US2719248A - Electron discharge device - Google Patents

Description

Sept- 27, 1955 B. A. s. JosEPl-lsoN ET AL 2,719,248

ELECTRON DISCHARGE DEVICE 4 Sheets-Sheet l Filed June 8, 1948 /4 s 4 4 4 N( Il MN 5 70 M f CG m f M H mf a Sept- 27, l955 B. A. s. JosEPHsoN ET A1. 2,719,248

ELECTRON DISCHARGE DEVICE Filed June 8, 1948 4 Sheets-Sheet 2 WM a 4 Sept. 27, 1955 B. A. s. JOSEPHSON ET AL 2,719,248

ELECTRON DISCHARGE DEVICE Filed June 8, 1948 4 Sheets-Sheet 3 WMM Jgd/rn Sept. 27, 1955 B A S JOSEPHSON ET AL 2,719,248 l ELECTRON DISCHARGE DEVICE Filed June 8, 1948 4 Sheets-Sheet 4 IN VEN TORS 5in/67 A2000' .s4/wa dwf/W50# @MF wmf Edam Jaffa/0 www M ,417' )WH/VE Y Alllited `Slftates .Patentfie 2,719,248 Patented Siif' 2,75 .159.155

'The present invention relateste an electron discharge tube, which is particularly intended' for use as a'frequeney divider, selector or' counting device.

Generally speaking, the tube cmpif-ises an electron gun, apluralit-y `oftarfget eleto'destoh which the electron-beam produced by the gun may intein-ge, and atleast two `independent ldarleating -elecfrde systems, one of which mltesit possi-ble to* di thesaid1 targets; whilfeitle 'other' makes it possible to" deect the" be'an -thfr'ougha sniall' anglef'cores'poding to a dis'- placernent of `the Beamfr'rii one tarl'ge't to anv adjacent target. The latter syste `ay consist `of adei'lectin'g coil.

'Flic-invention' is more specifically disclosedl the annexed drawings, AFigi 'l f'wliicli is' a schematic diagram illust-ratinginilbngitdil sectinfthe essential components cfa tube according" tothe invention; `v Fig. l'Av is a View taken in the direction of the arrows A"-A of Fig l. ig; 2 is circuit diagram showing suitable connections fr this tube. 3i is aviewsimilajto-Fig liAsh'OyViiig an alternative' target arrangement; Figi 4' is a' circuit diagram fsh'ovviii'gl a-p1iase2inve`rtbr applied to a target and afcorrespending ontrol'lelet'rode ,Fig. 51s aview similar to' Fig. A1V showing a modification-'of 'agt'ubei according to the* invention. yFigures `6ai1dI 7O are" schematicV `circuit arrangements for deflecting electrodes. Eig.' 8 is a' view sinur te Fig, 1' shevying affefnerem aiment erm@ tube. Fig. 8B a' vieit'jwtakeh iirthe'nir'e'ctiof vthe r'rws'BQBnlFig 8. Fig':9isaviewerajrnd1 at iq'n et Fig: 8'. Fig: isavieW-tak'en-inthedirctiofthe 'rev'vs C--C'e'fFlgg 9i Fig: 1 thejnumeral 1" designates@ electron gun; ii/liichdelivisa"narryv'el cti'onbeuni. The tubel further e prises t'w pairs jo'f enacting" platesz' eight centrer ee'efrodes--s pulse-electrode 4;' ae911ntere1eetfode-5 cooperating wi eonfrorelctre es; eight trg'tsg-two-gn s `7 ai; ,a @crescent screen s. The ilsctredes are ehcldsedfwithinavacum enveloped:

