US3070718A - Multiple-gap gas discharge tube - Google Patents

Description

Dec. 25, 1962 MARX MULTIPLE-GAP GAS DISCHARGE TUBE llllllllllllllllllll INVENTOR Georg Marx ATTORNEY 3,970,718 MULTWLEGAF GAS DTSCHARGE TUBE Georg Marx, Ulm {Danube}, Germany, assignor to Telefnnken G.m.b.l-l., Berlin, Germany Filed June 24, was, Ser. No. 38,606 Claims priority, application Germany June 27, 1959 11 Claims. (Cl. 3131) The present invention relates to a gas-filled plural-discharge-gap electron tube.

It has been known in the art to include several glow discharge gaps into one discharge tube, wherein these discharge gaps are connected electrically in series to produce a stabilized voltage which is a multiple of the number of discharge gaps times the relatively small voltage drop across each discharge gap, said latter voltage drop being constant over a large current range. Such tubes are known as plural-discharge-gap stabilizers and-they are relatively cheap and require less space than several singledischarge-gap stabilizer tubes.

The mutual arrangement of the various electrodes in a plural-discharge-gap tube has to be of such nature as to prevent the creation of a discharge are between those electrodes which have the highest difference in operating potential. In other words, the charge carriers of one discharge gap have to be kept separate from the charge carriers of each of the other discharge gaps. In known types of tubes, this has been accomplished by using one side of a disk-shaped electrode as a cathode for one discharge gap and the other side of the same disk as an anode for an adjacent discharge gap. Each discharge gap is further enclosed by insulating walls preventing any kind of gas or ion exchange between adjacent discharge gaps. The lead-in wires for the electrodes pass through these insulating walls.

Another type of voltage stabilizer discharge tube is known in the art and has disk-shaped electrodes penetrating a glass tube wall in parallel relationship. In order to have the entire tube evacuated and refilled by one pumping step and through one opening, the electrodes are provided with little holes covered with a porous ceramic to prevent a discharge from passing through these gas exchange holes.

It is apparent that the several discharge gaps of any of these tubes can only be operated in direct series circuit connection. It is impossible to use the several discharge gaps inside of-such tubes in various separate operating points within an electrical system and at various distinct potential levels. However, in numerous types of electrical systems, stabilizer tubes are used at ditferent and separated points in the circuit, wherein each discharge gap is completely separated galvanically from the other discharge gaps inside the same tube envelope. This is the case, for example, in the so-ealled cascaded stabilizer circuit which, until now, required separate glow-discharge tubes.

It is an object of the present invention to provide a new and improved gas-filled plural-discharge-gap electron tube overcoming the deficiencies of these prior art tubes, and said novel tube providing plural discharge gaps wherein each gap is galvanically separated from the other discharge gaps and may be operated at a completely ditferent voltage level, as compared with the other discharge gaps in the same tube.

It is another object of the present invention to provide a new and improved plural-discharge-gap tube in which gas exchange between the several discharge gaps is permitted, but wherein ion exchange is successfully suppressed.

According to one aspect of the invention, in a preferred embodiment thereof, a plurality of pairs of elecice trodes are associated with electrical insulating means respectively defining separate discharge gaps for each pair of electrodes, and said insulating means including relatively narrow gaps permitting limited gas exchange between the discharge gaps but arresting passage of electrical charges, thereby effectively preventing ion transit therethrough.

Additional objects and advantages of the present invention will become apparent from a consideration of the following description when taken in conjunction with the accompanying drawings, in which:

FIGURE 1 is a perspective view of a tube according to a first embodiment of the invention, having portions thereof broken away to illustrate internal structure.

FIGURE 2 is an enlarged cross sectional detail of a portion of the tube shown in FIGURE 1.

FIGURE 3 is a cross sectional view of a modified tube according to another embodiment of the invention.

Referring in detail to the drawings, FIGURE 1 shows a tube 1 having a glass envelope 8 and having a bottom portion 1a through which lead-in wires 2 are passed. The lead-in wires are circularly arranged as is known to fit tube sockets. Inside the tube, pairs of adjacently located wires are sealed into circular glass bosses 3, each having the shape of a truncated cone. The height of these bosses 3 is only a few millimeters. There are two wires supported in each boss 3. Small glass separator tubes 4 are seated on each boss 3, said glass tubes 4 having widened portions 4a, FIGURE 2, at their lower ends to closely match the truncated cone configuration of the bosses 3. The tubes 4 are closed at their tops, terminating in centrally positioned studs 5. The studs 5 are annularly arranged about the center axis of the envelope 8 and are received in holes 6 of a supporting disk 7. The disk 7 may, for example, be made of mica. The wires 2 terminate inside of tubes 4 and these wires may support any kind of suitable electrodes, or they may themselves serve as electrodes. The latter case is illustrated in FIGURES 1 and 2 and, here, the wires in each tube 4 are bent towards each other to acquire a predetermined spacing constituting the discharge gap. Preferably, the two wires in each tube 4 are arranged symmetrically with respect to the center axis of that tube. The supporting plate 7 can be secured to other lead-in wires 10, serving to tension the plate 7 towards the bottom 1a of the electron tube 1. This action, in turn, causes a tightening of the small tubes 4 on the bosses 3 and towards the bottom 1a.

