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Патент USA US3046455

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July 24, 1962
3,046,445
P. P. DERBY ETAL
MAGNETRON ELECTRON DISCHARGE DEVICES
Filed Sept. 10, 1959
2 Sheets-Sheet 1
/NVENTOR
PALMER
1D. DERBY
LEONARD W GE/ER
BY/VWM
A TTORNE Y
July 24, 1962
P. P. DERBY ETAL
3,046,445
MAGNETRON ELECTRON DISCHARGE DEVICES
Filed Sept. 10, 1959
2 Sheets-Sheet 2
INVENTOP
PAL/VIE}? P DERBY
LEON/4RD WGE/ER
By
ATTOii/Vf)’
3,046,445
Patented July 24, 1962
1
. 2
3,046,445
MAGNETRON ELECTRON DISTIHARGE DEVICES
Pairner P. Derby, Weston, and Leonard W. Geier, Natick,
Mass, assignors to Raytheon Company, Waltham,
Mass, a corporation ofDelaware
Filed Sept. 10, 1959, Ser. No. 839,148
8 Claims. (Qt. 315-3951)
This invention relates to electron discharge devices of
the magnetron type.
1
One of the objects of the presentinvention is to provide
rising-sun type, or- any con?guration which provides a
. resonant .anode structure. Although not shown, in ‘the
drawing, alternate anode vanes may be interconnected in
the usual manner by one or more pairs of concentric
straps set into slots in the anode vanes. Along one edge
of the anode ‘block 24 is disposeda pair of legs 28 which
facilitate mounting of the-anode block to the header sub
assembly 25:‘. A circular slot is provided along the oppo- ~
site edge 51 of the anode block 24 for receiving a ring 33.
10 A lead 34, one end. of which is attached to one of the
anode vanes 27, ‘serves as an output coupling lead for the
a magnetron which may be fabricated readily ‘and simply
magne ton, and, together withthe ring. 33, formsa short
coaxial line section. This output lead 34 preferably is
crirnped, as shown in. FIGS. 2 and 4,4 to provide an effec
tive ‘coupling loop for coupling energy out of the ‘mag
from subassemblies ‘which can be assembled, inspected
and stockepiled as independent units.
.
Another object of the invention is to provide a mag
netron in which‘ the assembly of units into- a completed
tube assembly is accomplished by the use of allowable
netron cavity resonator system.
and proven methods of construction, thereby achieving
cylinder 36 which maybe surrounded at the central-por
considerably reduction in cost of assembly and materials
and reducing the possibility of scrap and errors in manu
facture.
' Other and further objects and advantages of the present
invention will become apparent as the following descrip
tion progresses, reference being had tov the drawing ‘where
in:
_
.
FIG. .1 is ‘a pictorial view‘ illustrating a complete mag
netron package according to the invention;
i
. The cathode-heater subassembly 16 comprises a cathode
so
tion thereof by a wiremesh 37 containing an electron
emissive- material. The wire mesh may have metal pow
der brushed into it and may be sintered to the cathode
cylinder. Annular end "shields38 of diameter somewhat
in excess ofthat of the cathodezcylinder 36 are provided
at eachend of the cathodec-ylinder tominimizct-forma
25 tion ‘of deposits of emittinglmaterial on other parts ofthe
magnetron owing. to .endwise emission from the cathode.
A heater coil. 49 is disposed within the cathode cylinder 36
andpnerend ofthis heatercoil is attached to the inner
cording to the invention, with the various subassemblies
periphery of the cathode cylinder adjacent one end thereof.
partly broken away to illustrateinternal details;
30
Themagnetron header subassernbly 20,includes a more
vFIG. 3 is a view showing an input lead~in assembly for
or less cup-shaped member’ 42 of Csheet material provided
receiving cathode and heater leads;
with a central aperture forreceiving a portion of the lead
FIG. 4 is a view showing the manner of joining the
in.-subassembly 21. The cup-‘shaped member- 42, which
anode subassembly to the header‘ subassembly prior to
maybe ,m-ade. of a copper-nickel alloy, includes a base
FIG. 2 is an exploded view of a magnetron assembly ac
seal-in; and
,
'
portion 43 which is substantially ?at; this base portion is
35
FIG. 5 is a View ‘showing the complete magnetron tube
assembly minus the magnet assembly and output trans
missionli'ne.
bent .over along the periphery to provide a lip or rim por
tion 44. . The lead~in.subassembly_21, ‘shown in FIGS.
