JPH0374095A - Pulse electromagnet device - Google Patents

Abstract

PURPOSE:To prevent beam instability by forming a beam duct of a part on which a pulse electromagnet is provided, out of a ceramic superconductor or of an insulator, and in the latter case by coating the inside thereof so as to cool it into a superconducting state. CONSTITUTION:A beam duct 1 of a part on which a pulse electromagnet 4 is provided is formed by using a ceramic superconductor so as to obtain a non-superconducting state and high resistivity as well as low critical magnetic field, or by coating (1b) the inside of the beam duct formed out of an insulator with an superconductor and by cooling the superconductor into a superconducting state. When a pulse magnetic field is not applied from the pulse electromagnet, namely, in a driving state of accumulating a charging beam, the superconductor is in a superconducting state, and image current concomitant with the flow of the charging beam flows in the superconductor that is a perfect conductor as a path. Inability of beam is never to be generated thereby.

Description

[Detailed description of the invention] [Industrial application field]

The present invention relates to a pulsed electromagnet device to which a pulsed current is applied, which is used in a particle accelerator such as a synchrotron.
Particularly regarding perturbeta electromagnets.

[Conventional technology]

As this type of pulsed electromagnet, window-frame type electromagnets with iron cores such as ferrite, which have excellent magnetic field uniformity, are often used, but iron core materials such as ferrite emit a lot of gas, so they cannot be used in ultra-high vacuums. There is a problem in inserting the core into the required beam duct, and as shown in FIG.
Pulse electromagnets 4 consisting of coils 3 of iron cores 2 are provided on both sides of the beam duct l. In this case, in order to prevent the pulsed magnetic field emitted from the pulsed electromagnet 4 from flowing as an eddy current in the beam duct l and not passing through the beam duct l, the beam duct l is insulated at the portion where the pulsed electromagnet 4 is installed. However, when the charged beam flows in the beam duct l, the image current induced in the beam duct l stops flowing at the point made of the insulating material, and the charged beam Causes beam instability. Therefore, "Design of UV5OR Storage Ring" Molecular Science Research New Book, UV5OR-9 Magazine (December 1982 issue)
, or “THE RED BOOK”Europe
ean 5ynchrotron Radiation
In Facility (1987! Monthly), the inner surface of a beam duct made of ceramic material was made of gold or other material, with a thickness equal to or less than the penetration depth of the electromagnetic field in the conductor determined by the frequency of the pulsed magnetic field, as a path for the image current. Coating with a thin conductive film 1a is mentioned.

[Problems to be Solved by the Invention] Incidentally, as the ceramic material, sintered alumina is generally used, and when a coating film such as gold is formed on such a ceramic material, the adhesion between the two becomes insufficient. However, problems such as the coating film peeling off and the degree of vacuum decreasing due to localized discharge occur when a pulsed magnetic field is repeatedly applied, and small synchrotrons with short circumferences Alternatively, in the case of a barta-beta electromagnet used in a storage ring, the pulsed magnetic field is approximately IMHz, and in order to sufficiently transmit the pulsed magnetic field of this frequency, the coating film needs to be extremely thin, about 100 mm thick. However, it has been extremely difficult to uniformly coat the inner surface of a ceramic duct over a large area. The present invention has been made to eliminate the above-mentioned problems, and an object of the present invention is to provide a pulsed electromagnet device that has a simple configuration and can operate stably.

[Means to solve the problem]

A pulsed electromagnet device according to the first invention is a pulsed electromagnet device used in a particle accelerator such as a synchrotron, and the beam duct at least in a portion where the pulsed electromagnet is provided has a high resistivity in a non-superconducting state and a critical magnetic field. The method is characterized in that the inner surface of a beam duct made of a ceramic superconductor having a low value or an insulating material is coated with the superconductor, and the superconductor is cooled to a superconducting state. The pulsed electromagnet device according to the second invention is a pulsed electromagnet device used in a particle accelerator such as a synchrotron, and the beam duct at least in the part where the pulsed electromagnet is installed is made of a ceramic material that has 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

[Effect]

In the pulsed electromagnet device according to the first invention, the ceramic superconductor provided as a beam duct or as a coating film on a beam duct made of an insulator is
Since the superconductor is cooled with an appropriate refrigerant, when no pulsed magnetic field from the pulsed electromagnet is applied, that is, in an operating state in which charged beams are accumulated, the superconductor is in a superconducting state, and the charged beam is The image current generated by this flow does not cause beam instability because it flows through the superconductor, which is a perfect conductor. On the other hand, when the charged beam is incident on the beam duct,
When a pulsed magnetic field is emitted from a pulsed electromagnet, the superconducting state is broken only when the emitted pulsed magnetic field exceeds the critical magnetic field of the superconductor, and the superconductor becomes a normal conducting state.
The increased resistivity prevents the pulsed magnetic field from forming eddy currents in the superconductor and allows the pulsed magnetic field to pass through the beam duct. Furthermore, when applying a pulsed magnetic field,
Although the path of the image current is cut off, this time is short and corresponds to several to several dozen layers in terms of the number of turns of the particle, so it does not become a cause of beam instability. In the pulsed electromagnet device of the second invention, a constant current is passed through a superconductor and the critical magnetic field of the superconductor is set to a low value, so that when a particle is incident, a slight pulsed current is applied to the pulsed electromagnet. Just by applying electricity, the superconductor exceeds the critical magnetic field and becomes normally conductive.

