US2782343A - Glow discharge tube - Google Patents

Description

Feb. 19, 1957 H. J. GEISLER GLOW DISCHARGE TUBE 2 Sheets-Sheet 1 Filed May 22, 1952 FIG. 2

SUSTAINING VOLTAGE \COMPLETE ISOLATION NO ISOLATION ANODE CURRENT IN MILLIAMPERS I ai INVENTOR HELMUT J. GEISLER ATTORNEY :I'II:

FIG. 3

Feb. 19, 1957 H. J. GEISLER 2,782,343

GLOW DISCHARGE TUBE Filed May 22., 1952 2 Sheets-Sheet 2 COATED COATED FIG. 5a

0 OUTPUT INVENTOR HELMUT J. GEISLER E '5 BYE} ATTORNEY a United States Patent 2,782,343 GLOW DISCHARGE TUBE Helmut J. Geisler, Wappingers Falls, N. Y., assign-or to Interuauonal Business Machines Corporation, New York, N. Y., a corporation of New York Application May 22, 1952, Serial No. 289,304

2 Claims. (Cl. 315-169) This invention relates to gaseous discharge tubes and more particularly to switches or triggers of the gaseous glow discharge type.

Such tubes are generally of two types, both employ two cathodes and a single anode common thereto. One type employs intermediate or glow transfer means be! tween the two cathodes of the tube to provide a fast and positive glow transfer from each cathode to the other. The other type 'tube employs no internal coupling between the cathodes and depends upon external cir-.

A further object is to provide a trigger tube having two cathodes and a single anode whereinthe voltage drop between the anode and each cathode is of a diiferent value because of the inherent structure of the cathodes.

A still further object is to provide a novel cold cathode switch-trigger tube wherein one input pulse must be applied to produce an auxiliary glow discharge and a second input pulse must be applied to a second input to produce a main glow discharge which provides an output.

Other objects of the invention will be pointed out in the following description and claims and illustrated in the accompanying drawings, which disclose, by way of examples, the principle of the invention and the best mode, which has been contemplated, of applying that principle.

In the drawings:

Fig. 1 is a diagrammatic showing of a gaseous discharge trigger tube,

Fig. 2 shows characteristic curves representing the operation of a gaseous discharge trigged tube under different conditions of ionic migration,

Fig. 3 shows one embodiment of the trigger tube of the invention,

Fig. 4 shows another embodiment of the trigger tube of the invention.

Fig. 5 shows diagrammatically a further embodiment of the trigger tube of the invention,

Fig. 5a shows a variation of the embodiment shown in Fig. 5; and

Fig. 6 shows an embodiment of the switch-trigger tube of the invention.

Briefly, one embodiment of the gaseous trigger tube of the invention includes two cathodes and a single anode functionally common to and located intermediate the two cathodes. Triggering action is obtained by applying input pulses to the cathodes or the anode. In operation the glow discharge can exist between the anode and only one cathode. Each input pulse causes the glow discharge to be transferred to exist between the anode and the other cathode. The anode is in the form of either a plate having one or more holes connecting its planar faces or a screen wire. The holes through the plate or between the wires of the screen wire, as the case may be, provided for preselected ionic migration or leakage there through from the vicinity of the cathode to which the glow discharge exists to the vicinity of the other cathode. In this manner the breakdown voltage of the gaseous atmosphere in the vicinity of the latter cathode is lowered and a more positive glow transfer thereto is accordingly facilitated.

The switch-trigger tube of the'invention provides a first cathode which eifectively divides the tube envelope into two ionic compartments. An input pulse is applied to a first starter anode to establish a glow discharge between that anode and the first cathode. During the existence of this discharge ionic leakage occursinto the other compartment to lower the breakdown voltage thereis necessary that a glow discharge exist between the first cathode and the first starter anode before the second input pulse can be employed to establish a glow discharge between the main anode and main cathode.