The upper portion of tube 1, designated as the envelope 8, is evacuated in the usual manner and sealed at the top thereof, prior to refilling with a rare gas (helium, xenon and the like), or a mixture of several rare gases, or it may be refilled with another ionizable gas or vapor (mercury, sodium, etc), the pressure of which is below atmospheric.

It is important that the separator tubes 4 are not sealed by melting or bonding with bosses 3, nor is there provided any sealing cement in the space 9 between a tube 4 and a boss 3. The width of this space 9 may be of the order of a magnitude of one-tenth of a millimeter, while its length 11 may, for example, be 4 millimeters. Thus, when tube 1 is evacuated, the inner space of tubes 4 will also be evacuated, and upon refill of tube 1 with ioniz able gas, tubes 4 will also be refilled with this gas. In other words, gas exchange is permitted between the tubes 4, and between the tubes 4 and the inner part of the envelope 8 by the gas passing through the spaces 9 However, ions will not pass through these spaces 9, because they lose their charges at the glass walls defining the spaces 9. It is, therefore, possible to operate every one of the discharge gaps as confined within each separator tube 4 in a separate circuit, whereby the discharge gaps may have potiential differences between each other of several kilovolts.

The continuous gas exchange betwen the various tubes 4 and the gas within the envelope 8 has a number of advantages not found in the known plural-discharge gap tubes of the prior art, or in the use of several independent and completely separate single-discharge-gap tubes.

One of these advantages of the present tube is the equalization of the pressure inside of all the tubes 4. Thus, the electric properties of all of the various discharge gaps remain equal before and during operation. In particular, the gas consumption during operation and the initital burning effect affects the interior of all the small tubes 4 equally and uniformly, and any differences which might appear are equalized very fast, due to the continuous gas exchange between the separator tubes 4. Each tube 4 can be made very small in size, as compared with the volume of the envelope 8. Thus, this envelope 8 provides a relatively large gas reservoir out of which any gas losses inside any of the tubes 4 are compensated and, thus, the overall gas loss remains fairly small.

The fact that the tubes 4, i.e., the volume of every single-discharge-gap, can be made very small is of further advantage because the inner walls of tube 4 can then very easily be metallized, for example, by means of a forced sputtering of cathode. This sputtering treatment of the interior of every tube 4 serves to clean the electrode surfaces therein, which cleaning is particularly desirable in glow discharge tubes having a very critical discharge voltage drop. Furthermore, the effect of electrostatic charges on the inner walls of the tubes 4 are reduced if the walls are metallized, whereby also the contamination of these glass walls is avoided. Contamination leaving the walls of the envelope 8 will be rendered ineffective by placing a getter inside thereof but outside of the separator tubes 4, said getter being effective before any contamination can pass into tubes 4 through the gaps 9.

Tubes of this kind, when manufactured with a layer of sputtered material inside of tubes 4 and provided with a getter outside thereof, but inside of tube 1, have remarkably constant characteristics from tube to tube, particularly with respect to the electrical characteristics of the multiple individual discharge gaps thereof. It has been found that such precision stabilizer tubes have a life time of several ten-thousand hours with remarkably constant and uniform discharge-gap voltage drops.

FIGURE 3 illustrates another embodiment of the invention, the several discharge gaps being axially aligned rather than positioned circularly around a center axis, as shown in FIGURE 1.

A tube is divided into sections comprising stacked ceramic rings 21a and 21b of equal length, alternated with interconnecting metal disks 22, each having a recess 23 defining a cup-like portion having holes 24, the purpose of which will be explained below. Ceramic rings 21a and 21b are metallized at their end portions and soldered thereat to the disks 22 in a conventional manner. The rings 21a and 21b are positioned in alternate relationship, so that each disk 22 joins a ring 21a and a ring 21b. The stacked rings 21:: and 2112 form a composite envelope comprising a long tube terminating at one end in a cap-like ceramic member 26 having a flange 27 with a metallized end registering with the end of a ring 21a or 21b. The tube as defined by the combined rings 21a and 21b terminates at its other end in a socket structure including a terminal ring 31, a metal socket 28 and a pumping or evacuating tube 29. Metal socket 28 houses a getter support 30 carrying the getter. The tube defined herein is vacuum-sealed in a furnace, then evacuated and refilled with an ionizable gas and, finally, closed after the tube 29 has been sealed off.

