US2312232A - Liquid-cooled lamp - Google Patents

Description

Ar i 5 ,illlllllilillllllvllllllilllll Illllllllllllllllilllllll! Feb. 23, 1943. c1501.

, LIQUID-9001.111) LAMP Filed 05. 22, 1941 2 sheets-sheet 1 lhvervtof: Cornelis Bot His Afiovneg.

Feb. 23, 19430 c. BOL 2,332,232

LIQUID-COOLED LAMP Filed Dec. 22 1941 2 Sheets-Sheet 2 lnven'tov Conelis BoL, b

Hi5 A'H'm- PH 3 Patented Feb. 23, 1943 LIQUID- CO OLED LAMP .Cornelis B01, Palo Alto, .Calif., assignor to General Electric Company,

York

a corporation of New Application December 22, 1941, Serial No. 423,871

s Claims. (01. Moe-11.4)

My invention relates to an electric light projection device and moreparticularly to a liquidcooled light generating device in which the lightsource is constituted by one or more highressure high-intensity metal-vapor discharge lamps of the capillary type .disclosed and claimed in U. S. Patent No. 2,094,694, B01 et al., issued Octoher 5, 1937. v

High-pressure mercury lamps of the capillary type disclosed in the above mentioned patent employ a very small quartz tube, which may have a bore diameter of the order of 2 mm. or so, as the enclosing envelope. Such lamps are designed to be operated at relatively high wattage inputs, such as, for instance, 500 watts and above. higher wattage capillary lamps, such as those operating at 1000 watts and higher, it was found that in order to effectively dissipate such a great amount of energy within such a small volume and thereby prevent overheating and softening of the quartz tube, it was necessary to provide vigorous cooling of the lamp, aszby water or other liquid circulated over the surface of the quartz tube.

One object of my invention is to provide a liquid-cooled mounting arrangement for a highwattage tubular discharge lamp which will effectively cool the lamp so as to prevent overheating thereof with resultant damage thereto.

Another object of my invention is to provide a liquid-cooled mounting arrangement for such high-wattage tubular discharge lamps which is simple in construction and which permits ready removal and replacement of the lamp.

Still another object of my invention is to provide a liquid-cooled mounting arrangement for high-wattage tubular discharge lamps in which each lamp is equipped with a surrounding glass With the tube serving as a jacket therefor, the lamp and the surrounding tube being permanently fastened together so as to form an integral unit which may bereadily inserted and removed from the mounting device.

A still further object of my invention is to provide a liquid-cooled mounting arrangement for high-wattage tubular discharge lamps having a hollow reflector disposed externally of the lampjacketed portion of the device and extending closely adjacent the same, the reflector being substantially co-extensive with the arc discharge in the lamp and having its hollow interior in communication with the cooling liquid chamber surrounding the lamp so that the cooling liquid also circulates through the reflector to thereby prevent excessive heating and resultant deterioration of the reflecting surface or coating there- Further objects and advantages of my invention will appear from the following description of a species thereof and from the accompanying drawings in which:

Fig. 1 is an elevation of an electric light generating device comprising my invention on a reduced scale; Fig. 2 is a longitudinal medial section of one of the similar sides or halves of the device shown in Fig. 1; Fig. 3 is a detail View of one of the lamp units' of the device shown in Fig. 1; Fig. 4 is a transverse section taken on the line 4. 4 of Fig. 2; Fig. 5 is a transverse section taken on t'he line 5-5 of Fig. 2; Fig. 0 is a transverse section taken on the line 5-,fi of Fig. 2; and Fig. 7 is a diagrammatic illustration showing the manner in which the light generating device'a ccording to the invention is arranged with respect to a trough reflector to thereby form a light projection devicefor the projection of an extremely powerful fan-shaped beam of light.