Referring more particularly to Fig. l the gaseous discharge tube includes cathodes 10C and 11C and anode A, intermediate the cathodes. All electrodes are enclosed within the envelope 12 filled with any suitable gaseous atmosphere. Cathodes 10C and are connected to ground through resistors 13 and 14 respectively. Anode A is connected through resistor 15 to a suitable source of positive voltage designated B+. If the resistor 15 is of sutficiently high value it will permit a steady glow discharge from the anode A to either of the cathodes 10C and 11C but will not permit a glow discharge between the anode and both cathodes. In operation then a glow exists initially in a state of stable discharge between the anode and one cathode, called the fired cathode. If an appropriate positive pulse is applied to this fired cathode the glow discharge will be transferred to exist in a state of stable discharge between the anode and other cathode. This glow transfer may also be accomplished by applying an appropriate negative pulse to the unfired cathode or to the anode. Obviously, if negative pulses are applied to the anode to effect glow transfer a binary output is present at the cathodes.

Fig. 2 shows a group of characteristic curves illustrating the operation of the tube of Fig. 1. If each fired gap is completely isolated from the unfired gap, for example, if the anode A is a solid metallic sheet, the breakdown voltage of the unfired gap is substantially independent of the current flowing in the fired gap as indicated by the complete isolation curve. If no isolation is efiected between the cathodes; i. e., ions are permitted to migrate freely in the entire envelope 12, the no isolation curves approaches the sustaining voltage curve when appreciable anode current flows. It is seen from inspection of the sustaining voltage curve that the operating current value should be sufliciently large to avoid operating at the negative voltage characteristic of the curve. Such operation might produce self-oscillations or spurious glow transfer.

It is seen that ideal tube operation would be along a curve such as the curve C intermediate the no isolation and complete isolation curve. To obtain such operation it is necessary to control the ionic leakage or migration from the fired gap to the vicinity of the unfired gap.

Referring to Fig. 3 the novel glow transfer trigger tube 16 includes wire cathodes 17 and 18 each having an inwardly extending portion along their length which portions extend toward a wire mesh anode 19. The cathodes and anode are held in spaced relation by the upper and lower spacers 2t} and 21,.respectively. In operation the tube may be connected in circuit as shown. The terminals 22 and 23 connected to the cathodes 17 and 18, respectivcly, and the terminal 24 connected to the anode 19 may be employed as input and output terminals.

if a glow discharge exists between the anode 19 and the cathode 17 and a positive pulse is applied to terminal 22 or a negative pulse is applied to terminal 23 or 24 the glow discharge will transfer to exist in a state of stable discharge between the anode 19 and the cathode 18. Accordingly, the voltage at the cathode 17 will decrease and the voltage at the cathode 13 will increase. If a positive pulse is now applied to the terminal 23 or a negative pulse is applied to the terminal 22 or 24 the glow discharge will be transferred to exist in a state of stable discharge between the anode 19 and the cathode 17. Because the U-shaped, or inwardly extending portions of the cathodes, are nearest the anode the glow discharge is confined to those portions and does not extend to other parts of the cathode wires.

When glow discharge exists from the anode to one cathode ions migrate from the vicinity of that glow discharge through the screen wire anode into the vicinity of the other cathode or into the unfired gap. Such migration lowers the breakdown voltage of the unfired gap so that greater speed of glow transfer is possible as well as the use of input pulses of less amplitude. Operation is effected in accordance with the curve C of Fig. 2.

Referring to Fig. 4 the tube 30 includes the wire cathodes 31 and 32 and an anode 33 intermediate the cathodes. The cathodes and anode are held in a preselected spaced relation by the upper and lower spacers 34 and 35 respectively. The anode 33 is formed as a flat sheet and has a hole therethrough as shown to permit ion migration from the tired gap into the unfired gap to permit operation as indicated by curve C of Fig. 2. The number and size of the holes used will vary in accordance with the operating requirements, the electrode spacing and the pressure of the gaseous atmosphere within the envelope of the tube.

Referring to Fig. the cathodes 4t] and 41 are of the wire type. The cathode 40 has a relatively small and uncoatcd surface area as compared to the surface area of cathode 41 which is coated with any suitable material such as activated barium-strontium compounds. The object in making the area of cathode 41 large relative to that of cathode 4t and of coating cathode 41 is to provide a voltage drop between the anode 33 and cathode 41 which is less than the voltage drop between the cathode 40 and anode 33 when a glow discharge exists across those respective gaps and the values of resistors 13 and 14 are equal.

