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Патент USA US2409645

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Oct. 22, 1946.
' 2,409,644
Filed April 11, 1941
- "K24
M4215‘, 6. M _
Patented Get. 22, 1946
Arthur L. Samuel, Summit, N. J., assignor to Bell
Telephone Laboratories, Incorporated, New
York, N. Y., a corporation of New York
Application April 11, 1941, Serial No. 388,031
5 Claims. (Cl. 250-27 .5)
This invention relates to electron discharge ap
paratus and more particularly to such apparatus
including electron beam discharge devices of the
velocity variations are converted into density
velocity variation type.
tion, the electrode bounding the section of the
drift space is maintained at substantially cath
In accordance with one feature of this inven
Velocity variation discharge devices comprise, '
ode potential whereby the beam upon entering
in general, an electron gun for producing an elec- '
the drift space is subjected to a retarding ?eld.
tron beam which is accelerated toward and pro
In accordance with another feature of this in
jected through a region wherein the beam is sub
vention, the electrodes de?ning the input space
jected to a cyclically varying ?eld and thereby
velocity varied. The velocity varied beam is then 10 or gap are so constructed and arranged that the
beam in passing therethrough suffers a divergence
converted into a density varied beam and the lat
so that in passing through the drift space the
ter flows toward an output element to Which it
beam is of a diameter substantially equal to the
delivers energy. In one form of such devices, the
diameter of the electrode forming the drift space.
velocity variations are converted into density
In accordance with a further feature of this
variations by projecting the velocity varied beam
into a space, commonly designated as a drift
invention, the electrodes de?ning- the output
space, wherein a periodic bunching of the slow
moving and fast moving electrons in the beam is
effected. The operating characteristics, such as
the transconductance and percentage of density
variation, of such a device are dependent to a
large extent upon the effect produced in the drift
space or gap are so constructed and arranged
that the beam, after traversing the drift space, is
highly concentrated and focused upon the output
features thereof will be understood more clearly
and fully from the following detailed description
with reference to the accompanying drawing in
One general object of this invention is to im
prove the operating characteristics of electron
beam discharge devices of the velocity variation
type and, more particularly, to increase the ef
ficacy of the drift space in such devices.
t More speci?cally, objects of this invention are
Fig. 1 is an elevational view of an electron
discharge device illustrative of one embodiment
of this invention;
Fig. 2 is a detail view in section of the electrode
30 system included in the device illustrated in Fig.
1, showing the con?guration and relation of the
electrodes therein;
Increase the transconductance of electron
lgeam discharge devices of the velocity variation
Fig. 3 is a circuit diagram illustrating one man
ner in which the device shown in Fig. 1 may be
I Decrease the length of the drift space in ve
locity variation discharge devices;
Q0 til operated; and
Enable control of the gain of such devices;
Provide an electrostatic means for focusing the
electron beam;
Increase the bunching of the electrons in the
drift space whereby a high percentage density '
variation is produced; and
Decrease space charge effects in the drift space
of such devices,
The invention and the above-noted and other '
Figs. 4 and 5 are detail views in section show
ing the form and relation of electrodes in other
illustrative embodiments of this invention.
Referring now to the drawing, the electron dis
charge device shown in Fig. 1 comprises an elon
gated evacuated enclosing vessel It) having at the
ends thereof inwardly extending stems H and I2
from one, ll, of which there is supported, by
leading-in conductors l3, a collector electrode l4,
, y In one illustrative embodiment of this inven— 45
and from the other, l2, of which there is sup
tion, an electron discharge device comprises an
ported an electron gun l5. The electron gun,
electron gun, means including a pair of electrodes
which produces a concentrated beam of electrons
de?ning an input space or gap through which the
projected along and in the direction of the longi
electron beam emanating from the gun is protudinal axis of the enclosing vessel l8, may be of
jected and wherein the beam is velocity varied,
any one of a number of constructions such, for eX- means including a second pair of electrodes de
ample, as those disclosed in Patent 2,268,165,
?ning an output space or gap, and an electrode
granted December 30, 1941, to Carlyle V. Parker
and Arthur L. Samuel, and Patent 2,308,800,
intermediate the input and output spaces or gaps
granted January 19, 1943, to Alva Eugene Ander
bounding a section of a drift space into which the
son. It comprises generally, as shown in Fig. 3,
velocity varied beam is projected and wherein the
a cathode l5a, for example of the indirectly
heated type, and a pair of centrally apertured
ances. The gain of the device, it will be appre
ciated, may be controlled by varying the poten
electrodes I51) and I5c coaxial with the cathode.
tial of the electrode 22.
