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Патент USA US2409500

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Oct. 15,1946.
~
G, R; KILGORE
.'
2,409,499
BEAM DEELECTION ELECTRON DISCHARGE DEVICE
Filed March 6, 1942
2 Sheets-Sheet l
Ourpur
J40
I
“~57
I INPUT 1
PUT
INVENTOR.
.
George Eff/[gore
Oct. 15,1946.»
"
; G. R. MLGQRE
.
2,409,499
BEAM DEFLECTION ELECTRON DISC-HARGE DEVICE
Filed, March 6, ‘1942
1
2 Sheets-Sheet 2
INVENTOR
Georige R. K 1' 1301's.;
_ATTURNEY
2,409,499
Patented ‘Oct. 15, 1946
UNETED STATES PATENT OFFICE
2,409,499
BEAM DEFLECTION ELECTRON DISCHARGE
DEVICE
George Ross Kilgore, Verona, N. J., assignor to
Radio Corporation of America, a corporation of
Delaware
Application March 6, 1942, Serial No. 433,579
9 Claims.
(01. 250-158)
2
can be shown that the current density at an
My invention relates to electron discharge de
aperture depends upon the angle of convergence
vices, more particularly such devices utilizing a
of the beam, the cathode current density, the
beam of electrons which is de?ected during op
velocity of emission, and the velocity at the aper
eration.
In tubes of the type under consideration a beam
ture,
of electrons is directed between a pair of de?ect
ing electrodes toward an apertured electrode be
(1)
[1
sin (1)
hind which is usually placed a collector. Alter
nating voltages are applied to the de?ecting elec
Where
trodes to cause the electron beam to be de?ected 10
I1=current
density at aperture in amps/sq. cm.
across the aperture to thus control the amount of
Io=cathode current density amps/sq. cm.
current ?owing toward the collector or output
V=potential of de?ecting electrodes in volts.
electrode. In such types of tubes the de?ection
Vo=initial kinetic energy of electrons in volts.
sensitivity drops off rapidly as the frequency at
which the tube is operated is increased. Efforts 15 ¢:half angle of converging beam.
have been made to increase the sensitivity or the
Now in a simple de?ection device such as shown
transcond-uctance of the tube by increasing the
in Figure 1, ¢ is approximately equal to
separation between the end of the de?ecting
plates and the apertured electrode. Such efforts,
21
however, have not resulted in the expected im 20
provement of the transconductance of the tube
so that the current density at the aperture is
since the current density at the aperture in this
case falls o? in proportion to the increase in any
(2)
de?ection sensitivity which may have resulted by
spacing the de?ection plates farther from the 25 Where
apertured electrode.
Z=length of de?ecting plates in cm.
The principal object of my invention is to in
d=separation of de?ecting plates D1 and D2 in cm.
crease the transconductance of electron discharge
and the de?ection sensitivity for the parallel de
devices employing beam de?ection and to pro
vide for improved operation of devices of this 30 ?ecting plates is given by
kind.
(3)
The novel features which I believe to be char
acteristic of my invention are set forth with par
therefore,
ticularity in the appended claims, but the inven
tion itself will best be understood by reference to
the following description taken in connection with
the accompanying drawings in which Figure 1 is
a schematic diagram showing the conventional
de?ecting electrode and apertured electrode ar
rangements utilized in an electron beam de?ec
tion device, Figure 2 is a schematic diagram show
ing the electrode arrangement in a device made
according to my invention, Figure 3 is a longitu
dinal schematic section of an electron discharge
device embodying my invention and its associ
ated circuit, and Figures 4 and 5 show modi?
cations of an electron discharge device and its
associated circuits made according to my inven
tion.
Figure 1 shows schematically the conven
tional de?ecting electrode system comprising de
?ecting electrodes II and I2, apertured elec
trode l4 and collector [3, the means for applying
rj voltages being indicated at [5.
From an analysis of beam de?ection devices it
35
gmgsllgw VII-lib mhos.
I
(4)
gm%0.75%/§b.1'>< 107 mhos.
(5)
40 where
b=length of beam measured parallel to cathode.
¢=transit time through de?ecting plates
seconds
45
These expressions show that pm in the case of
Figure 1 is independent of the separation (12)
and is directly proportional to transit time (1-). '
50 It is well known that when '7' becomes an appre
ciable fraction of a period the de?ection sensitiv
ity drops off. rapidly, becoming a minimum for
r=period. Therefore, at U. H. F. the gm is limited
by the transit time regardless of the choice of Z
and V.
2,409,499
3
4
In accordance with my invention I propose to
sensitivity without decreasing current density.
