JP7294438B2 - electron gun - Google Patents

Description

The present invention relates to electron guns.

As an electron gun, an electron emission surface that emits electrons, an extraction electrode that generates an electric field between the electron emission surface and emits electrons from the electron emission surface, and a cone that has the same potential as the electron emission surface around the electron emission surface. A pierce-type electron gun having electrodes arranged in a shape is used (Patent Document 1).

Japanese Patent Application Laid-Open No. 2013-112894

An electron gun according to a first aspect includes an emitter having an electron emission surface, a first electrode as an extraction electrode, and a second electrode having a second surface facing the first surface of the first electrode, The second surface of the second electrode has a first region and a second region that are different in distance from the center of the electron emission surface, and the curvature in the first region is different from the curvature in the second region. .
An electron gun according to a second aspect includes an emitter having an electron emitting surface, a first electrode as an extraction electrode, a second electrode having a second surface facing the first surface of the first electrode, and an electron beam from the emitter. and a shield electrode having an opening into which electrons are incident, wherein the electrode surface of the shield electrode has a first region and a second region whose distances from the center of the opening are different from each other, and in the first region The curvature is different than the curvature of the second region.
An electron gun according to a third aspect comprises an emitter having an electron emitting surface, a first electrode as an extraction electrode, a second electrode having a second surface facing the first surface of the first electrode, and an electron beam from the emitter. an emitter cable that supplies a predetermined voltage to the emitter; a first electrode cable that supplies a predetermined voltage to the first electrode; and a predetermined voltage to the second electrode. and a shielded electrode cable for supplying a predetermined voltage to the shielded electrode, the emitter cable, the second electrode cable, the shielded electrode cable, and the first electrode cable is greater than the spacing between the emitter cable, the second electrode cable and the shield electrode cable.

FIG. 2 is a cross-sectional view showing the configuration of the electron gun of the first embodiment; FIG. 2 is a partially enlarged cross-sectional view of the electron gun of the first embodiment; 4 is a diagram showing an example of a cable of the electron gun of the first embodiment; FIG.

(Electron gun of the first embodiment)
The electron gun 100 of the first embodiment will be described below with reference to FIGS. 1 and 2. FIG. FIG. 1 is a cross-sectional view showing the electron gun 100 of the first embodiment, and FIG. 2 is an enlarged cross-sectional view of the electron gun 100 of the first embodiment, showing an area BL indicated by a dashed line in FIG. It is a diagram.
As for the X direction, Y direction, and Z direction indicated by arrows in FIGS. 1 and 2, the direction indicated by the arrows is the + direction. The X-direction, Y-direction, and Z-direction are directions perpendicular to each other.

The electron gun 100 includes an emitter 30, a first electrode 10, a second electrode 20, a shield electrode 40, and an acceleration electrode 50 arranged inside a housing 60 along an optical axis AX extending in the Z direction, which is the central axis. It has The acceleration electrode 50 may form part of the outer wall of the electron gun 100 in the same manner as the housing 60 . The emitter 30, the first electrode 10, the second electrode 20, the shield electrode 40, and the acceleration electrode 50 all have rotationally symmetrical shapes with respect to the optical axis AX at portions near the optical axis AX. Each of the emitter 30 , the first electrode 10 , the second electrode 20 and the shield electrode 40 is electrically insulated and held by the housing 60 .

The emitter 30 is a substantially cylindrical electrode whose center axis coincides with the optical axis AX. The end surface on the +Z side of the emitter 30 is an electron emission surface 31 (not shown in FIG. 1, see FIG. 2), which has, for example, a concave spherical surface. The center 32 of the electron emission surface 31 is the geometric center position of the electron emission surface 31 or the intersection of the electron emission surface 31 and the optical axis AX.
The electron emission surface 31 may be a flat surface, a convex spherical surface, a concave parabolic surface, or a concave hyperboloid surface.

The first electrode 10 is an extraction electrode for forming an electric field between itself and the electron emission surface 31 to emit electrons from the electron emission surface 31. It has an opening 12 for passing electrons. The first surface 11, which is the end surface of the first electrode 10 on the emitter 30 side (−Z side), is, for example, a convex surface that is convex toward the emitter 30 side (−Z side).
The first surface 11 may be a concave surface facing the emitter 30 (-Z side), or may be a flat surface.
A predetermined negative voltage is applied (supplied) to the first electrode 10 from a first voltage source V<b>1 (not shown in FIG. 2 , see FIG. 1 ) through the first electrode cable 15 .

