JP3117261B2 - filament - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a long filament, and is useful for a linear electron gun for generating metal vapor or the like in a vacuum.

[0002]

2. Description of the Related Art FIG. 4 shows a conventional linear electron gun, and FIG.
Shows an AA cross section in FIG. Long and rod-shaped cathode 1
Is heated uniformly by electron impact heating of the thermoelectrons 14 from the filament 2 provided behind it by a bombardment power source 7 or by heat radiation of the filament 2 or heat conduction through alumina or the like. When a positive acceleration voltage is applied to the anode 10, thermions e are extracted from the cathode 1 and become the electron beams 13. Here, a negative bias is applied to the grid 9 by the grid power supply 12 to control the trajectory and amount of the thermoelectrons e to be the electron beams 13.

[0003] The filament 2 for heating the cathode is fixed by a filament fixing block 8. However, since the section modulus is smaller than that of the cathode 1, it is necessary to shorten the span in order to prevent creep deformation. Are installed in series, or an intermediate support mechanism 20 is provided.

A target is provided in a long "crucible", and when this target is irradiated with an electron beam 13, the target is melted and evaporated to obtain a metal vapor. Vapor deposition or the like can be performed using the metal vapor.

[0005]

In order to uniformly obtain a vapor density in the longitudinal direction of a long crucible, it is necessary that the output density of the electron beam is uniform. However, when the cathode 1 is heated by one filament 2 for heating the cathode, the thermoelectrons 14 and the electron beam 13 are deflected by the magnetic field B (f) generated by the filament current I, thereby deteriorating the output density distribution. If short filaments are provided in series or an intermediate support mechanism 20 is provided in the middle, a decrease in the temperature of the joint or the intermediate support affects the temperature of the cathode 1,
It was difficult to obtain a uniform power density distribution.

SUMMARY OF THE INVENTION In view of the above prior art, an object of the present invention is to provide a long filament that uniformly heats a cathode and does not affect the electron beam with a magnetic field.

[0007]

According to the present invention, there is provided an elongated filament for heating a cathode in order to emit an electron beam from a rod-shaped cathode, comprising two upper and lower parallel wires. And a power supply unit for mechanically supporting the central portion of the lower wire and supplying power from the central portion to pass currents in opposite directions to the upper and lower wires, while allowing the wire to expand and contract in the longitudinal direction. It is characterized in that a slide support portion for slidably supporting both ends of the wire is provided.

[0008]

Since current flows in the upper and lower wires in opposite directions, the magnetic fields of the respective wires cancel each other, so that the electron beam is not adversely affected. In addition, the buoyancy acts on the upper wire to facilitate wire support. Also, since the lower wire is supported by the power supply, the temperature of the support is the same as that of the other wires, and the temperature becomes uniform.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below in detail with reference to the drawings. The parts performing the same functions as those of the prior art are denoted by the same reference numerals, and overlapping description will be omitted.

FIG. 1 shows a main part of a linear electron gun using the filament of the present invention, and FIG. 2 shows a steam generator using the linear electron gun. As shown in both figures, the filament 22 according to the present invention comprises two upper and lower parallel wires 22.
a, 22b, and both wires 22a, 22b
Are connected at both ends and bent at right angles. The lower wire 22b is connected to the power supply unit 5 fixed to the fixed block 8, and the power supply unit 5 and the fixed block 8 form an intermediate support mechanism that mechanically supports the filament 22.

Both ends of the filament 22 are connected to the slide plate 3
, And a slide pin 4 penetrates through the slide plate 3. Therefore, when the filament 22 expands and contracts in the longitudinal direction due to thermal expansion and thermal contraction, the slide plate 3 slides along the slide pin 4 according to the expansion and contraction. Thus, both ends of the filament 22 are supported by the slide plate 3 and the slide pin 4 while allowing the slide.

From the filament power supply 6 to the filament 22
Power is supplied to the power supply unit 5 via the power supply unit 5 and the central portion of the lower wire 22b. When a current flows through the filament 22, the temperature of the filament 22 increases due to resistance heating. Although the power supply unit 5 also functions as an intermediate support mechanism for the lower wire 22b, since current flows through the power supply unit 5, the temperature of the intermediate support unit does not decrease.

At this time, since the directions of the currents flowing through the wires 22a and 22b are reversed,
The trajectory is not bent by the magnetic field due to the current flowing through the a and 22b. Also, since the directions of the currents flowing through the upper and lower wires 22a, 22b are reversed, the wires 22a, 22b
A repulsive force is generated between 22b. Since the lower wire 22b is supported by the power supply unit 5, buoyancy is generated in the upper wire 22a. Since buoyancy is generated in the wire 22a in this manner, there is no need to provide an intermediate support member between the wires 22a and 22b, and the configuration is simplified.