This has the further advantage of bringing the
the structure shown the electrode 43 may be
coated with secondary emitting material so that
electrode 44 serves as the output electrode. Volt
age source 54 for the cathode heater is provided
as well as the voltage source 53 for the various
other electrodes. In order to prevent R. F. cur
electrodes closer to the electron beam and thus
rents from ?owing in the leads for providing D. C. ~
increase the transconductance by shaping the de
?ecting electrode in conformity with the con
verging beam so as to increase the de?ection
decreasing space charge eifects.
potentials, chokes 55, 56, 51 and 58 are provided.
In Figures 2 and 3 I show the electrode arrange
ment of the electron discharge device employing
beam de?ection and its incorporation in tubes
and its associated circuit. Brie?y the funda
mental electrode structure shown in Figure 2
comprises a concave surface cathode 20 for pro
viding a converging beam of electrons 25 directed
through the apertured electrode 23 to collector 24.
The beam de?ecting plates 2i and 22 extend be
tween the concave electrode 20' and apertured
electrode 23, converging toward the aperture in
the apertured electrode 23. A slight inward
curvature of these de?ecting plates might in
crease the ultimate gain but for practical pur
poses the ?at plates will serve just as well.
As shown in Figure 3 the envelope 30 Contains
These serve well for all but the very high fre
quencies.
In the arrangement shown in- Figure 5, which
is intended for operation at the higher fre
quencies, the input voltage is supplied to the de
?ecting electrodes by means of a Lecher wire
15 system comprising tubular elements 60 and 6!
shorted by the movable shorting bar 62." 'The
leads for carrying the D. C. potential to the de
fleeting electrodes pass through the tubular mem
bers and are capacity coupled thereto by means
20 of condenser 64 and 65 so that the R. F. poten
tial may be applied to the de?ecting electrodes
when the input signal is introduced into the
Lecher wire system by means of coupling loop 63.
The other numerals designate the same elements
at one end a concave surface cathode 3| heated 25 as those in Figure 4.
by the heater 32. The converging beam from this
cathode is directed through the aperture 34' in
the apertured electrode 34 to the collector 33, the
‘ beam passing between the converging de?ecting
In Figures 4 and 5, due to the large capacity
coupling between the outer plate members 45
and 46 and their associated sections 41, 49 and 48,
53, de?ecting plate 45 and plates 41 and 49 in the
plates 35 and 36. If desired, electrode 33 .could 30 one case are at one R. F. potential and plate 46
be coated with secondary emitting material and
and the sections 48 and 50 in the other case are
the secondary emission captured by electrode 34,
at the same different R. F. potential. Elements
electrode 34 in this case serving as the output
45' and 46' are D. C. connectors.
electrode. The input signal is introduced be
While I have indicated the preferred embodi
tween the de?ecting plates 35 and 33 by means 35 ments of my invention of which I am now aware
of the input 37 and the output is taken from the
and have also indicated only one speci?c appli
output transformer 48. Voltage sources 39 and
cation for which my invention may be employed,
38 provide the necessary potentials for the vari
it will be apparent that my invention is by no
ous electrodes, the collector electrode 33 in this
.means limited to the exact forms illustrated or
case being maintained at a higher potential than 40 the use indicated,~ but that many variations may
the apertured electrode 34. From an analysis of
be made in the particular structure used and the
the effects of space charge on focusing I have
purpose for which it is employed without depart
found the best radius of curvature of the cathode
ing'from the scope of my invention as set forth in
the appended claims.
is approximately one-half the de?ecting plate
length,
-
What I claim as new is:
a
p
7
-
In Figure 4 I show the longitudinal schematic
1. An electron discharge device having means
section of a modi?cation of an electron discharge
for supplying a converging beam of electrons, an
device made according ‘to my invention which,
apertured electrode through which'said beam of
due to its construction, maintains the beam better
focused than the arrangement shown in Figure 3
because of the lens action effect taking place be
tween vthe portions‘ of the de?ecting electrode
electrons .is directed, and a collector all in the
order named, and a single pair of oppositely dis
posed de?ecting electrodes positioned closely ad
jacent said-l beam and between said‘ beam’ sup
structure.
plying. means vand-said aperturcd; electrode and
‘
The envelope 4!! contains the cathode 4!, heater
having surfaces continuously approaching'each
42, apertured electrode 44, collector 43 and the 55 other inthe direction of movement of the beam,
modi?ed de?ecting plate construction. In this
said‘ beam supplying means and said output elec
case the de?ecting electrodes 45 and 46 have .po
trode being next adjacent said de?ecting elec
sitioned on the beam side the sections 4l—49 and
trodes.
