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Патент USA US2122285

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June 28, 1938.
2,122,285
a. HOLST ET AL
ELECTRICAL DISCHARGE DEV‘ICE
Filed May 15, 1937
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June 28, 1938.
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ELECTRICAL DISCHARGE DEVICE
Filed May 15, 1957
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2,122,285
Patented June 28, 1938
UNITED STATES
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ELECTRICAL DI semen
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Gilles Holst, Willem Elenbaas, and Aart van Wylr,
Eindhoven, Netherlands, assignors to General
Electric Company, a corporation of New York
Application May 15, 1937, Serial No. 142,931
In Germany May 18, 1936
% Claims.
The present invention relates to electrical dis
charge devices of the type which utilize a con
densible ionizing medium. It is especially con
cerned with improving the stability of operation
5 of high pressure devices of this kind.
In the operation of discharge devices of the
and advantages thereof, may best be understood
from the following description taken in connec
tion with the drawings, in which
Fig. 1 represents a longitudinal section of a
discharge device, speci?cally a lamp, suitably em
bodying the invention;
Fig. 2 is another view of an end portion of the
vapor density of the ionizing medium at some same lamp;
Fig. 3 shows the lamp combined with a suit
predetermined ?xed value in order to obtain a
10
able standard and re?ector;
re desired operating voltage. This may be accom
pllshed in some cases by providing within the ' Fig. 4 shows an alternative modi?cation of the
discharge envelope a carefully measured portion invention;
Fig. 5 is a detailed view of one of the elements of
of ionizing medium of such amount that it will
type speci?ed, it is desirable to maintain the
be entirely vaporized during normal operation.
15 However, in the routine fabrication of discharge
devices such as high pressure lamps consisting of
quartz, it is extremely dimcult to maintain the
internal volume of the discharge envelope perfect
ly uniform for each unit. Furthermore, a varia
20 tion in volume of the container will vary the
vapor density resulting from the introduction of
a given quantity of ionizing medium.
It is an object of the present invention to pro»
vide an improved means for regulating the vapor
25 pressure within an electrical discharge device and
for increasing the stability of operation of such
a device.
It is known that the pressure within a sealed
envelope containing an excess of a vaporizable
30 medium depends primarily upon the temperature
of the coldest point of the envelope wall. In ac
cordance with the present invention the pressure
within a discharge envelope is arti?cially fixed
by providing in the envelope a quantity of con
35 densible ionizing medium in excess of that which
can be vaporized during normal operation and
maintaining a portion of the envelope wall at a
substantially constant temperature. In a. particu
lar embodiment this latter function is accom
‘ill plished by appending to the envelope a sealed
container enclosing a vaporizable liquid normally
in heat-exchanging relation with a region of the
envelope wall. Excess heat is abstracted from
such region by vaporization or boiling of the
45 liquid and is dissipated by condensing the gen
erated vapor at some part of the container rela
tively remote from the discharge envelope. The
boiling temperature of the liquid may be ad
justed and ?xed by means of a non-condensible
50 gas provided within the container at a desired
pressure.
‘
‘
The particular features of the invention which
are desired to be protected herein will be pointed
out with particularity in the appended claims.
The invention itself, together with further objects
Fig. 4; and
Figs. 6 and ‘7 represent still further modi?ca 15
tions of which the invention is capable.
Referring particularly to Fig. 1, We have shown
a discharge lamp comprising an elongated enve
lope lel preferably of quartz, containing cooperat
ing discharge electrodes H and i2, and a quantity 20
of a condensible ionizing medium such as mercury.
The ionizing medium, which should be present in
such quantity as not to be completely vaporized
during the normal use of the lamp, is represented
at id as a small globule collected in the lower end
of the discharge envelope.
'
The electrodes it and it may suitably comprise
tungsten wires to which has been applied a mix
ture of barium and strontium oxides, or some
other strongly electron emissive substance. Dur
ing the use of the device the electrodes may be
supplied with heating current by means of lead-‘in
conductors ll which are connected outside the
tube with bayonet contacts W. A potential sui
?cient to produce a discharge may be applied be
tween ’the electrodes from any suitable source
(not shown). In order to facilitate starting, the
envelope may contain a quantity of a ?xed gas.
for example, argon at a pressure of about 5
40
millimeters.
