conductor of a pulse electromagnet Output characteristic diagram showing a comparative example of output characteristics of the conventional pulse electromagnet and the pulse electromagnet of the present embodiment The figure shown in the basic design example of the basic structure and parameters of the conventional pulse electromagnet and the pulse electromagnet of the present embodiment The figure which shows the actual value of the output high-speed characteristic and magnetic body dimension of the conventional pulse electromagnet and the pulse electromagnet of this Embodiment Comparison of dimensions between conventional pulse electromagnet and pulse electromagnet of this embodiment Configuration of conventional pulse electromagnet

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Yoke 2 ... Opening part 3 ... Septum coil 4 ... Return coil 5 ... Beam duct 6 ... Conductive board 10 ... Bump track 11 ... Iron core frame 12 ... Cooling pipe P1 ... Magnetic material saturation start point P2 ... Permanent magnetization start point DESCRIPTION OF SYMBOLS 20 ... Pulse electromagnet 21 ... Magnetic body block 22 ... Central space | gap part 23 ... Coil 24 ... Return coil

Claims (5)

A method for increasing the speed and strength of an electromagnet causing a magnetic field to be generated and extinguished instantaneously by passing a pulsed excitation current through an exciting conductor disposed along a magnetic body,
An electromagnet high-speed magnetic field-enhancing method characterized by exciting the magnetic material by setting the current value of the exciting current in a reversible region near the saturation point of the magnetic material.   The reversible region near the saturation point of the magnetic material is a magnetic material saturation start point at which the rate of increase in magnetic force begins to decrease with an increase in excitation current, and a permanent magnet that disappears even when the excitation current is turned off. 2. The method for forming a high-speed strong magnetic field in an electromagnet according to claim 1, wherein the region is between the start point and the starting point.   3. The method for producing a high-speed strong magnetic field in an electromagnet according to claim 1, wherein the period of the pulsed excitation current is less than 1 KHz.   The maximum output is 0.3 [T] by the pulsed excitation current having a time length of about 1 μsec, and the time required to reach the maximum output is 0.4 μsec. Item 4. The method for producing a high-speed strong magnetic field of the electromagnet according to any one of Items 3. A magnetic block having a gap for generating a magnetic field; an excitation conductor disposed along the gap of the magnetic block; and a high-voltage pulse generating means for applying a pulsed excitation current to the excitation conductor. A pulse electromagnet system that excites the magnetic block by setting a current value of the excitation current in a reversible region near a saturation point of the magnetic body.

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