close

Вход

Забыли?

вход по аккаунту

?

Патент USA US3084289

код для вставки
April 2, 1963
E. c. DENCH
3,084,277
TRAVELING WAVE TUBES
Filed April 30, 1958
2 Sheets-Sheet l
/0
92
Q
My.a
i
U
“Maw-4%”
\
9/25
2
/A/ vs' 702
Eawaeo c
Arm/ems!’
United States Patent 0 "ice
3,084,277
Patented Apr. 2, 1963
1
2
3,084,277
the delay line and the sole to the strength of the trans
verse magnetic ?eld. The electric ?eld strength, in turn,
is inversely proportional to the spacing of the delay line
and the sole.
TRAVELING WAVE TUBES
Edward C. Dench, Needham, Mass, assignor to Raytheon
Company, Lexington, Mass., a corporation of Dela
ware
Filer] Apr. 3a, 1958, Ser. No. 733,228
7 Claims. (cl. 315-39.»
This invention relates to a traveling wave tube, and
A traveling wave tube of the backward wave type is
discussed in United States Letters Patent of Edward C.
Dench and Albert D. La Rue, Patent No. 2,888,649 is
sued May 26, 1959, and includes a nonreentrant slow
wave energy-propagating structure or delay line, a con
tinuous electrode or sole spaced from and disposed sub
of the interaction space-bounding electrodes is so shaped 10 stantially parallel to said structure, and an electron gun
mounted adjacent one end of said structure for produc
that the interaction space varies across the transverse
ing an electron beam which, under the in?uence of an
dimension thereof.
electric ?eld existing between said structure and said sole
Traveling wave tubes are known which include a slow
more speci?cally, to a traveling wave tube wherein one
wave energy propagating structure or delay line, a con~
and a magnetic ?eld transverse to said electric ?eld, tra
tinuous electrode or sole spaced from and disposed sub 15 verses the interaction space bounded by the slow-wave
structure and the sole.
stantially parallel to said structure, and an electron gun
Because of the interaction between the electron beam
mounted adjacent one end of said structure for producing
and high frequency ?elds of wave energy propagating
an electron beam which, under the in?uence of an elec
along the slow-wave structure, energy may be transferred
tric ?eld existing between said structure and said sole
and a magnetic ?eld transverse to the electric ?eld and to 20 from the electron beam to the high frequency ?eld. An
R.F. signal introduced into one end of said structure may
the beam, traverses the interaction space bounded by
be ampli?ed in this manner, or, the tube may be made
the slow wave structure and the sole. Such traveling
to oscillate as the result of this energy exchange.
wave tubes are widely used either as ampli?ers capable
of operation over a large band width or as oscillators
Because of practical manufacturing conditions, it is
capable of being tuned electronically over a considerable
frequency range in the microwave region. Such devices
utilize the interaction between an electron beam moving
along paths adjacent a periodic non-resonant slow wave
propagating structure and the electromagnetic ?eld of
often di?icult to maintain constant the spacing between
the delay structure and the sole along the interaction
space. It has been found, for example, that in a tube
having a sole-delay structure spacing of 0.10 inch, a vari
ation in this spacing of as little as 0.001 inch represents
the radio frequency wave propagating along said periodic 30 a one percent variation in electron beam velocity, since,
as previously mentioned, the average electron beam ve
structure. The electromagnetic ?eld along such a period
locity of such a tube is equal to the ratio of the electric
ic structure may be resolved into a number of super
?eld strength to the magnetic ?eld strength, and since
imposed traveling waves or space harmonics each having
the electric ?eld strength is directly dependent upon the
its own phase velocity. Some of the space harmonics of
a phase velocity travel in the same direction as the wave 35 spacing between the delay structure and the sole. In
energy or group velocity and are referred to as forward
waves. Other space harmonics, on the other hand, have
a phase velocity of opposite sense, that is, the phase ve
order to render the traveling wave tube less sensitive to
sole-delay structure spacing, the sole surface along the
transverse dimension of the sole and the interaction
locity is in a direction opposite to the energy or group
velocity. Such harmonics are referred to as backward
waves. If the electron beam velocity is adjusted so that
space, that is, the dimension perpendicular both to the
direction of propagation of the electron beam and to the
electric ?eld between the delay structure and the sole, is
it is in substantial synchronism with the phase velocity
of a given space harmonic, interaction between the elec
made variable so that there is a slight variation of the
electric ?eld across any transverse section of the interac
tion space. By “transverse section” is meant a section
tron beam and this component will occur, and energy 45
disposed substantialiy perpendicular to the direction of
will be transferred from the electron beam to the electr0~
propagation of the electron beam and perpendicular to
magnetic ?eld. In a traveling wave ampli?er, a radio
the electric ?eid between the delay structure and the sole.