Between the electron gun I5 and the collector
The electrons leaving the drift space constitute
electrode I4 and in coaxial relation therewith is U! a density varied beam which is accelerated to
an electrode system including a pair of electrodes
ward the output gap 2| and, because of the form
IE and I7 de?ning an input gap I8, a second pair
of the portion 21 of the electrode 29 and because
of electrodes I 9 and 2|] de?ning an output gap 2|
of the electrostatic lens action produced by the
and an intermediate electrode 22 de?ning a sec
potentials applied to electrodes 11, 22 and 20, is
tion of a drift space 23, each of these electrodes 10 concentrated and sharply focused upon the out
including an annular disc portion 24, projecting
put gap 2|.
through and hermetically sealed to the wall of the
Although in the embodiment of the invention
enclosing vessel Ill. As shown clearly in Fig. 2,
illustrated in Figs. 1 and 2 the drift space elec
the electrodes I6 and I9 include central cylindri
trode is of curved radial section with its convex
cal portions 25 and 28 respectively extending
surface toward the longitudinal axis of the elec
toward the electron gun I5 and collector electrode
trode system, it may be of other forms two of
I4 respectively, and the electrodes [1 and 20 in
which are illustrated in Figs. 4 and 5. In the
clude frusto-conoidal or trumpet-shaped por
form shown in Fig. 4, the drift space electrode 22
tions 26 and 21 respectively ?aring in opposite
includes a central cylindrical portion 35 and in
directions and extending from immediately ad 20 the form shown in Fig. 5, the central portion of
jacent the drift space electrode 22.
the drift space electrode 22 is curved in longi
During operation of the device, as illustrated in
tudinal section with the‘ concave surface toward
Fig. 3, the electrode I5b may be connected direct
the axis of the electrode system. Also, as shown
ly to the cathode and the electrode I50 may be
in Figs. 4 and 5, the central portions of the elec
maintained at a positive potential, for example 25 trodes Il6 and I 9 may be frusto-conical, the small
of the order of 300 volts, with respect to the
er end thereof being toward the gap de?ning elec
cathode, as by a battery 29 connected across a
trode associated therewith.
suitable resistance 30, so that the electrons ema
Although speci?c embodiments of the invention
nating from the cathode are concentrated into
have been shown and described, it will be under
a beam and accelerated toward the input gap I8..
stood that they are but illustrative and that vari
The electrodes I6 and I1 de?ning the input gap
ous modi?cations may be made therein without
I8 and the electrodes I9 and 20 de?ning the out
departing from the scope and spirit of this inven
put gap 2| are connected by resonant circuits 3|
tion as de?ned in the appended claims.
and 32 respectively, which may be in the form of
What is claimed is:
cavity resonators such as described in Patent
1. An electron discharge device of the velocity
2,281,717, granted May 5, 1942, to Arthur L.
- Samuel, the several electrodes being biased at
variation type comprising a pair of electrodes
having juxtaposed aligned apertured portions de
positive potentials, for example of the order of
?ning an input gap, means opposite one end of
1500 volts, with respect to the cathode I511 as by
said input gap for projecting an electron stream
batteries 33. The circuit 3| may be energized by 40 thereinto, means opposite and spaced from the
a coil 34 coupled thereto. The collector electrode
I4 is maintained at a potential somewhat higher
than that of the electrode I5c.