After a predetermined period of operation of
the device a portion of the ionizing medium it
will become vaporized. Eventually a state of
stability will be reached determined by the di
mensions of the discharge envelope and the
energy supplied to the discharge stream. In ac
cordance with the present invention such stabili
zation should occur when only a portion of the
ionizable medium has been vaporized. The vapor
pressure then existing will depend on the tem 50
perature of the coolest portion of the envelope
which in the contemplated arrangement is ?xed
by means of a. constant temperature device opera.
tively connected to the envelope.
Referring to Fig. 1, such a. device is illustrated 555
2
' 2,122,285
as comprising an auxiliary container 2| attached
to an end wall 23 of the discharge envelope, the
arrangement being such that a portion of the
container is in heat-exchanging relation with
the envelope wall while a second portion of the
container is disposed relatively remote from the
envelope. In the particular modi?cation shown
the container and envelope are joined integrally
uid. The operation of such a tubulation in as
sisting boiling is well understood and need not
be elaborated upon herein.
The portion of the container 2| most remote
from the envelope may be additionally shielded
from heat radiated from the discharge space
by means of a metal sheath 34 applied extcriorly
to the end wall of the envelope. This sheath
in such a way that the wall 23 forms a common
may be of such nature as to act as a reflector
.to retain heat within the envelope.
10 partition between them.
Within the container 2! and in heat-exchang
tion currents set up within the discharge enve
lope Ill from playing over the surface of the wall
sisting, for example, of mercury or an organic
substance such as benzyl benzoate or cetyl alco
23 which is to be maintained at a constant con
hol. This liquid should have a boiling point
comparable with the wall temperature desired to
be maintained and is adapted to be vaporized
by absorption of heat from the wall 23 as soon
as that temperature is approached. The vapors
thus generated will travel toward the bulbous
portion of the container moreremote from the
discharge envelope where they will be cooled and
condensed by contact with the container walls.
25 If the condensing surface available is su?icient to
dissipate heat at an adequate rate, the pres
sure within the container will not increase ma
terially and the boiling temperature of the liquid
will remain at a substantially constant value.
30 It will be apparent, therefore, that the portion
of the envelope wall 23 which is in heat-ex-‘
changing relation with the liquid will also be
held at a constant temperature corresponding to
the boiling point of the liquid.
The ultimate
result will be that the vapor pressure within the
discharge envelope itself is maintained at a
substantially ?xed value.
last factor can be varied in a desired manner by
introducing into the container at non-condensible
gas, such, for example, as argon or neon.
The
introduction of the gas may be accomplished
after the discharge device is otherwise entirely
complete. Under these conditions the gas pres
sure may be adjusted with a high degree of ac
curacy so as to produce exactly the desired boiling
temperature of ‘the enclosed liquid and the desired
operation of the device.
For the successful operation of the device it is
necessary that the liquid 25 remain in contact
with the wall 23. In order to increase the va
55 riety of positions which may be assumed by the
discharge lamp without abrogating this condi
tion, it is advantageous to arrange the axis of
the container 2| at a sharp angle, say 25 to 65
degrees, with respect to that of the discharge
envelope.
densing temperature. The effect of such cur 15
rents varies considerably with the position of
the lamp and may produce uncertain and erratic
operation unless suitable precautions are taken.
In the present case, the possible effect of con
vection currents is minimized by means of a
shield 29 formed transversely across the dis
charge envelope between the discharge space and
the wall 23. This shield has an opening 3| which
permits vapors within the discharge envelope to
have ready access to the condensing surface. In
order to prevent condensed vaporswhich accumu
late on the upper surface of this shield from.
dropping down into the discharge space and ex
tinguishing the are, there may be provided a
?ange 32 surrounding the opening 3!.
In the operation of a discharge lamp such as
that illustrated, it is frequently desirable to sur
round the lamp with a light ?lter for the pur
pose of eliminating certain ultra-violet or other
radiations from the light emitted. Such a ?lter
is illustrated in Fig. 1 as comprising a cylindrical
tube 36 surrounding the discharge envelope. In
It will be understood that the temperature
at which the liquid 25 will boil is determined
40 in part by the nature of the liquid and in part
by the pressure within the container 2|. This
45
It is also desirable to prevent gaseous convec
ing relation with the wall 23 there is provided a
quantity of a readily vaporizable liquid 25 con
This being done, the lamp may be
tilted from the vertical position shown in Fig. 1
to the horizontal position shown in Fig. 2 with
out causing the vaporizable liquid to flow away
from the wall 23.
