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Патент USA US2409184

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Filed Dec. 5, 1941
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F/ G. l
Filed ‘D60. 5, 1941
3 Sheets-Sheet 2
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A E A N D E R 50 N
Filed Dec. 5, 1.941
3 Sheets-Sheet 3
Patented Oct. 15, 1946
2,409,179 I
Alva Eugene Anderson, New York, N. Y., assignor
to Bell Telephone Laboratories, Incorporated,
New York, N. Y., a corporation of New York
Application December 5, 1941, Serial No. 421,736
2 Claims. (Cl. 315-5)
This invention relates to ampli?ers, oscil
lators, harmonic generators, detectors and the
onator depends upon their geometric relation
ship or relative position. The coupling is in gen
eral varied by any relative motion between the
like, especially for operation at ultra-high fre
beam and the resonator. By varying the cou
quencies, and relates more particularly to de
vices involving energy interchanges between a 5 pling at a rate corresponding to the resonant
frequency of the resonating chamber, the beam
is enabled to energize the electromagnetic ?eld
beam of moving charged particles, for example
electrons, and hollow bodies resonant to elec
in the resonator. In accordance with one em
bodiment of the invention the desired de?ection
An object of the invention is to avoid energy
losses caused by the beam striking the walls of 10 of the beam is secured by ?rst impressing a suc
tromagnetic waves.
cession of velocity variations upon the particles
in the beam and then directing the beam at an
the resonating chamber.
Another object of the invention is to abstract
angle into a substantially constant direct cur
energy from a velocity varied stream of charged
particles without the necessity of ?rst develop
ing electron density variations.
rent electric ?eld thereby causing the particles
15 to travel in trajectories of different curvatures
A feature of the invention is the use of vari
able de?ection of an electron beam for the pur
pose of systematically altering the magnetic cou
pling between the beam considered as a current
and the conductive wall of an associated inter
effecting a suitable lateral motion of the beam.
radial vibration of a rotating beam in the vicin
ity of an annular aperture in a toroidal resonator.
A still further feature resides in the use of
electrodes, in one case resembling in appearance
of the system shown in Fig. "l; and
operation of the system of Fig. '7.
tern having an electric component which varies
beam may be given successively varying velocities
Various other more or less conventional ar
rangements may also be employed to secure the
desired de?ection.
The invention is described in greater detail
hereinafter in reference to a number of embodi
nally resonant hollow body.
ments illustrated in the accompanying draw
Another feature is the variation of such cou-~
ings while the scope of the invention is indicated
pling by axial variation of the focal point of a
in the appended claims.
focussed electron beam.
Another feature is the de?ection of an electron 25 In the drawings:
Fig. 1 is a diagram useful in explaining certain
beam with respect to a normal or initial posi
tion of symmetry with reference to the electric
embodiments of the invention;
Figs. 2 to 7, inclusive, illustrate a variety of
?eld pattern associated with a resonator for the
purpose of harmonic wave generation.
embodiments of the invention;
A further feature is harmonic generation by 30 Fig. 8 is a fragmentary view of a ‘component
Fig. 9 is a diagram useful in explaining the
In Fig. 1 there is shown an electron gun l0
a pair of toothed gears in juxtaposition, for im 35 arranged to direct a beam of electrons across a
gap H in a resonating chamber l2. Directed at
parting a radial vibration to a rotating electron
an angle to the path of the electron beam there
is maintained a steady direct current electric
The harmonic generating system disclosed
field as, for example, by means of a negatively
herein employing radial vibration of a rotating
beam is claimed in my copending application Se 40 charged plate I3, causing the electron path to
follow a substantially parabolic course indicated
rial No. 506,928, ?led October 20, 1943, assigned
by a dot-dash line l4. A second resonator I5 is
to the same assignee as the present application.
placed in the path of the electron beam so that
In accordance with the invention a beam of
a gap l6 therein is traversed by the beam sub
moving charged particles is directed into the
immediate vicinity of a gap in a hollow resonator, 45 stantially perpendicular to a pair of electrodes
l1 and is which constitute the gap. 'By exci
the region adjacent to the gap being character
tation of the resonator l2 the electrons of the
ized by a standing electromagnetic wave pat
as they pass ‘through the gap II. The faster
of the magnetic coupling established between the 50 electrons will then penetrate further into the
materially from point to point. The magnitude
beam considered as a current and the conductors
retarding ?eld and so follow paths such as one
constituting the boundary of the resonator is a
function of the geometry of the system. In
other words, the magnitude of the energy inter
change effective between the beam and the res 55
represented by the dot-dash line IS. The slower
electrons will follow paths such as one repre
sented at 20. The geometry of the system is evi
dently such that velocity variation of the beam
results in a movement of the beam with respect
to the resonator l5 as indicated by the di?erent
positions of the curves l4, l9 and 20 spread out
transversely of the gap l6.