A second surface 21 (not shown in FIG. 1, see FIG. 2), which is a surface on the +Z side of the second electrode 20, is arranged to face the first surface 11 of the first electrode 10. As shown in FIG.
The second electrode 20 is also called a Wehnelt electrode, and is an electrode that forms an electric field for converging electrons emitted from the electron emission surface 31 of the emitter 30 in the Pierce electron gun.

The acceleration electrode 50 is an electrode for forming an electric field for accelerating electrons emitted from the emitter 30, and its potential is normally set to the ground potential (0 V, reference voltage). Also in the electron gun 100 of the first embodiment, the acceleration electrode 50 is held in the housing 60 and its potential is set to the ground potential by the ground wiring 65 connected through the housing 60 . An opening 52 is formed in the vicinity of the optical axis AX of the accelerating electrode 50 for passing electrons emitted from the emitter 30 .

A negative voltage of about -50 kV to -100 kV is applied (supplied) to the emitter 30 from the third voltage source V3 through the emitter cable 35, for example. As a result, the electrons emitted from the electron emitting surface 31 of the emitter 30 with negative voltage are accelerated in the +Z direction toward the acceleration electrode 50 with ground potential (reference voltage), and pass through the opening 52 of the acceleration electrode 50. is emitted to the outside of the electron gun 100.
The inside of the housing 60 is connected to a low-pressure source such as a vacuum pump via the opening 52 of the acceleration electrode 50 or via an exhaust port (not shown) provided in the housing 60, and is decompressed to vacuum.

At least part of the shield electrode 40 is arranged between the first electrode 10 and the acceleration electrode 50 . A predetermined negative voltage is applied (supplied) to the shield electrode 40 from the fourth voltage source V4 via the shield electrode cable 45 . The voltage applied to the shield electrode 40 is, for example, a voltage approximately 2 to 5 kV higher than the voltage of the emitter 30 (a voltage on the positive side of the voltage of the emitter 30). Therefore, a high voltage of approximately 50 kV or more is applied between the shield electrode 40 and the acceleration electrode 50 .

An opening 42 is formed near the optical axis AX of the shield electrode 40 to allow electrons emitted from the emitter 30 to pass therethrough. Note that the shield electrode 40 is an electrode having a width in the Z direction as well, and the diameter of the opening 42 is, for example, the smallest near the +Z side (acceleration electrode 50 side) end of the shield electrode 40 . .
At least a portion of the first electrode 10 may be disposed between the emitter 30 and the shield electrode 40, as shown in FIGS.

The second electrode 20 is arranged along the peripheral surface of the substantially cylindrical emitter 30 so as to surround the emitter 30 . The second surface 21, which is the surface on the +Z side of the second electrode 20, is, for example, a concave surface whose center of curvature is on the +Z side. In addition, the Z-direction position of the inner peripheral end of the second surface 21 of the second electrode 20 approximately coincides with the Z-direction position of a surface obtained by extrapolating the spherical shape of the electron emission surface 31 of the emitter 30 .
In addition, the second surface 21 of the second electrode 20 is not limited to the shape described above, and may be a convex surface or a flat surface.

A predetermined negative voltage is applied (supplied) to the second electrode 20 from the second voltage source V2 via the second electrode cable 25 . A voltage equal to the voltage of the emitter 30 is applied to the second electrode 20 as an example.
A voltage different from the voltage of the emitter 30 may be applied to the second electrode 20 .

The first electrode cable 15, the second electrode cable 25, the emitter cable 35, and the shielded electrode cable 45 are connected from the outside of the housing 60 via current introduction terminals 61a to 61d provided on the outer wall of the housing 60. introduced internally.

As with conventional Pierce-type electron guns, a negative voltage applied to the electron emitting surface 31 of the emitter 30 and the second surface 21 of the second electrode 20 is approximately the optical axis AX between the emitter 30 and the first electrode 10. An electric field is created in the space containing the region Ee, which is the space along .
This electric field acts to converge a large number of electrons moving in the +Z direction within the region Ee near the optical axis AX.