65
In order to facilitate boiling of the vaporizable
liquid and thereby to make the temperature
regulating device more readily responsive to slight
changes in temperature, it is possible to provide
means for promoting the initiation of boiling.
70 Such means may comprise sharp metallic frag
ments suspended in the liquid or sharp points
projecting into it. In the present case we have
shown for this purpose a small tubulation 27
projecting toward the end wall 23 so that its open
75 end is below the surface of th? llaporizflbléi 3%"
order that this tube may not interfere with the
effective dissipation of heat from the container
2!, the container is allowed to project, at least 40
partially, through the end of the tube as shown.
In Fig. 3 we have shown a lamp embodying
the invention as applied in connection with an
adjustable re?ector 38 and a lamp standard 39
having a base Q0. The discharge lamp which
in this case is to be used in horizontal position,
is indicated in dotted outline at M. The ele
ment 42, also shown in clotted outline, corre
sponds to the container 2i described in connec
tion with Fig. 1. It will be seen that with this
container arranged at an angle to the main axis
of the lamp as indicated, the position of the
re?ector 38 may be varied considerably without
causing the vaporizable liquid to ?ow away from
the end wall of the discharge envelope.
Where one employs a non-condensible gas as
a means for ?xing the boiling temperature of the
vaporizable liquid, it is desirable to prevent the
gas from being appreciably compressed by the
vapor generated in the auxiliary container dur 60
ing operation of the device. Such compression
will obviously increase the gas pressure and
raise the temperature at which the liquid can
boil.
In Fig. 4 we have illustrated a modi?cation
of the invention embodying an arrangement of
parts which is effective to maintain substantially
constant gas pressure‘ within the container. In
this ?gure there is shown an electrode 43, cor
responding to the electrode I l of Fig. 1, and a 70
portion of a discharge envelope (is enclosing the
same.
Appended to the end wall 45 of the envelope
there is provided a container comprising a rela
tively small tubular portion 46 and an enlarged 75
aieaaea
bulbous portion dl preferably having a volume
at least four times as great as that of the portion
46. A quantity of a vaporizable liquid 68 is dis
posed in the container portion 46 and the bulbous
portion 41 contains a non-condensible gas as
previously described.
‘
Between the two portions of the container
there is provided means for condensing vapors
generated by the boiling of the liquid 48.
As
illustrated such means comprises a heat radiator
89 in heat-exchanging relation with the connec
tion between the lower and upper parts of the
What We claim as new and desire to secure
by Letters Patent of the United States is:
1. An electrical discharge device comprising 10
an envelope enclosing discharge electrodes and a
quantity of a condensible ionizing medium, an
held together and secured to the container by
means of a pair of clamps til.
Due to the condensing action of the radiator
tainer for condensing liquid vaporized therein,
tail in Fig. 5, may comprise a plurality of fins 5d
d9, penetration of vapor resulting from the boil
ing of the liquid d8 into the gas-?lled bulbous
20 container portion will be substantially prevented.
Consequently, if the volume of the bulbous por
tion is relatively large with respect to that of the
total container, there will be very little compres
sion of the gas with changing temperature con
ditions and correspondingly little variation in the
boiling point of the vaporizable liquid.
In order to facilitate the transmission of heat
through the envelope wall, it is advantageous in
some cases to provide a metallic connection be
the ‘container; means associated with the con-v
and an apertured shield interposed between the
said envelope wall portion and the main dis
20
charge space of the envelope.
2. An electrical discharge device comprising an
envelope enclosing discharge electrodes and a
quantity of a condensible ionizing medium, an
auxiliary container in heat exchanging relation
with the wall of the envelope, av quantity of va 25
porizable liquid within the container and means
in contact with the liquid in the container for
promoting boiling thereof and means associated
with the container for condensing liquid vapor
Such a connection may
30
ized therein.
3. An electrical discharge device comprising an
comprise a metal partition forming a common
wall between the container and the envelope, or
more simply, a metallic element connecting them.
The former possibility is illustrated in Fig. 4 and
the latter in Fig. 6.
