JPH0625881Y2 - Electron gun cathode support structure - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to a cathode support structure for an electron gun that generates an electron beam used for electron beam processing, etc. Lanthanum hexafluoride (L) which is a sintered material.
It is suitable for supporting a high-brightness cathode using aB ₆ ).

[Conventional technology]

The power density is increased by focusing the electron beam flowing in a certain direction with a large kinetic energy with an electromagnetic lens to focus it on the solid surface, and most of the kinetic energy of the electrons is converted into heat energy and Electron beam processing, which performs processing by vaporization and evaporation, has excellent features such as fine processing and processing to high melting point materials.
It is used in various fields such as vapor deposition, melting, welding, semiconductor manufacturing, various chemical reactions, and electron beam analysis.

An electron gun is used as a device for generating such an electron beam, and its schematic structure is, as shown in FIG. 2, that an anode 3 is provided in front of a cathode part 1 via a Wehnelt 2, A beam control lens system 4 is provided in front of the anode 3.

A cathode heating power source 5 is connected to the cathode portion 1, and an acceleration power source 6 is also connected between the cathode portion 1 and the anode 3.

When actually performing electron beam processing or the like, a processing chamber (not shown) is connected in front of the electron gun, and the target 7 installed in the processing chamber is irradiated with an electron beam to perform processing.

[Problems to be solved by the device]

The cathode part 1, which is one of the important parts of such an electron gun, has a support part 10a formed opposite to the holder block 10 as shown in an enlarged view in FIG.
The base end of a cathode support plate 11 made of a pair of leaf springs is attached to the lower end of the holder block 10, and the cathode 13 is attached between the tip end of the cathode support plate 11 via a carbon heater 12. A leaf spring 14 inserted between the supporting portion 10a of the holder block 10 and the back of the cathode supporting plate 11 presses the cathode 13 forward by pressing it forward.

However, when an electric current is passed through the cathode 13 to emit an electron beam while heating for a long time, or when temperature rise and decrease due to repeated operation stop occur repeatedly, the cathode support having a double leaf spring structure is formed. The plate 11 and the plate spring 14 are thermally deformed, causing the cathode 13 to be displaced or to fall off.

Then, there is a problem in that not only the trajectory of the electron beam is displaced due to such positional displacement of the cathode 13, but also the electron beam may collide with the anode 3 or the inside of the electron gun may be damaged.

In particular, when lanthanum hexafluoride (LaB ₆ ) which is a sintered material used as the cathode of the high energy electron gun is used, the temperature of the cathode 13 becomes about 1400 to 1500 ° C., which is a serious problem. There is.

The present invention has been made in view of the above-mentioned problems of the prior art, and it is possible to obtain a stable electron beam without the cathode being displaced or falling off even if it is heated for a long time or repeatedly heated and cooled. The present invention is intended to provide a cathode supporting structure for an electron gun.

[Means for Solving the Problems]

In order to solve the problems of the above-mentioned prior art, in the cathode supporting structure of the electron gun of the present invention, the position adjusting and clamping pressure supporting means are arranged in a straight line between the tips of the supporting portions of the holder block. Then, a pair of cathode supporting members are attached, and the cathodes are pressure-supported via the heating means at the supporting points on a straight line between the position adjusting and the pressure-supporting means. .

[Action]

The cathode is pressed by a cathode support member made of a leaf spring or the like through a heating means such as a carbon heater, and the cathode support member is attached to the holder block. The support means is used to tighten from the side surface of the cathode, and the leaf spring has a single-layer structure only for the cathode support member, and the linear tightening from the side surface with a round bar prevents the cathode from being displaced and prevents it from falling off. I have to.

〔Example〕

An embodiment of the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a schematic configuration diagram of an embodiment of a cathode supporting structure for an electron gun of the present invention.

The cathode supporting structure 20 of this electron gun is applied to the cathode part 1 which is one of the important parts of the electron gun shown in FIG. 2, and the holder block 22 is mounted on the base 21 of the insulator. A support portion 22a is attached to the holder block 22 so as to face the holder block 22, and a base end portion of a cathode support plate 23 made of a pair of leaf springs as a cathode support member is provided at a lower end portion of the holder block 22. It is attached with screws 24.