In the electron gun 100 of the first embodiment, the second surface 21 of the second electrode 20 is a concave surface whose center of curvature is on the +Z side, and which has different distances from the center 32 of the electron emission surface 31 . The surface curvature is different between the region 21a and the second region 21b. In the electron gun 100 of the first embodiment, this surface shape of the second surface 21 allows a large number of electrons emitted from the emitter 30 to be focused with higher accuracy.

Since a large number of electrons are emitted from the electron emitting surface 31, the electrons repel each other within the region Ee due to the space charge effect. If the curvature of the second surface 21 were constant regardless of the distance from the center 32 of the electron emission surface 31, the force to suppress the repulsive force between the electrons would not be sufficient, so the electrons would be converged with high accuracy. I can't let you.
On the other hand, in the electron gun 100 of the first embodiment, since the second surface 21 has two regions with different curvatures depending on the distance from the center 32 of the electron emission surface 31, the space charge effect causes An electric field that cancels the repulsive force can be formed, and the electrons can be focused with high accuracy.

As an example, when the distance from the center 32 of the electron emission surface 31 to the second region 21b is greater than the distance from the center 32 of the electron emission surface 31 to the first region 21a, the curvature of the second region 21b is It may be set larger than the curvature of 21a. For example, the curvature of the second region 21b may be 2.5 times or more the curvature of the first region 21a. With this configuration, electrons can be focused with higher accuracy.

Alternatively, the curvature of the second region 21b may be smaller than the curvature of the first region 21a.
In addition, the second surface 21 is not limited to a surface having two regions with different curvatures. It may be a variable aspect. With this configuration, electrons can be focused with higher accuracy.
In this case, the curvature of the second surface 21 may increase according to the distance from the center 32 of the electron emission surface 31 . With this configuration, electrons can be focused with higher accuracy. Conversely, the curvature of the second surface 21 may decrease according to the distance from the center 32 of the electron emission surface 31 .

Also on the first surface 11 of the first electrode 10 facing the second surface 21 of the second electrode 20, each of the third region 11a and the fourth region 11b having different distances from the center 32 of the electron emitting surface 31 Regions may have different surface curvatures. By setting the shape (curvature) of the first surface 11 to this shape, a large number of electrons emitted from the emitter 30 can be focused with higher accuracy.

As an example, when the distance from the center 32 of the electron emission surface 31 to the fourth region 11b is greater than the distance from the center 32 of the electron emission surface 31 to the third region 11a, the curvature of the fourth region 11b is It may be larger than the curvature of 11a. For example, the curvature of the fourth region 11b may be 2.5 times or more the curvature of the third region 11a.
Alternatively, the curvature of the fourth region 11b may be made smaller than the curvature of the third region 11a.

Also, the first surface 11 is not limited to a surface having two regions with different curvatures, and the curvature of each portion of the first surface 11 varies depending on the distance from the center 32 of the electron emission surface 31 to that portion. It may be a variable aspect.
In this case, the curvature of the first surface 11 may increase according to the distance from the center 32 of the electron emission surface 31 . Conversely, the curvature of the first surface 11 may decrease according to the distance from the center 32 of the electron emission surface 31 .
In the above configuration, the curvature of each region of the second surface 21 or the curvature of each region of the first surface 11 is set according to the distance from the optical axis AX instead of the distance from the center of the electron emission surface 31. It's okay to be there.

In the electron gun 100 of the first embodiment, a high voltage of approximately 50 kV or more is applied between the shield electrode 40 and the acceleration electrode 50 as described above. Therefore, if there is a convex portion with a large curvature on the surface of one of the shield electrode 40 and the acceleration electrode 50 facing the other, the electric field is concentrated on the convex portion, causing discharge from the convex portion to the other electrode. may occur.
In order to prevent this discharge, the third surface 41 of the shield electrode 40, which is the electrode surface facing the acceleration electrode 50, is divided into fifth regions 41a and sixth regions 41b having different distances from the opening 52 of the shield electrode 40. Each region may have a different surface curvature.

