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Патент USA US2408238

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Filed Dec. 17, 1941
f 2,408,235 '
Patented Sept. 24, 1946 `
y *
i, Spencer,
' MAcrNE'raoNfcasind
West Newton, Masts., c „
Raytheon Manufacturing‘v Company, Newton;
Mass.,'a corporation of Delaware’ . i
‘c comms. (c1. 25p-¿gral
This invention relates to amagnetron casing,
and more particularly to such aA casing ’which is
made of a metal, such as copper, and is provided
with a special end construction `to increase `the
effective magnetic iield within the magnetron,
t `In magnetron tubes of the conductive envelope
type, themagnetic ñel'd is impressed ori the'tubes
by magnetic poles placed adjacentbthe‘opposite
ends of thetube. Thus there _is an leffective air
gap'between the poles extendi?igl‘tiie entire length
calme-magnetron“ ,The 'metallic ’wallsI of the
envelope must> -'necessarily be of a certain thick
ness in order to possess the requisite rigidity to
An .additional lead >'I3 may be provided to ex
tend from' a'fs'uitalble'coupling means within the
envelope >~I', ,wherebyÁ high frequency oscillation
generated within the device may be conducted to
a suitable utilization device. ¿The lead I3 may
likewise be sealed throughÍ the 'outer end of a
glass.l chamber- Ilmounted at theL oute'd end of
the> pipe ,I5 'likewise hermetically »sealed within
the walls of [the envelope l. The magnetron is
designed and‘intendedto be placed between suit
fable1~mag'ne'tic „p'o'le’sï I6.Y andy I_f'lto create a longi
tudinal vmagneticl ‘ñeld " passing- through the space
between the cathode B and the surrounding walls
of the bore 5, constituting [the anode structure
withstand the differential atmospheric pressure
inside and outside of the tube. This length kof 15 forIf said
the end caps 2 and 3 were made entirely of
air gap makes it difficult to produce magnetic
copper, it will be seen that the air gap between
fields of the desired highintensity in the dis
the poles I6 and I1 would extend the entire
charge space within the magnetron.
length ofthe envelope I. Since it is desired to
An object of this invention is to devise a mag
high intensities ofy magnetic ñelds within
netron casing in which the effective air gap length 20 the discharge
space around the cathode 6, the
between the magnetic poles is substantially de
presence of a relatively long air gap makes it dif
ficult to set up fields of the desired intensity.
Another object is to produce such a structure’
Thus any way in which the length of this air
_in which the reduction in air gap is accomplished
gap can be decreased will greatly increase the
by the use of highly magnetic end caps provided 25 effectiveness
of the magnetron device. However,
with means whereby these caps may be readily
secured in place as by soldering.
The foregoing and other objects of this inven
tion will be best understood from the following .
as already indicaited, it is> necessary that the wall
thickness of the end caps 2 and 3 be a substan
til value in order to withstand the atmospheric
exerted upon them. One way in which
description of an exempliiication thereof, refer 30 pressure
the air gap might be decreased would be to make
ence being had to the accompanying drawing,
the end caps entirely of a magnetic material, such
Fig. 1 is a vertical cross-section through a
as iron.
However, if the end caps were made
' entirely of iron,
serious difficulties would arise
magnetron incorporating my invention, taken
in attempting to hermetically seal the iron'end
along line I-I of Fig. 2; and
35 caps to the copper walls of the envelope I. In
Fig. 2 is a top view of the magnetron as illus
accordance with my invention, the end caps, for
example the upper cap 2, is made of a thin copper
sheet I8 formed into a cup shape fitting relative
velope I which is preferably made of a block
snugly within the open upper end of theeh
of non-magnetic conductive material, such as 40 ly
velope I. A plate 20 of a magnetic material, such
copper. This block forms the anode of the mag
as iron, is fitted into the upper open end of the
netron, and is provided with hollow end sections
cup thus formed. The plate >20 may be fastened
which are covered by end caps 2 and 3„likewise
within the cup in any suitable way, as by solder
of conductive material. Between the hollow end
ing, so as to form a composite wall of the re
sections of the envelope I is the central bridging 45 quisifte physical strength. However, it is not
portion II. The portion 4 is provided with a cen
necessary to have the connection between the
tral bore 5 within which is supported substan
iron plate 20 and the copper sheet I8 in any way
tially at the center thereof a cathode 6, prefer
inasmuch as the copper plate I8 in it
ably of the indirectly-heated oxide-coated therm
an imperforate and impermeable wall
ionic type. The cathode 6 is supported by a pair
against the passage of atmospheric gases into the 1
of cathode lead-in conductors 'l and 8 sealed
device. The plate I8 may be sealed-to the wall
through the ends of glass chambers 9 and I0 on
-of the envelope I along the joint 22 in some suit
trated in Fig. 1.
Y The magnetron illustrated comprises an en
the outer ends of pipes II and I_2 hermetically
fastened within the walls of the envelope I ad
able way, as by silver solder. This _method of
jacent the upper and lowerl hollow end sections. 55 sealing two copper members together so as to
form a hermetic seal has been very satisfactory
and effective. In a particular embodiment I have
made` the sheet i8 of a copper sheet .015 of an
inch lthick, While the plate 2d could be of a sub
sealed to and closing one end of said hollow en
velope, said end cap comprising a sheet of a sub
stantially non-magnetic metal and an insert of
stantially greater thickness, for example one
magnetic material set into said sheet to decrease
the gap space through which said magnetic ñeld
eighth of an inch. The end cap 3 is made iden
tical with that of ythe end cap l2, yand comprises
must pass.
a copper sheet `lil With a magnetic insert 2 I.
Of course it is to be understood that this inven
tion is not limited to the particular details of
construction as described above as many equiva-v
composed substantially of copper and containing
cooperating electrode elements, said magnetron
lents will suggest themselves to those skilled in
the art. For example, instead of having the
magnetic plates extend across substantially> the
entire end of the magnetron, they could be `of'a
more limited extent so as to concentrate th'e
2. A magnetron comprising anhollow envelope
j being designed and adapted to have a magnetic
Yiield set up in the space between said electrode
elements, said envelope having an end cap sealed
¿to and closing one end of said hollow envelope,
_ AsaidY end` cap comprising a sheet of copper and
an insert ¿of magnetic material set into said >sheet
to ädecrease the gap space through which' said
~ magnetic-ñeldmust pass.
magnetic ñeld in the device 'more nearly along_31. A magnetron comprising a hollow envelope
the central bore â, where the greatest concentra
composed substantially of copper and containing
tion of the field is desired. Also the principles
of this invention might be applied to various 20 cooperating electrode elements, said magnetron
other types of devices utilizing the magnetic iield
being designed and adapted to 'have a magnetic
in which the size of the envelope plays a sub
ñeld VSet` up inthe space between said electrode
stantial part in limiting the magnetic field by
elements, >>said envelope having an end cap sealed
introducing a substantial airgap.
to' andY _closing one end of said hollow envelope,
What is claimed is:
said end _cap comprising a sheet _of copper and
1. A magnetron comprising a hollow envelope
an insert of magnetic material set >into said sheet
of a substantially non-magnetic metal contain
to decrease the gap space through which said
ing cooperating electrode elements, said magne
magnetic ñeld _must pass, said sealing being made
tron being designed and adapted to have a mag
between the copper part of said end cap and th
neticiield set _up in the space between said elec 30 ,copper of `said envelope.
trode elements,„said envelope h'aving an end cap
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