Since the voltage drop is less across a glow discharge between the cathode 41 and anode 33 than between the cathode 40 and anode 33 it is possible to transfer the glow discharge from the cathode 40 to the cathode 41 by applying a negative pulse of relatively low amplitude and short duration to the terminal 23 or positive pulse to terminal 22 as compared to the amplitude and duration of the negative pulse which must be applied to the terminal 22 or positive pulse to terminal 23 to transfer the glow discharge from the cathode 41 to the cathode 40. As an example, it has been found that for one given condition of operation a negative pip or spike pulse is suflicient to elfect glow transfer when applied to the terminal 23 as compared to a square pulse of approximately 100 microseconds duration which rnust be applied to the terminal 22 to insure reliable glow transfer. For equal ignition characteristics at starting or equal cathode spacing relative to the anode, the glow discharge to a desired cathode can be accomplished by applying the cold or initial striking voltage to the cathode to which. it is desired to create a glow discharge. This may be done by allowing that cathode to be more negative than the other cathode until ionization ensues.

Variations in the amplitude of the pulses applied to the terminals 22 and 23 may be obtained by varying the dis tance of the cathodes 40 and 41 from the anode 33. For example, if cathode 46 is sufficiently more distant from the anode 33 than the cathode 41 the pulse applied to the terminal 22 willhave to be of greater amplitude than that applied to the terminal 23. In this case the discharge will initiate between cathode 41 and anode 33provided the cold striking voltage is less than that required to create a glow discharge across 40-33. The size of the hole in anode 33 or the amount of ionic coupling permitted is dependent upon the spacing of the cathodes from the anode, the area of the anode and the area of the cathodes, and the mixture and pressure of the gaseous atmosphere employed. As in the previously described'embodiments it is desirable to permit suflicient ionic leakage into the unfired gap region to facilitate rapid glow transfer but not enough ionic leakage to cause instability. In other words, conditions illustrated by curve C (Fig. 2) are most desirable.

Voltage amplification may be effected by employing resistors 13 and 14 of different values. For example, suppose resistor 13 i of larger value than resistor 14 and the voltage drop between anode 33 and cathode 41 is less than that between anode 33 and cathode 40. Then, when the glow discharge is transferred from the cathode 40 to the cathode 41 there is no increase in the current through anode resistor 15 and a gain in voltage amplification is accordingly effected.

Referring to Fig. 5a the embodiment i of particular utility when used as a binary sealer; i. e., input pulses are applied to terminal 24 and an output is derived from either of the terminals 22 or 23. Resistor 15 is chosen so that it will sustain a glow discharge to only one of the cathode 40 or 41 and resistor 13 is larger than resistor 14. Condensers 43 and 44 in parallel with oath ode resistors 13 and 14, respectively, are provided to increase the stability of the glow transfer. Although the value of resistor 15 is too large to permit glow present to both the cathodes 4t) and 41 simultaneously the resistor 13 has a larger value than the resistor 14 and the tendency to prevent the existence of glow discharge between anode 33 and cathode 40 by the shorting out effect above referred to is accordingly decreased because the voltage drop across resistor 15 is substantially constant whether the glow discharge be to the cathode 40 or to the cathode 41. The condensers 43 and 44 ensure that the voltage between each cathode and the anode will be sufliciently high to prevent a spurious glow transfer while de-ionization is effected in the gap from which the glow discharge has just been transferred. If the impedance of 13 and 43 equals the impedance of 14 and ,44 and condenser dis charge time is matched to repetition rate and width of pulses at 24 such as ensured.

Referring to Fig. 6, the novel switch-trigger tube 46 is shown in cross-section and includes a starter anode SA] in spaced glow discharge relation to a disc-shaped cathode C-1, having a hole through its center. This cathode C-l effectively divides the tube envelope into two ioniza tion chambers linked together by the ionic leakage effected through the hole at the center of cathode 0-1. The starter anode SA-1 is situated in the first or left-hand ionic chamber and the main anode MA, starter anode SA-2, and main cathode MC are situated in the second or right-hand ionic chamber. The main anode MA is of the wire type, starter anode SA-2 is of the cylindrical wire mesh type and is positioned intermediate the main anode MA and the annular-shaped main cathode MC.

The enumerated electrodes are connected as shown and a positive input pulse is applied to the input ter minals 48 and 50 in turn to effect operation of the tube. That is a pulse must first be applied to the input terminal 48 and subsequently a pulse must be applied to input terminal 50 to derive an output from the output terminal 52 connected to the main anode MA. Because of this required sequence of input pulses the tube 46 is termed a switch-trigger tube.