2 and 4, includes a metal input sleeve 45 to one end of
Referring to the drawings, the numeral 13 (shown in _ which a glass or ceramic seal 46 is bonded for supporting
FIG. 1) generally designates a complete magnetron pack 40 a heater lead-in conductor 47 and a. cathode lead-in con
age includingan electron discharge tube 12 of the mag- '
ductor 48 in spaced relation with respect to one another
netron type, an accompanying magnet assembly 14, an
and to the metal sleeve 45. Conventional glass-toanetal
output transmission‘ line 75, ‘and accessories, to be de
scribed later, for clamping the tube 12 in the ?xed posi
sealing techniques may be ,used in forming, the lead-in
assembly 21'.’ The cylindrical sleeve 45 is inserted in the
tion with respect to the magnet assembly and to the trans 45 central aperture of the header subassernbly Ziland brazed mission line. The magnetron tube assembly 12 includes
to or otherwise secured thereto; ‘The input sleeve 45 is‘
’ a centrally disposed cathode-heater subassernbly 16 and
made of a material having a thermal coefficient of expan
a surrounding anode assembly 18. An electric ?eld is cre
ated between the anode and cathode, in the usual manner,
while a magnetic ?eld transverse to the electric ?eld is
sion approximating that of the vitreous sealing material so
that a good vacuum-tight bond is provided inthe region of
the" seal; this is particularly important {when the header
produced by the magnet assembly 14, shown in FIG. 1.
The magnetron tube assembly 12 further comprises a
header subassembly Ztl, a shell-'subassembly 22, and an
input lead-in subassembly 21 secured to the header sub
assembly and sometimes referred to as a part of the header 55
subassembly.
'
The anode assembly 18 includes an anode block 24 con
taining a cylindrical opening 25 from whose inner periph
ery radially extend several anode vanes 27, either integral
subassembly is made of arcopper-nickel alloy or other
material to which a vitreous material does not readily‘, '
bond.
7
Alternately, the central aperture in'the base portion 43’
of the header member 42 could be-upset to 'forma'n an-j
nular shoulder 45’ to which the glass seal; 46 is bonded,
as shown in FIG. 3. Withthis constructiomhowever,‘it
is essential to use a material, such as copper,- for the
header subassembly to which theglass can readily bond.
with the anode block or secured thereto, as by soldering. 60 The cup-shaped. member‘! 42 of the header'subassembly‘ 20
The space between each pair of adjacent anode vanes at
also includesran aperture for receiving an exhaust tube‘ 49.
least partially de?nes a cavity resonator, as is well under
As previously stated, the anode'subassembly 18 includes
stood in the magnetron art. Although the anode shown
a ring 33; this ring is brazed to the'edge ‘5110f the anode
is of the vane type,rthe invention is not limited thereto;
bl'ock24: The anode‘bl'ock is provided?with "an arcuy
for example, the anode may 1be of the hole-and-slot type, 65 ate slot to accommodate the ring. The ring serves e?ec
3,046,445
3
tively as an outer conductor of an output coaxial line
with the anode ‘output lead 34 serving as the inner con
ductor. The anode block is mounted on the base por
tion 43 ‘of the header member 42, as shown in FIG. 2,
and the legs 28 are spot-welded to the base portion 43.
The legs 28 facilitate spot-welding of the anode block 24
to the base portion 43 of header member 42 and provide
a current path between ‘welding electrodes positioned
along edge 51 of the anode block and the underside of
the header member 42. If the anode block 24 and the
header subassembly 20 both are made of a copper-nickel
alloy, an excellent bond between the anode subassembly
18 and the header subassembly 20 is achieved. The
anode subassembly 18 is positioned accurately on the
header member 42 prior to spot-welding by an appro
priate jig which insures that the anode block 24 is prop
erly located with respect to the periphery of the member
42. This desired location normally occurs when the edge
52 of the anode block 24 and the edge opposite thereto
are equidistant from the edge of the base portion 43_ and
when the end face 54 of the anode block 24 and the face
opposed thereto are equidistant from the rim of header
member 42.
The cathode-heater subassembly 16, with one end of
the heater 40 attached to the inner periphery of the cath
ode cylinder 36, is inserted in the space between the vane
tips of the anode block 24. While the cathode is main
tained centered in the anode space by an appropriate jig,
the free end of the heater 40 is spot-welded to heater
lead-in conductor 47 and the cathode lead-in conductor
48 is spot-welded to the cathode cylinder 36. The cath
ode and heater lead-in conductors each are bent, if neces
sary, to a position such that the conductors pass over
the magnetron anode block 24 along the edge of an
anode vane.