Referring torthe drawings, the lamp mounting arrangement there shown comprises an elongated base member ID, preferably in the form of an inverted chanel iron. Mounted above the base or channel member 10 and extending longitudinally on t c al porti the eof is an l at d hollow reflector member i 1 preferably made from sheet brass and coated with a suitable reflecting material, such as silver of chromium. The reflector member is supported on, and spaced from the Web I2 of the channel l0, by suitable support or spacer rings It. At its opposite ends, the reflector member ll is'provided with an externally threaded outlet tube or conduit is threaded into the reflector so as to communicate with the hollow interior thereof and extending down through an opening in the web I2 of the channel member I0. A nut 15, threaded onto each outlet pipe or conduit [4, engages the under surface of the channel web l2 so as to firmly clamp the reflector member II and the spacer rings l3 against the 'web I2 of the base member .10. At a point substantially midway between its ends, the reflector member H is further secured to the base [0 by means of an externally threaded inlet tube or conduit 16 threaded into the reflector and extending down through an Opening in the channel Web |2 ,.-anda nut I 5 threaded onto the inlet pipe or conduit, l6 against the under surface of the channel web 12. The inlet pipe 16 extends up through the hollow reflector member H so as to project from the top surface thereof, and accordingly is not in direct communication with the hollow interior of the reflector member. At their loweror free ends, the inlet and outlet pipes I 6 and 14 respectively, are each provided with suitable coupling elements I! for connecting the pipes to the inlet and. outlet hose connections (not shown) for the cooling liquid to be circulated through the device.

Mounted centrally on the reflector member I! and fitting over the upper projecting end of the inlet pipe I6 is a central lamp supporting member or block l8 having a horizontal bore |9 extending therethrough longitudinally of the base member ID. The said central support member I8 is also provided with a second or vertical bore 29 extending at right angles to, and communicating with the longitudinal bore l9, into which bore the inlet tube I6 is threaded. The opposite ends of the longitudinal bore l9 at each side of the hollow support member |8 are enlarged, as indicated at 2|, to form outlet chambers for the reception of the inner end portions of longitudinally extending cylindrical outer jackets or tubes 22 of suitable light-transmitting material, such as glass or quartz. Each of the enlarged recesses or outlet chambers 2| in the hollow supuort member l8 communicates with the hollow interior of the reflector member through the medium of a vertical slot or passageway 23, formed in the hollow support member |8 on each side of the vertical bore 20, and aligned slots 24 in the upper wall of the reflector membe I, the said slots 23 being located at the innermost portions of the enlarged recesses 2|.

Each outer jacket or tube 22 is concentrically mounted within the enlarged bore portion 2| of the support member l8, and is secured in place in the said member l8 by means of a rubber washer 25 surrounding the said tube and compressed against an annular shoulder 26 in the bore portion 2| by an annular compression or looking ring 21 threaded into the bore portion 2|. The compression of the rubber washer 25 by the ring 21 squeezes the washer against the outer jacket or tube 22 so as to securely hold the tube in place within the support member I8 and at the same time provide a liquid-tight seal therebetween, The outer jackets 22 are mounted in the support member l8 with their innermost ends spaced a slight distance rom the annular shoulders 28 formed in the bore l9 by the enlarged portions 2| thereof. In this manner, sufiicient clearance or passageway is provided for the flow of the cooling liquid from the outer jackets 22 into the enlarged bore portions or outlet chambers 2| and thence through the slots 23 and the openings 24 into the hollow reflector member l.