【Example】

FIG. 1 shows an embodiment of a pulsed electromagnet device according to the first invention. Note that the same parts as in the conventional example shown in FIG. 3 are given the same reference numerals. The beam duct 1 in the part where the pulse electromagnet 4 consisting 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 coating film 1b is formed of a ceramic superconductor having high resistivity and a low critical magnetic field value in a non-superconducting state. As will be described later, this coating *tb does not easily generate eddy currents, so there is no need to make the coating film extremely thin as in conventional equipment, and the coating process is easy. It can also be composed of only In order to cool the coating film tb to a superconducting state, the pulsed electromagnet 4 is housed in a cryostat 5, which is a cooling container, and the cryostat 5 is filled with a coolant 6 so that the pulsed electromagnet 4 is entirely submerged. The operation of the pulsed electromagnet device having the above configuration will be described below. The coating film lb made of ceramic superconductor is
Since it is cooled to below the critical temperature by the coolant 6, when the pulsed magnetic field from the pulsed electromagnet 4 is not applied, that is, in the operating state in which charged beams are accumulated, the coating I[1b is in a superconducting state. Since the image current generated by the flow of the charged beam flows through this coating @tb, it does not cause beam instability. On the other hand, when the charged beam is incident on the beam duct 1 and the pulsed electromagnet 4 is emitting a pulsed magnetic field,
Only when the generated pulsed magnetic field exceeds the critical magnetic field of the superconductor in the coating film tb, the superconducting state is broken and the coating 1llb enters a normal conductive state and has a high resistivity. As a result, the wax current generated by the pulsed magnetic field in the coating film tb is small, and the pulsed electromagnet 4
The pulsed magnetic field passes through the beam duct 1 containing the coating 1b membrane and acts on the charged beam. Furthermore, as described above, since the application time of the pulsed magnetic field is short, even if the path of the image current is interrupted, it will not cause beam instability. Next, a pulsed electromagnet device according to a second invention will be explained using FIG. 2. Here, a constant current is constantly passed through the coating film 1b, which is a superconductor, using a superconductor conductive lead lc, and the value of the critical magnetic field of the coating film 1b is controlled to be low to keep it in a superconducting state. The accompanying image current is allowed to flow through this coating 1ilb. On the other hand, when particles are incident, by simply passing a small pulse current through the pulsed electromagnet 4, the coating film "b" becomes a normal conduction state exceeding the critical magnetic field and has a high resistivity. The generation of eddy currents is prevented, and the pulsed magnetic field from the pulsed electromagnet 4 is transmitted through the beam duct 1. [Effects of the Invention] As explained above, the present invention allows the pulsed magnetic field to pass through by preventing the generation of eddy current by setting the coating film in a normal conduction state with high resistivity only when a predetermined pulsed magnetic field is applied. Otherwise, beam instability does not occur because the coating film is kept in a superconducting state and the image current can flow as a perfect conductor. Furthermore, there are fewer technical difficulties and troubles during use than with conventional pulsed electromagnet ducts, and it can be easily manufactured and stable operation can be expected. In addition, by selecting an appropriate material in consideration of the correlation between the magnetic field and resistivity of the superconductor, it is possible to change the waveform of the transmitted pulsed magnetic field, making it possible to apply a pulsed magnetic field waveform to the beam that is difficult to create with electric circuits. For example, it can be applied as a perturbator electromagnet for a small storage ring that requires a steeply falling pulsed magnetic field. Furthermore, if a method is used in which a constant current is passed through the superconductor of the duct as in the second invention, by selecting this current value, the same pulsed magnetic field can be transmitted through the duct using superconductors with different superconducting properties. characteristics can be obtained, making it easy to select a superconductor.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing an embodiment of a pulsed electromagnet device according to the first invention, FIG. 2 is a sectional view showing an embodiment of a pulsed electromagnet device according to the second invention, and FIG. FIG. 2 is a cross-sectional view of the pulsed electromagnet device of FIG. 1... Beam duct, 1b... Coating film, 1
c...Superconductor current-carrying lead, 2...Iron core, 3...
Coil, 4... Pulse electromagnet, 5... Cryostat, 6... Refrigerant.

Claims (2)

[Claims] (1) A pulsed electromagnet device used in a particle accelerator such as a synchrotron, in which the beam duct at least in the part where the pulsed electromagnet is installed is made of a ceramic superconductor that has high resistivity in a non-superconducting state and has a low critical magnetic field value. or an insulating material, the inner surface of a beam duct is coated with the superconductor, and the superconductor is cooled to a superconducting state. (2) In a pulsed electromagnet device used in a particle accelerator such as a synchrotron, at least the beam duct in the part where the pulsed electromagnet is installed is made of a ceramic superconductor that has high resistivity in a non-superconducting state, or A pulsed electromagnet device characterized in that the inner surface of a beam duct made of an insulating material is coated with the superconductor, a constant current is passed through the superconductor, and a critical magnetic field value of the superconductor is controlled to a low value. .