JPS63272012A - Fan-shaped deflection magnet with iron magnetic pole - Google Patents

Abstract

PURPOSE:To secure a favorable uniformity of a magnetic field over the whole circumference of a deflection magnet by providing slits at an iron core yoke part where the deflection magnet is made up and by making heights of the slits increase or decrease in order from an entrance to a center part of an electron orbit. CONSTITUTION:At a fan-shaped deflection magnet where a pair of magnetic poles 3 of a magnetic substance and a pair of deflection coils 1 at least are mounted in an arc-like hollow part that is formed at a magnetic substance yoke 2, slits 4 are provided at the magnetic substance yoke part 2 of inner and outer circumference sides located at a charged particle orbit part 5 and this device allows height dimensions Hout of the slits to vary with the change of an azimuth theta. For example, non-magnetic materials are inserted in the above slits 4 and the slits 4 where their height dimensions Hout are made up in the form of stepped parts, for example, are provided at an interval where the azi muth theta is a little less than 30 deg. in the case of the magnetic substance yoke 2 of the fan-shaped deflection magnet where theta=180 deg..

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a deflection magnet for an industrial small-sized electron storage ring, and more particularly to a fan-shaped deflection magnet with iron magnetic poles that has been improved so that magnetic field uniformity can be maintained over the entire circumference. It is something.

[Prior art]

Once is required.

FIG. 4 is a horizontal cross-sectional view of a conventional deflection magnet, and FIG. 5 is a cross-sectional view taken along line B--B.

The deflection magnet of this example has a structure in which a sector-shaped magnetic yoke 2 is provided with an arc-shaped hollow part, and a pair of magnetic poles 3 and a pair of deflection coils 1 are provided in the hollow part.

Regarding this type of deflection magnet, please refer to "Design of Superferritic Magnet for Marichi TEV Storage Ring" (DF, 5IGN OF 5UPERFE).
! RRICMAGNETS FOR＾ Aul, TI
-TEV 5TORAGE RING Farw+i National Accelerat
or LaboratoryBatavia, l1li
nois) is well known.

[Problem that the invention seeks to solve]

The known example of the deflection magnet according to the above-mentioned conventional technology has a wavelength of λ
Since the cross-sectional shape is the same regardless of the azimuth, good magnetic field uniformity cannot be obtained over the entire circumference of the electron orbit.

FIG. 6 is a chart showing the uniformity of the magnetic field in the above-mentioned known example.

This chart (Fig. 6) shows the magnetic field distribution when the values of θ shown in Fig. 4 are 10', 30°, 50°, 70', and 90°, respectively.

In the area where θ is close to 90°, the magnetic field density is relatively uniform, but in the area close to Oo it is non-uniform, making accumulation of the electron beam impossible.

The present invention has been made in view of the above-mentioned circumstances, and its object is to provide a fan-shaped deflection magnet with iron magnetic poles that has good magnetic field uniformity over the entire circumference.

[Means for solving problems]

The above purpose is to provide a slit in the iron core yoke that constitutes the deflection magnet, and to increase the height of the slit from the entrance of the electron orbit to the center of the electron orbit in a sequential manner (including a stepwise increase) or to decrease the height in a stepwise manner. (including).

[Effect]

When the above configuration is applied and a slit is provided in the core yoke portion, the magnetic field of the slit portion is reduced. The rate of decrease is determined by the two dimensions p of the slit shape, particularly the height dimension of the slit. Utilizing this fact, the magnetic field gradient in the gap can be adjusted, and good magnetic field uniformity can be ensured over the entire circumference of the deflection magnet.

〔Example〕

FIG. 1 is a horizontal sectional view of one embodiment of the present invention, and FIG. 2 is an AA sectional view thereof. This deflection magnet is an improved one by applying the present invention to the conventional deflection magnet shown in FIG. This is because we have established the following. (See Figure 1) The azimuth angle θ is determined as follows.

Assuming the direction of the edge of the end of the fan-shaped magnetic yoke 2 (indicated by the arrow X'), the angle θ made with this direction represents the azimuth angle. be.

FIG. 3 is a chart in which the horizontal axis represents the azimuth angle θ, and the vertical axis represents the height H8□ of the slit.