Assuming some initial electromagnetic dis
turbance in the resonator l5, such as will gener
ally occur spontaneously, any non-uniformity in
the slower electrons being de?ected to a greater
extent than the faster ones, as explained in con
nection with Fig. l. The de?ected beam in pass
ing through the gap in the resonator 26 is variably
coupled with the conductive boundary of the
resonator 26, causing an alternating electromag
netic wave to be set up and resonated in the cavity
the intensity of the electric ?eld between various
points along the gap I6 will give rise to a varia
tion in the amount of energy transferred to the
of the resonator 26 from which energy may be
field per electron, depending upon the position
of the electron path transversely of the gap I6.
Variations in the energy transferred to the res
onator will result in ?uctuations in the charges
present upon the electrodes I1 and I8. ' If the
?uctuations occur at the resonant frequency of
the resonator it is evident that energy will be ab
stracted from the electron beam to maintain the
electromagnetic oscillations in the resonator.
From another viewpoint the magnetic coupling between the electron beam considered as a cur
rent and the conductors forming the walls of the
resonator, depends upon the geometry of the ar
rangement and, in particular, depends upon the
taken off through the coupling 28.
Fig. 3 shows an arrangement generally similar
to that of Fig. 2. However, instead of the electron
gun 2|, producing a single pencil or beam of elec
trons, a gun” is provided having an annular
cathode producing a tubular beam of electrons
indicated in section by dot-dash lines 34 and 35.
Input and output resonators, 36 and 31, respec
tively, are provided each having an annular gap
through which the electron beam passes. Be
tween the resonators 36 and 31 is mounted a hol
low cylindrical electrode 38 to which a de?ecting
potential may be applied. The application of the
de?ecting potential in the arrangement of Fig. 3
causes the tubular beam to increase or decrease
in radius thereby moving radially with respect to
position in the gap l6 which the electron beam
the annular gap in the resonator 31. A collector
occupies at a given‘ time. In general, any gap be
electrode 39 is provided, which may advanta
tween electrodes will entail some non-uniformity
geously include an annular groove into which the
of the electric ?eld and hence by moving an elec
tubular beam may enter, the sides of the groove
tron beam about in the vicinity of a gap in a res
serving to intercept and absorb secondary elec
onator it is usually possible to vary the magnetic 30 trons produced by the impact of the beam against
coupling ‘and hence to establish alternating elec
the electrode. A source 60 of control potentials
tromotive forces in the conductors of the reso
may be inserted in the connections to the de?ect
ing electrode 38 for superimposing a modulation
Fig. 2 shows a practical embodiment of an ar
or control eifect. For example, the source 60 may
supply audio or video signals which will modulate
a carrier wave generated in the resonator 31.
electron gun 2| is mounted within one end por
Or, the source 60 may supply an automatic vol
tion of an evacuated envelope 22, Within the
ume control potential derived in well-known
opposite end portion of the envelope is provided
manner, for example from the output of the res
a collector electrode 23. Between the gun 2 l' and
onator 31.
collector 23 are arranged in succession an input
The system of Fig. 3 may be operated to gen
cavity resonator 24, an electrode 25 for providing
erate, the carrier wave either by means of the
a de?ecting potential and an output cavity res
variable electron coupling principle as in the sys
onator 26. If desired, the arrangement may be
tem of Fig. 2, or by virtue of electron bunching
accommodated to a straight-walled cylindrical 45 occurring while the electron stream traverses the
envelope by setting the electron gun 2| and col
space enclosed by the electrode 38. In either
lector 23 at an angle to the axis of the envelope
case, the coupling may be varied by means of
as shown, and providing apertured electrodes in
source 60. Adjustment of a suitable initial bias
the resonating cavities 24 and 26 in alignment
potential, either positive or negative, may be ef
with the direct and re?ected portions of the elec 50 fected by means of a potentiometer arrangement
rangement operable upon the principle which has
been explained with reference to Fig. 1. An
tron beam, respectively. Coupling devices 21 and
28 may be employed as input and output connec
tions respectively and may be connected together
if desired to provide feedback when the device is
6i, to de?ect the electron stream initially either
outwardly or inwardly to any desired extent.