The drift space electrode 22 is connected to the
resistance 30 as shown and is maintained at a low
potential, for example of the order of 20 volts,
with respect to the cathode I5a so that there is
produced in the drift space 23 a retarding ?eld
into which the velocity varied beam issuing from
the gap I8 is projected. In this drift space, which
extends from the input gap to the output gap, the
other end of said input gap de?ning an output
gap, said output gap de?ning means including an
apertured electrode in alignment with said input
5 gap and including
also a second electrode
mounted behind said apertured electrode relative
to said input gap, said input and output gaps be
ing separated by a drift space, and means for
producing a retarding ?eld in said drift space,
50 said retarding ?eld producing means comprising
a hollow electrode in said drift space and in align-
ment with said input and output gaps and having
faster moving electrons in the beam overtake the
its ends in ‘juxtaposition to said ?rst apertured
slower moving electrons so that a periodic bunch
electrode and to the electrode of said pair of elec
ing of the electrons results and the velocity varia
tions ‘are thus converted into density variations. 55 trodes toward said output gap, and the internal
transverse dimensions of said hollow electrode be
The density varied beam then flows through the
ing substantially greater than the transverse di
output gap 2| and excites the resonant circuit 32
associated therewith.
mensions of said input gap.
2. Electron discharge apparatus comprising a
The establishment of a retarding ?eld in the
drift space, it has been found, aids the electron 60 ?rst means for producing a concentrated elec
bunching effect therein so that a high percentage
tron beam, a second means opposite‘ said ?rst
density variation is obtained. Furthermore, such
means for velocity varying said beam and causing
?eld enables the use of a short drift space and a
divergence thereof, means opposite said second
low voltage electrode structure. In addition it
means de?ning a drift space region into which
will be noted that because of the form of the por
the diverged beam is projected, and an output
tion 26 of the electrode II, the electron beam, in
means beyond said drift space region, said out
?owing through this electrode, diverges and en
put means including a pair of electrodes de?ning
ters the region 23 bounded by the drift space elec
an output gap, one of said electrodes having a
trode 22 with a diameter substantially equal to
hollow portion extending from said drift space
. the diameter of the electrode 122. Hence, space 70 region and converging toward said output gap.
charge effects are reduced and a uniformity of
3. Electron discharge apparatus comprising an
interaction between the electrons constituting the
electron gun for producing a concentrated elec
beam and the drift space ?eld is realized. ,
The drift space, therefore, is highly efficient
and enables the attainment of high transconduct
tron beam, said gun including a cathode and an
accelerating anode, means for velocity varying
said beam including a pair of electrodes in spaced
coaxial relation with said gun and de?ning an
input gap, the electrode of said pair furthest from
said gun including a hollow portion ?aring away
from said gun, means for producing a retarding
?eld in a region adjacent the larger end of said
hollow portion including an electrode opposite the
larger end of said ?aring portion and having a
tubular portion the diameter of the end of which
toward the larger end of said ?aring portion is of
trodes having aligned apertured portions, a ?rst
frusto-conical electrode between said pair of elec
trodes and having its smaller end in juxtaposition
to, in aligmnent with and de?ning an input gap
with the apertured portion of one of said pair of
electrodes, a second frusto-conical electrode be
tween said ?rst irusto-conical electrode and the
other of said pair of electrodes, said second frus
to-conical electrode having its smaller end in jux
substantially the same diameter as said larger 10 taposition to, in alignment with and de?ning an
output gap with the apertured portion of said
end, and an output means opposite said last-men
other of said pair of electrodes, a hollow electrode
tioned electrode.
intermediate said frusto-conical electrodes and
4. Electron discharge apparatus in accordance
having its ends in juxtaposition to and of sub
prises a pair of spaced coaxial electrodes de?ning 15 stantially the same diameter as the larger ends
of said frusto-com'cal electrodes, said hollow elec
an output gap and one of which electrodes in
trode increasing in diameter from its ends toward
cludes a hollow portion extending from imme
its center, and means for projecting an electron
diately adjacent said tubular portion and con
stream into said input gap and toward said
verging away therefrom.
5. An electron discharge device of the velocity
hollow electrode.‘
variation type comprising a pair of spaced elec
with claim 3 wherein said output means com
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