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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.
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