US2618767A - Multicathode gaseous discharge device - Google Patents

Description

1952 H. VON GUGELBERG 8,7

MULTICATHODE GASEOUS DISCHARGE DEVICE Filed Dec. 15, 1949 FIG. 2

INVENTOR By H L. VON GUGELBERG ATTORNEY Patented Nov. 18, 1952 MULTICATH'ODE GASEOUS DISCHARGE DEVICE Hans L. von Guzelberg, Murray Hill, N. .11., dd signer to Bell Telephone Laboratory, Incorpo rated, New York, N. Y., a corporation of New York Application December 15, 1949, Serial No. lthltt 8 Claims. (Ci. 315-4169) This invention relates to electric discharge devices and more particularly to multicathode glow discharge devices of the general type disclosed in the applications Serial No. 101,322, filed June 25, 1949, of M. A. Townsend, now Patent No. 2,575,370, granted November 20, 1951 and Serial No. 117,316, filed September 23, 1949, oi H. L. von Gugelberg.

Devices of the type disclosed in the applications above identified comprise, in general and in one form, a plurality of glow cathodes mounted in a row and connected electrically in two groups, the cathodes of the two groups being in alternate relation, and an anode opposite the cathodes. The latter are of asymmetrical construction or relation relative to the anode, for example have two portions of different efiiciencies as glow discharge elements, whereby when a discharge obtains between any cathode and the anode, the discharge concentrates near one end portion of the cathode, that is at the portion of greater emciency, thereby providing a region of high ionization density. Further, the cathodes are arranged with the portion of higher efiiciency of each in juxtaposition to the less eflicient por- "tion of the next succeeding cathode in the row.

There is thus provided a preference mechanism such that when signal pulses are applied between the two groups of cathodes, the discharge is stepped from cathode to cathode in a prescribed direction along the row of cathodes. The asymmetrical construction or relation of the cathodes provides a, marked difference in the voltage requisite to effect stepping of the discharge from any cathode to the next succeeding or next preceding cathode, this difference being designatcd the counting margin.

Cathodes of the type included in such devices are subject to contamination which reduces the efficiency thereof as glow discharge elements. In multicathode devices of the general type above described, such contamination, it has been found, reduces the counting margin, alters the operating characteristics of the several cathodes, and may substantially shorten the operating life of the devices.

One general object of this invention is to improve the construction and operating performance of multicathode glow discharge devices. More specifically, objects of this invention are to simplify the construction of multicathode discharge devices of the general type hereinabove described, to increase the operating life thereof, to maintain the counting margins, and to realize uniformity of operating characteristics for the several cathodes over long operating periods.

In one specific and illustrative embodiment of this invention, an electric discharge device comprises a plurality of glow cathodes mounted in a row and an anode opposite the cathodes, the cathodes being connected together electrically in two groups with the cathodes of the two groups in alternate relation.

In accordance with one feature of this invention, a plurality of auxiliary or grid electrodes is provided, each grid electrode being positioned between two respective adjacent cathodes and connected or arranged to be connected to one of the cathodes of the respective pair.

In the operation of the device, signal pulses are impressed between the two groups of cathodes, whereby the discharge is stepped from cathode to cathode along the row. Each grid electrode functions to draw positive ions from the vicinity of the cathode at which the discharge obtains toward the next succeeding cathode in the row, whereby transfer of the discharge to the latter cathode is facilitated. The grid associated with the cathode from which the discharge is stepped, being at the same potential as this cathode, partially prevents the passage of positive ions from the discharge-toward the next preceding cathode. Thus, the grids provide a preference mechanism whereby the dis-- charge will be shifted only in the desired directionalong the row of cathodes.

The cathodes may be of symmetrical and simple construction. Further the grid electrodes are "inactive elements. Thus, the problem of contamination of the cathode surfaces is minimized whereby long operating life, uniform cathode characteristics and maintenance of counting margin are realized.

