JPH0648619B2 - Electron gun device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an electron gun device, and more particularly, to a structure of a grid of an electron gun device that outputs a linear electron beam.

(Prior Art) In order to uniformly heat and dissolve or evaporate a long sample without scanning the electron beam, it is necessary to make the current density distribution of the linear electron beam, that is, the intensity uniform. .

FIG. 10 is a conceptual configuration diagram of an electron gun device that outputs such a line-shaped electron beam. In the figure, reference numeral 1 is a filament formed in a line shape, and outputs a first thermoelectron 2 in response to energization. Reference numeral 3 denotes a line-shaped cathode having a length of, for example, about 100 mm, which is arranged so as to face the filament 1 at a constant interval. The cathode 3 is formed in a U shape and is supported by the cathode support 3a. The cathode 3 has a predetermined potential difference with respect to the filament 1. The first thermoelectrons 2 emitted from the filament 1 are attracted by the potential difference and collide with the cathode 3 to heat the cathode 3. The cathode 3 emits second thermoelectrons 4 in response to heating.

Reference numeral 5 denotes a grid, which is fixed to the end surface of the first cover 6 including the fiment 1. The grid 5 focuses and forms the second thermoelectrons 4 output from the cathode 3. 7
Is an anode and is fixed to the inner circumference of the opening of the second cover 8. The anode 7 extracts the second thermoelectrons 4 focused and formed by the grid 5 as an electron beam 9.

In addition, for example, when the acceleration voltage is not applied to the cathode 3, −2 KV is applied to the filament 1, and the cathode 3 is 0 V.
-6KV is applied to the grid 5. As a result, the potential difference between the filament 1 and the cathode 3 is 2 KV.
Then, the potential difference between the cathode 3 and the grid 5 becomes 6 KV, and the potential difference between the filament 1 and the grid 5 becomes 4 KV. Then, the cathode 3 is heated to a high temperature of 2000 ° K or higher by the impact of the first thermoelectrons output from the filament 1.

By the way, the plane of the grid 5 used in such a conventional electron gun apparatus is formed so as to form an obtuse angle with respect to the vertical axis Z of the filament 1 as shown in the sectional view of FIG.

This is considered to be the result of applying the shape of each electrode of the conventional spot beam electron gun as shown in FIG. 12 to a long structure that outputs a linear electron beam as it is. In FIG. 12, 10 is a filament which also serves as a cathode, 11
Is a grid and 12 is an anode. Filament 10
The negative electrode of the first power supply 13 is connected to one end of the, and the positive electrode of the first power supply is connected to the ground potential. The positive electrode of the second power supply 14 is connected to the other end of the filament 10,
The negative electrode of the power supply 14 is connected to the grid 11. That is, a constant negative voltage with respect to the ground potential is applied to the filament 10, and the filament 11 is applied to the grid 11.
A negative variable voltage with respect to 0 will be applied.

In such a configuration, the plane of the grid 11 is formed so as to form an obtuse angle with respect to the vertical axis Z of the filament 10. A vacuum tube is formed by these filaments 10, grid 11 and anode 12,
By adjusting the output voltage of the second power supply 14, the current distribution density and the like can be arbitrarily adjusted.

(Problems to be Solved by the Invention) However, the electron beam intensity in the apparatus configured as described above has a normal distribution curve as shown in FIG. 13, and it is difficult to obtain an electron beam of uniform intensity. That is, in the case of the apparatus of FIG. 10, the intensity of the electron beam has a normal distribution characteristic between the opposing grids 5,
An electron beam with a uniform intensity cannot be obtained in the rectangular area.

The present invention has been made in view of such points,
An object thereof is to provide an electron gun device which can obtain an electron beam having a uniform intensity in a rectangular area.

(Means for Solving the Problem) In the present invention for solving the above-mentioned problem, a first thermoelectron output from a linear filament is caused to collide with a linear cathode to generate a second thermoelectron, An electron gun device configured to focus and form the second thermoelectrons by a grid arranged so as to face the cathode from both sides in parallel with the cathode and to take out the focused thermoelectrons as an electron beam through the anode. In the above, the plane of each grid is formed to form an angle of less than 90 degrees with respect to the vertical axis of the filament.