Referring to Fig. 4, it will be seen that a por
tion of the end wall 45 is closed by means of a
dium and means associated with the device for
regulating the vapor pressure of the ionizing me 35
dium within the envelope, said means including
va sealed container having a portion thereof, in
heat-exchanging relation with a wall of the dis
30 tween the constant temperature device and the
' interior of the envelope.
hollow metallic body 553, ‘for example, of tungsten,
40 such body being sealed into the quartz by means
of a transition glass 55 having an expansion co
emcient intermediate between that of quartz and
of tungtsen. The lower end of the body 5% pro
jects into the discharge envelope and serves as
45 a screen against convection currents within the
envelope. An opening 58 is provided in the side
of the body- to permit entrance of the condensible
ionizing medium. This opening is so positioned
that it prevents condensate accumulated within
the body from. ?owing back into the discharge
space.
'
.
In the alternative arrangement of Fig. 6 there
is‘ provided a metallic conductor 58 projecting
through the end wall of the discharge envelope
into a body of vaporizable liquid 59. At the
end of the conductor which projects within the
envelope there is provided a metallic'shield fill
of substantially umbrella form adapted to per
form the shielding function previously referred
60 to. The effectiveness of the shielding may be
still further increased by the use of an addi
tional shield comprising an apertured partition
6i disposed transversely of the discharge enve
lope.
65
While we have shown particular embodiments
of our invention, it will be understood by those
skilled in the art that many modi?cations may
be made without departing from the invention,
and we aim by the appended claims to cover all
such modi?cations as fall within the true spirit
and scope of the foregoing disclosure.
auxiliary container in good heat-exchanging re
lation with a portion of the wall of the envelope,
a quantity of readily vaporizable liquid within
container. This radiator, which is shown in de- .
50
3
envelope enclosing discharge electrodes and a
quantity of a readily condensible ionizing me
charge device envelope and another portion rel
atively remote from the envelope, a quantity of 40
a vaporizable medium in the ?rst portion, a non
condensible gas in the second portion, and means
arranged between the first and second portions
for condensing liquid vaporized within the con
45
tainer.
4.1m electrical discharge device comprising
an elongated envelope enclosing discharge elec
trodes, and a quantity of a readily condensible
ionizing medium, an auxiliary container attached
exteriorly to an end wall of the envelope, said 50
container comprising a portion in heat-exchang
ing relation with the envelope, a bulbous portion
relatively remote from the envelope and a con
nection between said portions, a quantity of a
vaporizable liquid within the ?rst portion of the 55
container, a non-condensible gas within the sec
ond portion of the container and a heat radiator
in heat-exchanging relation with the connection
between the ?rst and second portions of the con
tainer for condensing liquid vaporized within the 60
container.
5. An electrical discharge device comprising
an envelope consisting principally of insulating
material, discharge electrodes and a quantity of
a condensible ionizing medium enclosed within v65
sponds generally to that shown in Fig. 1, and the envelope, a container attached to a wall of
parts corresponding to those illustrated in that - the envelope, a metallic connection between the
interior of the envelope and the interior of the
?gure are similarly numbered. There is addi
container, and a vaporizable liquid Within the
tionally provided, however, a ?ange 65 project
ing inwardly toward the discharge space from container and in heat-exchanging relation with 70
the end wall‘to which the temperature-regulating said metallic connection during the normal use
means is secured. Its function is to facilitate of the discharge device, said container having a
portion thereof relatively remote from the dis
the accumulation of a body of condensed ioniz
The discharge device shown in Fig. '7 corre-.
ing medium at the cooled region of the end
75 wall 23.
charge device for condensing liquid vaporized
within the container.
75
4
9,129,885
6. A discharge device according to claim 5 in
which a metal shield is provided between the
discharge space and the region of the envelope
to which the container is attached, said shield
being in good heat-exchanging relation with the
metallic connection.
7. A discharge device according to claim 5 in
which the metallic connection comprises a. hollow
member extending between the container and
the envelope and having an opening only to the
interior of the envelope.
8. An electrical discharge device comprising an
envelope enclosing discharge electrodes and a
quantity of a readily condensible ionizing me
15 dium, and means associated with the device for
regulating the vapor pressure of the ionizing
medium within the envelope, said means includ
ing a container having a portion thereof in heat
exchanging relation with the interior of the dis
charge device and another portion thermally
isolated from the discharge device, a quantity of
a vaporizable medium in the first portion, a. non
condensible gas in the second portion, and heat
dissipating means arranged between the ?rst
and second portions for condensing liquid va 10
porized within the container.
GILLES HOLST.
WILLE'M ELENBAAS.
AART VAN WYK.
16
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