The invention and the above-noted and other features thereof will be understood more clearly and fully from the following detailed description with reference to the accompanying drawing in which;

Fig. 1 is a schematic illustrating the principal elements and the association thereof in a glow discharge device constructed in accordance with this invention and illustrating also one way in which the device may be operated;

Fig. 2 is an elevational view of a multlcathode gaseous discharge device illustrative of one embodiment of this invention, a portion of the enclosing vessel being broken away to show the internal structure more clearly;

Fig. 3 is a plan view of the electrode assembly 3 taken along plane H of Fig. 2, certain of the cathodes being broken away to show details of construction;

Fig. 4 is a, detail perspective view of one of the cathodes and an adjacent auxiliary or grid electrode; and

Fig. 5 is a schematic showing another way in which the device illustrated in Fig. 2 may be utilized. I

Referring now to the drawing, Fig. 1 illustrates the principal components and the cooperative relation thereof in a device constructed in accordance with this invention. For purposes of simplicity of illustration, the device has been shown as a two-stage one involving four cooperating cathodes although as will appear presently a much greater number of stages may be utilized. The device comprises an enclosing vessel l having therein an ionizable atmosphere such as a rare gas or mixture of rare gases. Mounted in a row within the vessel are two groups of glow cathodes B1 and Ba and A: and A4, the cathodes of each group being connected together electrically by a tie wire II or l2 as illustrated.

Mounted adjacent one end of the row of cathodes A and B is an auxiliary or reset glow cathode l 3, the function of which will be described hereinafter. Opposite all the cathodes is an anode [4. A plurality of auxiliary or grid electrodes I5 is provided in association with the cathodes, each of the auxiliary or grid electrodes being between a respective pair of the cathodes and connected to a corresponding cathode of the respective pair as shown in the figure. The connection between corresponding cathodes and auxiliary or grid electrodes, it will be understood, may be established either interiorly or exteriorly of the enclosing vessel Ill.

The A cathodes are biased negatively with respect to the B cathodes by a suitable source [6 and the anode is biased positive relative to all the cathodes by a source [8 in series with the anode resistor l9. Negative pulses from a source II are applied between the two groups of cathodes. Associated with the auxiliary or reset cathode I 3 by way of a resistor 20 is a source, not shown, for applying a sharp negative pulse to this cathode.

In the operation of the device, upon the application of a negative pulse to the auxiliary cathode l3, a discharge is initiated between this cathode and the anode [4. It then a negative pulse is applied to the B cathodes by the source I! the cathode B1 and grid electrode coupled thereto are driven negative relative to the cathode l3. Because of the negative potential of the grid associated with the cathode B1, positive ions from the discharge between the cathode I 3 and the anode II are attracted to the vicinity of the cathode B1 whereby the discharge is transferred from between the cathode l3 and anode M to between the cathode B1 and anode I4. When the applied negative pulse from the source I! ceases, the cathode A2 is more negative relative to the anode l4 than is the cathode B1. Consequently the discharge transfers from the cathode B1 to the oathode Ar. A succeeding negative pulse from the source I! applied to the B cathodes steps the discharge from cathode A: to cathode B3 and on cessation of this pulse the discharge shifts to cathode A4.

It will be appreciated, thus, that in response to the application of pulses from the source I! the discharge is stepped along the row of cathodes, advancing two cathodes for each P11 5?- When a pulse is applied to the B cathodes the grid con. nected to the B cathode nearest the A cathode at which the discharge obtains, attracts positive ions from the discharge thereby to facilitate breakdown of the anode-cathode gap at the B cathode following the A cathode at which the discharge obtains. However, the grid associated with the A cathode at which the discharge obtains, being at the same potential as this cathode, substantially inhibits the flow of positive ions from the discharge towards the next, preceding B cathode. Thus, the grids provide a preference mechanism whereby the discharge may be transferred along the row of cathodes only in a prescribed direction.

Individual load circuits indicated generally by resistors 2| may be provided for each ofthe A cathodes. Thus a discharge may be transferred from the auxiliary cathode is to any one of the A cathodes to operate the load associated therewith by the application of a corresponding number of pulses from the source I1. I

In one illustrative construction of the glow discharge device illustrated in Fig. 2, the enclosing vessel I0 is affixed to a suitable base 2| having terminal prongs 22 thereon. The several cathodes and auxiliary or grid electrodes are mounted in a circular row as illustrated in Fig. 3 coaxial with the anode H which may be, for example, a cylinder of sheet refractory material such as molybdenum. Each of the A and B cathodes, as shown clearly in Fig. 4, comprises a channelshaped section or portion 23 of refractory metal, such as molybdenum or tantalum, extending radially with respect to the anode, and a supporting stem 24, for example, of nickel. The auxiliary or grid electrodes l5, as seen most clearly in Fig. 4, may be inverted L-shaped wires, for example of nickel, the plane of each electrode being radial with respect to the anode. As illustrated in Fig. 3, each grid electrode may be positioned mid-way between two adjacent cathodes. The auxiliary cathode l3 also may be channel-shaped and extends radially with respect to the anode H. The supporting stems 24 for the A cathodes are joined to a metallic ring I I which is connected to a respective one of the terminals 22 by leadingin conductors 21. Similarly, the stems of the B cathodes are affixed to a metallic ring I2 connected to one of the terminals 22. The several grid or auxiliary electrodes l5 are connected in two groups to metallic rings 25 and 26, alternate grid electrodes being connected to the same ring. The rings 25 and 28 also are coupled to corresponding terminals 22.