frequency input signal is coupled to the periodic struc
Experiments with a traveling wave oscillator using a sole
ture adjacent one end thereof, and, owing to the inter
action between electron beams moving along a path ad 50 of this type have indicated that the power output is less
sensitive to change in voltage between the sole and the
jacent the periodic structure and the electromagnetic ?eld
cathode over a predetermined frequency band than a
of the radio frequency wave propagating along said struc
traveling wave oscillator using the conventional sole of
ture, ampli?cation of the input signal may be obtained,
under proper operating conditions. This ampli?ed sig
rectangular con?guration.
The sole electrode is arranged generally parallel to the
nal may then be extracted from the periodic structure 55
delay structure, in the case of a traveling wave tube of
adjacent the other (output) end thereof. In the forward
linear con?guration, and generally concentric with said
wave ampli?er the interaction is between the electron
delay structure, in the case of a circular traveling wave
beam and a forward wave; the electrons thus are pro
tube, and usually includes vertical walls or side mem
jected toward the output end of the periodic structure.
In the backward wave ampli?er, interaction occurs be 60 bers at each edge of the peripheral portion of the sole
facing the electron beam which approach or may even
tween the electron beam and a backward wave and the
slightly overlap the delay structure. These vertical walls
electrons then move toward the input end of the periodic
serve as a beam-forming end shield to keep the electron
structure. In a traveling Wave oscillator, when the elec
beam centered in the system and from diverging in a
tron beam current exceeds a critical current at which os
cillations can begin, and when the electron beam ve 65 direction normal to the main path of the electrodes as
the result of mutual repulsion of the electrodes in the
locity is substantially equal to the velocity of a suitable
space charge existing along the length of the tube. In
space harmonic of the propagated wave, oscillations may
some instances, these side members may be omitted.
be generated within the device and the generated energy
In one example of the invention, the peripheral por
will propagate along the periodic structure and may be
tion of the sole exposed to the electron beam—-—which,
extracted at one end thereof.
70 in the case of soles having side members, is the portion
The average velocity of the electron beam is equal to
of the sole disposed between the side members-is curved
the ratio of the intensity of the electric ?eld between
3,084,277
4
so that the spacing between the delay structure and the
sole progressively increases as one approaches the center
of the transverse section, or thickness dimension, of the
sole from the edges of said sole. With this arrangement,
the continuous electric ?eld between the delay structure
scribed and illustrated as an interdigital network struc
ture, the invention is not limited thereto; the delay line
may consist, for example, of a strapped vane structure,
a loop-loaded waveguide, a strapped loop structure, a
disk-loaded coaxial structure, or any type of ladder line.
The sole 14 consists essentially of a cylindrical block;
and sole tends to focus the beam toward the more active
constructed of an electrically-conductive material and in
central portion of the delay structure. The amount of
cluding a web portion 45 bounded by an arcuate section
variation of the cross-section of the sole is adjusted em
46 whose periphery consists of an active surface 47 and
pirically for optimum operation. It should be under
stood, however, that the variation should not be so great 10 side or edge members 48. The purpose of these side
as to change appreciably the average velocity of the elec
members 48 is to con?ne the electron beam within the
trons in the interaction space.
interaction space 50 ‘between surface 47 of sole 14 and
Another advantage of the tube according to the inven
the interdigital line 12. The surface 47 of sole 14 be
tion is that any slight off-centering of the sole, or any
tween the side members 48 is curvilinear, as is more
taper in sole-delay structure spacing of the tube of the
clearly apparent in the enlarged fragmentary view of sole
14 of FIG. 3. Other embodiments of sole 14 are shown
present invention, will be compensated, at least partially,
by the fact that at all points along the active length of
in FIGS. 4 to 8, inclusive. The sole 14 of FIG. 4 in
the tube there will be some part of a cross section hav
cludes the usual side or edge members 48 and a substan
tially planar central portion 47 joined to the edge mem
The arrange
ing the same electric ?eld as any other cross section.
