US2443205A - Gaseous discharge device - Google Patents

Description

June 15, 1948. P. W. STUTSMAN 2,443,205

GASEOUS DISCHARGE DEVICE Filed May 5, 1945 s sheets-sheet 1 June 15, 1948. P. w. snnrsMANA -2,443,2o5

, GASEOUS DISCHARGE DEVICE Filed May 3, 1945 3 Sheets-Sheet 2 June 15, 1948. P. w. sTUTsMAN 2,443,205

GSEOUS DISCHARGE DEVICE Filed may s, 1945 5 sheets-sheet 5 Patented June 15, 1948 GASEOUS DISCHARGE DEVICE Paul W. Stutsman, Needham, Mass., assignor to Raytheon Manufacturing Company, Newton, Mass., a corporation of Delaware Application May 3, 1945, Serial No. 591,778

(Cl. Z50-27.5)

13 Claims.

This invention relates to an electrical system utilizing a grid-controlled gaseous discharge tube and to a novel tube utilized in said system and to a circuit for said tube.

One of the objects of the present invention is to provide an improved system and tube of the `type described.

Another object of the present invention is to provide a circuit for the improved tube of the type referred to.

A further object of the present invention is to provide a tube of the general type referred to in which the gain, that is to say the ratio of output to input, is greatly increased.

These and such other aims and objects of the present invention as may hereinafter appear will be best understood from the following description of an exemplication thereof, reference being had to the accompanying drawings, wherein:

Fig. 1 is a broken away perspective viewof a tube incorporating an illustrative embodiment of the present invention;

Fig. 2 is a sectional View of the mount assembly illustrated in Fig. l, taken on line 2--2 of Fig. 4;

Fig. 3 is a view similar to Fig. 2 taken on line,

circuit including a tube of the type illustrated in Fig. 1; and

Fig. 6 is a, schematic diagram of an illustrative circuit including two tubes of the type illustrated in Fig. 1, in cascade. I

The tube incorporating the illustrative embodiment of the invention shown in Figs. 1 to 4 comprises an elongated envelope 2 provided with a reentrant stem 4 at the base thereof, the in turned end of said stem being closed by a press 6 which carries the mount assembly 8. A conductor l!) (see Fig. l) is sealed through a glass bead I2, hermetically secured in the top wall of said envelope 2, and is soldered to a metal contact cap I4 cemented exteriorly to the top of the envelope 2 at I6. The other end of said conductor I0 is connected to the middle of a conductor I8 having its ends welded to diametrically opposed points, upon the inner surface of a hollow cylindrical cathode 2i) of the glow discharge type, which it supports. Said conductor ill serves as a lead-in for the cathode 29], which is preferably open at both ends, it having been found that the cathode operates more efficiently if the opening through it is unobstructed. As clearly appears from the drawing, the area of the cylindrical walls of the cathode, which are substantially parallel to the side walls of said envelope, is relatively large. The cathode is formed of sheet metal, preferably nickel, the nickel sheet being preferably stamped out and then bent into cylindrical form.

It has been found that the presence of thorium oxide, 4or other suitable non-gasifying radioactive substance, aids in producing the constant low starting `voltage which is characteristic of the Apresent tube. This action is believed to be due to the radio activity of these substances. Particles :of the thorium oxide or other radioactive substance may be stamped into or otherwise imbedded in the surface of the cathode, but it is not necessary that said substance be on the cathode.

The cathode will preferably be oxidized to form thereon a coating of nickel oxide and is then coated with an alkaline earth metal or an alkali metal, hereinafter referred to as alkaline metals.

I preferably usek pure barium, which may be obtained by flashing a getter of the type known as "batalum getter, within the tube.

Said getter (see Fig. 3) is shown at 22 and is conveniently connected at one end to the free end of an auxiliary electrode24, serving as a stabilizing electrode, `and at its other end to a conductor 26, extending through an electrically conductive eyeletZB, one of four which serve to hold the elements of :the mount assembly together, said conductor being connected to a lead-in 34 (see Figs. 1 and 2) sealed through the pressv 6. Said stabilizing electrode 24 extends through a second eyelet of the aforesaid four eyeletsA 23, and is connected to a lead-in 30 sealed through said press B.