The outer end of each outer jacket or tube 22 is mounted in an end support sleeve 29 which is supported on a suitable insulator 39 bolted or otherwise fastened to the base member I0, the sleeve 29 being secured to the insulator by suitable means, such as a clamp member 3| suitably fastened to the insulator as by a bolt 32. The inner end of the sleeve 29 is formed with an enlarged portion 33 having an enlarged bore 34 within which the outer end of the jacket 22 is received. The outer jacket or tube 22 is concentrically mounted and secured in place within the sleeve 29 by means of a rubber washer 35 which is compressed by a compression ring 36 against the annular shoulder 31 formed in the sleeve by the enlarged bore portion 34, the compression ring 36 threading into the enlarged bore 34 in the sleeve to thereby compress the rubber washer. As in the case of the rubber washer 25 at the shown more particularly in Fig. 3. The lamp unit is readily removable through the outer end of the outer jacket 22 and comprises an inner jacket or velocity tube 39 of suitable light-transmitting material, such as glass or quartz, and a high- 3 pressure mercury lamp of the capillary type described and claimed in the above mentioned I U. S. Patent No. 2,094,694 of B01 et al., the lamp inner end of the tube 22, the compression of the 49 being mounted concentrically within the velocity tube 39 adjacent the inner end thereof. The formation of the velocity tube 39 and the capillary lamp 40 as a single unit permits the easy assembly of such parts in the device and therefore the easy replacement thereof. With the lamp unit 38 in place within the outer jacket 22, the velocity tube 39 and outer jacket 22 surrounding the lamp 40 form, in effect, a jacket structure therefor.

The inner end of the velocity tube 39 is provided with an inner metal cap 4|, preferably of brass, which is cemented or otherwise secured to the velocity tube 39 and which fits into the longitudinal bore |9 in the central support member l8 to thereby support the inner end of the lamp unit. An annular shoulder 42 formed in the central support member |8 within the bore |9 provides an abutment or stop against which the metal cap 4| seats to limit the inward movement of the lamp unit into, and properly position the inner end of the lamp unit in, the central support member H3. The engagement of the inner end caps 4| of the two lamp units 38 with the annular abutment shoulders 42 in the support member I8 serves to close off or separate the inner or reduced diameter portion of the bore |9 from the enlarged outer portions 2| thereof so as to form, in effect, an inlet chamber in said support member.

The metal cap 4| is provided with a suitable lamp socket comprising a plurality (preferably four) of spring fingers 43 extending inwardly from the end wall 44 of the cap into the velocity tube 39 and resiliently engaging the metal lamp base or terminal 45 at the inner end of the capillary lamp 49 to thereby support the lamp at said end and electrically connect the metal cap 4| to the said base 45. Such a spring-finger socket arrangement permits the lamp base 45 to slide therein thus relieving the lamp of any strain which might otherwise result from the expansion and consequent elongation of the lamp during the operation thereof. The end wall 44 of the metal cap 4| is provided with a plurality of inlet openings 46 therethrough preferably of circular form and communicating with the interior of the inner jacket or velocity tube 39, the openings 46 being arranged preferably in a circle about,

the lamp socket 43 and being of sufiicient size to provide sufficient passageway for the free flow of adequate cooling liquid therethrough into the velocity tube 39.

The outer end of the lamp 49 is supported by means of a glass support tube 41 disposed concentrically within the velocity tube 39 and enclosing the seal portion 48 of the lamp at the said outer end thereof; a rubber sleeve 49 fitting over the said lamp seal portion 48 and being compressed between the said seal portion and the enclosing glass support tube 41 to thereby form a liquid-tight seal therebetween. A rubber washer 50, fitting over the glass support tube 44 and resting against a flange or enlargement 5| formed on the support tube 41 at a point intermediate the outer end 48 of the lamp and the outer end of the jacket or velocity tube 39, serves to support and more or less center the support tube 4.1 within the velocity tube 39. The support tube is further held in position within the velocity tube 39 by means of a filling 52 of a suitable insulating compound which completely fills the glass support tube 41 as well as the outer end of the jacket or tube 39 up to the rubber washer 50, the latter thus serving as a retaining member for confining the filling compound 52 to that portion of the jacket 39 outwardly of the rubber washer. The filling compound 52 provides a liquid-tight seal between the lamp support tube 4'! and the velocity tube 39 so as to prevent leakage of the cooling liquid out of the outer end of the lamp unit.