In a specific and illustrative device, the channels in the several cathodes may be 0.020 inch wide by inch deep and inch long, the grid electrodes may be formed of 0.015 inch diameter nickel wire, the cathode to anode spacing may be 0.040 inch and the cathode to grid spacing may be 3 inch. For a gas filling in the vessel ll] of neon at a pressure of 35 to 40 millimeters of mercury, the breakdown voltage is substantially 180 volts and the sustaining voltage at a current of 5 milliamperes is about volts. The B cathodes may be biased, as by the source IS in Fig. 1, approximately 20 volts positive with respect to the A cathodes. Stepping of the discharge may be effected by negative pulses of approximately 60 volts peak value. Stepping frequencies up to about 1,500 cycles per second may be employed.

The device shown in Figs. 2 and 3 is particularly suitable for use as a pulse counter and may be operated for this purpose as in the manner described in the application of M. A. Townsend identified hereinabove. It will be understood, oi course, that although in the specific construction illustrated the cathodes and auxiliary electrodes are connected in groups within the vessel, individual leading-in connections for the electrodes may be provided whereby, for example, individual load circuits may be associated with the A cathodes and selective switching effected as discussed hereinabove with reference to Fi 1.

The cathodes and auxiliary or grid electrodes may be associated electrically also in such manner that stepping or the discharge in either direction along, the row of cathodes may be obtained. Une arrangement suitable for this purpose is illustrated in Fig, 5. As shown in this figure, the A and B cathodes are connected in two groups by the, conductors ii and 12 each of which is connected to a respective pair of terminals l and t of the two-pole switch 28. The grid or auxiliary electrodes i5 also are coupled in two groups by the conductors 25 and 26 each of which is connected to the respective terminal 3 or 4 of the switch it. A second switch 29, the function oi which will appear presently, is provided between the A and B cathodes and the negative terminal of the source iii. The auxiliary cathode i3 is connected to this terminal through a series resistor til opposite ends of which lead to the output or indicator terminals St.

The mechanism and principles of stepping the discharge from cathode to cathode are similar to those discussed in connection with Fig. 1. However, the direction of stepping will be determined by the relative polarities of the two groups of auxiliary or grid electrodes. This will be understood from detailed consideration of an example. Assume that the discharge obtains at the cathode As, that the switch 28 is in the position shown and that a pulse is applied by the source i1. Such pulse drives all of the B cathodes and all the grid r auxiliary electrodes 15 connected by the conductor 25 to the left-hand terminal I, in Fig. 5, more negative. It will be noted that, upon application of the pulse, the grid electrode adjacent and to the left of the cathode A4 is at the same potential as this cathode and thus inhibits now of positive ions from the discharge toward the cathode B3. However, the grid electrode adjacent and to the right of the cathode A4 is driven negative relative to this cathode and, thus, attracts positive ions from the discharge toward the cathode B5. Hence, upon application of the pulse, the discharge is stepped or shifted from the cathode A4 to the next succeeding cathode B5 and upon cessation of the pulse to the cathode As.

Assume now that the switch 28 is operated to close the circuits over terminals 2, that the discharge obtains at the cathode A4 and a pulse is applied by the source i1. As in the case discussed above, the pulse drives all of the B cathodes negative. However, the pulse now is applied to those grid electrodes connected by the conductor 26 to the right-hand terminal 2 of the switch 28. Thus, upon application of the pulse, the grid electrode adjacent and to the right" of the cathode A4 is at the same potential as this cathode whereas the grid electrode adjacent and to the left of this cathode is negative with respect thereto. Thus, in response to the pulse, the discharge shifts from the cathode A4 to the cathode B3 and, upon cessation of the pulse, to the oathode As.

