US1993108A - Vacuum tube - Google Patents

Description

March 5, 1935. o. T. MCILVAINE VACUUM TUBE Filed Nov. 15, 1927 firm/ 46 amt;

Patented Mar. 5, 1935 PATENT OFFICE vacuum was Oran T. McIlvaine, East Cleveland, Ohio, as-

signor, by mesne assignments, to Mcllvaine Patent Corporation, St. Charles, 111., a corporation of Delaware Application November 15, 1927, Serial No. 233,519

6Claims.

This invention relates to an improvement in vacuum tubes.

The object of the invention is to prevent the destruction of emission of oxide coated cathodes, such as barium dioxide, or strontium dioxide, or strontium or barium metals or the nitrates or carbonates of these metals. When a carbon or nickel anode is used, the latter sputters onto the cathode and destroys or seriously prevents the 10 emission after a very few hours of life of the tube.

This invention obviates these objections by constructing the anode out of silicon metal or alloys of silicon, such as barium silicon alloy, or

silicon lithium alloy. The anode of silicon metal may be made in the form of a button, sleeve or cylinder, of it may be in the form of a film on the bulb itself. The use of silicon or alloys of silicon-as the anode of a vacuum tube has a further advantage, namely, that it tends to reduce back emission either secondary or thermionic from the anode.

On cathodes of oxides or carbonates of barium, strontium or lithium, or of these metals, the

silicon may be evaporated from the anode. going into the wire when it is heated at a high flashing temperature on exhaust and siliconizing the filament, thus reducing'the barium, strontium or lithium metal, keeping it in an active state, thus improving the life of the bulb. A silicon hydride gas may also be used, in which to treat the wire.

Further advantages of a silicon or silicon alloy anode are that it helps the gas clean-up, keeps emitters active by removing oxygen and other gases, helps diflusion ot emitting metals through the base metal of the cathode, which may be nickel, iron, molybdenum, tungsten, etc. Silicon is found to be much better as a cathode activator in that it does not contaminate the emitter as is true of carbon and hydrogen when used in or on cathodes.

The manner of constructing a vacuum tube andthethereinottheanodeand .talning magnesium barium alloy.

cathode as well as the filament is well known to those familiar with the art and need not be described in detail. The present invention is directed to the making of the anode of the vacuum tube of silicon or silicon alloy such as silicon barium or carborundum, and tothe use of such an anode in connection with carbonates or oxides of barium or strontium or with an amalgamated cathode of mercury and magnesium barium alloy. The invention may be applied to thermionic vacuum tubes or gas filled tubes and rectiflers. The anode and cathode may be in any of the well known forms, such as a sleeve, cylinder, plate, etc.

The accompanying drawing illustrates an application oi. the invention, and in which:

Fig. 1 is a side elevation partly in section of a vacuum tube in which the invention may be employed;

Fig. 2 is a similar view of a slight modification; and

Fig. 3 is a perspective view of an electrode.

In the drawing, the conventional discharge tubes are illustrated to show the application of the invention thereto and, being well known in the art, need not be described in detail.

I claim:-- 0

1. An anode for thermionic tubes comprising silicon and alkaline earth metal composition.

2. A vacuum tube comprising an anode, and a cathode of mercury and magnesium barium alloy.

3. A vacuum tube comprising an anode containing silicon, and a cathode of mercury and magnesium barium alloy.

4. An anode for vacuum tubes comprising sili- 6. A cathode for space discharge tubes conoaan '1'. ucmvama.

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