As an example, when the distance from the opening 42 of the shield electrode 40 to the sixth region 41b is greater than the distance from the opening 42 of the shield electrode 40 to the fifth region 41a, the curvature of the sixth region 41b is set to that of the fifth region 41a. It may be set larger than the curvature. For example, the curvature of the sixth region 41b may be 2.5 times or more the curvature of the fifth region 41a. Alternatively, the curvature of the sixth region 41b may be smaller than the curvature of the fifth region 41a.
Each of the fifth region 41 a and the sixth region 41 b of the third surface 41 of the shield electrode 40 may be a curved surface having a center of curvature on the emitter 30 side of the opening 42 of the shield electrode 40 .
In the above configuration, the curvature of each area of the third surface 41 may be set according to the distance from the optical axis AX instead of the distance from the center of the aperture 42 .

As described above, the first electrode 10 is supplied with a predetermined negative voltage from the first voltage source V1 via the first electrode cable 15 . Similarly to the conventional electron gun, in the electron gun 100 of the first embodiment as well, the voltage of the first electrode 10 is controlled to control the emission and suppression of electrons from the electron emission surface 31 . That is, by supplying a voltage higher than the voltage of the emitter 30 by 2 kV or more (a voltage on the positive side of the voltage of the emitter 30) from the first voltage source V1 to the first electrode 10, electrons are emitted from the electron emission surface 31. let it release. Further, the emission of electrons from the electron emission surface 31 is suppressed by supplying a voltage lower than the voltage of the emitter 30 by, for example, 2 kV or more (more negative voltage) from the first voltage source V1 to the first electrode 10 .

In order to control the emission and suppression of electrons from the electron emission surface 31 at high speed, a high frequency (not limited to, but here for example 5 MHz) is applied from the first voltage source V1 to the first electrode 10 via the first electrode cable 15. It is necessary to supply a voltage that fluctuates at In this case, electromagnetic waves are radiated around the first electrode cable 15 due to voltage fluctuations. When this electromagnetic wave is absorbed by either the emitter cable 35, the second electrode cable 25, or the shield electrode cable 45, the voltage of the emitter 30, the second electrode 20, or the shield electrode 40 fluctuates, and the electron gun 100 Characteristics may change.

In order to reduce the adverse effects of electromagnetic waves radiated from the first electrode cable 15, the first electrode cable 15 is routed away from the emitter cable 35, the second electrode cable 25, and the shielded electrode cable 45. Also good. That is, the distance L1 between the emitter cable 35, the second electrode cable 25, the shielded electrode cable 45, and the first electrode cable 15 is the distance between the emitter cable 35, the second electrode cable 25, and the shielded electrode cable 45. It may be set larger than L2, L3, and L4.

FIG. 3 is a diagram showing an example configuration of the first electrode cable 15, the second electrode cable 25, the emitter cable 35, and the shielded electrode cable 45 in the regions W1 and W2 indicated by broken lines in FIG.
As shown in FIG. 3, the emitter cable 35, the second electrode cable 25, and the shielded electrode cable 45 are arranged within the multicore shielded cable 26, and the first electrode cable 15 has a different shield than the multicore shielded cable 26. It may be arranged within the cable 16 .

In the multi-core shielded cable 26, the emitter cable 35, the second electrode cable 25, and the shielded electrode cable 45 are covered with a shield 27 made of a net-like conductor, for example, and electromagnetic waves from the outside are blocked by the shield 27.
On the other hand, in the shielded cable 16, the first electrode cable 15 is covered with a shield 17 made of a mesh conductor, and the shield 17 reduces the leakage of electromagnetic waves to the outside.

In the electron gun 100 of the first embodiment described above, each of the emitter 30, the first electrode 10, the second electrode 20, the shield electrode 40, and the acceleration electrode 50 is necessarily rotationally symmetrical with the optical axis AX as the center of rotation. It doesn't have to be

According to the electron gun of the first embodiment described above, the following effects are obtained.
(1) The electron gun 100 of the first embodiment includes an emitter 30 having an electron emission surface 31, a first electrode 10 as an extraction electrode, and a second surface 21 facing the first surface 11 of the first electrode 10. The second surface 21 of the second electrode 20 has a first region 21a and a second region 21b whose distances from the center 32 of the electron emission surface 31 are different from each other. The curvature in the region 21a is different from the curvature in the second region 21b.
With this configuration, the electron gun 100 of the first embodiment can converge a large number of electrons emitted from the emitter 30 with higher accuracy by suppressing mutual repulsion due to the space charge effect.
As a result, an electron gun with a higher space charge density, that is, an electron gun that emits a larger current, or an electron gun with a smaller aperture can be realized.