A metal cap 53, fitting over the outer end of the velocity tube 39, closes the outer end of the lamp unit 38 and forms the outer terminal therefor. The outer cap 53 is held in place on the end of the velocity tube 39, and is electrically connected to the tungsten leading-in wire 54 of the lamp at the outer end 48 thereof, by means of a connecting wire 55 soldered or otherwise secured to the outer cap 53.

At a point approximately opposite the outer end of the effective light-producing extent of the lamp 49, the surrounding jacket or velocity tube 39 is provided with a plurality of outlet openings 56 in the wall thereof through which openings the cooling liquid flows out of the inner jacket 39 into the outer jacket 22. As'in the case of the inlet openings 46 in the metal inner cap 4| at the inner end of the lamp unit, the outlet openings 56 should together provide adequate passageway for the free flow of the cooling liquid therethrough. However, each individual opening 56 should be small enough to trap the larger-sized broken quartz parts of the lamp should the latter break, thus preventing such broken glass parts from passing into the cooling liquid system.

Each lamp unit 38 is supported adjacent its outer end by means of a rubber sleeve which is compressed against the outer end of the support sleeve 29 and against the wall of the inner jacket or velocity tube 39 by a cap nut 58 fitting over the velocity tube 39 and threaded onto the support sleeve 29, the compressed rubber sleeve 57 thus serving also to provide a liquid-tight seal between the velocity tube 39 and the support sleeve 29. It will be evident from the above that the various elements constituting the support for the outer end of the lamp unit 38 are entirely. insulated from both sides of the power supply to the lamp so as to be under no potential whatever, thus avoiding power losses thereat.

To prevent the lamp units 38 from being ejected. or blown out of the tubes 22 through the open outer ends of the sleeves 29 by the pressure of the cooling liquid therein, suitable stop members in the form of cylindrical metal blocks or contacts 59 are provided, the said stop members 59 being slidably mounted in suitable clamp members 69 having clamping bolts 6| and fastened in a suitable manner, as by bolts 62, to insulators 63, bolted or otherwise secured to the base member l9. Connector lugs 64 provided with binding screws 65 are clamped between the insulators 63 and the clamp members 60 and provide a suitable means for connecting the current supply Wires from one side of the line to the device so as to be electrically connected through is made through the central support member l8, $51

against which the inner end terminal rests, and through the frame or base III of the device, the current supply wires from the other side of the line being connected to a suitable part of the frame or base I!) of the device, or to a related member.

. As shown particularly in Fig. 6, the upper wall 66 of the hollow reflector II is so shaped in transverse cross-section as to present a concave reflecting surface facing the lamps 40 and symmetrical therewith. The reflecting surface may be of any suitable shape, but is preferably formed of two halves 61, 68 each of circular cross-section with their axes of curvature 61., 68' (Fig. 7) parallel to but displaced a slight distance to one side of the longitudinal center line of the lamp; i. e., to that side on which the corresponding half-section lies, so that the reflected rays of light from the reflector will not pass through the discharge space within the lamp but instead will form images 69 slightly to one side thereof. In this manner the limit on the energy input of the lamp which is set where the reflected images of the lamp discharge are allowed to form in the discharge itself, is entirely obviated. The axes of curvature 61', 68 of the two circular reflecting surfaces 61, 68 are preferably displaced to one side of the lamp a distance such that the reflected images 69 of the light source are formed outside of the lamp 40 but inside of the inner jacket or velocity tube 39, as shown in Fig. 7.

To strengthen the upper wall 66 of the reflector ll, centrally arranged longitudinal reinforcing ribs or webs 1'9 are provided within. the hollow reflector between the upper and lower walls thereof. Midway of its length, the reflector ll is provided with transverse baflie members or partitions N (Fig. 4) disposed within the reflector on opposite sides of the inlet tube l6 passing therethrough, the said ballle plates dividing the reflector into two separate sections or compartments so that the cooling liquid entering each section will flow therethrough in one direction only and with a regular flow.