The cathode 26 is sandwiched between the tip end portions of the cathode support plate 23 via the carbon heater 25, so that the support portion 22a of the holder block 22 and the back portion of the cathode support plate 23 are attached to each other. A position adjusting screw 27 forming a position adjusting and pressure supporting means between the two and a round rod-shaped cathode supporting pin 28 connected to the tip end thereof.
The cathode 26 and the carbon heater 25 are pressure-supported from the side surface by changing the amount of protrusion of the position adjusting screw 27.

Further, a current introducing pin 29 for energizing the carbon heater 25 is attached to the lower portion of the base 21, and is connected to the cathode heating power source 5.

In the cathode supporting structure 20 of such an electron gun, as the cathode 26, for example, lanthanum hexagonal oxide (LaB) made of a sintered material is used.
₆ ) is used so that a high-energy electron beam can be generated, and the carbon heater 25 uses 1400 to 1500 ° C.
Heated to a degree.

In addition, the cathode support plate 23 and the cathode support pin 28 are provided so that the cathode 26 can be sufficiently supported even at high temperatures.
Is made of a high melting point material such as tungsten (W), molybdenum (Mo) or tantalum (Ta).

Furthermore, the position adjusting screw 27 is adapted to be screwed into a penetrating female screw formed from the outer side to the inner side of the support portion 22a of the holder block 22, and by operating from the outer side of the holder block 22, The amount of protrusion can be changed.

In the cathode supporting structure 20 of the electron gun configured as described above, the cathode supporting plate 23 is attached to the holder block 22 by the screw 2
4, the cathode 26 is sandwiched by the carbon heater 25 and positioned between the cathode support plates 23, and then the position adjusting screw 27 is operated to move the cathode support pin 28.
To advance the cathode 26 to support the cathode 26 from the side.

After that, the current introduction pin 29 is connected to the cathode heating power source 5 and energized to emit an electron beam.

In this way, the cathode part 1 becomes hot while the electron beam is emitted from the cathode 26. At this time, by operating the position adjusting screw 27 to adjust the protrusion amount of the cathode support pin 28, the cathode 26 can be moved to a predetermined position. The position of the cathode 26 can be maintained at a predetermined position without operating the position adjusting screw 27 during operation if the position can be maintained and the thermal deformation is adjusted in advance before operation. .

Therefore, even if the operation is performed for a long time, the position of the cathode 26 is not displaced, and a stable electron beam can be emitted for a long time.

In addition, in the above embodiment, the position adjusting and pressure supporting means is constituted by the screw and the pin, but the present invention is not limited to this, and any mechanism capable of changing the position and supporting force of the cathode may be used.

The cathode is a lanthanum hexafluoride (La) sintered material.
Not limited to the case of using B ₆ ), another material may be used.

[Effect of device]

According to the cathode supporting structure of the electron gun of the present invention, as described in detail with reference to one embodiment, a pair of cathode supporting members is provided between the opposing supporting parts of the holder block via the position adjusting and pressure supporting means. Since the members are attached and the cathode is sandwiched between the cathode supporting members via the heating means, the tightened state of the cathode can be adjusted, and the displacement and the falling of the cathode can be prevented. .

Further, since the cathode can be always held at a predetermined position, the electron beam can be stably emitted for a long time, which is particularly effective for a high energy electron gun.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of an embodiment of a cathode supporting structure for an electron gun according to the present invention, and FIG. 2 is an overall configuration of an electron gun to which the cathode supporting structure for an electron gun according to the present invention is applied and a conventional cathode portion. 2 is a schematic configuration diagram of FIG. 1: cathode part, 2: Wehnelt, 3: anode,
4: Beam control lens system, 5: Power supply for cathode heating,
6: power source for acceleration, 7: target, 20: cathode support structure of electron gun, 21: base, 22: holder block, 2
2a: support part, 23: cathode support plate, 24: screw, 2
5: carbon heater, 26: cathode, 27: position adjusting screw, 28: cathode support pin, 29: current introducing pin.

Claims (1)

[Scope of utility model registration request] 1. A pair of cathode supporting members are attached by arranging position adjusting and pressure supporting means in a straight line so as to oppose each other between tip ends of opposing supporting portions of a holder block, and a pair of cathode supporting members are mounted between the cathode supporting members. A cathode support structure for an electron gun, wherein a cathode is pressure-supported via a heating means at a support point on a straight line of a position adjusting and pressure-supporting means.