The control electrodes 3 are in the form ofs'tiaiglit or slightly curved rods and annularly disposed around and slightly iiliiied Witlirespect ttl' aiisf tletbe. The irnpulseA-electrodeA-has th'egshapeyof afr-ustoconical shell. 'I l1ejcounterelectr ode5y isslightly funnel shaped and is disposed@ within-,1 the; impulse: electrode: 4J- and; the annulus formed b y. i the? controll electrodes i 3f.A '1hetargets 6' are `sofshapedfandfpositicned that-it is' possible by: radial dis placement ofl thefbeam tomove'it -from one target tor the other-1 The targets 61 have the-1 further characteristic that;

whenstrucleby theelectror'l bea-IngtheyA give'ot a numbe'r ofseeondaryi,electronstinexcess of the numberl of imping-ingelectrons. f Each target' 6l is directly: connected toria?controlwelectrddefaligned with `an innerportion the teamA toward any one of Fig. 2 show a circuit arrangement for the tube. The cntrol electrodes 3 and th targets 6 connected iX/ith them are connected to a common p'oin`t via coupling rsistors Ri-R8. The potentials on the electrodes 4 and 5 are' adjusted b'yrnieans "of petentiemter's P55' 'nd Pr so as to give a suitable deflection to the beam outwardly from the tube axis.- `Volta-ge impulses' are applied to electrode 4 via the terminals shown connected across the resistorincluded inthe lead to the electrode from potentiometer P26 and are superposed on .the polarizingv potential Yobtained( from the potentiometer.

T he operation of the Itube is as follows: n First switch S1 is closed, whereby the control electrode 3g connected to a terminal designated, by numeral 1'1 obtains a higher potential than the other control 4electrodes. I., Voltage is then; applied to theacceleration anodes of electron gun 1 by closing of switch S2. The electron beam is thereby directed pastncontrol electrode 3a towards the target designated 6a in Fig. 1A, which is connected to `terminalV 11. .This target then gives oi'a secondary emissioncurrent greater than the primary current, whereby both the target- 6a and its control electrode 3a assume aliigherpositive potential than the other targets and control electrodes. The ,eld' thus set upbetween the control electrode'a and the counterelectrode 5; by proper dinensioning'of the potentials applied to the electrodes of the tube and suitable positioning of the control electrode with respectto the target, maintains the beam position to strike the target V6a in point;P11 (-Fig=`1A)-. lheUelectrorl beam will thus be automatically retained in-this' position as long as the potentialsapplied to electrodes 4 and 5 are constant.-

If there is applied to the impulsey electrode 4a positive impulse' of suitable amplitude the electronbeam is'deected radially from p'oint P11 s o as to strike the adjacent target 6b at the point`P12. Target 6bf and itscontrol electrode 3b' thenl begin; to charge positively' while the potential'ofjthenanode 6aV and control electrode 31a falls due to the leal ingfol of itsv charge over coupling resistor R1. The beam is deected alongtarget 6b byy the increased potentialof electrode 3b. The im'p'uls' shape has,to beso' selected with regard to the time' constant provided by the groundY capacitance of a" target and thele'sistance of its coupling resistor that the? beain is displaced'- approximately along' the brokenline shovvn'in Fig.- 1-Atothe po'inrPia, Where itis retained inthe-'manner described above until another"` impulse is appliedto electrode-4r If a-se'ries of impulses arel applied to' electrode 4-the beamlwillr thus successively strike all the targets' andreturn to the rst; From Aterminals`ll"1-"1$'o'f Fig; 2

- there will" then; be obtainedJ a correspondingseriesA of thereoft lThe-g'r-idslabsorb theysecondarynemission from the-targets 6 andthe uorescent screen 38;

positivefimplses.' Each terminal thusigives an impulse for" ev'er-yf eighth applied impulse, which is" equivalent1 to a divisie-nefI die applied frequency by 8.

Thtrfgefse nay beeiineff'wncuy r'rfd ufr df'v ann'eiy riished grid or perforated, at least in the' vicinity of points correspondingto' points P11 and Pia" o`f Fig. llAzl Wlien'theben strikes' the targets at these point, vfh'ich occurs wlerit'is in" its idle position, a portion ofthe elec'- t'rn'spassthrough"z the'tar'get and hit the screen 8, which fluoresces at the corresponding spot and indicates the position ofthe beam. These positions may be numbered on the outside of the tube. Instead of making'a portion of the electron beamstrike the screen 8 to Vindicate its position it is` possible toma-ke a portion ofthe secondary emission-from'- the'targets-hit the screen and similarly indicate the position of the beam. This self-indicating feature is independent of the construction of the tube in other respects.

