JPS5842132A - Direct-heated dispenser cathode and manufacturing method - Google Patents

Abstract

PURPOSE:To facilitate the manufacture and to operate with the current lower than conventional one, by premolding a heat-resistant metallic wire into a coil then adhering the heat-resistant metal powder around said coil through the sintering and impregnating the electron emission substance at the sintered section. CONSTITUTION:The tungsten wire having the diameter of 0.5mm. is coiled with the pitch of 15mm. and the outer-diameter of 12.5mm. then annealed under the hydrogen environment for 5min to produce a coil. Then the tungsten coil thus produced is immersed in the tungsten paste and dried, thereafter the power is applied on the coil under the hydrogen environment or the vacuum to burn the tungsten powder. Then the electron emission substance is heated at 1,650 deg.C under the hydrogen environment to be solution impregnated into the sintered section and the excessive impregnation member is finally removed to produce the cathode.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in a dispenser cathode in which a porous sintered body of a melting point metal is impregnated with an electron emitting substance.

In recent years, dispenser cathodes have been used in variable power laser tubes such as argon ion laser tubes because they are capable of variable density operation, have a long lifespan, and have excellent ion impact resistance and arc discharge resistance. ing.

1 Figure 1 shows the outside of the dispenser cathode used in such a laser tube! [is. Mo-
The material 3, 31 has a barium melting point such as BaB, and is coated with barium oxide (Bad) in the cathode substrate l.
), calcium oxide (Cab) and acinium oxide (
It is impregnated with an electron-emitting material (not shown) consisting of Muj*Oa).

Such a cathode is electrically heated via electrode 2.2I,
It has the function of emitting electrons from the substrate surface and exciting the gas inside the laser tube.

Conventionally, such a coil-shaped direct heat source dispenser cathode is made by press-forming tungsten powder into a cylindrical shape, sintering it, and then impregnating it with #I or plastic to improve the machinability. It is machined into a coil shape like IML, then heated in vacuum or air to remove the aforementioned copper or plastic to form a cathode substrate, and then impregnated with an electron-emitting material and an electrode at the end. I completed it with 11 attachments.

As mentioned above, in the conventional manufacturing method for directly heated dispenser cathodes, a cylindrical porous tungsten sintered body is machined into a coil shape, so the machining process itself is difficult and requires skill. It required experience and was not suitable for mass production. Additionally, a step of impregnating copper or plastic and removing it was necessary as a protective material for machining. Furthermore, since the base itself is porous tungsten, it is impossible to reduce the coil wire diameter in terms of strength, so a large current of several tens of amperes is required to obtain the high temperature necessary for cathode operation. It was.

The present invention was made in view of these conventional disadvantages.
The present invention provides a directly heated dispenser cathode that is easy to manufacture and can be operated with a lower current than conventional ones.

That is, after a heat-resistant metal wire such as tungsten is previously formed into a coil shape, tungsten powder is sintered and adhered to the shoulder circumference of this coil shape.

The conventional disadvantages could be overcome by impregnating the sintered part with an electron-emitting substance.

Hereinafter, one embodiment of the present invention will be described in detail using the drawings.

No. 2m is a main process diagram of the method for manufacturing a directly heated dispenser cathode according to the present invention. Engineering 1MA.

B is a process of forming a tungsten core wire into a coil shape. 1 For example, a tungsten wire with a diameter of 0.5 cm is wound with a pitch of 1.5 mm so that the outer diameter of the coil becomes 12.5 m, and the coil is heated at 1600°C in a hydrogen atmosphere. Dulling was performed for 5 minutes. Steps C and D show the manufacturing process of the tungsten paste to be applied to the tungsten coil mentioned above.
044) 4209, Satsuri Loose Acetate Isopralate 180II.

7 tons of acetic acid 90ml! A lacquer was prepared by mixing 810 ml of A7Tone and ball milling for 48 hours.

To 1fSOmJ of this lacquer, 650I of tungsten powder having an average particle size of 5 tones was mixed and ball-rubbed for about 1 hour. Create tungsten paste D.

Next, in step F)-G, the above-mentioned tungsten coil is immersed in tungsten paste, and after drying, electricity is applied to the fill in a hydrogen atmosphere or vacuum to heat the tungsten powder and sinter the tungsten powder.Thickness of the sintered layer For lifting platforms with a height of 0.255 m or less, return to step E and repeat the same operation.

Step Hd In the step of adjusting the electron emitting material, barium carbonate, calcium carbonate, and aluminum oxide are each added in a molar ratio of 4
: After mixing in a ratio of 1:1, the mixture was heated in air at 1350° C. for 8 hours to thermally decompose the charcoal salt and convert it into barium calcium alisonate. In step I, this was heated to 1650° C. in a hydrogen atmosphere to melt and impregnate the aforementioned sintered body. Finally, the impregnating material of the henchmen was removed to form a cathode. In this way, the complicated steps of preparing the cathode, impregnating steel or plastic, machining the shield, and removing copper or plastic are no longer necessary, and mass productivity is improved.

An even more important advantage is that the diameter of the wire can be reduced, which means that the high temperature required for cathode operation, which conventionally required 4V and 5 people, was required to raise the temperature to 1050°C. However, in the embodiment of the present invention, 2. IV
-14A, and the power supplied to the cathode of the laser device was reduced to about 1/3, which was a drastic reduction.

[Brief explanation of the drawing]

Figure 1 is an external view of a conventional directly heated dispenser cathode that was used with an argon ion laser RK, and Figure 2 is an external view of the directly heated dispenser cathode of the present invention. E
! ! ! % FIG. 2 is a main process diagram of an embodiment of the method for manufacturing a directly heated dust dispenser cathode of the present invention. 1... Cathode base, 2.2'... Electric bridge, 3...
Brazed part.

Claims (1)

[Claims] (1) Direct heat source dispenser cathode consisting of heat-resistant gold J41 [having a porous sintered body of heat-resistant metal powder around it, and holding an electron emitting substance in the sintered body (2) Heat-resistant gold A method for manufacturing a direct heat source dispenser cathode, comprising the steps of sintering heat-resistant metal powder around J411a, and impregnating the sintered part with an electron emitting material.