US2541335A - Glow discharge device - Google Patents

Description

Feb 13, 1951 CARNE 2,541,335

GLOW DISCHARGE DEVICE Filed Aug. 19, 1948 5 UV E H TO R GERALD G. CARNE Patented Feb. 13, 1951 UNITED STATES) PATENT; OFFICE GLOW DISCHARGE DEVICE Gerald G. Carne, Rockaway N." .L, assignor-to Radio Corporation-of America, a corporationof:

Delaware Application august 19, 1948,. Serial 45,173 1 3 Claims.

The presentinventionrelates to a glow disprovided with fillets 3 for-accommodation of concharge device sometimes characterized as theis meant the value of the current requiredto pass 7 between theicathodeiand the trigger-or-grid anode before conduction can take place to the anode,

ductors 4. gas such as argon or neon; or-mixtures of-- such gases, at a pressure ofthe order of from 5 to -100.

millimeters ofmercury.

ode 5 is supported from;-the-leadwires 4 on an insulating member--16 by means of. tabs whichextend through the insulating member, and .may be of any suitable material such asnickel coated on itsinner. --surface-6 with an emission matethis transfer current, being a function of theelectric field-intensity at the'surface of the oathode, varies with different cathodeshapes.

It is an object of the present invention to provide a trigger type tube having a cathode, the curvature of which is drawn with the anode at the center of the radius of curvature. This arrangement makes it possible to greatly reduce the transfer current between the cathode and the anode grid.

Another object is the provision of an electrode construction that has the curvature of the oathode designed to give maximum tube operating efficiency so that the electrode assembly may be incorporated in a miniature construction.

Another object of the invention is the provision of an anode grid between the cathode and anode concentric with and having a curvature conforming substantially to the curvature of the cathode. This gives a greater functional area to the trigger anode close to the cathode, thus preventing excessive deterioration of the cathode surface adjacent the curvature of the trigger anode.

Other objects having to do with features of construction and arrangement of parts will manifest themselves as the description proceeds.

The accompanying drawing illustrates a form of a tube embodying the invention in which:

Figure 1 is a central, longitudinal fragmentary view, partly in elevation, of a glow discharge device of one embodiment of the invention; and

Figure 2 is a cross section, on the line 22 of Figure 1, illustrating the arrangement of the electrode assembly.

Referring to the drawing, the present discharge device comprises an envelope I having a header 2 rial, such as barium --or---strontiu-m carbonates. The outer surface 1 of-the cathode-is'preferably coated with aluminum oxide to-prevent-a dis-.-.

charge from-occurring; at the back side of-the "cathodeas is customarily-done in this form-of tube,

The anode; l 3'- consists ofa carbon rod partly enclosed in a hollow-glasspant-leg l 0 cemented to thestem or header 2 of thetube and extending "up through insulating member =16. The-lead ll is surrounded by the rod Ill: of-theanode. Carbon is used for the anode proper because it has very poor electron emission and thus tends to avoid a breakdown during the negative half cycle of alternating voltagewhich is universally used in the operation of my tube. That is to say, the tube is intended to function or breakdown on the positive half of 'the cycle only, but due to copious emission which frequently occurs with certain types of anode materials, the breakdown occurs with the negative side or cycle which is detrimental to proper circuit control operations.

A wire trigger or anode grid I2 has depending legs l2a which extend down through accurately located holes in insulating member It and are connected to leads 15. Above insulating member 16 and resting on the same, the anode grid extends radially toward the cathode so that the upper arcuate portion of the anode grid which is concentric with the cathode is closely spaced with respect thereto as shown in Figure 2 and therefore has substantially the same curvature as the cathode. The cathode and anode grid are readily formed accurately dimensioned according to well known practices. However, to attain the accurate positioning of the two required for the proper functioning of the device, I accurately locate the holes provided in insulating member I 6 for the cathode lugs and legs I2a.

It should be pointed out that there is a critical radius of curvature in the formation of the oathode and the anode grid. If they are made of too large radii, they require excessive field intensity which produces a disproportionate trans-Q The envelope is filled with a rare:

An effectively large elongated cold type oath-- fer current with a consequent deleterious effect upon the operation of the tube. The same objection is substantially true if they are made of too small radii. This follows from the fact that the transfer current, being a function of the elec-.

where the center of the radius of curvature of the cathode was materially reduced from an optimum, as was the case where the center of the cathode was on a circle with the anode, there would also be an increase in the transfer current.

I have discovered best results are obtained when the anode is positioned at the center of the radius of curvature of the cathode and the trigger grid.

The spacing between the cathode and the anode grid will vary for different types of tubes. It will also be appreciated that with a reduction in the size of the tube, there will be an inherent variation in its operation. However, these are matters of technique which can be easily determined by those skilled in the art from the foregoing description.

While I have set forth a preferred embodiment of the invention and described it in detail with respect to said embodiment, I do not wish to be limited to the exact construction set forth but desire to claim all modifications thereof that come within the scopeof the appended claims.

.What I claim as new is:

1. A glow discharge device comprising an &

elongated arcuate cathode, a wire anode grid,

and a rod-shaped anode, said anode grid having an arcuate portion concentric with and conformingsubstantially to the curvature of the cathode, said anode being coaxial and concentric with said cathode and anode grid, said anode grid being mounted intermediate the ends of said cathode and adjacent one end thereof and between the cathode and anode.

2. A glow.discharge' device comprising an elongated arcuate cathode forming less than half of a cylinder, a rod anode concentric and coaxial with said cathode, and an arcuate wire anode grid concentric and coaxial with said cathode and within the space between said anode and said cathode.

3. A glow discharge device comprising an elongated arcuate cathode, a rod shaped anode concentric and coaxial with said cathode, an arcuate wire anode grid concentric and coaxial with said cathode, said anode grid extending transversely of said cathode intermediate the ends thereof spaced from but adjacent one end thereof and between said cathode and said anode, and an insulating member having locating holes formed therein, said cathode having lugs extending through two of said holes, said anode grid having depending legs which extend through two other locating holes and which extend radially toward said cathode on said insulating member.

GERALD G. CARNE.

REFERENCES CITED The following references are of record in'the"

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