Immediately adjacent the electron gun 1 in Fig. l are two pairs of deecting plates 2. By this means it is possible by adjustment of potentiometers P23 and P24 of Fig. 2 to accurately center the beam, so that, in the presence of equal potentials on the control electrodes, it is directed along the tube axis towards the tip of electrode 5. An indication of the proper centering of the beam is provided in that the beam, when properly centered, passes through the hole in the tip of electrode onto the iluorescent screen to produce thereon a brilliant spot.

Alternative target arrangements Independently of the construction of the other tube electrodes it is possible, instead of giving all targets the same shape and position relative to the axis of the tube, as shown in Fig. 1A, to dispose them in a staggered arrangement, as indicated in Fig. 3. The control electrodes 3 are so disposed relative to the targets 6 with which they are connected, that, when electrode 4' has a predetermined potential, the beam is at rest on the inner targets at points such as P31, P33, and P35 and when electrode 4 has a certain higher potential, the beam is at rest on the targets at points P32, P34, etc. Fig. 3 shows a manner of connecting the targets and control electrodes.

In operation, if a positive impulse is applied to electrode 4', the beam will move outwardly from P31 to P32 approximately along the broken line indicated in Fig. 3 and if electrode 4 then reassumes its former potential the beam proceeds inwardly from P32 to P33. The tube of Fig. 3 is then assumed to differ only with regard to its target arrangement from that of Fig. l.

In the tube of Fig. 1 the beam is displaced by a step (from one target to the next) for each positive impulse applied to electrode 4. The Fig. 1 tube thus counts positive impulses. from an inner target to an outer one for a positive irnpulse and from an outer target to an inner one for a negative impulse. Thus both positive and negative impulses are counted. If it is desired to count positive im- In the Fig. 3 tube the beam is deected pulses with the latter tube the impulse electrode 4' is preferably made to receive its impulses from a frequencyhalving triggering device of well-known kind.

The number of targets obviously may be varied in both embodiments described, the number 10 being of special importance.

In the Fig. 1 and Fig. 3 tubes the targets emit secondary electrons. Tubes according to the invention may also be used without secondary emission. In such case, in the Figs. l and 3 arrangements, each target, instead of being connected to the nearest control electrode, should be connected to the diametrically opposite one, since the target potential will now fall when the beam strikes a target. Preferably, however, phase Shifters are then interposed between targets and control electrodes. The phase Shifters may comprise, for instance, small triodes, which may suitably be disposed within the tube. Fig. 4 is a schematic diagram showing a triode connected between a target 41 and its corresponding control electrode 42. The same coupling is provided for all the targets in the tube. The cathodes of all the triodes are joined together, while the anodes and grids thereof obtain their biases via separate resistors.

The use of amplifier tubes as phase shifters between the targets and control electrodes of the tube has the advantage that the control electrode potentials may be more easily controlled than in the Fig. 1 arrangement, since it is possible to select the voltages in such a manner that, when target 41 in Fig. 4 is hit by the beam, the tube 45 is cut off completely, which makes the potential on control electrode 42 equal the potential applied via resistor R44, Whereas in the case when the target is not being struck by the beam the control grid potential of tube 45 is limited by grid current flowing through R41, which makes the voltage drop in tube 45 and thus also the potential on control electrode 42 relatively constant.

Alternative control electrode arrangements Independently of the construction of the tube in other respects the control electrodes of the tubes may take various forms, one of which has already been described in connection with Fig. l and Fig. 3. In these cases the number of the control electrodes equalled that of the targets. Approximately the same function, except with regard to the swiftness of operation, may be achieved with two pairs of conventional type deflecting plates. Fig. 5 shows how the electrodes may then be arranged. 51 is an electron gun, 52 and 53 are pairs of plates for electrostatic deection in two mutually normal directions. 54 and 55 are a pair of impulse electrodes causing radial deection of the beam, 56 is a number of targets, for example as shown in Fig. 1 or Fig. 3. 57 is a secondary emission collecting electrode. Fig. 6 shows how it is possible in a tube with ten targets suitably to connect the targets 66 with the plates 62 and 63 via resistors and apply a positive voltage. If, in a tube of the last-mentioned type, targets of the type exhibiting no secondary emission are used, in which case the targets will be charged negatively by the beam, it is possible to use the Fig. 6 coupling arrangement with the modification that the pairs of plates 62 and 63 are turned through an angle of with respect to the targets, the coupling arrangement otherwise remaining as indicated. If it is intended to make the targets 66 function without secondary emission it will be necessary to place a suppressor electrode in front of the targets, as viewed from the electron gun, and possibly also to insert screens between the targets. The screens as well as the suppressor electrodes have to have a lower potential than the targets.