The slit 4 of this embodiment has a height dimension shaped like a single step, as shown by curve a in FIG. Immediately, θ=
A slit 4 is provided in a portion close to O (an area where θ is slightly less than 30°).

As in the conventional example, in the magnetic field distribution of a deflection magnet whose cross-sectional shape is constant regardless of the azimuth angle θ, as shown in FIG. 6, the uniformity of the magnetic field deteriorates as it approaches the end. In the example of FIG. 6, the magnetic field distribution is shown upward to the right in the radial direction at the end.

As a preface to explaining the effects of this embodiment, let us assume an example of the magnetic field distribution when the slit is provided all around the circumference and its height dimension H out changes with the azimuth angle. It will look like the figure. That is, FIG. 7 is an example in which numerical calculations were performed using Hout as a parameter with a two-dimensional cylindrical symmetry, and the height dimension of the slit was sequentially increased in the direction of the arrow in the figure. From this figure, it can be seen that as the Hout dimension increases sequentially, the magnetic field distribution upward to the right gradually becomes flat, and finally becomes the magnetic field distribution upward to the right.

Therefore, by providing a slit 4 of a certain height at the end, a uniform magnetic field distribution in the form of a superposition of FIGS. 6 and 7 can be obtained.

As a different embodiment from the above, the height of the slit H out may be continuously changed with the azimuth θ, as shown by curve b in FIG. Further, as a further different embodiment, the curve C may be changed in multiple stages.

Furthermore, depending on the design conditions, it is possible to construct a magnetic field distribution in which the magnetic field distribution shifts to the lower right as the azimuth angle becomes smaller, contrary to the distribution shown in FIG. In such a case, as shown in the sectional view of FIG. 8, a nonmagnetic slit 4 having a height Hin that changes with the azimuth θ is provided on the inner peripheral side of the magnetic yoke 2.

Then, according to the above-mentioned calculation method, H
As i.sub.n increases, a magnetic field that slopes upward to the right is obtained, so it can be seen that if H+n is set to increase from the center of the deflection magnet to the ends, good magnetic field uniformity can be obtained.

Although the above description has been made regarding the case where a slit is provided in the iron yoke, it is clear that the same effect can be obtained even if a non-magnetic material is inserted into a part of the slit 1.

〔Effect of the invention〕

As explained above, by applying the present invention, it is possible to construct a fan-shaped magnet with iron magnetic poles having good magnetic field uniformity over the entire circumference.

[Brief explanation of drawings]

FIG. 1 is a plan sectional view of one embodiment of the present invention. FIG. 2 is a sectional view taken along line AAa in FIG. FIG. 3 is a chart showing changes in the height of the non-magnetic slit provided on the outer circumference of the magnetic yoke with respect to the azimuth angle. FIG. 4 is a plan sectional view of a conventional deflection magnet which has a constant cross section regardless of the azimuth angle of zero. 5th @ is a sectional view taken along the line BB in FIG. 4. Fig. 6 is a chart showing the magnetic field homogeneity of the conventional deflection magnet shown in Fig. 4, and Fig. 7 is an example of calculating the magnetic field homogeneity with two-dimensional cylindrical symmetry using H8ut as a parameter in Fig. 1. This is a diagram to explain. FIG. 8 is a longitudinal sectional view of an embodiment in which a non-magnetic slit is provided on the inner peripheral side of the magnetic yoke of the deflection magnet. Figure 9 shows Hs in Figure 8.
, 1 is a chart showing an example of calculating a magnetic field distribution with two-dimensional cylindrical symmetry using parameters. 1... Deflection coil, 2... Magnetic yoke, 3...
Magnetic material height 3 days' ri 0 躬 4 fig. S fig. 6 fig. '1 范 8 fig. q fig.

Claims (1)

[Claims] 1. In a fan-shaped deflection magnet in which at least one pair of magnetic poles and a deflection coil are provided in an arc-shaped hollow part formed in a magnetic yoke, the inner peripheral side of the charged particle orbital part and a sector-shaped deflection magnet with iron magnetic poles, characterized in that a slit is provided in the magnetic yoke portion on the outer peripheral side, and the height dimension of the slit is changed according to the azimuth angle. 2. The fan-shaped deflection magnet with iron magnetic poles as set forth in claim 1, wherein the slit has a non-magnetic material inserted therein.