(2) Furthermore, the distance of the second region 21b from the center 32 of the electron emission surface 31 is greater than the distance of the first region 21a from the center 32 of the electron emission surface 31, and the curvature of the second region 21b is the first By making the configuration larger than the curvature of the region 21a, a large number of electrons emitted from the emitter 30 can be focused with higher accuracy.
(3) Furthermore, by configuring the curvature of the second surface 21 to change according to the distance from the center 32 of the electron emitting surface 31, a large number of electrons emitted from the emitter 30 can be converged with higher accuracy. can be made

(4) Further, the curvature of the second surface 21 is configured to increase according to the distance from the center 32 of the electron emission surface 31, thereby converging a large number of electrons emitted from the emitter 30 with higher accuracy. can be made
(5) Furthermore, the first surface 11 of the first electrode 10 has a third region 11a and a fourth region 11b that are different in distance from the center 32 of the electron emission surface 31, and the curvature of the third region 11a is , and the curvature different from that of the fourth region 11b, it is possible to focus a large number of electrons emitted from the emitter 30 with higher accuracy.

(6) Furthermore, the distance of the fourth region 11b from the center 32 of the electron emission surface 31 is greater than the distance of the third region 11a from the center 32 of the electron emission surface 31, and the curvature of the fourth region 11b is the third By making the configuration larger than the curvature of the region 11a, a large number of electrons emitted from the emitter 30 can be focused with higher accuracy.
(7) Furthermore, the curvature of the first surface 11 of the first electrode 10 changes according to the distance from the center 32 of the electron emitting surface 31, so that a large number of electrons emitted from the emitter 30 Furthermore, it can be converged with high accuracy.

(8) Furthermore, the curvature of the first surface 11 of the first electrode 10 is configured to increase according to the distance from the center 32 of the electron emitting surface 31, so that a large number of electrons emitted from the emitter 30 Furthermore, it can be converged with high accuracy.
(9) Furthermore, by configuring the second surface 21 of the second electrode 20 as a concave surface, a large number of electrons emitted from the emitter 30 can be focused with higher accuracy.
(10) Furthermore, by applying the same voltage as the voltage applied to the emitter 30 to the second surface 21 of the second electrode 20, a large number of electrons emitted from the emitter 30 can be detected with higher accuracy. can be converged to

(Second Embodiment of Electron Gun)
The configuration of the electron gun 100 of the second embodiment is almost the same as the configuration of the electron gun 100 of the first embodiment described above. Therefore, only the differences between the electron gun of the second embodiment and the electron gun of the first embodiment will be described below. Further, the same reference numerals are given to the structures common to the electron gun of the second embodiment and the electron gun of the first embodiment.

In the electron gun 100 of the first embodiment described above, the second surface 21 of the second electrode 20 has a first region 21a and a second region 21b that are different in distance from the center 32 of the electron emission surface 31. It is assumed that the curvature of the surface is different in the region.
In the electron gun 100 of the second embodiment, the second surface 21 of the second electrode 20 does not necessarily consist of the first region 21a and the second region 21b that are different in distance from the center 32 of the electron emission surface 31. The regions do not have to have different surface curvatures.

In the electron gun of the second embodiment, the third surface 41 of the shield electrode 40, which is the electrode surface facing the accelerating electrode 50, has a fifth area 41a and a sixth area having different distances from the opening 52 of the shield electrode 40. 41b and 41b have different surface curvatures.
The configuration of the electrode surface (third surface 41) of the shield electrode 40 in the electron gun of the second embodiment is similar to that of the electrode surface (third surface 41) of the shield electrode 40 in the electron gun 100 of the first embodiment. Since it is the same as the configuration of the configuration, detailed description is omitted.

In the electron gun of the second embodiment, the above-described fifth area 41a, not the above-described first area 21a, of the third surface 41, which is the electrode surface of the shield electrode 40, is interpreted as the "first area". Alternatively, the sixth region 41b may be interpreted as the "second region" instead of the second region 21b.