The capillary lamps 40 employed have an inside diameter of approximately 2 mm. and an outside diameter of approximately 6 mm., and have a discharge gap of approximately mm. The lamp exhaust tube tip 12 is located closely adjacent one end of the lamp and inclined toward such end; and each lamp is mounted in its corresponding velocity tube 39 so that the inclination of the exhaust tube tip 12 is in the direction of, and does not interfere with the flow of the cooling liquid as it passes through the velocity tube. The lamps are designed to operate at an internal pressure above 70 atmospheres with an operating voltage of about 6,000 volts and an operating current of about 1.3 to 1.5 amperes. The supply circuit should have an open circuit voltage of about 9,300 volts and a short circuit current of approximately 2.5 amperes. During operation, the lamps 49 emit light in an amount approximating 65 lumens per watt. The lamps are operated from a suitable step-up transformer, the outer end terminals 53 of the lamps being connected to the opposite ends of the transformer secondary and the inner end terminals 45 of the lamps being connected to a grounded center tap of the secondary." The primary of the transformer is connected to a 220-volt source of current.

As shown in Fig. 7, the lighting unit according to the invention ispreferably used in conjunction with a relatively large trough-shaped reflector I3 of paraboloidal shape to thereby provide a wide fan-shaped beam of light of exceptionally high intensity and. especially suitable for airport lighting and other similar purposes, the unit being mounted with the lamps 40 extending along the focal axis of the main reflector I3 and with its reflecting surfaces 61, 68 facing the main reflector I3 so that the light reflected by such surfaces is directed onto the main reflector.

To operate the lighting unit, the inlet and outlet pipes I4 and I6 are joined by the couplings I! to the inlet, and outlet hose connections of the cooling liquid system, and the cooling liquid circulated under pressure through the device. As shown by the arrows in Fig. 2, the cooling liquid from the inlet pipe I6 first enters the longitudinal bore I9 in the central support member I8, then enters the velocity tubes 39 of the two lamp units, through the inlet openings 46 in the inner end caps 4| thereof, and flows along the lamps 40 so as to effectively cool the same. The cooling liquid in each lamp unit then flows out of the velocity tube 39, through the outlet openings 56 therein, into the outer jacket 22 through which it then flows in a direction opposite to that of the flow in the velocity tube 39. The cooling liquid flows out of the open inner end of the outer jacket 22 into the enlarged portion 2I of the longitudinal bore in the central support member I8, and then passes through the aligned slots 23, 24 in the said support member and the reflector l l into one section of the said reflector through which it then flows in one direction only towards the outlet end of such reflector section, the cooling liquid leaving the reflector through the outlet pipe I4 connected thereto.

After the flow of cooling liquid through the device has once been initiated, the electrical circuit through the lamps 49 may be then energized so as to start the operation of the lamps. The heat thereafter generated by the discharge within the lamps is then dissipated by the cooling liquid continually circulating through the device, so that the said device is thus effectively cooled at all times during its operation and softening of the quartz lamp tubes prevented. The circulation of the cooling liquid through the reflector I I serves to cool the same and so prevent the deterioration of the reflecting coating thereon by the heat developed by the discharge in the lamps.

When it is desired to stop the operation of the device, the lamps, 40 are first de-energized and then the flow of cooling liquid through the device interrupted. In this way, continuous cooling of the device is assured throughout the entire period of lamp operation, right up to the time lamp operation ceases.

Where it is desired to prevent ultraviolet rays from leaving the device, the velocity tube 39 or the outer jacket 22, or both, may be made of a glass which will absorb the ultraviolet rays, such as a soft glass, for instance. Preferably, however, the velocity tube and the outer jacket are made of a suitable hard glass, such as Pyrex o-r Nonex, which transmits the visible rays of the spectrum as well as the higher wave-length ultraviolet.

