JPS59158505A - Superconductive equipment - Google Patents

Abstract

PURPOSE:To reduce the number of power leads and reduce the heat invasion into a superconductive magnet by a method wherein the density of each isolated winding is varied in accordance with the required magnetic field distribution and those isolated windings are excited in series. CONSTITUTION:A superconductive coil is composed of a plurality of isolated windings divided along the axial direction and the winding density of each isolated winding is varied in accordance with the required magnetic field distribution and those isolated windings are excited in series. For instance, the isolated windings 2A, 2B, 2C of the superconductive coil are connected in series and these windings are wound in such a manner that their density N(l) versus the position (l) of the coil along the center axis is thicker at the positions of the isolated windings 2A, 2C of both sides.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a superconducting device υ, and more specifically to a coil winding method for making a magnetic field distribution into a predetermined distribution.

[Prior art]

Recently, superconducting magnets have been used for millimeter wave oscillation tubes (Gyroto, Ron), nuclear resonance resonance CT (Computer Tomo
graphy), etc.

In these application fields, superconducting magnets are used as a means to constantly generate a uniform magnetic field or a magnetic field with a certain gradient in a certain region on the axis of a coil.

In the conventional superconducting equipment used for this building, in order to obtain the desired magnetic field distribution, ffA, which constitutes the superconducting magnet, is used in order to obtain the desired magnetic field distribution.
A method is adopted in which the electric coil is divided into a plurality of parts in the axial direction and the excitation current supplied to each divided coil is adjusted independently. For example, as shown in Fig. 1 [F], the superconducting coil 2 housed in the cryostat 1 is divided into three parts, and in order to obtain a uniform magnetic field distribution in the central region 4 of these windings (Fig. 1 [F])). It is necessary to make the value of the excitation current 2 of the two divided windings 2c located at both ends slightly larger than that of the divided winding 2B located at the center (FIG. 1(C)). Furthermore, the first
In Figure (g), a3), the solid line shows the magnetic field distribution and the excitation current in the case of a uniform magnetic field, and the broken line shows the magnetic field distribution and excitation current in the case of a gradient magnetic field, respectively.

Now, in order to make the excitation current value of the divided windings 2h and 2c at both ends much higher than that of the divided winding 2B, three power supplies 1.6 and 17°18 were used as shown in Figure 2. The excitation current L is applied to each divided winding 2A, 2B, and 2C independently.
, I2 , I3 (II≧12) I, =I. ) was playing. Therefore, power supply 16° 17.18JJ each divided winding 2
A, 2B, 2CK, 6 power leads 10, 11, 12, '13, 14, 15 are required to pick up the power leads. Normally, the amount of heat intrusion from room temperature into a superconducting device is controlled by the number of power leads, which in turn determines the amount of liquid helium consumed. And the amount of heat intrusion from the power lead is 1 DC (excitation current)
■Since it is proportional to the square of o, in the conventional example shown in FIG. 2, the current flowing through each power lead 10 to 150 is ■. Since the values are close to each other, the heat intrusion itW is W≧6x f (, I7) ・・・・・・・・・
(1) becomes. However, in the above formula, if r(itF)≧,
[(k is a constant). In other words, if a superconducting coil is divided into N parts in order to obtain a predetermined magnetic field distribution, the amount of heat penetration will be approximately N times that of a single coil, and the amount of liquid helium consumed will increase significantly. There were drawbacks.

[Object of the present invention]

An object of the present invention is to provide an entire superconducting device in which the amount of heat entering a superconducting magnet is reduced by reducing the number of power leads.

[Summary of the invention]

The present invention is a super 'PIL' which uses seven super electric coils that are divided and wound in the axial direction. 4 device, by changing the winding density of the valley-divided winding according to the required magnetic field distribution and by configuring these divided windings to be excited in series, the number of divisions of the superconducting coil can be changed in a similar manner. The number of power leads can be reduced to two to reduce the number of heat-invading vehicles.

[Embodiments of the invention]

An embodiment f of the present invention is shown in FIG. As shown in Figure 2), each divided winding 2A, 2B of the superconducting coil.

2C are connected in series, and the winding density N(4) of these windings is dense with the divided windings 2A and 2C at both ends, as shown in the same figure (B), with respect to the position #t on the central axis of the coil. is wrapped around. In this case, the winding density N (force) of each divided winding is determined as shown below.

For example, the total length of a superconducting coil (cylindrical coil).