According to the electron gun 100 of the second embodiment described above, the following effects are obtained.
(11) The electron gun of the second embodiment has an emitter 30 having an electron emission surface 31, a first electrode 10 as an extraction electrode, and a second surface 21 facing the first surface 11 of the first electrode 10. It comprises a second electrode 20 and a shield electrode 40 having an opening 42 into which electrons from the emitter 30 enter, and the electrode surface (third surface 41) of the shield electrode 40 differs in distance from the center of the opening 42. It has a first region (fifth region 41a) and a second region (sixth region 41b), and the curvature in the first region (fifth region 41a) is different from the curvature in the second region (sixth region 41b) .
With this configuration, the electron gun 100 of the second embodiment can reduce local electric field concentration in the vicinity of the shield electrode 40 and prevent discharge from the shield electrode 40 .

(12) Furthermore, the distance of the second region (sixth region 41b) from the center of the opening 42 of the shield electrode 40 is greater than the distance of the first region (fifth region 41a) from the center of the opening 42 of the shield electrode 40. Largely, the curvature of the second region (sixth region 41b) on the electrode surface (third surface 41) of the shield electrode 40 is larger than that of the first region (fifth region 41a) on the electrode surface (third surface 41) of the shield electrode 40. , the local electric field concentration in the vicinity of the shield electrode 40 can be further alleviated.

(Third Embodiment of Electron Gun)
The configuration of the electron gun 100 of the third embodiment is almost the same as that of the electron gun of the first embodiment described above. Therefore, only the differences between the electron gun of the third embodiment and the electron gun of the first embodiment will be described below. Also, the same reference numerals are assigned to the structures common to the electron gun of the third embodiment and the electron gun of the first embodiment.

In the electron gun 100 of the first embodiment described above, the second surface 21 of the second electrode 20 has a first region 21a and a second region 21b that are different in distance from the center 32 of the electron emission surface 31. It is assumed that the curvature of the surface is different in the region.
In the electron gun 100 of the third embodiment, the second surface 21 of the second electrode 20 does not necessarily consist of the first region 21a and the second region 21b that are different in distance from the center 32 of the electron emission surface 31. The regions do not have to have different surface curvatures.

In the electron gun 100 of the third embodiment, the distance L1 between the emitter cable 35, the second electrode cable 25, the shield electrode cable 45 and the first electrode cable 15 is the distance between the emitter cable 35, the second electrode cable 25 and the shield. greater than the spacings L2, L3, L4 between the electrode cables 45;

The configurations of the first electrode cable 15, the emitter cable 35, the second electrode cable 25, and the shielded electrode cable 45 in the electron gun of the third embodiment are the same as those of each cable (15, 35) in the electron gun 100 of the first embodiment. , 25, 45), detailed description thereof will be omitted.

According to the electron gun 100 of the third embodiment described above, the following effects are obtained.
(13) The electron gun of the third embodiment has an emitter 30 having an electron emitting surface 31, a first electrode 10 as an extraction electrode, and a second surface 21 facing the first surface 11 of the first electrode 10. a second electrode 20; a shield electrode 40 having an opening 42 into which electrons from the emitter 30 enter; an emitter cable 35 that supplies a predetermined voltage to the emitter 30; Equipped with an electrode cable 15, a second electrode cable 25 that supplies a predetermined voltage to the second electrode 20, and a shield electrode cable 45 that supplies a predetermined voltage to the shield electrode 40, an emitter cable 35 and a second electrode cable 25 and the shielded electrode cable 45 and the first electrode cable 15 are greater than the distances L2, L3 and L4 between the emitter cable 35, the second electrode cable 25 and the shielded electrode cable 45. FIG.
With this configuration, it is possible to reduce the adverse effects of electromagnetic waves radiated from the first electrode cable 15 on the emitter cable 35, the second electrode cable 25, and the shielded electrode cable 45 when a voltage that fluctuates at high frequencies is applied. . As a result, fluctuations in the voltage of the emitter 30, the second electrode 20, or the shield electrode 40 are also reduced when a voltage that fluctuates at high frequency is applied to the first electrode cable 15 and the first electrode 10. FIG. Therefore, the voltage of the first electrode can be changed at high speed without changing the characteristics of the electron gun 100, and the emission and suppression of electrons from the electron gun 100 can be switched at high speed.

(14) Furthermore, the emitter cable 35, the second electrode cable 25, and the shielded electrode cable 45 are arranged in the multicore shielded cable 26, and the first electrode cable 15 is a shielded cable 16 different from the multicore shielded cable 26. By arranging it inside, it is possible to further reduce the adverse effects of the electromagnetic waves radiated from the first electrode cable 15 on the emitter cable 35, the second electrode cable 25, and the shielded electrode cable 45.