Referring more particularly to Fig. 1, the top of said mount assembly 8 bears against a shoulder 36 formed in the side Walls of the envelope 2, said shoulder thus imparting rigidity to the internal structure of the tube and cutting off any paths around the outside of said mount assembly, whereby the electron discharge is cornpelled to take place through openings provided in said mount assembly. Insulating sleeves 38 and 40 (-see Fig. 2) fused in said press `l support said mount assembly.

In accordance with the present invention said mount assembly 8 comprises s, plurality of circular insulating washers 42, preferably of mica, each provided with a relatively large central'opening 44 (see Fig. 4) for the passage of the electron discharge, in addition to four smaller openings it for the reception of the before mentioned four eyelets 28, and two suitable openings 48 for the reception of the upper portion of the previously mentioned insulating sleeves 38 and 40.

said suppressor grid are superposed in the .ordernamed, a screen grid 54, a control grid 56, anda cathanode grid '53, each of said gridsbe'ing separated from the one above andthe one .below it by one of said insulatingwas'hersdz." R'efe'r'-V I ring to Fig. 5 it will be noted that in accordance. with the present invention the screen grid 54Y is connected back to the control `grid 56 through This increases the signal.

a suitable resistance. input impedance and enables the device to operate with a low power signal.

All'of said grids completely coverthe central openings 4'4 Iin said Washers. The upper ends of the 'aforementioned eyelets 28 grip the insulating lead-in 68 also sealed in said press. The control grid 55 (see Fig. 2) is connected to a rigid con-` ductor 'l2 by a ribbon i4, said conductor being sealed in said press 6 and connected to a lead-in 'I6 also sealed in said press. The cathanode 58 is ,connected by a ribbon 'i8 to a conductor 80 sealed in said press and connected to a lead-in 82 also sealed in the lattter.

After the tube has been exhausted, a current is passed through the getter 22 from the lead-ins 34 and- 30 (see Fig. l) and heats the getter to a p oint atv which barium is liberated to clean up 'residualgases Vand also to deposit on the surface ofthe cathode 2G for the purpose described above. Thereupon an inert ionizab-le gaseous atmosphere is introduced, said gaseous atmosphere washer restingupon the cathanode'gridA 58,- and the lower ends of said eyelets grip the bottom washer-ofsaid mount assembly so that the parts ofthe latter are securely clamped together. Two or more'. additional insulatingwashers, provided only with centralwopenings for the passage of the cathode drop. The `suppressor 'or ion collector grid .52 has a negative potential, so that'it .tends to attract-positive ions in their passage and. preyvent them from showering the control grid 56.

The suppressor grid 52 'consists of .parallel wire strands, twenty-wire strands .tothe square inch;y

the-wire being Ypreferably of Ztungsten'and .0007 inch` in diameter. The. screen grid 5'4will preferably be made ofwire of a diameter 'of .005 inch Vand a mesh of 30 x 30 (900) 'openings' toithe square inch. This grid in picle'ng .up positivel ions tends to fbe driven positive in proportion to the number of .ions which in turn is proportional tothe number of electrons 4flowing. This tends to amplify theplate swingand thus Vincrease the amplification of the tube. Which controlsl the electron V130W from theV cathode to the anode responsiveto the input signal Y and the cathanode grid vwhich draws an electronic.dis'charge Yfrom `the cathode and Adirects f it toward. the anode -are preferably woven f-rornwire of less than .005 inch and preferably .003 inch in diameter and haveamesh' of'o'x 60 (3600") openings per square inch. It is also'pref; erable Vthat .the .openings of these two.' last-named grids coincide.