Various speci?c arrangements for de?ecting
the electron beam will occur to those skilled in
to be employed either as an oscillator or as a re 55 the art, two examples being shown in Figs. 4 and
generative ampli?er. The resonators 24 and 26
5, respectively. Fig. 4 illustrates the use of a
and the collector 23 may be provided with elec
transverse magnetic ?eld for de?ecting an elec
tron accelerating potentials from a battery 29.
tron beam. The ?eld may be maintained by‘
The cathode of the electron gun 2| may be heated
magnetic coils 40 and 4| suitably energized and
by energy from a battery 30 and the de?ecting 60 mounted outside the envelope enclosing the elec
potential for the electrode 25 may be provided
tron beam. Fig. 5 shows the use of electrostatic
by a battery 3|. Other suitable sources of poten
de?ection plates 42 and 43 mounted inside the
tials may of course be substituted for any of the
envelope and effective to deflect an electron
batteries illustrated herein.
beam passing therebetween. While in the ar
In the operation of the arrangement of Fig. 2
rangement of Fig. 4 the de?ection of the beam is
as an ampli?er, the resonators 24 and 26 may be
to be made variable as in the preceding arrange
tuned to the desired operating frequency to res
ments by velocity variation effected by a reso
onate with a wave to be ampli?ed, the latter being
nator, in the arrangement of Fig. 5 the beam may
impressed upon the interior of the resonator. 24
be variably de?ected by impressing alternating
through the coupling 21. A standing electromag
electromagnetic waves upon the plates 42, 43 ,
netic ?eld set up inside the resonator 24 is effec
tive at the gap to impress electron velocity varia
tions upon the electron beam passing through the
gap from the electron gun 2|. In the neighbor
either with or without an accompanying direct
current biasing potential.
hood of the electrode 25 the electron beam is. bent.
beam arranged to have a focal point at the gap
In the arrangement of Fig. 6 an electron gun
44 is employed of a type producing a. convergent
a collector BI is arranged ,for intercepting the
beam after it passes the aperture 49.
In the operation of the arrangement of Fig.
45 of an input resonator 48. A magnetic coil 41
is provided to produce an axial magnetic field
whereby the electron rays diverging after passing
the gap 45 may be brought together at a second
7, the electron beam sweeps out a circular con
focal point 48, for example. The focal point 48
may be, for example, somewhat beyond the gap
ical surface except for the modifying in?uence of
the electrodes 44, 45. These electrodes have
49 in an output resonator 50.
In the operation of the system of Fig. 6, veloc
ity variations impressed upon the electron beam
regularly spaced projections alternately arranged,
as for example in the form shown in detail in a
at the gap 45 cause a variable de?ection of the
teeth in Fig. 8 is merely illustrative of various
suitable forms that may be used, the effect being
fragmentary view in Fig. 8. The shaping of the
individual electrons in the axial magnetic ?eld,
thereby serving to shift the focal point from 48
to de?ect the beam radially inwardly and out
wardly alternately, causing the beam to de
to other positions such as the one indicated at
scribe a surface of wave-like outline as shown by
5|, for example. Velocity variation of the elec
tron beam thus causes the focal point to execute 16 the line 52 in the sectional diagram Fig. 9. There
axial excursions, thereby continually varying the
the undisturbed path of the beam is indicated
relative position of the electron beam and the
by a circle 53. The effect of the electrodes 44
and 45 is to cause the beam to alternately ap
proach and recede from the aperture 49 at a
conductors of the resonating chamber 50. The
shifting of the focal point of the beam consti
tutes an alternative method of varying the cou
20 rate determined by the input frequency of the
pling between the electron beam and the resonant
source 40 and the number of teeth in the elec
system thereby energizing the resonating cham
trode 44 or 45.
The effect of the relative move- .
ment between the electron beam and the boun
daries of the resonator 48 as in the other appli
preceding ?gures.
25 cations of the invention is to generate in the
resonator an alternating electro-magnetic ?eld.