(Operation) The intensity of the electron beam between the opposing grids of the device of the present invention becomes substantially flat, and an electron beam having a uniform intensity in a rectangular region can be obtained.

(Example) Hereinafter, an example of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a diagram illustrating the principle of the present invention, and the same parts as those in FIG. 12 are designated by the same reference numerals. In the figure, the difference from FIG. 12 is that the plane of each grid 11 is the filament 1
It is formed so as to form an angle of less than 90 degrees with respect to the vertical axis Z of 0.

The electron beam intensity in the device configured in this way is
As shown in FIG. 2, the distribution curve becomes almost rectangular, and
An electron beam with a uniform intensity can be obtained over a wider range than the apparatus shown in FIG.

The present invention applies the structure shown in FIG. 1 to an apparatus as shown in FIG.

FIG. 3 is a configuration diagram of a main part of an embodiment of the present invention, FIG. 4 is a sectional view taken along the line AA ′ in FIG. 3, and the same portions as those in FIG. 10 are designated by the same reference numerals. . In these figures, the plane of each grid 5 is formed to form an angle of less than 90 degrees with respect to the vertical axis of the filament 1, and the anode 7 is formed to be convex with respect to the grid 5.

In such a configuration, when operating as an electron gun, a negative high voltage (acceleration voltage) with respect to the ground potential is applied to the cathode 3. An electric current is applied to the filament 1 to heat it to a temperature of about 2600 ° K at which thermoelectrons are sufficiently emitted. A negative grid potential Vg with respect to the potential of the cathode 3 is applied to the grid 5, and the potential is set to the cutoff voltage (cutoff) of the electron beam.

A positive potential is gradually applied to the cathode 3 with respect to the filament 1. The cathode 3 is heated by the electron impact of the bombard current Ib emitted from the filament 1. The temperature of the cathode 3 is the bombarded power Pb (= Ib ×
Vg), and by controlling the bombarded power Pb, a predetermined operating temperature (generally 2600 ° K to 2700)
Set to ° K). When the grid potential is made smaller (shallow) from the cutoff voltage, the electron beam emitted from the cathode 3 is accelerated by the anode 7 having the ground potential and is irradiated toward the sample.

Thus, the cross-sectional shape of the electron beam and the value of the beam current obtained from the electron gun are the shapes of the grid 5 and the anode 7, the distance between the grid 5 and the cathode 3, the distance between the grid 5 and the anode 7, the acceleration voltage and the grid. Although set by the voltage or the like, the intensity of the electron beam between the opposing grids 5 becomes substantially flat, and an electron beam having a uniform intensity in a rectangular area can be obtained.

FIG. 5 is an example in which the plane of the grid is 90 degrees with respect to the vertical axis of the filament, and FIGS. 6 and 7 are configuration diagrams showing other embodiments of the present invention, which are the same as FIG. The same symbols are attached to the parts.

In the apparatus of FIG. 5, the plane of each grid 5 is formed flat so as to form an angle of 90 degrees with respect to the vertical axis Z of the filament 1, and the anode 7 is also flat so as to be parallel to the grid 5. Has been formed.

In the device shown in FIG. 6, the plane of each grid 5 is formed to form an angle of less than 90 degrees with respect to the vertical axis Z of the filament 1, and the anode 7 is formed flat. However, each grid 5 is formed of a thin member.

In the device of FIG. 7, as in FIG. 4, the plane of each grid 5 is formed to form an angle of less than 90 degrees with respect to the vertical axis Z of the filament 1, and the anode 7 is convex with respect to the grid 5. However, each grid 5 is formed of a thin member as in FIG.

The difference in electron beam characteristics between the embodiments shown in FIGS. 4, 6 and 7 causes difference in electron beam characteristics as a difference in lens action when driven with the same operation parameter.

FIG. 8 is a grid characteristic diagram in which such a difference in electrode shape is used as a parameter, the vertical axis represents the beam current Ib, and the horizontal axis represents the grid voltage Vg. In the figure, A shows the characteristic of FIG. 4, B shows the characteristic of FIG. 5, C shows the characteristic of FIG. 6, and D shows the characteristic of FIG. Here, the larger the rise of the beam current Ib with respect to the change of the grid voltage Vg, the better the performance.