In the Fig. 5 electrode arrangement, also, it is important to properly center the beam in the tube. Instead of an additional pair of deflecting plates, as in Fig. l, the Fig. 7 coupling arrangement may be employed, according to which the deflecting plate potentials may be adjusted by means of potentiometers P71 and P72 so as to center the electron beam upon the geometrical axis of the tube, when the beam is not striking and charging any of the targets. The Fig. 7 coupling arrangement can be employed also with control electrode tubes, as that shown in Figure 1.

Since the pairs of plates 52 and 53 of Fig. S lare differently spaced from the impulse electrodes S4 and 55 and the targets 56, the beam, if targets 56 are successively charged to a certain potential leaving all the other targets at a different potential, will trace an elliptic path. By providing diierent angular deection sensitivity values for the two pairs of plates 52 and 53 it may nevertheless be achieved that the beam traces a circular path in a plane including electrodes 54 and 55 normal to the tube axis, in which case electrodes 54 and 55 may be of circular cross-section. Targets 56 should be positioned along the elliptic path of the beam in the target plane.

Alternative impulse feed arrangements Instead of making the impulse cause radial deflection of the beam, the tube may be arranged to cause in response to an applied impulse a tangential deflection of the beam corresponding to the angular distance between two adjacent targets, in which case the beam Will thus follow a path with substantially constant radius in the target plane. This has the advantage that the targets may be of simpler shape, for instance rectangular or trapezoidal, as shown in Fig. 8. The tangential deection can be achieved either electrostatically or magnetically. In the case of electrostatic deflection the impulse electrodes may consist of rods 82 disposed between the control electrodes 81, as shown in Fig. 8. Allimpulse electrodes 82 are connected together and are brought by an applied impulse to a vhigher potential than that of the control electrodes 81including the one 81b, for example, that is holding the beam on `target 83b at the instant ofthe impulse. The beam is then attracted towards that impulse electrode 82a` whose lower end is closest to the electron beam and is -thereby deflected to the next target 83a. p Y t I Magnetic deflection in a tangential direction "(by impulses) may be achieved by a cylindrical coil 90 disposed outside the tube envelope 80 so as to have its axis coincide with the axis of the tube, as shown in Figs. 9 and 9C. This coil should reach from the upper part of the control electrode system 81 to the region of the targets 83. When receiving an impulse the coil 90 then generates a radial field immediately behind the control electrodes 81, as viewed from the electron gun, and this field deflects the beam, Whereas the field lines running in the opposite direction at the upper end of the coil are behind the targets and therefore do not affect the beam. In order to emphasize the radial field a tubular iron powder core 92 may be disposed surrounding the coil 90 and the tube and a cylindrical core 94 may be placed inside the tube envelope 80 so as to have its axis coincide with that of the tube.

Automatic control of the idle positions of the beam The secondary emission collector electrode 7 in Fig. l yhas been described as a wide-meshed grid. It may also have the form of a plate having apertures of target shape and size in registerwith the targets or of two concentrical annuli of such dimensions that they cover thin strips at the outer and inner rims of the targets from the beam, which is otherwise given free access to the targets. If, in the Fig. 1 tube, the last mentioned electrode is inserted instead of the inner one of the grids 7 and the electrode potentials are adjusted in such a manner that the beam has its idle positions on the outer parts of the targets, for instance at points corresponding to P12, an automatic control is afforded of the radial position of the beam when idle, in that an excessive radial deflection will cause a portion of the beam to be intercepted by the secondary emission collector annulus and a reduced electron` current will reach the target, causing a change in control electrode potential tending to decrease the radial deflection. This implies a more reliable functioning of the tube. In the case when the idle positions are at the outer rim of the targets the impulses obviously have to be of negative sign, making the beam move in a direction opposed to that previously assumed.