Where the transmission of all the ultraviolet as well as the visible rays of the spectrum is desired, both the velocity tube 39 and the outer jacket 22 are made of quartz. However, where the transmission of only the ultraviolet is wanted, then the velocity tube 39, and if desired the outer jacket 22 as well, may be made of a glass which absorbs the visible light but transmits the ultraviolet rays, such as, for instance. red Uviol glass or that commercially known as Red Purple Ultra glass. The velocity tube 39 in such case serves as a filter to absorb all the visible light, and such absorption therefore results in the heating up of the velocity tube. However, the cooling of both sides of the velocity tube 39 by the cooling liquid circulating through the device insures the adequate cooling of such tube so as to prevent any damage thereto from excessive heating. of the same.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. A liquid-cooled mounting device for a high intensity tubular electric lamp comprising a cooling-liquid jacket structure including a tubular outer jacket of material permeable to radiations of the lamp and a tubular inner jacket of material permeable to radiations of the lamp disposed within said outer jacket and spaced therefrom so as to provide an outer cooling chamber therebetween, a support member for one end of said tubular jacket structure, said support member being provided with inlet and outlet chambers separate from one another, the ends of said inner and outer jackets supported by said support member being open and in communication respectively with the said inlet and outlet chambers in said support member, and closure means for closing said inner and outer jackets at the ends thereof opposite from those ends supported by said support member, said inner jacket being formed with an opening in the wall thereof at a point intermediate its ends to thereby provide communication between the interior of said inner jacket and the said outer cooling chamber.

2. A liquid-cooled mounting device for a high intensity tubular electric lamp comprising a tubular outer jacket of material permeable to radiations of the lamp, a support member for one end of said outer jacket, said support member having inlet and outlet chambers separate from one another and the said supported end of said outer jacket being in communication with said outlet chamber, a removable lamp unit disposed within said outer jacket and removable therefrom,-said lamp unit comprising an inner jacket of material permeable to radiations of the lamp and spaced from said outer jacket so as to provide an outer cooling chamber therebetween, and support means within said inner jacket for supporting the said lamp therein and in spaced relation thereto so as to provide an inner cooling chamber, one end of said inner jacket being closed and the other end thereof being supported by said support member and in communication with the said inlet chamber therein, said inner jacket being formed with an opening in the wall thereof as a point intermediate its ends to thereby provide communication between said inner and outer cooling chambers, and closure means for closing that end of the said outer cooling chamber remote from said support member.

. 3. A liquid-cooledmounting device for a highintensity tubular electric la'mp comprising a support member having a hollow interior with inlet and outlet passageways in communication therewith, a readily removable tubular lamp unit having one end extending into the hollow interior of said support member and supported thereby so as to divide the said hollow interior into two separate chambers with the supported end of said lamp unit in communication with one of said chambers, an outer jacket of material permeable to radiations of the lamp and. surrounding said lamp unit so as to provide an outer cooling chamber therebetween, said outer jacket also having one end thereof extending into the hollow interior of said support member and supported thereby with the supported end of said outer jacket in communication with the other of said chambers in said support member, said lamp unit comprising a tubular inner jacket of material permeable to radiations of the lamp and support means in said inner jacket for supporting the said lamp therein and in spaced relation thereto so as to form an inner cooling chamber therebetween, the end of said inner jacket opposite that end thereof supported in said support member being closed, said inner jacket being formed with an opening in the wall thereof at a point intermediate its ends to thereby provide intercommunication between said inner and outer cooling charmbers, and closure means for closing that end of the said outer cooling chamber remote from said support member.