FIG. 9 is an electron beam emission angle characteristic diagram in which the difference in electrode shape is used as a parameter. The vertical axis represents the electron beam aperture angle α, and the horizontal axis represents the grid voltage Vg. In the figure, as in FIG. 8, A shows the characteristic shown in FIG. 4, B shows the characteristic shown in FIG. 5, C shows the characteristic shown in FIG. 6, and D shows the characteristic shown in FIG. . Here, the smaller the opening angle α with respect to the change in the grid voltage Vg, the better the performance.

As is clear from the characteristic diagrams of FIGS. 8 and 9,
The electrode shapes shown in FIGS. 4, 6 and 7 are superior in characteristics to the electrode shapes shown in FIG. Also, grid 5
As for, even if the structure is thick as shown in Fig. 6, Fig. 6,
Even with the thin structure as shown in FIG. 7, there is almost no difference in characteristics.

(Effects of the Invention) As described in detail above, according to the present invention, it is possible to provide an electron gun apparatus capable of obtaining an electron beam having a uniform intensity in a rectangular region.

[Brief description of drawings]

FIG. 1 is a diagram illustrating the principle of the present invention, FIG. 2 is an electron beam intensity characteristic diagram of FIG. 1, FIG. 3 is a configuration diagram of a main part of an embodiment of the present invention, and FIG. 4 is a diagram of FIG. AA 'sectional view, FIG. 5 is an example in which the plane of the grid is 90 degrees with respect to the vertical axis of the filament, and FIGS. 6 and 7 are configuration diagrams showing other embodiments of the present invention, respectively. FIG. 8 is a grid characteristic diagram with a difference in electrode shape as a parameter, FIG. 9 is a radiation angle characteristic diagram of an electron beam with a difference in electrode shape as a parameter, and FIG. 10 is an electron gun that outputs a linear electron beam. FIG. 11 is a schematic configuration diagram of the apparatus, FIG. 11 is a sectional view of FIG. 10, FIG. 12 is a conceptual configuration diagram of a conventional spot beam electron gun apparatus, and FIG.
It is an electron beam intensity characteristic diagram of FIG. 1 ... Filament, 3 ... Cathode 5 ... Grid, 7 ... Anode

 ─────────────────────────────────────────────────── ─── Continuation of the front page (71) Applicant 999999999 Hokuriku Electric Power Co., Inc. 3-1, Sakurabashi-dori, Toyama City, Toyama Prefecture (71) Applicant 999999999 Kansai Electric Power Co., Inc. 3-22-3, Nakanoshima, Kita-ku, Osaka City, Osaka Prefecture ( 71) Applicant 999999999 Chugoku Electric Power Co., Inc. 433 Komachi, Naka-ku, Hiroshima City, Hiroshima Prefecture (71) Applicant 999999999 Shikoku Electric Power Co., Inc. 2-5 Marunouchi, Takamatsu City, Kagawa Prefecture (71) Applicant 999999999 Kyushu Electric Power Co., Inc. Fukuoka 2-82 Watanabe-dori, Chuo-ku, Fukuoka (71) Applicant 999999999 Japan Atomic Power Company, Inc. 1-16-1 Otemachi, Chiyoda-ku, Tokyo (71) Applicant 999999999 Mitsubishi Heavy Industries Marunouchi, Chiyoda-ku, Tokyo 2-5-1 (71) Applicant 999999999 JEOL Ltd. 3-1-2 Musashino, Akishima-shi, Tokyo (72) Inventor Waka Ikuo 4-6-22 Kannon-Shinmachi, Nishi-ku, Hiroshima-shi, Hiroshima Prefecture Hiroshima Research Laboratory, Mitsubishi Heavy Industries, Ltd. (72) Inventor Shigeo Konno 3-1-2 Musashino, Akishima-shi, Tokyo Japan Electronics Co., Ltd. (56) References Special Kai 49-40475 (JP, A) JP 64-54652 (JP, A) JP 58-145050 (JP, A)

Claims (1)

[Claims] 1. A first thermoelectron output from a linear filament collides with a linear cathode to generate a second thermoelectron, and the second thermoelectron is sandwiched from both sides of the cathode. In the electron gun device configured to focus and form the focused thermoelectrons as an electron beam through the anode, the planes of the grids are aligned with the vertical axis of the filament. An electron gun device characterized by being formed so as to form an angle of less than 90 degrees.