An “in phase” variation in which an increase of
In this case, it is evident that the frequency of
electron velocity in accompanied by an increase
the ?eld will be a multiple of the frequency of
in output current is obtained by adjusting the
the source 40, the number of the multiple being
beam‘ to focus initially at a point beyond the
determined by the number of teeth in either
gap 49, such as point 48. Conversely, an “out
electrode 44 or 45. In other words; the input ‘
of phase” variation in which an increase of elec
frequency is multiplied by one half the number
tron velocity is accompanied by a decrease in
of teeth in either of the two electrodes.
output current is obtained by locating the initial
In any of the systems illustrated the effects due
focal point ahead of the gap 49, at a point such
to beam de?ection may be accompanied by the
as 5|.
ordinary electron grouping action resulting from
In any of the arrangements of Figs. 1 to 6, in
faster moving electrons overtaking slower ones
elusive, it will be noted that if the normal posi
in the space between the velocity varying elec
tion of the beam is located at an axis of sym
trodes and the output resonator. Simple theory
metry of the electric field pattern at the gap, as
for example, at the center of the gap in a sym 40 indicates that the two effects, electron grouping
and variable coupling, will combine in quadrature
metrical system, there will be two cyclic changes
relation at the output. They are therefore not
of coupling accompanying each cycle of the de
in opposition and may be advantageously com
?eeting potential. The output wave will in that
bined. If desired, the electron grouping effect
case have a wave form rich in harmonics, par
may be minimized by using short electron paths
ticularly the second harmonic, and will be de
or increased initial electron speeds. The modu
?cient in the fundamental frequency component.
lation and control features described in connec
Hence in such an adjustment any of the arrange
tion with Fig. 3 may be applied to any of the
ments functions as a frequency multiplier. To
de?ecting mechanisms and used as adjuncts
secure a fundamental component in the output
ber 54 in accordance with the same general meth
od that has been explained in connection with the
wave it is only necessary to shift the normal, or 50 either to an electron grouping or beam de?ecting
zero position of the beam to a position unsym
As the operation by means of variable coupling
obtained by beam de?ection is not dependent
metrical with reference to the space pattern of
the electric ?eld. "
upon any electron grouping action to generate
Fig. 7 shows another adaptation of the inven
tion particularly designed for harmonic genera 55 large induced electromotive forces in the output
system but relies upon the extent and rapidity of
tion but not depending upon locating the normal
de?ection of the beam, the output with a given
position of the beam symmetrically with respect
beam current may be increased by increasing the
to the electric field pattern. A source 40 of
amplitude of the impressed velocity variation.
waves the frequency of which is to be multiplied,
Large output currents maybe generated using a
is connected through a quarter phase network 4| 60
large induced electromotive force in conjunction
to the respective pairs of de?ecting plates of a
a resonator of low effective resistance. For
conventional beam rotating arrangement 42 op
this purpose an internally‘ resonant hollow con
erating upon the electron beam from an electron
gun 43 to cause the beam to sweep over a conical
surface passing between two annular electrodes
44 and 45. The electrodes 44, 45 are polarized
at unequal potentials by means of batteries 46
and 41, respectively. Beyond the electrodes 44,
45 and adjacent to the path of the electron beam 70
is mounted a- toroidal resonating chamber 48
having an annular slot or aperture 49 surround
ing and adjacent to the path of the rotating
ductive body is well adapted.
What is claimed is:
1. Means for producing and maintaining a
beam of moving electrically charged particles,
an internally resonant hollow conductive body
having an aperture in the path of said beam,
means for bringing said beam to a substantial
focus at a point near said aperture and means
to vary the position of said focal point with ref
erence to said aperture while maintaining the
beam. An output coupling arrangement 50 is
beam current substantially steady, said aperture
provided in conjunction with the resonator 48 and 75 being sufficiently large compared with the trans
~ verse dimensions of the beam to freely pass sub
stantially the whole beam throughout the normal
range of variation of the position‘ of said focal
means actuated by said waves to vary the position _
of said focal point along said axis with reference
to said aperture while maintaining the beam cur- "
rent substantially constant in magnitude, said‘ '
2. Means for producing and maintaining an 8 hollow body being resonant to said waves and
electron beam moving along a substantially rec
tilinear axis, an internally resonant hollow con
ductive body having an aperture in the path of
said aperture being sumciently large compared
with the transverse dimensions of the beam to
freely pass substantially the whole beam through
out the normal range of variation of the position
said beam, means for bringing said beam to a
substantial focus at a point on said axis near said 10 of said focal point.
aperture. a source of waves to be repeated, and
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