The cathode lead-in conductor is radially '
disposed in juxtaposition with the edge of a ?rst anode
vane, while the heater lead-in conductor is radially dis
posed in juxtaposition with the edge of a second anode
4
made of a material having a thermal coe?icient of ex
pansion substantially equal to that of the glass bead 46,
while the portions 47" and 48” are made of a refractory
material, such as tantalum, which is capable of operating
at high temperatures. The compound leads shown in
FIG. 3, of course, may be used in the device shown in
FIGS. 2 and 4, while the leads shown in FIGS. 2 and 4
may be used in the input lead-in assembly 21’ of FIG. 3.
The sealed-in heater and cathode lead-in conductors 47
and 48 are bent slightly until they are in line and so that
they will not interfere with either the anode subassembly
18 which is to be bonded to the portion 43 of header
member 42, or with the enclosure portion 63 of the shell
subassembly 22 which, as will be seen subsequently, ?ts
over the anode block 24 and the lead-in conductors.
This alignment of the lead-in conductors may be done
visually with sufficient accuracy.
The shell subassembly 22 may be stamped out of sheet
metal and comprises a cup-shaped element 60 including
a ?at circular base portion 61 bent over at the edges to
form a lip or rim 62 and an enclosure portion 63 of sub
stantially rectangular cross section extending from the
?at portion. The enclosure portion 63 is‘ adapted to fit
over and enclose the anode subassembly 18, as well as
the heater and cathode lead-in conductors. The shell
subassembly may be accurately formed by placing a piece
of circular sheet metal in a die and ‘deforming the cen
tral part of the disk gradually to draw out the enclosure
portion 63. A series of dies and drawing steps is usually
necessary for proper formation of the enclosure portion
of the shell assembly. Alternately, the shell assembly
may be fabricated from a circular disk by cutting out
an accurately located central hole, brazing the enclosure
portion 63, already formed, around the edge of the hole
and later bending the periphery of the disk downward
to form the rim 62.
An output coupling means 65 is
provided at the end of the enclosure portion 63 of the
shell subassembly 22 and includes a sleeve 66 inserted
within an aperture in the enclosure portion 63 of the
vane along which an RF. current flows in the same
phase as the RF. current ?owing in said ?rst vane. With 40 outer shell assembly and secured thereto. The output
coupling means further includes a thin-bored tube 67
this arrangement, the R.F. magnetic ?elds linking the
coaxial with tube 66 and hermetically ‘sealed thereto, as
lead-in conductors are in the same direction in both con
by a glass bead 68. The shell sub-assembly 22 next is
ductors and the current induced in the cathode and heater
positioned over the assembly, shown in FIG. 4, made up
lead-in conductors is in the same ‘direction in both con
of the anode subassembly 18 and the header subassembly
ductors. Consequently, the net RF. current induced in
20, with the anode output coupling lead 34 inserted
the heater-cathode circuit is a minimum. This position,
through the bore of tube 67 in the shell subassembly 22
then, is the position of minimum RB pickup by the
and with the rim 62 of the shell subassembly engaging
cathode and heater leads. The heater conductor 47 is
the rim 44 of the header subassembly 20. The sleeve 66
crimped to allow it to occupy the desired position for
minimum R.F. energy pickup. A clamp 56 surrounding ' of output coupling means 65 is adapted to ?t inside ring
33 10f the anode subassembly 18, so that there is capaci~
the cathode lead-in conductor 48 is secured, as by weld
tive coupling between the coaxial line including output
ing, to the face 54 of anode block 24 to lend support to
coupling lead 34 and ring 33 and the coaxial line made
the cathode lead-in conductor 48 and, hence, to the
up of output sleeve 66 and tube 67. The R.F. output
cathode-heater subassembly. A ferrule 57 made of an
electrically insulating material, such as ceramic, sur- ‘ lead 34 is sealed hermetically to the hollow tube 67 and
the rings of the two nested cup-shaped members 42 and
rounds the cathode lead-in 48 and is disposed within the
6B of the respective subassemblies 20 and 22 are sealed in
clamp 56; this ferrule serves to insulate the cathode from
a vacuum-tight manner, as by welding or brazing.
the anode. An additional clamp may be provided, if
The magnetron 10 then is exhausted by attaching a
necessary, around the heater lead-in conductor.