4. A liquid-cooled mounting device for a highintensity tubular electric lamp comprising an elongated base member having inlet and outlet conduits for the cooling liquid, a hollow support member secured to said base member and having an inlet chamber in communication with the said inlet conduit in said base member, said support member also having an outlet chamber, a tubular cooling-liquid jacket structure for said lamp mounted on said base member and supported at one end by said hollow support member, said jacket structure having an inlet opening in communication with the said inlet chamber in said support member and an outlet opening in communication with the said outlet chamber in said support member, and an elongated hollow reflector member mounted on said base member externally of said jacket structure and extending longitudinally thereof and closely adjacent thereto, said support member having a passageway connecting the said outlet chamber therein with the hollow interior of said reflector member.

5. A liquid-cooled mounting device for a highintensity tubular electric lamp comprising a base member having inlet and outlet conduits for the cooling liquid, a hollow support member secured to said base member and having passageways communicating with said inlet and outlet conduits, a tubular open ended outer jacket of material permeable to radiations of the lamp and having one end thereof supported by said hollow support member and in communication with one of said passageways therein, a tubular lamp unit disposed within said outer jacket and spaced therefrom so as to provide an outer cooling chamber therebetween, said lamp unit comprising a tubular inner jacket of material permeable to radiations of the lamp with the said electric lamp mounted longitudinally therein and spaced therefrom so as to provide an inner cooling chamber, said inner jacket being closed at one end and having its other end supported by said hollow support member and communicating with the other of said passageways therein, said inner jacket being also formed with an opening in the wall thereof intermediate its ends so as to provide intercommunication between said inner and outer cooling chambers, and sealing means between said outer and inner jackets for closing the said outer cooling chamber at that end thereoi remote from said hollow support member,

6. A liquid-cooled mounting device for supporting a plurality of high intensity tubular lamps in end to end relation comprising a common support member for supporting the adjacent ends of said lamps, said support'member having a common inlet chamber and a plurality of outlet chambers, and a plurality of cooling-liquid jacket structures for said lamps, one for each lamp, each of said jacket structures being supported at their inner ends in said common support member and having an inlet opening in communication with the said common inlet chamber in said support member and an outlet opening in communication with one of said outlet chambers in said support member.

'7. A liquid-cooled mounting device for a plurality of high intensity tubular electric lamps comprising a common support member for supporting the inner end of each of the lamps, said support member having a hollow interior with inlet and outlet passageways in communication therewith, a plurality of readily removable tubular lamp units each having its inner end extending into the hollow interior of said common support member and supported thereby so as to divide the said hollow interior into a common inlet chamber and a plurality of outlet chambers separate from said inlet chamber with the said inner ends of the lamp units in communication with said inlet chamber, a plurality of outer jackets of material permeable to radiations of the said lamps and each surrounding one of said lamp units so as to provide outer cooling chambers therebetween, each of said outer jackets having its inner end extending into the hollow interior of said support member and supported thereby with the inner end of each of said outer jackets in communication with one of said outlet chambers in said common support member, each of said lamp units comprising a tubular inner jacket of material pervious to radiations of the said lamps and support means in said inner jackets for supporting one of said lamps therein and in spaced relation thereto so as to form an inner cooling chamber therebetween, the outer ends of said inner jackets being closed, said inner jackets being formed with openings in the walls thereof at points intermediate their ends to thereby provide intercommunication between said inner and outer cooling chambers, and closure means for closing the outer end of said outer cooling chamber.

8. A replaceable lamp unit for a liquid-cooled light generating device comprising a high intensity tubular electric lamp, a tubular jacket surrounding said lamp and spaced therefrom so as to provide a cooling chamber therebetween, said jacket being made of a material permeable to radiations of said lamp, support means at one end of said jacket for supporting one end of said lamp and for closing the said end of said jacket to thereby render the same liquid-tight, and terminal means at the other end of said jacket for supporting the other end of said lamp and providing a terminal therefor, said terminal means having an opening therethrough providing a passageway into the said cooling chamber and said outer jacket having an opening in the wall thereof at a point intermediate its ends to provide a second passageway into the said cooling chamber.

CORNELIS BOL.

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