Oct. l; 1946. v F, A.1. G.>vAN DEN BcscH ELECTRON MULTIPL’IER ' 2,408,709 ' Filed Aug. 10, 1942 ' BY .Hau A/„zav ATToR/vgy '2,408,709 Patented Oct. 1, 1946 f " STATES >rzrrlëzN'r* _"oFFIcE ELEc'raoN MULTIPLIER Francois Joseph' Gerard van denßosch, Surrey, " ',England, assigner to Radio Electronics Lim Application August 10, 1942, rseriali No. 454,214 InAGreat Britain August 5, 1940 - y s'olwai’ms. e (ci. 25o-27) . . , r 2 eiïect of» a secondary cathode is to arrest the slow » TheY invention 'relates'. Í'to _ apparatus primarily for dealingwith ultra-high frequencies butV applicable also for ldealingwith er velocity electrons, while thek impact of the higher.' velocity 'electrons will release additional -Thejiollowing is a'description of two embodi electrons." lòwer'frequencies.' " ' n y ' Í ' According tothis invention'an electron multi plier comprisesa number of >pairs of electrodes for controlling the Velocity of the electrons (here . , . ' ' ments of the'inventio , reference being made to thëÍ accompanying " drawing, A in which Y Figure 1 and Figure 2 are diagrammatic views inafter 'referred to> as velocity-controlling pairs each showing diagrammatically an electron mul of electrodes) disposed ink the stream of elec tipli'er, together with its external circuit. trons between’a'p?imary/ cathode and an anode, 10 According to the construction shown in Figure one or more secondary cathodes also disposed in 1, the electron multiplier isv provided with a pri said streamJneans for generating an alternating mary cathode ID and secondary electron-emitting> field between the electrodes of each velocity-con- V cathodesvII, I2, I3, I4, I5 and 22. Acontrolgrid trolling pair,‘the distance -apart _between adja I‘I i's„providedbetween the primary cathode and Y cent electrodes ofsuccessive pairs being selectedV 15 theñrstsecondary cathode I I, and a final collect in accordance’witl'i?the'phaserelationship of their ing- ‘anode rIt is provided at the back of the last secondary cathode 22. The primary electron potentials, so that the time of transit of an Velec tron fis such thatv it passes‘through a succeeding stream may be modulated by a modulator I9 con field approximately at the same stage inthe cycle nected‘ to the control grid, and the potential of as that when it passed through the "preceding 20 the grid may be biased through one part 28 ofa field. ' ' l ’ ' potentiometer whichis connected at suitable tap ' The,> alternating ñelds may be applied to -said pairs of velocity-controlling electrodes so that the adjacent electrodes of successive pairs are in ping points along its length to the secondary cathodes. It vwill be seen that in front of the sec ondary cathode I2 is disposed a pair of Velocity phase'and at equal potentials while the two al 25 controllingpelectrodes 2I and I8, while a second ternating iields produced by`said adjacent pairs pair of velocity-controlling electrodes Y23 and 24 are 180° out of phase,l the‘spacing apart of equi are provided at the back of the electrode. The potential' electrodes- being' such as ‘ to 'provide' ‘a time of transit corresponding te thetime vof half a vcycle'ïor multiples thereof. Alternatively, fthe alternating field vbetween. each pair ‘of velocity controllíng electrodes> y may be provided by con- two electrodes I8 and' 23 are both connected to one poleof’van valternator A8, whereas the elec 30 trodesf2IA and 24 are connected to the other pole _ necting the electrodes- through suitable " imped of theV alternator. The secondary cathodel I2 is fthus -disposed in an equipotential riield. The al ternating fields betweeny the electrodes 2l and I8 ances with av terminal of'an alternator; In any and between the electrodes 23 and 24 are, how of they arrangements referred to'above, one or 435 ever, 180° out „of phase.v Thus, in order to-effect more secondary cathodes >may -be‘rarranged be velocity modulation, -the time of transit of an tween ’.the adjacent electrodes of ‘successive pairs. electron between the electrodes I8 and 23 should Y The effect of this arrangement 'is that theve ybe equivalent to half the time of a complete cycle of the alternating generator, or odd multiples others are decreased and a location lwill occur 40 thereof. Although the secondary cathode I2 has alongv the stream where a maximum density of the effect of arresting the low-velocity electrons, the secondary electrons released by it do not upset _locity _oi certain electrons‘is increased, while electrons occurs. " ‘ Y ' . Y « ' 'A‘ collector electrode is> preferably disposed in the ‘stream of electrons at the location of maxi ~ the velocity modulation. The next two-secondary