If a separate electrode is placed in the vicinity of one of the targets of the tube in order to collect the secondary emission from that target and is coupled via a resistor to the same, or a slightly higher, potential than that applied to a second collector electrode common to the remaining targets, an impulse will be obtained at the resistor each time the first-named target is struck by the beam. By this means it is avoided to have impulses derived from a target and all the targets remain unloaded, Which may be important in case high-frequency impulses are to be counted.

In the Fig. 4 tube it is possible to a certain extent to modulate the beam without affecting the potential of the control electrode holding the beam. The modulation frequency can be derived from the target being struck by the beam.

What is claimed is:

l. An electron discharge device comprising: an electron gun for projecting along the axis thereof an electron beam, a plurality of targets disposed around said axis so as to form a substantially annular structure and having a secondary emission coeficient greater than unity, and means comprising a plurality of electrodes equal in number to the number of targets and each directly connected to a corresponding target and responsive to the position of said beam when striking any one of said targets to retain the beam on Said target, whereby when struck by the beam each target becomes more positive and transmits a positive charge to the electrode connected thereto.

2. An electron discharge device as in claim l, further comprising means for deflecting said beam from one target to an adjacent target. j

3. An electron discharge deviceas in claim 2, wherein said deliecting means comprises a plurality of electrostatic deiecting elements positioned in the path of said beam and between said electrodes and said targets.

4. An electron discharge device as in claim 2, wherein said deflecting means comprises a magnetic coil having its axis coinciding with the axis of said device and adapted to be pulsed to generate a radial magnetic field in the region of said electrodes.

5. An electron discharge device comprising: an electron gun for projecting along the axis thereof an electron beam, a plurality of targets disposed around said axis so as to form a substantially annular structure and having a secondary emission coefficient greater than unity, a number of electrodes equal in number to the number of targets, each directly connected to a corresponding target whereby when struck by the beam each target becomes more positive and transmits a positive charge to the electrode connected thereto, said electrodes being substantially annularly disposed around said axis, and means for adjusting the inoperative position of said beam with respect to said electrodes.

6. An electron discharge device comprising a plurality of elongated targets arranged in two concentric circles, each target in one circle overlapping portions of two adjacent targets in the other circle, means for projecting an electron beam toward said targets, and means for sweeping said beam over all of said targets in succession.

7. A device as in claim 6, wherein said last-named means comprises means for defiecting said beam in a circular path along each target and means for deecting said beam radially from one circle of targets to the other circle of targets.

8. A device as in claim 7, wherein said first-named defiecting means comprises a plurality of defiecting electrodes equal in number to the number of targets mounted in a circular array around the path of the beam and each coupled with one of said targets located in the same angular position as a part of said one of said targets, whereby the beam is retained on a particular target by the deecting electrode coupled thereto until said secondnamed deflecting means is energized.

9. A device as in claim 8, wherein each of said targets has a secondary emission coeicient greater than unity and is directly connected to the corresponding defiecting electrode, whereby when Struck by the beam each target becomes more positive and transmits a positive charge to the defecting electrode connected thereto.

10. An electron discharge device comprising: an electron gun for projecting along the axis thereof an electron beam, a first plurality of targets annularly disposed around said axis, a second pluralityof targets annularly disposed outside of said first plurality, each target of said second plurality overlapping angularly a portion of two adjacent targets of said first plurality, means responsive to the current drawn by any one of said targets when struck by the beam to retain the beam on said one target in an angular position corresponding to the overlapping portion of a succeeding target, and means selectively responsive to impulses of alternating signs to increase or decrease the radial deection of said beam, so as to cause said beam to be stepped successively from one target to another.

(Other references on following page) References Cited in the le of this patent UNITED STATES PATENTS Hearing July 26, Hollmann Apr. 11, Mertz Jan. 2, Heymann May 14, Shelby May 21, Hanscom Dec, 10, Gray July 29, Hadekel Oct. 31,

8 Knoop Ir. et al. Dec. 19, 1944 *Si's Oct. 26, 1948 l Munster' et'al. Jan. 4', 1949 Overbek Nov. 15, 1949 .Anderson Feb. 6, 1951 Anderson Sept. 11, 1951 Houghton Sept. 18, 1951 Arditi Nov. 27, 1951 Deloraine Feb. 12, 1952 Moon May 20,

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