Although various embodiments have been described above, the present invention is not limited to these contents. Moreover, each embodiment may be applied independently, or may be used in combination. Other aspects conceivable within the scope of the technical idea of the present invention are also included in the scope of the present invention.

100: electron gun, 10: first electrode, 11: first surface, 11a: third area, 11b: fourth area, 20: second electrode, 21: second surface, 21a: first area, 21b: third 2 area, 30: emitter, 31: electron emission surface, 40: shield electrode, 41: third surface (electrode surface), 41a: fifth area, 41b: sixth area, 50: acceleration electrode, 60: housing, 15: first electrode cable, 25: second electrode cable, 35: emitter cable, 45: shielded electrode cable, V1: first voltage source, V2: second voltage source, V3: third voltage source, V4: fourth Voltage source, 61a to 61d: current introduction terminals, 16: single-core shielded cable, 26: multi-core shielded cable

Claims (33)

an emitter having an electron emitting surface;
a first electrode as an extraction electrode;
a second electrode having a second surface facing the first surface of the first electrode;
The second surface of the second electrode has a first region and a second region that are different in distance from the center of the electron emission surface, and the curvature in the first region is different from the curvature in the second region. , electron gun. The electron gun of claim 1, wherein
the distance of the second region from the center of the electron emission surface is greater than the distance of the first region from the center of the electron emission surface;
The electron gun, wherein the curvature of the second region is greater than the curvature of the first region. The electron gun according to claim 1 or claim 2,
The electron gun, wherein the curvature of the second surface changes according to the distance from the center of the electron emission surface. The electron gun according to claim 3,
The electron gun, wherein the curvature of the second surface increases with distance from the center of the electron emitting surface. In the electron gun according to any one of claims 1 to 4,
the electron emission surface is concave;
The electron gun, wherein the first surface is convex. The electron gun according to claim 5,
The electron gun, wherein the electron emitting surface is spherical. The electron gun according to claim 5 or claim 6,
The first surface of the first electrode has a third region and a fourth region having different distances from the center of the electron emission surface, and the curvature of the third region is the same as the curvature of the fourth region. Different, electron gun. An electron gun according to claim 7, wherein
the distance of the fourth region from the center of the electron emission surface is greater than the distance of the third region from the center of the electron emission surface;
The electron gun, wherein the curvature of the fourth region is greater than the curvature of the third region. The electron gun according to claim 7 or 8,
The electron gun, wherein the curvature of the first surface of the first electrode changes according to the distance from the center of the electron emission surface. The electron gun according to claim 9,
The electron gun, wherein the curvature of the first surface of the first electrode increases with distance from the center of the electron emitting surface. In the electron gun according to any one of claims 1 to 10,
The electron gun, wherein the second surface of the second electrode is concave. In the electron gun according to any one of claims 1 to 11,
The electron gun, wherein the second electrode is applied with the same voltage as the voltage applied to the emitter. In the electron gun according to any one of claims 1 to 12,
a shield electrode having an opening through which electrons from the emitter are incident;
The electron gun, wherein the electrode surface of the shield electrode has a fifth region and a sixth region that are different in distance from the center of the opening, and the curvature in the fifth region is different from the curvature in the sixth region. 14. The electron gun of claim 13, wherein
the distance of the sixth region from the center of the opening of the shield electrode is greater than the distance of the fifth region from the center of the opening of the shield electrode;
The electron gun, wherein the curvature of the sixth region is greater than the curvature of the fifth region. The electron gun according to claim 13 or 14,
The electron gun, wherein each of the fifth region and the sixth region is a curved surface having a center of curvature on the emitter side with respect to the opening. An electron gun according to any one of claims 13 to 15,
An electron gun, wherein at least a portion of the first electrode is positioned between the emitter and the shield electrode. An electron gun according to any one of claims 13 to 16,
Equipped with accelerating electrodes,
at least part of the shield electrode is disposed between the first electrode and the acceleration electrode;
The electron gun, wherein the electrode surface of the shield electrode is a surface on the acceleration electrode side. An electron gun according to any one of claims 13 to 17,
an emitter cable that supplies a predetermined voltage to the emitter;
a first electrode cable that supplies a predetermined voltage to the first electrode;
