JP2862090B2 - Pulse electromagnet device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial applications]

The present invention relates to a pulse electromagnet apparatus to which a pulse current is applied, which is used for a particle accelerator such as a synchrotron, and particularly to a perta beta electromagnet.

[Prior art]

As this type of pulsed electromagnet, a window frame type electromagnet using an iron core such as ferrite, which is excellent in magnetic field uniformity, etc., is often used. However, as shown in FIG. 3, there is usually a problem in that the window core is provided around the beam duct 1 and the cores 2 provided on both sides of the beam duct 1. Coil 3
A pulse electromagnet 4 is provided. In this case, the beam duct 1 where the pulse electromagnet 4 is provided is insulated so that the pulse magnetic field generated from the pulse electromagnet 4 does not flow as eddy current in the beam duct 1 and does not pass through the beam duct 1. It is necessary to use a ceramic or the like as an object, but the image current induced in the beam duct 1 due to the flow of the charged beam in the beam duct 1 stops flowing at the portion made of the insulator, and the Causes beam instability. Therefore, "Design of UVSOR Storage Ring" by Institute for Molecular Science, UVSOR-9 magazine (December 1982), or
“THE RED BOOK” European Synchrotron Radiation Faci
In lyty (January 1987), on the inner surface of the beam duct 1 made of ceramic material, as a path for image current, the thickness was set to be less than the electromagnetic field penetration depth in the conductor determined by the frequency of the pulse magnetic field, such as gold. Coating a thin conductive film 1a is described.

[Problems to be solved by the invention]

Incidentally, as the ceramic material, a material obtained by sintering alumina is generally used. When a coating film such as gold is formed on such a ceramic material, the adhesion between the two is likely to be insufficient, and a pulse magnetic field is repeatedly applied. In the meantime, the coating film is peeled off, problems such as a decrease in vacuum due to local discharge are likely to occur, and a pertabeta magnet used for a small synchrotron or a storage ring with a short circumference has the following disadvantages. A pulse magnetic field of about 1 MHz is required.To sufficiently transmit a pulse magnetic field of this frequency, the thickness of the coating film must be an extremely thin film of about 100 mm, but the inner surface of the ceramic duct must be covered over a large area. It was extremely difficult to coat uniformly. The present invention has been made in order to eliminate the above-described problems, and has as its object to provide a pulse electromagnet device capable of performing stable operation with a simple configuration.

[Means for Solving the Problems]

A pulse electromagnet apparatus according to a first aspect of the present invention is a pulse electromagnet apparatus used for a particle accelerator such as a synchrotron, and at least a beam duct at a portion provided with a pulse electromagnet is changed from a superconducting state by applying a pulse from the pulse electromagnet. It is composed of a ceramic superconductor having a critical magnetic field value that switches to a normal conducting state, or the inner surface of a beam duct composed of an insulator is coated with the superconductor, and the superconductor is cooled to a superconducting state. Features. A pulsed electromagnet apparatus according to a second aspect of the present invention is a pulsed electromagnet apparatus used for a particle accelerator such as a synchrotron, wherein at least a beam duct at a portion where the pulsed electromagnet is provided has a high resistivity in a non-superconducting state. The inner surface of a beam duct made of a superconductor or an insulator is coated with the superconductor, a constant current is passed through the superconductor, and the critical magnetic field value of the superconductor is controlled to a low value. It is characterized by the following.

[Action]

In the pulsed electromagnet apparatus according to the first aspect of the invention, the ceramic superconductor provided as a beam duct or as a coating film on the beam duct made of an insulator is cooled by an appropriate coolant, so that the pulsed electromagnet is used. When no more pulsed magnetic field is applied, that is, in an operation state in which a charged beam is accumulated, the superconductor is in a superconducting state, and the image current generated with the flow of the charged beam becomes a perfect conductor. Since the superconductor flows as a passage, it does not cause beam instability. On the other hand, when the charged beam is incident on the beam duct and a pulsed magnetic field is emitted from the pulsed electromagnet,
By the generated pulse magnetic field, only when the critical magnetic field of the superconductor is exceeded, the superconducting state is broken and the superconductor becomes a normal conducting state, and the resistivity increases, so that the pulse magnetic field becomes an eddy current in the superconductor. And the pulsed magnetic field penetrates the beam duct. When a pulse magnetic field is applied, the path of the image current is cut off. However, this time is short, and the number of rounds of the particle is equivalent to several to several tens of rounds. It does not cause instability. In the pulse electromagnet device according to the second aspect of the present invention, by applying a constant current to the superconductor and setting the critical magnetic field of the superconductor to a low value, a small pulse current is applied to the pulse electromagnet when particles are incident. , The superconductor exceeds the critical magnetic field and enters a normal conducting state.