Theanode is connected toa rigid conductor 760sea1ed in the press 6 and` connected to a leadin'62`"(see Figs. 2. and 3). The suppressor grid 52 lis-coni'iected to the cathanode' by a ribbon conductor |22. to a conductor VGili b'ya ribbonl, said conductor being sealed in 'said' press Biand' connectedto a The control grid.`

The 'screen grid k54 is connected.

preferably consisting of a rare gas, such as argon orkrypton, but preferably Xenon at a suitable pressure. ,The pressureis critical. I have found that a critical. pressure region'o about-300 to 1500 rmicrons exists'within which-the tubewill operate satisfactorily for the purposes herein indicated If lthe pressure is lower than 300 microns, the cathodedrop tends to increase, and if the pressure is above 1500 microns, the mean free path of the electrons is too short to keep control of them in the embodiment described. y

Referring to Fig. 5 and the circuit therein delineated, the cathode 20 is connected by conductors84,86, andil to the negative terminal 900i a source of direct current which is grounded at 925 while the anode 50 is 'connected to the positive terminal 94s of said source by a conductor 96 through a load resistance 98 of 10. megohms.v The stabilizing electrode 24 for .maintaining kan ionizing discharge to said cathode is adjacent said cathode and connected to said positive terminallM-through a resistance |66 of 30 megohms by conductors |2, W4, and Qt. The foraminous cathanode 58 is mounted adjacentsaid ionizingspace and isv connected by conductors |03, |04, and S6 throughfa' series resistance |06 of 10 megohms with said positive terminal=94- -The control grid 5t islocated within the control section upon the opposite side of said cathanode fromsaid ionizing space, and is connected through conductors |96, |28, H4, condenser |26 and conductor |6 to a signal input terminal I8. 'It'is' also connected lto the cathanode 58 through conductors |03 and H0, resistance H2 of 20 megohms, and conductor |03. V'The cathanode 58 is connected back to the cathode 20' through conductor |03, condenser |30, and conductors 86, and 84.

Said condenser |30 may have a value of 0.002 microfarad and functions as aV cathanode bypass condenser to bypass any variable voltages between thev cathode and the cathanode; rThe stabilizing electrode 24, by maintaining a, continuous discharge to the cathode, eliminates any objectionable oscillations that might otherwise oc cur in this circuit due to the presence ofv said condenser |30; The screeny grid 54 is connected through resistance |20 and conductors |28 and |08 to the control grid 5t which as already pointed out above increases the input impedance of the control grid.` Condenser |26 functions as a, grid'coupling condenser, and may have a value of 0.002 microfarad. The suppressor grid 52 is adjacent th-e anode and connected back to the cathanode 58 by the conductor |22 as described above. K

Two tubes constituted as herein described in accordance with my invention and connected in cascade will materially increase the gain. Fig. 6 shows schematically two tubes A and A' in accordance with the present invention in cascade, and an illustrative circuit therefor. Referring to said Fig. 6, the cathode 20 of tube A is connected to the negative terminal |32 of a. source of direct current by a conductor |34, the cathode 20 of tube A being connected to said terminal by said conductor |34, conductor |36, and conductor |31. The anode 50 of tube A is connected to the positive terminal |38 of said source by conductors |40, |42, |44,k |46, and |48 through a load resistance |50 of 10 megohms, and to the output terminal 224 by conductor |40, resistance |50, conductor |42, and a resistance 226 of megohms. The anode 50' of tube A is connected by conductors |52 and |54 with terminal 2|6 of the output device 2|1; thence through said output device to the other terminal 224 of said output device; and thence through the resistance 226 and conductors |42, |44, |46, and |48 to said positive terminal |38.

The stabilizing electrode 24 of tube'A, for main taining a discharge to the cathode of said tube, is connected to the positive terminal |38 of said source of direct current by conductors |10, |12, |46, and |48 through a resistance |14 of 30 megohms, and the stabilizing grid 24' of tube A', for maintaining a discharge to the cathode of tube A', is connected to said positive terminal |38 of said source by conductors |16, |18, |46, and |48 through a resistance |15 of 30 megohms.