a second electrode cable that supplies a predetermined voltage to the second electrode;
a shield electrode cable that supplies a predetermined voltage to the shield electrode;
with
The distance between the emitter cable, the second electrode cable and the shielded electrode cable and the first electrode cable is greater than the distance between the emitter cable, the second electrode cable and the shielded electrode cable. , electron gun. 19. The electron gun of claim 18, wherein
the emitter cable, the second electrode cable, and the shielded electrode cable are arranged in a multicore shielded cable;
The electron gun, wherein the first electrode cable is arranged in a shielded cable different from the multicore shielded cable. 20. The electron gun according to claim 18 or 19,
The electron gun, wherein the first electrode is supplied with a voltage that fluctuates at high frequency via the first electrode cable. an emitter having an electron emitting surface;
a first electrode as an extraction electrode;
a second electrode having a second surface facing the first surface of the first electrode;
a shield electrode having an opening into which electrons from the emitter are incident;
The electron gun, wherein the electrode surface of the shield electrode has a first region and a second region that are different in distance from the center of the opening, and the curvature in the first region is different from the curvature in the second region. 22. The electron gun of claim 21, wherein
the distance of the second region from the center of the opening of the shield electrode is greater than the distance of the first region from the center of the opening of the shield electrode;
The electron gun, wherein the curvature of the second region on the electrode surface of the shield electrode is greater than the curvature of the first region on the electrode surface of the shield electrode. 23. The electron gun according to claim 21 or 22,
The electron gun, wherein each of the first region and the second region is a curved surface having a center of curvature on the emitter side with respect to the opening. An electron gun according to any one of claims 21 to 23,
An electron gun, wherein at least a portion of the first electrode is positioned between the emitter and the shield electrode. An electron gun according to any one of claims 21 to 24,
Equipped with accelerating electrodes,
at least part of the shield electrode is disposed between the first electrode and the acceleration electrode;
The electron gun, wherein the electrode surface of the shield electrode is a surface on the acceleration electrode side. An electron gun according to any one of claims 21 to 25,
an emitter cable that supplies a predetermined voltage to the emitter;
a first electrode cable that supplies a predetermined voltage to the first electrode;
a second electrode cable that supplies a predetermined voltage to the second electrode;
a shield electrode cable that supplies a predetermined voltage to the shield electrode;
with
The distance between the emitter cable, the second electrode cable and the shielded electrode cable and the first electrode cable is greater than the distance between the emitter cable, the second electrode cable and the shielded electrode cable. , electron gun. 27. The electron gun of claim 26, wherein
the emitter cable, the second electrode cable, and the shielded electrode cable are arranged in a multicore shielded cable;
The electron gun, wherein the first electrode cable is arranged in a shielded cable different from the multicore shielded cable. 28. The electron gun according to claim 26 or 27,
The electron gun, wherein the first electrode is supplied with a voltage that fluctuates at high frequency through the first electrode cable. an emitter having an electron emitting surface;
a first electrode as an extraction electrode;
a second electrode having a second surface facing the first surface of the first electrode;
a shield electrode having an opening into which electrons from the emitter are incident;
an emitter cable that supplies a predetermined voltage to the emitter;
a first electrode cable that supplies a predetermined voltage to the first electrode;
a second electrode cable that supplies a predetermined voltage to the second electrode;
a shield electrode cable that supplies a predetermined voltage to the shield electrode;
with
The distance between the emitter cable, the second electrode cable and the shielded electrode cable and the first electrode cable is greater than the distance between the emitter cable, the second electrode cable and the shielded electrode cable. , electron gun. 30. The electron gun of claim 29, wherein
the emitter cable, the second electrode cable, and the shielded electrode cable are arranged in a multicore shielded cable;
The electron gun, wherein the first electrode cable is arranged in a shielded cable different from the multicore shielded cable. 31. An electron gun according to claim 29 or 30,
The electron gun, wherein the first electrode is supplied with a voltage that fluctuates at high frequency via the first electrode cable. An electron gun according to any one of claims 1 to 31,
The electron gun, wherein the first surface of the first electrode faces the electron emitting surface of the emitter. An electron gun according to any one of claims 1 to 32,
The electron gun, wherein the second surface of the second electrode is arranged along the perimeter of the electron emitting surface of the emitter surrounding the electron emitting surface.

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