Next, the overall operation will be described. When an electric current is passed through the filament 22, the filament 22 is heated by resistance. When a pure metal such as tungsten is adopted as the cathode 1, a voltage is applied by a bombard power supply 7 provided between the cathode 1 and the filament 2, and the cathode 1 is heated by emitting thermoelectrons of the filament 22 by electron impact heating. .

If LaB ₈ (lanthanum boride) or barium-impregnated tungsten, which can be operated at a lower temperature than pure metal, is used as the material of the cathode 1, the filament 22
Of the filament 22 through the heat radiation of
It is also possible to heat the cathode 1 to a predetermined temperature by conducting heat from the cathode 1.

Electron beam 14 emitted from cathode 1
Is extracted by an acceleration voltage applied to the anode 10 from the anode power supply 11, is deflected 270 ° in the uniform magnetic field B, and is irradiated on the target 16 in the crucible 15. Then, the target 16 is melted to obtain the metal vapor 17.

The grid 9 to which a negative voltage is applied by the grid power supply 12 controls the trajectory and emission amount of the electron beam 14.

FIG. 3 shows an ultra-long electron gun according to another embodiment of the present invention. In this device, a long (1 m or longer) cathode 1 is supported by a cathode support mechanism 18, and a large number of filaments 22 are installed in series, and the filaments 22 are supported by a slide pin support block 19. Then, the long cathode 1 is uniformly heated by the filament 22, and an electron beam 13 having a beam length of 1 m or more is generated.

After all, since the power supply section 5 and the filament fixing block 8 are provided at the center of the wire 22b below the filament 22, the filaments 22 can be arranged in series with a minimum gap, and the cathode length can be reduced. Ultra-long electron guns of 1 m or more can be manufactured.

[0020]

According to the present invention, as described above in detail with the embodiments, the filament is constituted by two upper and lower parallel wires, and the direction of the current flowing through the upper and lower wires is reversed. The magnetic field caused by the filament current flowing through the electron beam is canceled, and the trajectory of the electron beam is not adversely affected. In addition, since buoyancy is generated in the upper wire, an intermediate support mechanism is not required between the upper and lower wires, and the configuration may be simple.

In the center of the wire below the filament,
Since power is supplied and supported, uniform heating can be performed without lowering the temperature at the support portion.

By using the filament of the present invention, a long cathode can be uniformly heated, and a long linear electron gun having a uniform beam output density can be obtained. By using this linear electron gun, a uniform vapor density can be obtained in the longitudinal direction, and vapor deposition and the like can be uniformly performed at a higher speed.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a main part of a linear electron gun using a filament of the present invention.

FIG. 2 is a cross-sectional view showing a steam generator using the filament of the present invention.

FIG. 3 is a configuration diagram showing an ultra-long linear electron gun using the filament of the present invention.

FIG. 4 is a configuration diagram showing a conventional linear electron gun.

FIG. 5 is a sectional view showing an AA section in FIG. 4;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Cathode 2 Filament 3 Slide plate 4 Slide pin 5 Power supply 6 Filament power supply 7 Bombard power supply 8 Filament fixing block 9 Grid 10 Anode 11 Anode power supply 12 Grid power supply 13 Electron beam 14 Thermoelectron 15 Crucible 16 Target 17 Metal vapor 18 Cathode support mechanism 19 slide pin support block 20 intermediate support mechanism 22 filament 22a, 22b wire

Continued on the front page (72) Inventor Takamasa Nakamura 4-2-2 Kannon Shinmachi, Nishi-ku, Hiroshima-shi, Hiroshima Mitsubishi Heavy Industries, Ltd. Hiroshima Works (72) Inventor Tohru Takashima 3-1-2 Musashino, Akishima-shi, Tokyo Sun (56) References JP-A 1-296547 (JP, A) JP-A 2-278638 (JP, A) JP-A 2-278639 (JP, A) JP-A 4-107264 ( JP, A) JP-A-4-192242 (JP, A) JP-A-1-166449 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H01J 37/06 C23C 14/24 H01J 37/30

Claims (1)

(57) [Claims] 1. A long filament for heating a cathode in order to emit an electron beam from a rod-shaped cathode, comprising two upper and lower parallel wires and mechanically supporting a central portion of a lower wire. And a power supply unit for supplying power from the central portion and passing currents in opposite directions to upper and lower wires,
A filament, comprising: a slide support portion that slidably supports both ends of the wire while allowing the wire to expand and contract in the longitudinal direction.