The distance from the end of the coil to any point on the central axis of the coil is l, the coordinate axis indicating the position in the direction of the central axis of the coil is y, and the coordinate axis orthogonal to the y-axis is the total magnetic field distribution B(y) If the magnetic field formed by the winding between the distance t and L + dt is G (y, !-), then the magnetic field B (y) formed in the entire superconducting coil can be expressed as Ru.

Bυ)=fN(4)G (y, t') d4 ... Curve (2) From the above equation (2), determine the winding density N (Ak) that forms the desired magnetic field distribution.In this way, each When the same excitation current is passed through the windings 2A, 2B, and 2C of the winding density N (4), a predetermined current density and magnetic field distribution are obtained. The configuration is shown in Figure 4.As shown in the figure, the cryostat 1
The divided windings housed within 0 are serially excited by the power supply 20. Note that the resistors R1, R2, and R3 are protective resistors.

In this way, in this example, a predetermined magnetic field distribution can be obtained by series excitation, so even if the coil is divided into 3 parts, the power lead is 2.
A book is sufficient, and the conventional example shown in Fig. 2 is insufficient. In this case, only one power supply is required. Next, FIGS. 5 and 6 show another embodiment of the present invention. In this example, in order to make the magnetic field distribution formed by the superconducting coil a predetermined distribution, not only the winding density of each divided winding is changed, but also the fine adjustment of the excitation current is applied to each divided winding. A power source is provided to correct the magnetic field distribution. In other words, when adjusting the winding density of the coil, there is a limit to the uniformity of the magnetic field, etc. due to the winding precision, etc., and it is approximately 1%.
The extent is the limit. In order to achieve greater uniformity, it is necessary to finely adjust the excitation current to each divided winding. For this purpose, in this embodiment, as shown in FIG. 5, in addition to the main power supply 33, a fine adjustment power supply: 31.
, 2C is the excitation current ■ from the main power supply 33. In addition to correction current ■. A current containing I + IO1+IO2 flows.

This state is shown in FIG. At this time, the correction current ■. ,.

Since the magnetic field distribution of IO2 is adjusted by the winding density of each divided winding, the exciting current is ■. Approximately 1% of the amount is sufficient.

Therefore, the correction current■. l r The amount of heat input W from the power lead 36.37 required to flow IO2 is I,
! ≧101' + I6: Therefore, it can be ignored, and even if the number of power leads is increased by two, the amount of heat penetration W is the same as in the embodiment shown in FIG.

In this way, according to this embodiment, the magnetic field distribution can be improved with certainty +cg
ll adjustment is possible.

In addition, in the embodiment described above, only a superelectric coil was explained, but it is also applicable to a normal conductive coil. - Also, in the embodiment, the case of a three-divided winding has been described, but the present invention is not limited to this.

As explained above, in the present invention, in a superconducting device having a superconducting coil that is divided and wound into a plurality of parts in the axial direction, the winding density of each divided winding is changed according to the required magnetic field distribution, and Since the divided windings are configured to be excited in series, according to the present invention, the power lead is subject to equal constraints [2
It is possible to realize a high-precision superconducting device that only requires a book and completely reduces the amount of heat intrusion.

[Brief explanation of the drawing]

Figure 1 shows the relationship between the winding structure of a superconducting coil, magnetic field distribution, and excitation current of each winding in a conventional superconducting device.
An explanatory diagram, FIG. 2 is a circuit diagram of a conventional superconducting device in which the superconducting coil shown in FIG. 4 is a circuit configuration diagram of a superconducting device in which the superconducting coil shown in FIG. 3 is used, and FIG. 5 is a circuit configuration diagram of a superconducting device showing another embodiment of the present invention. 6 are diagrams showing the characteristics of the excitation current flowing through the valley-divided windings 2'A, 2B, and 2C in FIG. 5. 1, 10 = 7 (male 7, 2A, 2B,
2C...divided winding, 31.32...power supply for fine adjustment,
33...11 Figure 7 1) L,
-1112-J -Ir Funeral Figure 3 Figure 4-(G) 0 Funeral Figure 5 Figure 6] I1-4 Standing

Claims (1)

[Claims] 1. In a superconducting device having a superconducting coil divided and wound in a plurality of parts in the axial direction, the winding density of each divided winding is changed according to the required magnetic field distribution. A superconducting device characterized in that these divided windings are excited in series. 2. A patent claim characterized in that the divided windings located at both ends of the superconducting coil are wound so that the winding density thereof is denser than that of the divided windings in the cow's core. A superconducting device according to scope 1. 3. The device according to claim 1 or 2, characterized in that some or all of the plurality of divided windings are provided with a power source for fine adjustment of the excitation current. Superconducting device.