【Example】

FIG. 1 shows an embodiment of the pulse electromagnet apparatus according to the first invention. The same parts as those in the conventional example of FIG. 3 are denoted by the same reference numerals. The beam duct 1 at the portion where the pulse electromagnet 4 composed of the iron core 2 and the coil 3 is provided is made of a ceramic material. On the inner surface of this ceramic material, a ceramic material having a high resistivity in a non-superconducting state and a low critical magnetic field value is provided. A coating film 1b is formed by the superconductor described above. Since the eddy current hardly occurs in the coating film 1b as described later, it is not necessary to make the coating film extremely thin unlike the conventional device, so that the coating operation is easy and the beam duct 1 is connected to the superconductor. It can also be constituted only by. In order to cool the coating film 1b to a superconducting state, the coating film 1b is accommodated in a cryostat 5 which is a cooling container including the pulse electromagnet 4, and the cryostat 5 is filled with the refrigerant 6 so that the entire pulse electromagnet 4 is immersed. The operation of the pulse electromagnet device having the above configuration will be described below. The coating film 1b made of a ceramic superconductor
The cooling film 6 is cooled below the critical temperature, so that when the pulse magnetic field from the pulse electromagnet 4 is not applied, that is, in an operation state in which a charged beam is accumulated, the coating film 1b is in a superconducting state. Since the image current generated by the flow of the charged beam flows through the coating film 1b, the beam does not cause instability. On the other hand, when the charged beam is incident on the beam duct 1 and a pulsed magnetic field is generated from the pulsed electromagnet 4, the generated pulsed magnetic field only causes the coating film 1b to exceed the critical magnetic field of the superconductor. Then, the superconducting state is broken, and the coating film 1b enters a normal conducting state, and the resistivity increases. As a result, the pulse magnetic field is changed to the coating film 1b.
Generates a small eddy current, and the pulse magnetic field from the pulse electromagnet 4 passes through the beam duct 1 including the coating 1b film and acts on the charged beam. Further, as described above, since the application time of the pulse magnetic field is short, even if the path of the image current is cut off, it does not cause beam instability. Next, a pulse electromagnet device according to the second invention will be described with reference to FIG. Here, a constant current is always passed through the superconductor conducting lead 1c to the coating film 1b, which is a superconductor, and the superconducting state is maintained while controlling the value of the critical magnetic field of the coating film 1b to be low to keep the flow of the charged beam. The accompanying image current flows through the coating film 1b. On the other hand, when particles are incident, the coating film 1b can be formed by applying a slight pulse current to the pulse electromagnet 4.
Is in a normal conduction state beyond the critical magnetic field, and has a high resistivity, so that eddy current is prevented from being generated in the coating film 1b, and the pulse magnetic field from the pulse electromagnet 4 is
Through.

【The invention's effect】

As described above, the present invention makes it possible to transmit a pulse magnetic field by preventing the generation of eddy current by setting the coating film to a high resistivity state in a normal conduction state only when a predetermined pulse magnetic field is applied, Since the film is kept in a superconducting state so that an image current can flow as a perfect conductor, beam instability does not occur. Moreover,
There are few technical difficulties and troubles during use as with conventional ducts for pulsed electromagnets, it can be easily manufactured, and stable operation can be expected. Also, by selecting an appropriate material in consideration of the correlation between the magnetic field and resistivity of the superconductor, the waveform of the transmitted pulse magnetic field can be deformed, so that a pulse magnetic field waveform that is difficult to create with an electric circuit can be applied to the beam. Thus, for example, the present invention can be applied as a pertabeta electromagnet of a small storage ring requiring a steep falling pulse magnetic field. In addition, if a constant current is supplied to the superconductor of the duct as in the second invention, by selecting this current value, the same pulse magnetic field transmission can be performed even in a duct using a superconductor having different superconducting characteristics. Characteristics can be obtained, and selection of a superconductor becomes easy.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing one embodiment of the pulse electromagnet device according to the first invention, FIG. 2 is a cross-sectional view showing one embodiment of the pulse electromagnet device according to the second invention, and FIG. It is sectional drawing of the pulse electromagnet apparatus of FIG. DESCRIPTION OF SYMBOLS 1 ... Beam duct, 1b ... Coating film, 1c ... Superconductor energizing lead, 2 ... Iron core, 3 ... Coil, 4 ... Pulse electromagnet, 5 ... Cryostat, 6 ... Refrigerant.

Claims (2)

(57) [Claims] 1. A pulse electromagnet device used for a particle accelerator such as a synchrotron, wherein at least a beam duct at a portion provided with a pulse electromagnet is switched from a superconducting state to a normal conducting state by application of a pulse from the pulse electromagnet. A pulsed electromagnet device comprising a ceramic superconductor having a critical magnetic field value or an inner surface of a beam duct formed of an insulating material coated with the superconductor and cooling the superconductor to a superconducting state. . 2. A pulse electromagnet apparatus used for a particle accelerator such as a synchrotron, wherein at least a beam duct at a portion where the pulse electromagnet is provided is made of a ceramic superconductor having a high resistivity in a non-superconducting state. Alternatively, the inner surface of a beam duct made of an insulator is coated with the superconductor, a constant current is applied to the superconductor, and the critical magnetic field value of the superconductor is controlled to a low value. Electromagnet device.