The active portion of the sole, in addition to being con
tinuously curved, may be similar to the conventional U
20 bers 48 by arcuate corner portions 49.
ment of FIG. 4, while not as effective as that shown
in FIGS. 1 and 3, has provided increased operating cf»
shaped sole except for rounded ?llets in the corner re
gions adjoining the active surface and the two vertical
side members. An alternative to the above arrange
ments may be a sole active surface consisting of two or
more linearly varying portions across the transverse di~
mension of the sole; for example, the sole surface may
be V-shaped, or may consist of several interconnected
?ciency as compared to a sole having square corners,
such as that shown in Dench Patent No. 2,809,328, issued
October 8, 1957. For example, in one tube wherein the
curvature at each edge covered approximately 15 percent
of the width of the interaction space de?ned by the inside
dimensions ‘between the end shield edges, the tube op
regions of varying slope, as the periphery of a polygon.
erated at 36 percent e?iciency, whereas the same tube
using a sole with square corners operated at approximately
In some instances, it is desirable that the sole be
grooved so that secondary electrons resulting from im
pingement of primary electrons of unfavorable phase
traveling toward the sole are caught within the grooves
and prevented from reentering the interaction space
owing to the shielding effect of the walls of the grooves.
In this type of line the various ridges of the sole cross
section may be made of variable length; in other words,
the surface of the ridges lies along either tapered straight
30 percent efficiency. Another arrangement of sole 14
is shown in FIG. 5 and includes a V-shaped surface 47
in the active region between the edge member 48. This
arrangement is more readily machinable than the version
shown in FIGS. 3 and 4 and offers advantages of the
order of magnitude of those obtainable in the sole of
FIG. 3. In FIG. 6, a grooved sole 14 is shown which
includes a plurality of longitudinal grooves disposed be
lines or a curve.
tween adjacent ridges 51. The transverse sole-to-anode
Other objects and features of this invention will be 40 spacing of tubes using this type of sole is altered by vary
understood more clearly and fully from the following
ing the height of the ridges 51. The ridges may ‘be
detailed description of the invention with reference to
curved, as shown in FIG. 6, so that the locus of the tips
the accompanying drawing wherein:
of the ridges follow a smooth curve, or the ridges may
be machined in such a way that the locus of the ridge
tips lie along a V-shaped path, as in FIG. 5, or along
paths similar to those shown in FIGS. 4, 7, and 8. The
sole of FIG. 7 is similar to that of FIG. 3, except that
the lateral extremities of the curved surface 47 coincide
FIG. 1 is a cross-sectional view, partly in elevation,
of a traveling wave tube according to the invention;
FIG. 2 is a cross-sectional view, partly in elevation, of
the traveling wave tube of FIG. 1 taken along the line
2--—2;
FIGS. 3 to 8 are detail views showing various con?gu
with the free extremities of edge portions 48. In FIG.
rations of the sole electrode of the tube of FIGS. 1 and 2; 50 8, a sole 14 is shown whose surface 47 comprises a plu
FIG. 9 is a schematic view of a linear traveling Wave
tube;
FIG. 10 is a transverse sectional view of the sole elec
\
rality of adjoining planar surfaces, each of different
slope.
This composite surface 47 of FIG. 8 may be
considered as a compromise between a curvilinear sur
trode of the tube of FIG. 9 taken along line 10—10;
face, such as in FIGS. 3 and 7 and the V-shaped sur
and
face of FIG. 5. Although the multiple'planar surface
FIG. 11 is a fragmentary sectional view of an ampli
47 of FIG. 8 terminates in the tips of edge portions 48,
fier version of the tube of FIGS. 1 and 2.
as in the case of the sole of FIG. 7, the surface 47 of
‘Referring to the drawing, a traveling wave oscillator
FIG. 8 may, of course, terminate at each edge and at a
tube 10 is shown which comprises a slow wave energy
point spaced from the tips of edge members 48, as in
propagating structure or delay line 12, a cylindrical elec 60 FIGS. 3 and 5. This is also true of the V-shaped sur
trode 14, otherwise referred to as a sole, concentric with
face of FIG. 5.