In fabricating the magnetron tube assembly 12, the
vacuum pump to the exhaust tube 49. After exhausting
the tube,‘ the exhaust tube 49 is pinched closed. Flexi
lead-in conductors 47 and 48, which are ?exible wires
ble leads 69, shown in FIG. 5, are attached to the
of relatively small gage, are ?rst sealed into input sleeve
lead-in wires 47 and 48 and the entire input side of the
45 by means of a glass head 46. The sleeve 45 is made
magnetron, including the exhaust tube 49 and the in
of a material which will bond readily with glass. The‘
put lead-in subassembly 21 is encapsulated with a plug
sleeve 45, with the conductors 47 and 48 in place, next
71 made of an electrically insulating compound, such as
is brazed into the center hole of header member 42 of
rubber or plastic, to protect these parts from breakage
the header subassembly 20 at the same time that the
during handling of the tube. The plug 71 may be formed
exhaust tube 49 is brazed to the header member 42. In
by placing a cylindrical shell against the lower side of
the arrangement shown in FIG. 3, of course, it is neces
sary only to glass-in the leads 47' and 48’ to the exten~ 70 member 42 of the header subassembly 20 and inserting
the encapsulating material into the shell under pressure.
sion 45' of the header member 42. In FIG. 3, the
The shell is then removed after the plug has been fully
heater lead-in conductor of lead-in assembly 21’ is shown
formed.
as composed of two separate wires 47' and 47", while
It will be noted that the axis of symmetry of the anode
the cathode lead-in conductor is shown as constituting
two wires 48' and 48". The portions 47' and 48’ are 75 block 24, indicated by the dashed line 90 in FIG. 2,
3,04e,44-5
6
that is an .axis passing through the center of the cathode
space of the magnetron anode block 24 perpendicular
to the face 54, is substantially perpendicular to the lon
gitudinal axis of the magnetron tube assembly 12 which
is indicated by the dashed line 92 in FIG. 2.
It is now necessary to mount the tube assembly 12
in the vicinity of a magnet assembly for providing a mag
netic ?eld transverse to the interaction space between the
cathode and the" tips of the anode vanes. In one em
.
,
and heater lead-in conductors, and an anode assembly in
cluding an anode block having a pair of opposite end
faces, said anode block surrounding said cathode and
having a plurality of anode members adjacent ones of
which at least partially de?ne cavity resonators, said
anode block being mounted edge-wise on said member,
said cathode and heater lead-in conductors being posi
tioned in alignment with diiferent anode members which
conduct high frequency current in the same phase and
bodiment, the magnet structure is secured, as With glue, 10 extending from said cathode and heater respectively in
to an output transmission line in the form of a wave
guide 75 having a closure plate 77 at one end and an
open end leading to a load. A coupling hole is pro
vided in the wave guide 75 through which the tube 67
of the output coupling means. 65 of the magnetron tube
assembly 12 may. be inserted. A pair of threaded mount
ing posts 78 are secured ?xedly to the wave guide 75,
as by brazing at 79. The magnet is positioned along
the Wave guide 75 so that the center of the pole pieces
81 and 82 of the magnet assembly 14 coincides with the 20
1 axis of symmetry 90 of the anode block 24 of the tube
assembly 12. This position of the magnet, assembly,
in turn, is such that the distance of the magnetron output
coupling probe 67 from the shorted end of the wave
guide 75 provides for maximum transfer of energy from
the magnetron tube to a load. The center line of the
pole pieces of the magnet assembly 14 and that of the
output coupling probe 67 of the magnetron tube 12 is
approximately an odd multiple of quarter wavelengths
distant from the closure plate 77 of the Wave guide, at
the operating frequency of the magnetron. The correct I
position of the magnet and tube assembly with respect
to the wave guide closure, however, is determined em
a plane parallel to one end face of said anode block.
3. A magnetron comprising a cathode, a heater for
said cathode, a header assembly including a member to
which is attached an input sleeve for receiving cathode
and heater lead-in conductors, and an anode assembly in
cluding an anode block having a pair of opposite end
faces, said anode block surrounding said cathode and
having a plurality of anode members adjacent‘ones of
which at least partially de?ne cavity resonators, said
anode block being mounted edge-wise on said member,
said cathode and heater lead-in conductors being posi
tioned in alignment with‘ different anode members which
conduct high frequency current in the same phase and
extending from said cathode and heater respectively in a
plane parallel to one end face of said anode block, said
lead—in conductors each lying over and in alignment with
anode members which conduct high frequency currents
of like instantaneous phase.