Pairs of adjacently positioned disks 22 define separate discharge gaps, particularly the juxtaposed bottom portions of their recesses 23. Each discharge gap is enclosed by a ring 21a and is separated from its neighboring dis- 4 charge gap by a ceramic plug 25 inserted in the rings 21b, respectively. The diameter of each of these disks 25 is one or more tenths of a millimeter smaller than the inner diameter of its associated ring 21b. The length of each of these disks (i.e., the axial length) is also only one or more tenths of a millimeter smaller than the axial length of its associated ring 2112. The space 32, thus defined, between any ring 211) and its associated ceramic disk 25, and the holes 24, permit gas exchange between adjacent discharge gaps throughout the entire volume of the tube. However, these spaces prevent ion exchange by arresting charges contacting the glass walls of rings 21a and disks 25 defining such spaces 32. Tubes of this kind have a large mechanical strength and resistance to temperature variations and they are highly shock-resistant.

It will be seen that in each of the above-described embodiments of the present invention, the openings which allow the flow of gas but prevent the flow ions are so arranged as to leave no line-of-sight from any one discharge gap to any other.

It will be understood that the above description of the present invention is susceptible to various modifications, changes and adaptations, and the same are intended to be comprehended within the meaning and range of equivaients of the appended claims.

I claim:

1. A gas-filled plural-discharge-gap electron tube comprising: a plurality of electrically insulated electrodes grouped in pairs; and electrical insulating means each enclosing a separated discharge gap for one pair of electrodes, said insulating means having relatively small openings permitting gas exchange between said separated discharge gaps but arresting the exchange therethrough of gas ions.

2. A gas-filled plural-discharge-gap electron tube comprising: a plurality of pairs of electrodes; support means insulating the electrodes from each other but maintaining between the electrodes of each pair a free space; ionizable gas filling the electron tube; and separator means exclusively confining each of said pairs, said means including gas exchange openings between the various separated spaces, said openings being too small to permit the exchange of ions therethrough.

3. A gas discharge tube comprising: a tubular gas filled envelope; a plurality of separator tubes in said envelope, each substantially closed at its ends and oriented in said housing to define a gas chamber; a pair of electrodes in each chamber, and said separator tubes having openings large enough to permit gas exchange between the chambers and the envelope but too small to permit the exchange of ions between the chambers and the envelope. t

4. In a tube as set forth in claim 3, said envelope having a bottom portion including a plurality of bosses, each of said pairs of electrodes passing through one of said bosses, and said separator tubes each having its end enclosing a boss loosely to provide an intervening gas exchange opening.

5. In a tube as set forth in claim 4, the separator tubes being disposed mutally parallel and the ends opposite each boss having a stud, and insulating disk-shaped support means having holes therethrough for receiving all of said studs as a common support for the separator tubes.

6. A gas-filled plural-discharge-gap electron tube comprising: a glass envelope having a bottom portion; a plurality of glass bosses in said housing integral with said bottom portion and extending thereabove in truncatedcone configuration; lead-in wires passing in pairs through said glass bosses and terminating in spaced electrode pairs within the envelope; glass separator tubes relatively loosely seated on said bosses and leaving spaces defining gas exchange gaps between each separator tube and a boss which spaces, however, are too small to permit ion exchange therethrough, each separator tube having a closed upper end and enclosing one pair of said electrodes;

and supporting means in said housing for supporting the upper ends of said separator tubes.

7. In a tube as set forth in claim 6, means connected between said supporting means and said envelope to yieldably urge said glass tubes towards said studs.

8. A gas-filled plural-discharge-gap electron tube comprising: a plurality of insulating rings disposed in axial alignment to form an envelope; a plurality of disk-shaped electrodes interposed therebetween and each having at least one hole, each electrode serving as a sealing and interconnecting means between two rings; and insulating disk means inserted in every alternate ring, substantially filling the space therein, and permitting slight gas flow in the space defined between each disk means and its associated ring while preventing ion exchange through said last-mentioned space.

9. In a tube as set forth in claim 8, the width of the space between said disks and said rings being a few tenths of a millimeter.

10. In a tube as set forth in claim 8, said disk-shaped electrodes being provided with a recess having a bottom portion, the outer surfaces of the bottom portions of adjacent disks facing each other and defining a gas-discharge gap.

11. A gas-filled plural-discharge-gap electron tube comprising: a plurality of electrically insulated electrodes grouped in pairs; and electrical insulating means each enclosing a separated discharge gap for one pair of electrodes, said insulating means having relatively small openings permitting gas exchange between said separated dis charge gaps but arresting the exchange therethrough of gas ion-s, said openings being so arranged as to leave no line-of-sight from any one discharge gap to any other.

References Cited in the file of this patent UNITED STATES PATENTS 1,754,158 Goodwin Apr. 8, 1930 2,444,427 Busignies et a1. July 6, 1948 2,527,552 Hough et a1. Oct. 31, 1950 2,593,429 Foulke Apr. 22, 1952 2,890,383 Olsen June 9, 1959

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