It will be apparent, then, that groups of pulses the discharge being indicative of the diflerence in the number of pulses in the two groups. Whenever the discharge shifts to the cathode it a pulse is produced across the resistor 30 which may be utilized, for example, to operate an indicator connected to the terminals 3|- 0d course, individual load circuitsmay be coupled to the B cathodes as discussed in connection with Fig. l.

The discharge may be reset, that is returned to the cathode it, by opening the switch 29, whereby the A and B cathodes are disconnected from the source i8. Alternatively, the discharge may be reset by applying a large negative pulse to the cathode H as in the manner described in the discussion of Fig. 1.

Reference is made of the application, Serial No.

133,196, filed December 15, 19th of W; A. Depp, wherein a related invention is disclosed and claimed.

Although specific embodiments of the invention have been shown and described it will be understood that they are but illustrative and that various modifications may be made therein without departing from the scope and spirit of the invention. For example, it will be understood that auxiliary or grid electrodes may be provided in devices of the constructions disclosed in my application heretofore identified.

What is claimed is:

i. A gaseous discharge device comprising an array of two groups of cathodes, the cathodes of the two groups being mounted in alternate relation, an anode opposite said cathodes, a plurality of auxiliary electrodes each positioned between a corresponding pair of adjacent cathodes in said array, and means for electrically connecting each auxiliary electrode directly to one of the cathodes of the corresponding pair.

2. A gaseous discharge device comprising a plurality of glow cathodes mounted in a row, an anode opposite said cathodes, a plurality of inactive auxiliary electrodes each mounted between a corresponding pair of adjacent cathodes, means for establishing a discharge between said anode and one of said cathodes, and means for energizing said cathodes and auxiliary electrodes simultaneously to step the discharge along said row.

3. A gaseous discharge device comprising an array of two groups of cathodes, the cathodes of the two groups being in alternate relation, a plurality of grid electrodes each mounted between a corresponding pair of adjacent cathodes, an anode opposite said cathodes, means for establishing a discharge between said anode and one of said cathodes, and means for simultaneously pulsing said grid electrodes and one of said groups of cathodes negative relative to the other group of cathodes.

4. A gaseous discharge device comprising an array of two groups of glow cathodes, the oathodes of the two groups being in alternate relation, means electrically connecting the cathodes of each group together, an anode opposite said cathodes, a plurality of auxiliary electrodes, one for each pair of adjacent cathodes and disposed therebetween, means biasing one group of cathodes negative with respect to the other, means for establishing a discharge between said anode and one of said cathodes, and means for stepping said discharge from cathode to cathode comprising means for impressing negative pulses upon the other group of cathodes and certain of said auxiliary electrodes.

may be added algebraically, the final position of 5. A gaseous discharge device comprising a row of cathodes,,a plurality of auxiliary electrodes..

one for each pair of adjacent cathodes and mounted therebetween, an anode opposite said cathodes, means electrically connecting one group of alternate cathodes together, means electrically connecting the other cathodes together, and means for electrically connecting each of said auxiliary electrodes directly to the next succeedins cathode in said row.

6. A gaseous discharge device comprising a plurality of glow cathodes mounted in a row, each cathode having therein a channel portion, an anode adjacent said cathodes. and a plurality of auxiliary electrodes, one for each pair of adjacent cathodes, each 01' said auxiliary electrodes having an L-shaped wire portion positioned be-' tween the channel portions of the respective pair of cathodes.

7. A gaseous discharge device comprising a cylindrical anode, a plurality of channel-shaped glow cathodes mounted adjacent said anode, in a circular boundary coaxial therewith and each extending substantially radially with respect thereto, and a plurality of wire electrodes, one for each pair of adjacent cathodes and positioned therebetween.

8. A gaseous discharge device comprising a cylindrical. anode, two groups of glow cathodes mounted in a circular row coaxial with said anode, each 01' said cathodes having a channelshaped portion extending substantially radially outward from adjacent said anode, a pair of conductive members each electrically interconnecting the cathodes in a respective one of said groups, a plurality oi. grid electrodes, one for each pair 01 vadjacent cathodes and positioned therebetween, a conductive member electrically interconnecting one group of alternate grid electrodes, and another conductive member electrically interconnecting the other grid electrodes.

HANS L. vox GUGELBE'RG.

REFERENCES CITED The following references are of record in the file or this patent:

UNITED STATES PATENTS Number Name Date 1 2,184,756 Rockwood Dec. 26, 1939 2,398,150 Mumma et al'. Apr. 9, 1946 2,443,407 Wales June 15, 1948 2,473,159 Lyman June 14, 1949

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