cathodes I3 and I4 mum' density. The vconversion of the rvelocity 45 Vare grouped together, and~have on one side there modulation jinto density modulation‘may be‘ob of a pair of velocity-modulating electrodes 24 'tained 'at ‘a following secondary cathode -of the multiplier since the secondary emission is de ,velocity-modulating electrodes 26 and 21. Again, 'pendent Y `upon vthe v elocity of the electrons _im vpinging Íon’ft'he‘r secondary cathode. `Alterna tiv`e1y,ÍOI‘ >in"addition,’other Iknown means may be employed to obtainthe required conversion. Ä, Furthermore', either or -both of the electrodes and 25, and on the otherside thereof a pair of . in this instance, the adjacent electrodes 25 and 50 26 of the two pairs are connected to one pole of k Athe alternator, Whereas theelectrodes 24 and_2`l are connected to the other pole. Similarly, the ysecondzjn'ycathode I5 has two -pairs of velocity vof'-a"velocity-controllingpair of electrodes may ccintrailing’electrodes,v one pairpn.Vv each’Í side "beconstitnted by a secondary cathode, since the 55 2,408,709 3 thereof, viz., the electrodes 2'! and 28, and the electrodes 29 and 3i), the electrodes 28 and 29 beinsr connected to one pole of the generator, and the electrodes 27 and 3€) being connected to the tentials, while the two alternating ñelds pro duced by two adjacent pairs are 180° out of phase, the spacing apart of the electrodes being such as to provide a time of transit of an elec other pole. A dual antennae 'l is either connected Cl tron between the,electrode 3i] and the two electrodesl 28 and 29 or between the electrode 30 and the between equipo-tential electrodes corre sponding to the time of odd multiples of half a cycle including a single half-cycle and to- cause anode i6 as shown in the drawing. One side of said electron to pass through a succeeding ñeld the dual antennae could either be connected to at-approximately the same stage in the cycle as the secondary cathode 22 or to the anode as „10. that when it passed through the preceding field. shown in Figure l. In any of these arrangements) ' ` 3. An electron multiplier apparatus compris the secondary cathode 22 may operate to convert` , , ¿ing a primary cathode, an anode, a number of the velocity modulation to density .modulationáas ‘pairslcf velocity-controlling electrodes and at least one secondary cathode disposed between the In the arrangement shown in Figure _2, the 15 primary cathode and anode, an alternator ar set out above. ` ' ` " " ` alternating ñeld between the variousN _pairs ort, « vranged -to apply an >alternating ñeld between the velocity-controlling electrodes is obtained byconä- - '" «electrodes-fof Veach pair of velocity-controlling necting each electrode through a suitable imped- ~ ,I electrodes, means for applying direct current ance to a terminal of the alternator. The sec potentials of ascending order to said primary ondary cathode 3| is arranged in an equipoten- 20 cathode, secondary cathode and anode, an im tial ñeld betweenrelectrodes v32; 33, ‘which 'are pedaviricve-‘tconnected rbetween saidy alternator and connected through a variable impedance 34 to a. terminal of the alternator 8. ' Velocity modulation doesnottake place until afterthis electrode. The next Vsecondary cathode,` 35; however, has'a pair of velocity-controlling electrodes 'on each side each jpair `of, >said velocityecontrolling electrodes, ` the values-of which impedances are selected s_o- that the two alternating neldsfproduced 'by twov adjacentpairs of'electrodes‘are *180° out of phase andthe spacing Aapart of the electrodes `of the thereof, viz., the électrodes 33 and 36, and the two pairs being >'such as to 'provide a timeV ofA electrodes 3lA and 38. . „Alternating Yiields are cre transit'of an' electron between‘the'adja'cent elec ated between the electrodes of each pair by rea Y trode's of two pairs corresponding tc'the 'time of son ofthe fact thatthe electrode 33 is 'connected through a variable impedance 34" with the a1 30 an'od’d multiple'of half a' cycle 'including hali‘a cycle and Ato cause said electron'to pass 'through tern'ator, and the "electrode 38 lis connected through `a different variable vimpedance 39 with' said alternator. Similarly, `the electrodes '3'1v vand 33 are connected throughv the diiîerent variable impedances .3S and dû. The secondary cathodes a succeeding AIield at‘approximately‘thejsaid stage in the cycle as that when it’passe‘d through ltne‘ , preceding 'field- V‘Lnn electron multiplier apparatus compris ing 'a 'primary cathode, an anode, ‘a number of «tif-and 42 each have a pair of velocity-controlling electrodes oneach Vside thereof,.'in -the