The cathanode 58 of tube A, which draws a discharge from the cathode of said tube, is con'- nected to said positive terminal |38 of said source of direct current through conductors |62, |12, |46 and |48, through a resistance |68 of 10 megohms; and the cathanode 58' of tube A is connected to said terminal |38 through a resistance |80 of 10 megohms, similar to the aforesaid resstance |68, and conductors |32, |84, |46, and |48.

The control grid 56 of tube A is connected to the cathanode 58 of said tube by conductors |86, |58, and |60 through a resistance |66. Said control grid is also connected to the signal input termina-l 208 through conductors |86, 2|0 and condenser 2 |2. The cathanode is connected back to the cathode by conductor 224, condenser 230, and conductors 226, |36, and |34. The condenser 230, inserted between the conductors 224 and 226. is a bypass condenser to bypass any variable voltages between the cathode and the cathanode.

VVSimilarly the control grid 56 of tube A' is connected by conductors |88, |80, and |92 through a resistance |94 similar to the resistance |66 of tube A, to the cathanode 58' of said tube A. said control grid 56 is supplied with the amplined output of tube A by conductor 222 connected to the anode lead |40 and thence through condenser 2 |8 and conductor |88 to said control grid. The cathanode 58 is connected back to the cathode 20' by conductor 236, condenser 240, and conductors 238 and |31. The condenser 240 is a cathanode .bypass condenser having the same function as the aforesaid condenser 230 and of the same capacity as the latter. l

The screen grid 54 of tube A is connected to the control grid 56 of said tube through a resistance |64 of 10 megohms and the conductors |56 and |86, and similarly the screen grid 54' of tube A' is connected to the control grid 56 of said tube A' through resistance |96 of 10 megohms and conductors 200 and |88.

The suppressor grid 52 of tube A is connected 6 back to the cathanode 58 by conductor |22, and the suppressor grid 52' of tube A' is connected back to the cathanode 58' by conductor |22. The above connections of suppressor grids markedly lower the signal input power required to operate the system.

All of the above-mentioned resistances have been selected of predetermined values to give the optimum results in tubes as herein constituted in accordance with the present invention.

The signal input is indicated at 208 and is led in directly to the control grid 56 of tube A by conductors 2|0 and |86 through a coupling condenser 2|2, which may be of the order of 0.002 microfarad, to arrest any direct current, while allowing alternating current to pass. After being amplified in tube A, voltage is lled from said tube A through conductors |40, 222, and |88 directly to the control grid 56 of tube A', and said voltage is thus still further amplified by said tube A. A coupling condenser 2|8between conductors 22 and |88 exercises the same function as the aforesaid condenser 2|2 of tube A and may be of 0.002 microfarad.

After being thus twice amplified, rst in tube A and then in tube A', a, portion of the output is reconducted from tube A' back to tube A through conductors |52, |54, condenser 2 |4, and conductor 2|5 to the screen grid 54 of tube A. Thus the signal is still further amplified and led back to tube A through the connections previously described. The coupling condenser 2|4 functions similarly to the coupling condenser 2|8, and may be about .000005 microfarad.

'It will thus be seen that the output is regeneratively amplified, which accounts in part for the remarkable gain obtained with the system of my invention. l'I'wo tubes in cascade as above described will produce a voltage gain of 20 at 1000 cycles and one of at 100 cycles and at 130 volts.

I am 4aware that the present invention can be embodied in other specific forms without departing from the spirit o1' essential attributes thereof, and I therefore desire the present description to be considered in all respects as illustrative and not restrictive, reference being had to the appended claims rather than to the aforesaid description to indicate the scope of the invention.

What is claimed is:

1. An electrical-discharge tube containing an inert ionizable gas, a glow discharge cathode, an auxiliary electrode for maintaining an ionizing discharge to said cathode, a foraminous cathanode adjacent the space in which said ionizing discharge occurs, a control grid on the opposite side of said cathanode from said ionizing discharge space, a screen grid adjacent said control grid, a suppressor grid adjacent said screen grid and connected to said cathanode, and an anode adjacent said suppressor grid.