4. A magnetron comprising a cathode-heater assem
bly containing a cathode and a heater for said cathode, a
header assembly including a member to which is at
tached an input sleeve for receiving cathode and heater
lead-in conductors, an anode assembly including an anode
pirically for optimum coupling to the load. The space
between the magnet pole pieces 81 and 82 is just suf
?cient to permit insertion of the enclosure portion 63
‘block having’ a pair of opposite end faces, said anode
Iblock surrounding said cathode, said anode 'block being
of the shell subassembly 22 of the magnetron tube as
sembly 12; and magnet assembly 14 thus serves as a
heater lead-in conductors being positioned in alignment
mounted edge-wise on said member, said cathode and
with different anode members which conduct high fre
guide for insertion of the tube assembly 12.
quency current in the same phase and extending from
In order to hold the tube 12 ?xed, a clamp ring 80, 40 said cathode and heater in a plane parallel to one end
having a central aperture surrounding the encapsulating
face of said anode block, a ferrule of electrical insulat
plug 71 and two mounting holes aligned with the mount
ing material surrounding at least one ofsaid lead-in con
ing posts 78, is inserted in position over the sealed edges
ductors, and a clamp surrounding said ferrule and at
of the rims 44 and 62 of the tube assembly 12. A part
tached to said one end face of said anode block for sup
of the base portion 61 of the shell element 60 of the 45 porting said cathode-heater assembly.
shell subassembly, into which the member 42 of the
5. A magnetron comprising an anode block of uni
header subassembly 20 nests, rests against one face 82 of
form thickness with a substantially circular opening
the magnet assembly 14. Wing nuts 81 may be screwed
‘through the broadest face thereof, a plurality of anode
onto the threaded mounting posts 78 to clamp the tube
members disposed radially within said opening ‘and at
assembly 12 ?rmly against the magnet assembly 14.
50 tached to said block forming cavities within said open
Alternately, the portion 61 of shell element 60 may be
ing, a cathode disposed within said opening and coaxial
sealed, as with glue, directly to the face 82 of magnet
therewith, va cathode heater disposed within said cathode
assembly 14, in which case the mounting posts 78, clamp
and cathode and heater leads positioned in alignment
ring 89, and wing nuts 81, may be dispensed with.
with different. anode members which conduct high fre
This invention is not limited to the particular details 55 quency currents in the same phase.
'
of construction, materials and processes described, as
6. A magnetron comprising an anode block of unij
many equivalents will suggest themselves to those skilled
form thickness with a substantially circular opening
in the art. It is accordingly desired that the appended
throughv the broad face thereof, a plurality of anode
claims be given a broad interpretation commensurate
members disposed radially within said opening and at
with the scope of the invention within the art.
60 tached to said block forming cavities within said open
What is claimed is:
e y
,
ing, a cylindrical cathode ‘disposed within said opening
.1. A magnetron comprising a cathode, a heater for
coaxial therewith, a cathode heater disposed within said
said cathode, a header assembly including a member to
cathode and cathode and heater leads contiguous with
which is attached an input sleeve for receiving cathode
said broad face and in aligrnnent with different anode
and heater lead-in conductors, and an anode surround
members which conduct high vfrequency currents in the
ing said cathode and having a plurality of anode mem
same phase.
'bers at least partially de?ning cavity resonators, the por
'7. A magnetron comprising an anode block of uni-form
tion of said cathode and heater lead-in conductors juxta
thickness with a substantially circular opening through
posed to said anode being positioned in alignment with
the ‘broad face thereof, a plurality of anode members dis
?rst and second anode members respectively, said ?rst 70 posed radially within said opening and attached to said
and second anode members conducting high frequency
block forming cavities within said opening, a cylindrical
currents which are in the same instantaneous phase.
cathode disposed entirely Within said opening coaxial
;2. A magnetron comprising a cathode, a heater for
therewith, a cathode heater disposed entirely within said
said cathode, a header assembly including a member to
cathode and cathode and heater leads both contiguous
which is attached an input sleeve for receiving cathode 75 with the same broad face of said anode block and in
3,046,445
7
.
alignment with di?Ferent anode members which conduct
high frequency currents in the same phase.
8. A magnetron assembly comprising; a header includ
ing a base portion and rim portion, said base portion be
ing centrally apertured to permit passage of the mag
netron cathode and heater leads; an anode shell includ
ing a base and rim portion dimensioned to snugly en
close said header base and rim portions and an anode
enclosure attached to said anode shell base with its major
dimension perpendicular to the major dimension of said 10
anode shell base, said anode enclosure enclosing said
magnetron anode and cathode which are arranged con
8
centrically on an axis parallel to said major dimension
of said anode shell base.
References Cited in the ?le of this patent
'UNITED STATES PATENTS
2,408,239
Spencer ____________ -_ Sept. 24, 1946
2,458,142
2,475,960
2,624,865
Brown ________________ _._ Jan. 4,
Hegbar ______________ __ July 12,
Nichols ______________ __ Ian. 6,
Millman ______________ __ Oct. 2,
Peters ______________ __ Feb. 18,
2,765,425
2,824,261
1949
1949
1953
1956
1958
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