»
V
V
-
-
a
»
‘
48 and 50 insulatingly separated from the plates
2. An electron discharge device having a cath
45 and 46 by means of insulating elements 5| and 60 ode having a concave emitting surface for sup
52 for example of mica. It is thus possible to ap
plying a converging beam of electrons; an aper;
ply to the plates 41 and 48 a lower positive poten
tured electrode through which said beam of ‘elec
tial than the plates 39 and 56 thus having an in
trons is-directed,‘ and a collector allin the order
creasing accelerating ?eld in moving from the .
named, and asingle pair of oppositely disposed
cathode to the apertured electrode. The result 65 de?ecting electrodes positioned closely adjacent
of the arrangement is to provide a lens action be
said beam-andbetween said cathode‘ and said
tween the sections 41-48 and 49—59 which assist
apertured electrode and having surfaces contin
in maintaining the beam focused in a converging
uously approaching each other in the direction
manner toward the aperture. In the arrange
. of the movement of the electron beam; said cath
ment shown the exterior plates 135 and 46 may be 70 ode and-said apertured. electrode being next ad
electrically connected to plates .49 and 50' so that
jacent said de?ecting electrodes. >
~.
. . ~
’
these four plates are at the‘ same positive poten
3. An electron discharge device having means
for supplying a converging beamof electrons,.an
The input is provided by means of transformer
apertured electrode through which said beam of
55 and output by means of transformer 56. In 75 electrons is directed, and a collector all in’ the
tial.
'
.
.
‘
‘
2,409,499
5
6
order named, and a single pair of oppositely dis
posed de?ecting electrodes positioned closely ad
jacent said beam and between said beam sup
plying means and said apertured electrode and
viding a lens action during operation of said elec
tron discharge device for maintaining said beam
of electrons focused.
7. An electron discharge device having means
having ?at converging surfaces approaching each
for providing a converging beam of electrons, an
other in the direction of the movement of the elec
tron beam, said beam supplying means and said
apertured electrode being next adjacent said de
are directed, and a collector all in the order
?ecting electrodes.
4. An electron discharge device having means 10
for supplying a converging beam of electrons, an
apertured electrode through which said beam of
electrons is directed, and a collector all in the
order named, and a single pair of oppositely dis
apertured electrode toward which said electrons
named, a pair of de?ecting electrodes positioned
between the cathode and the apertured electrode,
and including conducting elements converging
toward the apertured electrode, a plurality of
conducting sections insulatingly supported by
said converging conducting elements and adapted
jacent said beam and between said beam sup
plying means and said apertured electrode and
to have increasingly positive direct potentials ap
plied to successive conducting sections for pro
viding a lens action during operation of said
electron discharge device for maintaining said
having surfaces continuously approaching each
beams of electrons focused, and an electrical
posed de?ecting electrodes positioned closely ad
other in the direction of the electron movement,
said collector electrode having a secondary elec
tron emitting surface for releasing secondary
electrons which are received by said apertured
electrode during operation of said electron dis
charge device, said beam supplying means and
said apertured electrode being next adjacent said
connection between each conducting section ad
jacent the apertured electrode and its support
ing converging conducting element.
8. An electron discharge device having a cath
ode provided with a concave emitting surface for
supplying a converging beam of. electrons, an
apertured electrode through which said beam of
de?ecting electrodes.
electrons is directed, and a collector all in the
5. An electron discharge device having means
for providing a converging ‘beam of electrons, an
order named, and de?ecting electrodes positioned
apertured electrode toward which said electrons
and said apertured electrode and having surfaces
approaching each other in the direction of the
movement of the beam, the radius of curvature
are directed, and a collector all in the order
adjacent said vbeam and between said cathode
named, a pair of de?ecting electrodes positioned
of the concave surface of said cathode being
between the cathode and the apertured elec
equal to one-half the length of the de?ecting
trode, and including conducting elements con
electrode.
verging toward the apertured electrode, a plu
9. An electron discharge device having a cath
rality of conducting sections positioned closely ad 35
ode provided with a concave emitting surface for
jacent the converging inducting elements and
supplying a converging beam of electrons, an
between said elements and the beam, and insu
apertured electrode toward which said electrons
latingly separated from said elements whereby
are directed, and a collector all in the order
different direct potentials may be applied to said
40 named, a pair of de?ecting electrodes positioned
elements and said sections.
between the cathode and the apertured electrode,
6. An electron discharge device having means
and including conducting elements converging
for providing a converging beam of electrons, an
toward the apertured electrode, a plurality of
apertured electrode toward which said electrons
are directed, and a collector all in the order
conducting sections positioned closely adjacent
named, a pair of de?ecting electrodes positioned
between the cathode and the apertured electrode,
and including conducting elements converging
toward the apertured electrode, a plurality of
the converging conducting elements and between
said elements and the beam, and insulatingly
separated from said elements whereby different
direct potentials may be applied to said elements
and said sections, the radius of curvature of the
conducting sections insulatingly supported by
said converging conducting elements and adapted 50 concave surface of said cathode being equal to
one-half the length of the de?ecting electrode.
to have increasingly positive direct potentials ap
GEORGE ROSS KILGORE.
plied to successive conducting sections for pro
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