the delay line 12 and normally maintained negative with
A tubular metallic insert 52 is brazed into position
respect thereto, a lead-in assembly 15, an electron gun
against the inner periphery of a centrally disposed aper
assembly 20 including at least a cathode 21 and heater
ture 53 in the web portion 45 of sole 14. One end of
22, a magnetic ?eld-producing means 25 and an output F a hollow supporting member 54 is inserted within insert
coupling means 17. The circular delay line 12 includes
52 and secured ?rmly thereto. Supporting member 54, in
several interdigital ?ngers or elements 31 and 32 extend
addition to providing support for sole 14, forms a portion
ing from respective oppositely disposed annular mem
of lead-in assembly 15 and allows for passage of external
bers 33 and 34. Members 33 and 34 are secured by
circuit connecting leads, in a manner to be described
subsequently.
‘screws 35, visible in FIG. 1, to the shoulder portion of
a cylindrical electrically-conductive ring 36, said ring
Sole 14 contains a slot 27 to accommodate the electron
‘gun assembly 20. Since the invention does not involve
forming a part of an evacuated envelope for tube 10.
details of the electron gun 20, the latter is shown sche
The remainder of the delay line 12 includes a pair of
matically in FIGS. 1, 2, and 9. The construction and
oppositely located cover plates 38 and 39 hermetically
manner of mounting of the electron gun 20 may be as
sealed to ring 36. Although the delay line has been de
3,084,277
5
shown in United States Letters Patent of Roy A. Paananen,
Patent No. 2,914,700 issued November 24, 1959. Elec
‘tron gun 20 includes a cathode 21, a heater 22, a grid
electrode 23 which may ‘be used for control of beam
current (as for amplitude modulation), and an accelerat
ing electrode 24 which likewise may be used for control
of beam current. The cathode 21 may be in the form of
a rectangular prism provided with a circular bore in
which a heater wire 22 is inserted and electrically insulated
from cathode 21; the heater may be connected at one
end to the cathode. Electrical energy from appropriate
sources is supplied to the cathode 21, heater 22, grid
6
interaction space 50 between sole 14 and delay line 12.
By a proper adjustment of the magnitude and polarity
of the magnetic and electric ?elds so established, the elec
tron beam may be made to move along a more or less
circular path along the interaction space 50 under the
combined in?uence of these transversely disposed ?elds.
Although the tube 10 which has been described may be
used as an oscillator, the invention also is applicable to a
traveling Wave ampli?er, which structurally may be the
same as the oscillator 10 of FIGS. 1 and 2 except that an
additional energy coupling means 19 is provided at the
end of the delay structure 12 opposite the output cou
electrode 23 and accelerating electrode 24 by way of
pling means 17. Such a tube is indicated in fragmentary
respective lead-in wires 61, 62, 63, and 64, which are
form in FIG. 11 in 'which elements corresponding to those
brought out from the tube envelope through the lead-1n 15 of the tubes of FIGS. 1 and 2 are indicated by like ref
assembly 15. In FIG. 1, the cathode only of ‘the elec
tron gun 20 is shown, for the sake of simplicity and
clarity, the remaining elements of the electron gun bemg
omitted.
erence numerals. With the connections as shown in
FIG. 10, this tube is adapted to operate as a backward
wave ampli?er; by reversing the input and output cou
pling means, the tube could be adapted for operation as a
Lead-in assembly 15 includes an electrically-conduc
forward Wave ampli?er.
tive sleeve 66 a?ixed to the inner periphery of cover
The invention may also be incorporated in nonreen
plate 38, as indicated in FIG. 1. A section of cylin
form in FIG. 11 in which elements corresponding to those
drical glass tubing 67 interconnects sleeve 66 and a
FIGS. 9 and 10. Elements of the tube of FIGS. 9 and
second electrically-conductive sleeve 68. The other end
it) corresponding to those of FIGS. 1 and 2 are shown by
of tube 68 is provided with a glass seal 69 for sealing 25 the same reference numerals. The tube of FIG. 9 is
the traveling wave tube 10 after evacuation. One end
constructed so that its fundamental mode of wave propa
of sole-supporting member 54 contains an outwardly ?ared
gation is a backward Wave. The tube envelope 11 may
portion which is connected to the inner surface 01 sleeve
be constructed of an electrically-conductive material and
68. The leads 61, 62, 63, and 64 are mounted in elec
may be provided with ceramic or similar electrically-in
trically-insulated relation with supporting member 54 by 30 sulating bushings 13 through which electrical connections
one or more glass beads 71.
