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Патент USA US2411506

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Nov. 26, 1946.
2,41 ‘1,506 ‘
Filed Feb. 6, ‘1943
P?l/L c1.‘ CHEV/GNY
Patented Nov. 26, 1946
Paul’ Georges Chevigny, New York, N. ~'Y.~, assignor '
to Federal Telephone and Radio-1 Corporation,
Newark, vN.’"J., a corporation of Delaware
_ Application February 6, 1943, Serial _No. 474,953
(01. 1250-275)’ 1 - '
This invention relates to improveinentsin cath
rode structures and ‘methods'of assembling the
same, andimore particularly to indirectly heated
cathodes for vacuum tubes.
lead 28 extends downwardly substantially to the
- bottom of the cathode ' l0, andat this point is
1 connectedto one end of a concentric spiral?la
ment 32. {The upper end 34 of the ?lament-32
' An object of this. inventionis'to provide an
' is vco'nnectedgto thesecond lead 30.
The; leads
"improved, easily assembled cathode structure.
Another object ‘of this inventionv is to provide
28> and-30 are also adapted to pass through and
be, supported by thevacuum tube seal.
' an’im'proved novel cathode assembly.
, .fIn'place orna single closely wound spiral cath~
7 l A further‘obje'ct of this invention is the pro-v
‘ ode 10, there may be provided a cathode in the
vision of an improved indirectly heated cathode 10 form of two or morewidely spaced spirals screwed
comprising an easily assembled, closely spaced
:one intothe other, the spacing; between spirals
spiral or a plurality of interwound spirals, pre
senting a continuous emitting surface having a
relatively large emitting area.
‘being such that they will form a continuous emit
Other objects and advantages of the present
invention will become apparent from the follow
ing detailed description of a preferred embodi
ment of the invention, together with a modi?ca
tion thereof, illustrated in the accompanying
drawing in which:
Fig. 1 is a longitudinal sectional view of a
cathode assembly formed in accordance with the‘
present invention;
"tin'g surface‘ .when'fully, interwound.v
rangement illustratingtwo such spirals forming
a composite cathode is illustrated in Fig. 3. This
?gure shows the spiral 50 partially screwed into
the spiral 52. In use, the two spirals would be
screwed together so that total length of the oath
‘ode would be the same as that of a single spiral
cathode such as illustrated in Fig. 1; they have
been illustrated as partially unscrewed in Fig. 3
solely for the sake of clarity.
The advantages of the foregoing invention will,
Fig. 2 is a bottom view of the assembly illus
trated in Fig. 1; and
Fig. 3 is a plan view of a composite interwound
cathode, which may be used in connection with
1 the assembly illustrated in Fig. 1.
it is believed, be clear to those skilled in this art.
25 A cathode of the form disclosed in which the
turns are so closely spaced as to be touching one
another will form a, continuous emitting surface
which will have a greater emitting area than a
In the preferred form of invention shown in
comparable cathode wound, for example, from
Figs. 1 and 2, the cathode l0 consists of a single 30 ?at hands. This is due to the fact that the emit
spiral of pre-set carburized tungsten wire, the
ting surface is increased by half of the circum
turns of which are closely spaced so that they
ference of each turn relatively to its diameter or
in the ratio of
will form a substantially continuous outer emit
ting surface. The cathode III is slipped over a
plurality of supporting rods l6 formed, for exam 35 '
ple, of tungsten. These rods are‘circumferen
tially spaced in such a manner that their com
This will result in appreciable gain although not
mon outer circumference is‘substantially equal
entirely proportional to the increased area, since
to the inner periphery of the spiral cathode; as
the electrons emitted between the wires are more
a result the cathode will fit snugly about the rods 40 di?icult to draw out. The fact that in all cases
and the rods will prevent relative lateral move
the turns of the spiral are touching to form a
ment of the cathode spiral.
The cathode I0 is held on the rod it against
longitudinal movement between a pair of end
substantially closed cylinder permits the advan
tageous use of this type of cathode with a ?la
ment which is adapted to heat the cathode by
rings l8 and 20 which may be, for example, tan
bombardment.’ One of the outstanding advan
talum wires welded to and about the rods 16.
tages of the present structure lies in its ease of
The rods 16, illustrated aS four in number are
assembly. It is only necessary to attach one end
preferably mounted in a supporting member 22,
ring such as the ring I8 about the supporting
as more clearly shown in Fig. '2, this supporting
rods l6, slide the cathode over the rods against
member being held in place, in turn, by a rod 50 this ring, and then add the ring 20 at the other
24 serving as a , cathode lead and projecting
end of the cathode, squeezing the cathode against
through the seal of the vacuum tube (not shown).
the ring l8, and attaching the ring 20 to the
supporting rods.
The member 22 may be formed with a radial
slot 26 through which pass a pair of heater ?la
Other advantages of the present structure to
ment leads 28 and 30. The centrally positioned 55 gether with obvious modi?cations thereof, all
coming within the scope of the present invention
as set forth in the objects and claims, will be
apparent to those skilled in this art.
uniform diameter extending about said rods and
I claim:
1. A cathode for electron discharge devices
comprising, in combination, a supporting mem
ond ring extending about and attached to all of
ber, a,plurality of circumferentially positioned
rods mounted in-saidirsllpporting:member, .a ring
supported by said ring, said winding consisting
of a plurality of interwound closely spaced spirals
forming a continuous outer surface, and a sec
said rods at the other end of said winding for
holding the same in place on said rods between
thetwo rings.
"5. An electrode for electron discharge devices
extending about and attached‘to all of said rods,
a closely spaced helical winding of substantially 10 comprising, in combination, a supporting mem
‘ber, a plurality of circumferentially positioned
uniform diameter extending about said rods and '
‘rods mounted in said supporting member, a cy
supported by said ring and unattached :to- the
lindrical member of substantially uniform diam
rods, and a second ring extending about and at
»eter extending about said rods and capable of
tached to all of said rods at ‘the other end of
said winding for holding the same in place 'on 15 longitudinal movement in relation to said rods,
and means for preventing longitudinal move
said rods between the two rings.
ment of said cylindrical member, said means
2. The combination according to claim 1, in
comprising solely a pair of rings attached to each
which said winding consists of a single closely
of said rods adjacent and abutting opposite ends
spaced spiral of wire forming a continuous outer
of said cylindrical member.
6. An electrode for electron discharge devices
3. The combination according to claim ‘1, in
which the-common outer circumference of the
comprising, in combination, a supporting mem
her, a plurality of circumferentially positioned
rods mounted in said supporting member, -a
25 closely spaced helical Winding of substantially
uniform diameter-extendingabout said rodsand
against lateral movements and the rings hold
capable of longitudinal movement'in'relation to
the winding against longitudinal movement.
said rods, and means'for preventinglongitudinal
4. A cathode "for electron :discharge devices
movement of said winding, said means compris
comprising, in combination, a supporting -mem
ing solely a pair of :rings attached to each ofgsaid
vber, a plurality‘of @circumferentially positioned
~rods adjacent and abutting opposite ends of said
rods mounted in saidsupporting member, a ring
' extending-aboutandattached'to all of said rods,
a closelyzspacedfhelical windingof substantially
circumferentially positioned rods ‘is substantially
equal to the inner periphery of the rings and of
the winding, whereby ‘therods hold the‘winding
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