one case thejp’airsrê‘i, 38Vand ¿63, M and inthe other case, thegelectrodes 43, 44 and the electrode 45 and the secondary cathode 22, a further variable im-l pairs 'of velocity-‘controlling electrodes disposed inthe stream ofV electrons between the primary cathode 'and anode, ‘at 'least Vone 'secondary cath ode arranged between adjacent electrodes of suc pedance ‘i6 ¿being provided between the equipo tential-_electrcdes 4d and 45' andthe alternator. . ¿Ingthe two arrangements referredto above the velocity-,controlling electrodes are shown as ordi- l nary grids; these, however, could'be replaced ‘by ` secondary cathodes. ' v ‘ ' ' ` ` " cessive pairs of velocity-.controlling electrodes,r means tor applying direct current '.potential‘s'of ascending -orders “to said ‘primary cathode, sec ondary cathode and' anode, means for applying anY alternating neld between ‘the electrodes vof each pairfof velocity-'controlling electrodes, the „fljclaimz ; ,1,n Anfelectron , multiplierY apparatus comprising distance apart vbetween 'electrodes' 'of successive pairs of` velocity-controlling `electrodes being aA primary cathode,v an anode, a number ‘öf'pair's ojf ,velocity-controlling `electrodes fand atleast selected 1in accordance with the 'phase relation ship "of their potentials so "that theï time 'of transit onesecondary cathode >disposed between 'the pri' inary cathode and anode, means ~for"applying direct rcurrent potentials of ascending "orde'r'to said primary cathode, secondary cathode 'and ancde,ni_eans between the electrodes `ior applying ci each an pair alternating'fì'e‘ld oi velocity controlling electrodes, the distance apart between electrodes of successive pairs of velocity-control ling electrodes being `selected in accordance with thephase relationship of their 'potentials s'o' ‘that the -transit time of an electron is such'th'at it passes -through a succeeding -rleldl at approxi mately the same stage inthe "cycle 'as that when it passed through the preceding field. " " 2. An'electron multiplier 'apparatus comprising a primary‘cathode, an anode, a number of 'pairs of velocity-controlling 'electrodes and at ‘lea-st on'e secondary-cathode disposed between the primary cathode and'anode, means for applying direct current potentials >of ascending `>order to said primary cathode, secondary cathode and ofanelectron i's such that it passes Ythrough va succeeding> ñeld‘at approximately the same stagevin the- cycle' als vthat when it lpassed.tlfiro'ugh the `preceding held. v - 5. An `electron multiplier apparatus compris ing a -primary cathode, anA anode-a;Y number‘cf pairs of. velocity-controlling electrodes disposed in -a'stream of electrons between> the primary cathode andanode, atïleas't one secondary cath ode disposed between Veach'pair of velocity-con trolling electrodes, a secondary cathode imme diately preceding said anode, an outputl 'circuit associated with said ’secondary cathode, 'means 4for >applying potentials of ascending ~order to , 55 said ,primary cathode, vsecondary "cathode 'and anode, >-mea'nsffor applying an alternating‘ñeld v'between .theelectrlo'des of each pair of velocity controlling electrodes, rthe distance rapart .between _electrodes of successive ¿pairs of velocity-control ling electrodes being sélectéd'inlaccordance Vwith the phase relationship ofv theirlpótentials So‘th‘at anode,»means for applying an alternating, ñeld the time of transitY of4 an electron is 'such' `that between Áthe electrodesof each pair of velocity Ait passes through a» succeeding held/'atv 'approxi vcontrolling.electrodes so that adjacent electrodesk i _ately-thesame stage in the cycle as “that when of successive pairs are in phase and at equal po- 7.5 Ait passed through the preceding'?leld. 2,408,709 6. An electron multiplier apparatus compris ing primary cathode, an anode, a number of» pairsa of velocity-controlling electrodes disposed 6 ity-controlling electrodes, the distance apart be tween electrodes of successive pairs of velocity controlling electrodes’being selected in accord in the stream of electrons -between the primary ance with the phase relationship of their poten cathode and anode, one of which Velocity-con- 5 tials so that the time and transit of an electron trolling electrodes in each pair being formed as is such that it passes through a succeeding ñeld a secondary cathode, means for applying direct at approximately thethrough same stage in the cycle as that when it passed the preceding ñeldf current potentials the primary cathode and anode, meansbetween for applying an alternating ñeld between the electrodes of each pair of veloc- 10 FRANCOIS JOSEPH GERARD vAN DEN BOSCH.