D
The coaxial output coupling means 17 is sealed in an
opening of wall 36 of delay line 12 and is impedance
matched to the delay line.
The inner conductor 73 of
the output coupling means 17 is connected to a ?nger
of delay line 12 at or near the end of the delay line ad
can be made to the various tube electrodes. An output
coupling means 17 is connected to the delay structure 12
adjacent the electron gun 20. The sole electrode 14 is
arranged substantially parallel to the delay structure 12.
A typical cross-sectional con?guration for sole 14 of the
tube of FIG. 9 is shown in FIG. 10. It should be under
jacent electron gun 20.
_
.
stood that any of the con?gurations shown in FIGS. 3
Traveling Wave tube 10 may be provided with a collec
to 8 maybe used in the tube of FIG. 9, except, of course,
tor electrode 75, shown in FIG. 2, for intercepting elec
that the sole is linear rather than circular. A unidirec
trons after one traversal of the arcuate interaction space 40 tional voltage source 83, cooperating with a sole bias
50.
This collector electrode may be in the form of a
projection from back Wall 36 of delay structure 12. In
some instances, however, the collector electrode may be
source 86, establishes an electric ?eld in the interaction
space 50 bounded by delay structure 12 and sole 14. A
uniform magnetic ?eld B is established transverse to the
omitted and the electron stream made reentrant.
electric ?eld in the interaction space 50, as by a perma
The necessary electric ?eld between the slow-wave 45 nent magnet. A heater voltage and accelerating anode
structure 12 and sole 14 may be obtained by means of a
voltage for the electron gun are provided by batteries 87
unidirectional voltage applied therebetween; such a volt
and '85, respectively. The linear tube of FIGS. 9 and 10,
age may be supplied by a battery 83. The sole 14 may
like the circular tube of FIGS. 1 and 2, may be constructed
be ‘biased negatively relative to the cathode 21 by means
to operate as an ampli?er by the addition of an input
of a source 81 of voltage connected between cathode lead 50 coupling means.
61 and sole-supporting member 54 by Way of sleeve 68.
This invention is not limited to the particular details of
The cathode 21 may in some instances, however, be at the
construction, materials and processes described, as many
same potential as sole 14; in this case, a source 81 would
equivalents will suggest themselves to those skilled in the
be omitted. Similarly, the delay line 12 may be main
art. It is accordingly desired that the appended claims be
tained at a potential positive relative to both sole 14 and
given a broad interpretation commensurate with the scope
cathode 21 by means of the source 83 of unidirectional
of the invention within the art.
voltage connected between the cathode and sleeve 66, the
What is claimed is:
latter being connected, in turn, to delay line 12. The
1. A traveling wave electron discharge device compris
accelerating electrode 24 may be maintained at a poten
ing a slow Wave energy propagating structure producing
tial positive relative to cathode 21 by means of a source 60 in the region adjacent thereto ?elds of electromagnetic
85 of unidirectional voltage connected between leads 61
and 64. The control grid lead 63 may be connected by
way of terminal 88 to an appropriate energy source for
wave energy, an electrode spaced from and substantially
co-extensive with said slow wave structure, and means for
directing electrons in a beam along said region in energy
exchanging relation with said ?elds of wave energy, said
controlling the magnitude of the electron beam current in
the traveling Wave oscillator 10. A suitable heater volt 65 electrode having a peripheral portion of its thickness di
age from a source 82 is connected between heater lead 62
mension facing said slow wave structure, at ‘least part of
and cathode lead 61.
said peripheral portion of said electrode having a con
A uniform magnetic ?eld transverse to the direction of
tinuously varying surface contour across its thickness di
propagation of the electron beam is provided by a perma
mension resulting in points on said contour towards the
nent magnet or electromagnet having cylindrical pole 70 ends thereof being progressively closer to said slow wave
pieces 91 and 92 radially positioned on or adjacent the
structure.
