JPS5827308A - Generator of magnetic field - Google Patents

Abstract

PURPOSE:To obtain a directional magnetic field proportional to the value at the observed point by a method wherein current oppositely polarized with the same value is supplied to each coil in order to maintain the relation the radius of the center of the coil section rqX3<0.5>/2=(the distance between the center of the coil and Z=0 plane). CONSTITUTION:For a pair of circular current loops arranged in a manner that an axis Z is their common central axis and symmetrical against the Z=0 plane, the values of currents flowing in the loops are made equal, whereas their directions are opposite. The radius of the loop and the distance between the loop and the Z=0 plane are set to rq and Zq, respectively. When the functions g<(2)> (rq, Zq) commonly combined with the expansion terms of the second degree of the radial magnetic field Br and axial magnetic field Bz at the observed point (rp, Zp) satisfy the relation Zq=3<0.5>rq/2, they become zero. As a result, the expansion terms of the second degree of the generated magnetic field become zero, so that highly accurate magnetic fields can be obtained.

Description

Detailed Description of the Invention Magnetic field generators composed of coils of various general widths are used in a large number of applications, including the field of controlling electron beams. Coordinates (r
sLz) System 6; Locus of observation point r @ (rp, Zν)
It is often necessary to have radial and axial magnetic fields that are highly accurately proportional to rp and Z, respectively. The present invention relates to a device 62 for generating this special magnetic field.

First, the basic principle of the present invention will be explained.

Figure 1 (= As shown, the two axes of the cylindrical coordinate (r, θSZ) system are the common central axis, and a pair of circular current loops (1) arranged symmetrically with respect to the ztsO plane C2 is considered. (
1) l: What is the value of the flowing current? And their directions are mutual (=
Let's do the opposite. The radius of loop (1) is r4, and the distance between loop (1) and the 2-0 plane is 2q. At this time, the radial magnetic field Br at observation point P (11 in polar coordinate system, rteZp in θt1 cylindrical coordinate system) and the axial magnetic field B are given by the following equation.

Br= p E fr (gp)'is'1(ru'
q)"4"-" (mu) thought-1 --) - Bs"-u Σ fs (God'v)"f (r
qsZJ'j'p (B) Transcript -1 Ko ζ ku 2, now = 9 o'clock θp
(C) (B) P, a (→ is a 2n-order Legendre function.

Equations (5) to 0 above), the first order term of h (i.e. n
= l) contributes to the magnetic fields Bt and Bz, which are given by the following equations.

Br eBm are the coordinates r, ,Zν of the observation point P, respectively
Each of these is a magnetic field that is proportional to two, and this magnetic field is used as an effective magnetic field in various applications including those for controlling electron beams.

However, as shown in formulas (2) and (2), the actual generated magnetic fields nr, n, l2 are such that higher-order expansion terms of parrot = 2 or higher are added to the above effective magnetic field. Therefore, In order to obtain a highly accurate effective magnetic field, it is necessary to remove at least 41=2 expansion terms. ,,z,)C2 pay attention. This function can be expressed as.

Therefore, now, hypothetically, zq=ILrq (line (a) shown in Figure 2) (K
), then f! (rq #Zq)' O(L) and the generated magnetic field B
The quadratic expansion term of r@BH becomes the identity C2 zero. Therefore, the principle of the present invention is that a highly accurate magnetic field is provided in the application field for which the present invention is aimed. An example is shown below. In the example, the coil (2) has a constant cross-sectional area, but the distance between the coil (2) cross-sectional center half t rq and the concentric Z=Q plane is smaller than the width and height of the cross-sectional area. Ordinary electromagnetism teaches that if the current is sufficiently large, the current flowing through this coil (1) 42rIL is expressed as a concentrated current. Therefore, it is clear that according to the present invention, it is possible to provide a generator having a highly accurate magnetic field.

In Example C2 of the present invention, the cross-sectional shape of the coil (2) was rectangular. The present invention can be applied even if this shape is a circular shape.

Further (:, the center of the coil cross section and the same center of z =
Distance from O plane2. Even when the width and height of the cross-sectional area are not sufficiently large, the principle of the present invention can be achieved by taking r□z at the electrical center rather than at the cross-sectional center.

As stated above, the present invention is capable of various applications and modifications without departing from the principles of the present invention.

[Brief explanation of drawings]

FIG. 1 is a layout diagram of a pair of circular current loops showing the principle of the present invention, and diagram M'x is a layout diagram of a coil showing an embodiment of the invention. (11...Circular current loop (2)...Cylindrical coil with rectangular cross section

Claims (1)

[Claims] With the two axes of the cylindrical coordinate system (r, θ, 2) as a common central axis, N symmetry across the z==9 plane (; two cylindrical coils arranged and with exactly the same structure) Construct, high intensity area; rp of viewing point (rteZp) and each of 4 C2, to obtain proportional radial magnetic field and axial magnetic field C2, each coil C; flow direction is opposite to each other and its value energize the same current, and the distance 11&l between the radius r- of the coil rain cutoff center and the Z=Q plane is ZqW4, zα1166
01. A magnetic field generating device characterized in that the magnetic field generating device is arranged so as to have the following relationship.