2. An electrical discharge tube containing xenon gas, a glow discharge cathode, an auxiliary electrode for maintaining an ionizing discharge to said cathode, a foraminous cathanode adjacent the space in which said ionizing discharge occurs, a control grid on the opposite side of said cathanode from said ionizing discharge space, a screen grid adjacent said control grid, a suppressor grid adjacent said screen grid and connected to said cathanode, and an anode adjacent said suppressor grid.

3. An` electrical-discharge tube containing an inert icnizable gas, a glow discharge cathode.y an

auxiliary electrode for maintaining an ionizing discharge to said cathode,l ayforaminous; cathanode adjacent the space in which-said ionizing discharge occurs, a control grid on the opposite side of said cathanodefrom said ionizing discharge space, a screen grid adjacent said control grid, a suppressor grid adjacent said screengridyand connected back to said control grid, 21nd an anode adjacent said suppressor grid.

4. An electron-discharge tube containing an inert ionizable gas, a glow discharge cathode, an anode, an auxiliary electrode for maintaining an ionizing discharge to said cathode, and four additional electrodes comprisinga suppressor grid adjacent said anode, a screen grid, a control grid adjacent said screen grid, and a foraminous cathanode adjacent the space inwhich said'ionizing discharge occurs, said control grid being on the opposite side of said cathanode from said ionizing discharge space, and a plurality of insulating washers, said anode and said four additional electrodes being superposed in the order named and separated yone from another by at least one of said insulating washers, eachof said washers being providedwith a central opening, said openings being aligned with each other and with said anode and said four additional electrodes.`

5. An electron-dischargeftube containing an inert ionizable gas, a glow discharge cathode, an anode, 'an auxiliaryelectrode for maintaining an ionizing discharge to said cathode, and four additional electrodes comprising a suppressorgrid adjacent said anode, a screen grid, a control grid adjacent said screen grid anda foraminous cathanode adjacent the space in which said ionizing discharge occurs, said control grid being on the opposite side of said cathanode from said ionizing discharge space, said screen grid, control grid and cathanode consistingo a wire mesh and said suppressor grid consisting of parallel wire strands, and a plurality of insulating washers, said anode and said four additional electrodes eing superposed in the order named and separated one from another by at least one of said insulating washers, each of said washersbeing provided with a central opening, said vopenings being aligned with each other and with said anode and' said four additional electrodes.

6. An electron-discharge tube containing an inert `ionizable gas, a glow discharge cathode, an anode, an auxiliary electrodefor maintaining an ionizing dischargevto said cathodeand four additional electrodes comprising. a suppressor grid adjacent said anode, a screen grid, a control grid adjacent said screen grid, and a foraminous cathanode adjacent the space in which said ionizing discharge occurs, said control grid being on the opposite side of said cathanode vfrom said ionizing discharge space, and a pluralityl of insulating washers-said anode and said four additional electrodes being'superposed in the order named and separated one from another-by at least one of said insulating washers, each of said insulating washers being provided with .a central opening,v saidv openings being aligned with each other and `with said anode and said additional electrodes, and clamping means to clamp said anode and said fourv additional electrodes-and the Vintervening washers together to form thereof avunit.

'7. 'An electron-,discharge tube comprisingy an envelope:V provided with a press. and containing an inert ionizable gas', a glowdischarge cathode,

.'a; relatively at anode, an auxiliary-electrode for vrriai-ntaining 1an ionizing discharge to said lcathode, and a mount assembly comprisingaplu; rality-of insulating washers and superposedlupcn one another in theorder named, said relatively nat anode, and four additional'electrodesnamely a suppressor grid, a screen grid, a control grid and a foraminous cathanode, each one-.sandwiched between vtwo ofsaid insulating washers, each of said washers being provided with a central opening, the openings-inv said washers being covered by said anode-and said additional-electrodes between them, extending through said mount: assembly and headed upon the exterior surfaces of the two. end washers of said mount assembly, and supporting means orsaid mount assembly, anchored in said press -andin said mount assembly. v