anode cover plates 38 and 39, respectively. Pole piece 91
2. A traveling wave electron discharge device compris
is apertured to receive lead-in assembly 15, While pole
ing a slow wave energy propagating structure producing
piece 92 is apertured to maintain symmetry of the mag
in the region adjacent thereto ?elds of electromagnetic
netic ?eld. The ?ux lines should be concentrated in the 75 wave energy, an electrode spaced from and substantially
3,084,277
7
co-extensive with said slow wave structure, and means
for directing electrons in a beam along said region in
energy-exchanging relation with said ?elds of wave energy,
said electrode having a peripheral portion across its thick
ness dimension facing said slow wave structure, at least
a part of said peripheral portion being composed of inter
connected surfaces of continuously varying slope across
8
extensive with said slow wave structure, and means for
directing electrons in a beam along an interaction space
bounded by said structure and by said electrode in energy
exchanging relation with said ?elds of wave energy, the
spacing between said slow wave structure and said elec
trode continuously decreasing from the center of said
electrode in directions transverse to the length and thick
ness of said electrode.
its thickness dimension, points on said surfaces toward
6. A traveling wave electron discharge device compris
the edges of said contour being spaced closer to said slow
ing
a slow wave energy propagating structure producing
wave structure than points toward the middle of said 10 in the region adjacent thereto ?elds of electromagnetic
contour.
3. A traveling wave electron discharge device compris
ing a slow wave energy propagating structure, an electrode
spaced from and substantially co-extensive with said slow
wave structure, and means for directing electrons in a
beam along a region adjacent said slow wave structure
in energy-exchanging relation with ?elds of electromag
netic wave energy present in said region, said electrode
having a peripheral portion and side walls at the edges
of said peripheral portion, at least part of said peripheral
portion facing said slow wave structure, said peripheral
portion having a continuously varying contour over its
thickness resulting in points on said contour toward the
ends thereof being spaced progressively closer to said
propagating structure.
4. A traveling wave electron discharge device compris
ing a slow wave energy propagating structure producing
in the region adjacent thereto ?elds of electromagnetic
wave energy, an electrode spaced from and substantially
co-extensive with said slow wave structure, said structure
in said electrode bounding an interaction space, an elec
tron source, means for producing an electric ?eld in said
interaction space, means for producing a magnetic ?eld
transverse to said electric ?eld, electrons from said source
being directed in a beam along said interaction space in
energy-exchanging relation with said ?elds of wave energy,
the spacing between said electrode and said structure con
tinuously varying across the thickness dimension of said
electrode whereby points at the center of said electrode
are spaced farther from said slow Wave structure than
points toward the edges of said electrode.
7. A traveling wave electron discharge device compris
ing a slow wave energy propagating structure, and an
electrode spaced from and substantially co-extensive with
said slow wave structure, a peripheral portion of said elec
trode facing said slow wave structure being concave as
wave energy, an electrode spaced from and substantially
viewed from said slow wave structure, while said slow
co-extensive with said slow wave structure, said electrode 30 wave structure is planar as viewed from said electrode.
having a peripheral portion facing said slow wave struc
ture, said electrode further having a plurality of alter
nating ridges and slots across its thickness dimension, the
locus of the tips of ‘said ridges lying along a continuously
varying path whereby said ridges at the center of said
electrode are farther from said slow wave structure than
said ridges at the edges of said structure, and means for
directing electrons in a beam along said region in energy
exchanging relation with said ?elds of wave energy.
40
5. A traveling wave electron discharge device compris
ing a slow wave energy propagating structure producing
in the region thereto ?elds of electromagnetic wave
energy, an electrode spaced from and substantially co
References Cited in the ?le of this patent
UNITED STATES PATENTS
2,600,509
2,681,427
2,786,959
2,812,473
Lerbs _______________ __ June 17,
Brown et al ___________ _- June 15,
Warnecke et a1 ________ __ Mar. 26,
Mourier _____________ __ Nov. 5,
1952
1954
1957
1957
2,992,354
Lerbs et a1 ____________ __ July 11, 1961
743,519
1,100,854
Great Britain _________ __ Jan. 18, 1956
France ______________ __ Sept. 26, 1955
FOREIGN PATENTS
Документ
Категория
Без категории
Просмотров
0
Размер файла
772 Кб
Теги
1/--страниц
Пожаловаться на содержимое документа