When an input pulse is applied to input terminal 48 and hence to the starter anode SA-1 the voltage difierence between the anode SA-l and the cathode C1 is increased sufficiently to initiate a glow discharge therebetween. This glow discharge is referred to as an auxiliary glow discharge. Ions. and electrons then migrate through the hole in the cathode C-1 into the right-hand ionization chamber and thereby cause a decrease of the breakdown voltage required to effect a glow discharge therein. While a glow discharge exists between the anode SA-l and cathode C1 an input pulse is applied to the input terminal 50. This input pulse creates a sufficient voltage difference between the starter anode SA-2 and the main cathode MC to create a glow discharge therebetween. This glow discharge between anode SA-2 and cathode MC effects a further ionization of the gaseous atmosphere within the right-hand chamber. Thi ionization is sufiicient to cause the glow discharge to be extended from the starter anode SA-Z to the more positive main anode MA and thereby exist between the main cathode MC and the main anode MA. This glow discharge is referred to as a main glow discharge. In other words, the glow discharge between the main cathode MC and the starter anode SA-2 provides the transfer current to initiate the glow discharge between the main cathode MC and the main anode MA. When the input pulse applied to input terminal 48 ceases or the voltage across the glow discharge between the starter anode SA-l and cathode C-1 is caused to decrease below the required sustaining voltage such as by removal of the B+ voltage source that glow discharge is extinguished. Also, when the input pulse applied to input terminal 50 ceases the glow discharge between the main cathode MC and the starter anode SA-2 is extinguished. The glow discharges between the starter anode SA-l and the cathode C-1 and between SA2 and MC may be extinguished at any desired time after a glow discharge is created between MA and MC in the right-hand chamber without etfecting the operation of the tube. A negative output voltage pulse appears at the output terminal 52 while a glow discharge is present between the main cathode MC and the main anode MA.

The various electrodes are so positioned that the application of an input pulse to either of the input terminals 48 and 50 alone will not produce an output pulse or create a glow discharge in the right-hand chamber. An output is produced only when an input pulse is applied to the input terminal 48 to produce a glow discharge between the starter anode SA-1 and the cathode -1 and while that glow discharge exists an input pulse is applied to the input terminal 50.

While there have been shown and described and pointed out the fundamental novel features of the invention as applied to a preferred embodiment, it will be understood that various omissions and substitutions and changes in the form and details of the device illustrated and in its operation may be made by those skilled in the art, without departing from the spirit of the invention. It is the intention, therefore, to be limited only as indicated by the scope of the following claims.

What is claimed is:

l. In a trigger tube of the glow transfer type, a single anode providing a preselected ionic leakage path therethrough, two cathodes unequally spaced from and positioned on opposite sides of said anode; load impedances of different ohmic value connected in circuit with each cathode so that the voltage drop across a glow discharge between the anode and that cathode having the higher ohmic impedance value in circuit therewith is less than the voltage drop across a glow discharge between the anode and the cathode having the lower ohmic value in circuit therewith; and a load resistor connected between the anode and a source of voltage, said load resistor being of such ohmic value that a glow discharge exists between the anode and only one of said cathodes at any given time, whereby voltage amplification is obtained when a glow discharge is transferred from the cathode having the lower ohmic impedance in circuit therewith to the cathode having the higher ohmic impedance in circuit therewith.

2. A trigger tube of the glow transfer type having input and output terminals; two cathode electrodes Within said tube; a single anode electrode intermediate said cathodes, said anode providing an ionic leakage path of predetermined limited area from the vicinity of each cathode to the vicinity of the other; circuit means including individual impedances coupled to said electrodes for rendering said tube operative to establish a glow discharge between said anode and one of said cathodes; said cathodes being of different physical size, having diiferent glow characteristics and being unequally spaced from said anode so that the voltage drop across said glow discharge is different when it exists to each of said cathodes; and means including at least one of said terminals for receiving a pulse input to effect a transfer of said glow discharge to a position between said anode and the other of said cathodes.

References Cited in the file of this patent UNITED STATES PATENTS 1,420,824 Donle June 27, 1922 1,919,263 Smith July 25, 1933 1,951,416 Hund Mar. 20, 1934 1,992,493 Los Feb. 26, 1.935 2,575,516 Hagen Nov. 20, 1951 2,638,564 Williams et al May 12, 1953

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