8. An electron-dischargetube, comprising an envelope provided withV a press and containing an inert ionizable gas, a glow discharge; cathode, a relatively flat anode, anfauxiliary electrode for maintaining an ionizing discharge to'` said cathode, and a mount assemblyV comprising aphirality of insulating washers and superposedupon one another in the order named,` said relatively flat anode, and four additional electrodes, namely a suppressor grid, a screen grid, a. control grid, and a foraminous cathanode, each onesandw'iched between two of said insulating washers, eachof said washers being provided with aA centralopening, said openings in Vsaid washers being Vcovered by said anode and said additionalelectrodes between them, means forfastening jsaid mount assembly together to form thereof a unit, and-supports for said mount assembly anchored in said press and in said mount assembly.

9. An. electrical-discharge tube comprising yan inert ionizable gas, 1a glow discharge cathode, an auxiliary electrode for maintaining an ionizing discharge to said cathode adjacentthelatten. a foraminous cathanode adjacent the spacei in which said ionizing discharge occurs a. control grid in the opposite side of said cathanode from said ionizing discharge space,:a screengrid-adjacentV said control grid, a suppressor grid adjacent said screen grid and connected; to said cathanodey and back through :a resistance,v to said control grid, and an anode adjacent said screen grid..

10. An electrical-discharge tube containing an inert ionizable ga'sunder a pressure of. from. 300 to 1500 microns, a. glow discharge cathode, an

.auxiliary electrode for maintaining an .ionizing discharge to said cathode, a f oraminous cath- ,anode adjacent the space in which said ionizing discharge occurs, a control grid on theopposite side of said cathanodefrom said ionizing dis- `charge space, a screen grid adjacent said control grid, a suppressor grid adjacentsaidrscreen grid and connected to said cathanode, and :an anode adjacent said suppressor grid.,`

11. An electrical-discharge tubecontaining Xenon gas undera pressure ofy from 30d` to 159i) microns, a glow dischargefcathode, an auxiliary electrode for maintaining an ionizing discharge to said cathode, a foraminous cathanodeadjacent the space in which said ionizing discharge occurs, a` control grid on theV opposite side-of said cathanodefrom said ionizingdischarge spacefa screen grid adjacent; saidcontrol grid, a suppressor gridadjacent said'scr'een grid and connectedto saidcathanode, and-an anodeadjacent said suppressor grid.

12. Anelectrical-discharge .tube containing an inert ionizable gas under a pressure-@3550 microns, a ,glow discharge, cathode., varr-'auxiliary electrode for maintaining an ionizing discharge to said cathode, a forarninous cathanode adjacent the space in which said ionizing discharge occurs, a control grid on the opposite side of said cathanode from said ionizing discharge space, a screen grid adjacentl said control grid, a suppressor grid adjacent said screen grid and connected to said cathanode, and an anode adjacent sai-d suppressor grid.

13. An electrical-discharge tube containing xenon gas under a pressure of 550 microns, a glow discharge cathode, an auxiliary electrode for maintaining an ionizing discharge to said cathode, a foraminous cathanode adjacent the space in which said ionizing discharge occurs, a control grid on the opposite side of said cathanode from said ionizing discharge space, a screen grid adjacent said control grid, a suppressor grid adjacent said screen grid land connected to said cathanode, and an anode adjacent said suppressor grid.

PAUL W. STUTSMAN.

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

UNITED STATES PATENTS Number Name Date 1,145,735 Ainsworth July 6, 1915 1,629,009 Snook May 17, 1927 1,878,341 Spencer Sept. 20, 1932 2,051,609 Langmuir Aug. 18, 1936 2,097,157 Jameson Oct. 26, 1937 2,106,847 Kniepkarnp Feb. 1, 1938 2,229,138 Schwartz Jan. 21, 1941 2,238,595 McNall Apr. 15, 1941 2,243,121 Preisman May 27, 1941 2,275,023 White Mar. 3, 1942 FOREIGN PATENTS Number Country Date L113,302 Great Britain July 9, 1934

Images