JPH02114442A - Energy analyzing device - Google Patents

Abstract

PURPOSE:To satisfy the Wien conditions even in a fringe field by connecting mirrors with each other through a mirror yoke, and providing an electric field distribution in the same form as the magnetic field distribution. CONSTITUTION:Mirrors 2 installed at the incident hole and emission hole of a Wien filter 1 are connected with each other by a mirror yoke 3. This forms a return circuit for the line of magnetic force absorbed by the mirror yoke 3 with no generation of magnetic field between oppositely situated mirrors, and mag. field distribution damps smoothly without producing any step to yield a mag. field distribution in the same form as the electric field distribution. Thereby the Wien condition can be met even in a fringe field, and a beam having a certain energy can proceed straightly.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to an energy analyzer, and more particularly to an energy analyzer in which the shape of the electric field distribution and the shape of the magnetic field distribution in a fringe are made equal.

[Prior art] The Wien filter, which analyzes the energy of charged particles by using electric and magnetic fields that are orthogonal to each other, converts the electric field into El
When the magnetic field is B, the velocity V of the charged particle is B=E/v
Although it has the excellent property of traveling in a straight line when the (Wien condition) is satisfied, there are many difficulties in achieving the conditions for the beam to travel in a straight line.

One of the causes of the difficulty is the fringe field. In other words, it is easy to satisfy the above conditions inside the Wien filter, but in the fringe regions existing at the entrance and exit of the Wien filter, the electric field distribution 10 and the magnetic field distribution 11 are different as shown in FIG. It will be different.

However, as is clear from the Wien condition above, the beam travels straight only when the electric field E and the magnetic field B have the same distribution, so if the electric field distribution and the magnetic field distribution are different as shown in Figure 3, The trajectory of the beam is significantly bent before it enters the Wien filter.

Therefore, conventionally, electrodes and magnetic poles (hereinafter referred to as mirrors) called mirrors or shunts have been arranged.

FIG. 4(a) is a diagram showing an example of a mirror for an electric field. Near the entrance and exit of the Wien filter 120, the electrodes that form the electric field of the Wien filter 12 are set at ground potential. Electrodes 13 are arranged. As a result, the electric field becomes suddenly weaker in the fringe region, as shown in FIG. 4(b), and the electric field distribution can be made to have a steep characteristic. Note that the two axes in the figure are optical axes.

The same goes for the magnetic field, and as shown in FIG. 5, by arranging the mirror 14 made of a magnetic material so as to face the pole piece that forms the magnetic field of the Wien filter 12, the magnetic field distribution of the fringe salt becomes as follows. As shown in FIG. 4(b), similarly steep characteristics can be obtained.

As described above, by arranging mirrors for electric and magnetic fields on the fringe salt, the width of the fringe salt can be controlled, and the electric and magnetic field distributions can be made to have similar steep characteristics. It is possible to make a beam with energy of

[Problems to be Solved by the Invention] However, in the conventional method, the electric field distribution of the fringe salt can be easily controlled by arranging mirrors, but the magnetic field distribution can be easily controlled by arranging mirrors. As a result, smooth damping may not be exhibited, and a stepped portion as shown at 15 in FIG. 6 may occur.

This is because the lines of magnetic force are absorbed by the mirror and 1. This is because a magnetic field is generated between opposing mirrors.

Therefore, the electric field distribution and magnetic field distribution of the fringe salt will differ, resulting in a region where the Wien condition cannot be titrated.

The present invention solves the above problems, and aims to provide an energy analyzer that can make the electric field distribution and magnetic field distribution of a fringe salt the same shape.

[Means for Solving the Problems] In order to achieve the above object, the energy analyzer of the present invention includes a configuration in which mirrors are arranged on the fringe salt of the energy analyzer and the mirrors are connected to each other by a mirror yoke. Features.

[Function] In the present invention, not only are mirrors arranged in the fringe salt to control the distribution of electric and magnetic fields, but also the mirrors are connected with mirror yokes, so that undesired steps are not generated in the magnetic field distribution. There is no. Therefore, it is possible to titrate the Vienna conditions even in fringe salts.

[Example] Examples will be described below with reference to the drawings.

FIG. 1 is a diagram showing the configuration of one embodiment of the energy analyzer according to the present invention, FIG. 1(a) is a cross-sectional view of the energy analyzer along the y-axis, and FIG. A perspective view of the filter is shown. In the figure, 1 is a Wien filter,
2 shows the mirror, 3 shows the mirror yoke, 4 shows the Wien filter pole piece, and 5 shows the Wien filter yoke.

As shown in FIG. 1(b), the pole pieces 4 of the Wien filter 1 are arranged to face each other in the y-axis direction and are surrounded by a yoke 5. This forms a desired magnetic field in the y-axis direction. Although not shown, electrodes are arranged inside the yoke 5 to form a desired electric field in the X-axis direction. Note that a coil for excitation is omitted in the figure.

The Wien filter 1 is surrounded by a mirror yoke 3 as shown in FIG.
A mirror 2 is formed at a portion corresponding to the entrance and exit ports.

As shown in FIG. 1(a), if a mirror yoke 3 is provided that connects the mirrors 2 placed at the entrance and exit of the Wien filter 1, the mirror yoke 3 will serve as a return circuit for the absorbed lines of magnetic force. , no magnetic field is generated between the opposing mirrors, and the magnetic field distribution attenuates smoothly without creating a step as shown in Figure 2, so the electric field distribution and magnetic field distribution have the same shape, and the fringe salt It is also possible to titrate the Vienna conditions.

Although the mirror for the electric field is not shown in FIG. 1, the mirror 2 and mirror yoke 3 are made of metal,
If it is set to earth potential, it acts as a mirror for the electric field, so it can serve as a mirror for both the electric and magnetic fields. Moreover, the mirror yoke 3 is the first
The entire Wien filter 1 may be surrounded as shown in FIG. 1(a), or only the vicinity of the entrance and exit ports of the Wien filter 1 may be surrounded.

Although the Wien filter has been taken as an example in the above description, the present invention can be generally applied to magnets for charged particle beam analysis devices.

[Effects of the Invention] As is clear from the above explanation, according to the present invention, mirrors are arranged on the fringe salt of the energy analyzer, and the mirrors are connected to each other by a mirror yoke, so that the electric field distribution and the magnetic field distribution are the same. Since it can be a distribution of shapes,
Even fringe salts can satisfy the Vienna condition. Furthermore, by forming the mirror and mirror yoke with metal, they can also serve as a mirror for the electric field.

[Brief explanation of drawings]

Fig. 1 is a diagram showing the configuration of an embodiment of the energy analyzer according to the present invention, Fig. 2 is a diagram showing the magnetic field distribution of the fringe salt according to the present invention, and Fig. 3 is a diagram showing the magnetic field distribution of the fringe salt in the conventional energy analyzer. Diagram showing distribution of electric field and magnetic field, 4th
5 shows a conventional mirror for an electric field, FIG. 5 shows a conventional mirror for a magnetic field, and FIG. 6 shows a conventional magnetic field distribution when mirrors are arranged for a magnetic field. 1... Wien filter, 2... Mirror 3...
Mirror yoke, 4... Wien filter pole piece, 5... Wien filter yoke. Applicant JEOL Co., Ltd. Agent Patent attorney Hideo Sugai (5 others) Figure 1 (a) Figure 2 (b) Figure (a) (b) Figure

Claims (1)

[Claims] (1) An energy analyzer characterized in that mirrors are arranged in the fringe field of the energy analyzer and the mirrors are connected to each other by a mirror yoke.