US2098315A

US2098315A - X-ray tube

Info

Publication number: US2098315A
Application number: US735181A
Authority: US
Inventors: Sharp David Gordon
Original assignee: Westinghouse Electric and Manufacturing Co
Current assignee: CBS Corp
Priority date: 1934-07-14
Filing date: 1934-07-14
Publication date: 1937-11-09
Anticipated expiration: 1954-11-09

Description

Nov. 9, 1937. D. G. SHARP` 2,098,315

X-RAY TUBE Filed July 14, 1934 INVENTOR 6'. SHA/ip BYI/-of ATTORN Cal Patented Nov. 9, 1937 UNiThD STAEES hA'ifN'i Qtr-FISE X-RAY TUBE Application `uly 14, 1934, Serial No. 735,181 Y temperature drop between a surface tobe cooled occurs 'at'thepoint of contact'of the lm'with the heated surface as compared with about '75% ofthe temperature drop .occurring at thispoint `6 Claims.

My invention relatesto X-ray devices and comprises in ,particular anew X-ray anode or target which is particularly'adapted'for use in connection with the continuousgeneration of X-rays,

for example, in the administration of therawith Water. 5 peutical treatments. Also consideration ofthe factors of `density and It is usual in the construction of X-rays tubes specific heat vmakes it vessential that at least to provide a surface of refractory metal, such as rtwice Ithe flow 'of oil is necessary to dissipate a tungsten or the like, molecularly secured to a given amount of heat as Would be required in stem of good heat conducting metal, such as water cooling assuming identical ticonditions of l0 copper. During operation of the tube the electransfer which, as Vabove noted, do not exist. tron stream is more or less concentrated upon Moreover, this necessity'for increased owwhen the refractory metal surface resulting in the utilizing oil lsrfmade still more difficult by the generation of considerableheat, which is transgreater viscosity thereof 4at all temperatures, mitted to the stem. The energy for-the tube is which `diierence is very marked yin 4the y'cooler 15 supplied from a high'tension source to be rectiparts of the circulating-system, fled by the' tubeitself OIbY'IlteImttent direct kOf :all .theafo-renoted factors those of density, current when a `separate rectifier is employed. thermal conductivity and specific heat remain Under either ofv these conditions the anode surface constantfor a given medium, but I have found the or targetis subject to `severe mechanicalshocks .factors ofl .lming and Viscosity canbe advan- .20 caused .by the intermittent bombardment thereof tageously dealt with. .By increasing' theY turbuaccompanied by periods 0f intense heating fol- `lence of cw the thickness of-the nlm at the lowed by like intervalscf cooling. This has a tensurfaces of greatest heat may be reduced, which denCY vt0 Cause 'Cracking and tearing of the reit should be noted, is augmented by thefact that 'fractory metal surface as Well as a buckling away the viscosity ofthe oil is'lowest because of the v25 from the back plate. high rtemperature at` this point thus reducingthe For the purpose of preventing undue heating resistance tofow. of the anode in X-ray tubes when employed for Furthermore, by increasing'the Velocity Yof flow therapeutical treatments or other conditions re- .of the medium notonly is the thickness 'ofthe quiring a heavy load, it is common to circulate a film reduced, but the tendency of hydrocarbon 30 cooling and insulating material through the anoils t0 carhonize `at the points of high temode narl endeavor to maintain an even teIIl- Yperature is also substantiallyeliminated, due to Delatllle- If Water 1S employed the deVCe CaImOt the fact that the oil is in vContact with the highly be adVantageOuSly rendered Shockproof because heatedsurface but a verybrief instant owing to of thehigh voltages to which the tube is subjected the high turbulence and Velocity thereof. '.35 and the fact that Water is not dependable as a kIt is. accordingly an object of my present indelectlc medium- AS a COIlSeGlllEIICe a high dvention to provide an .X-ray tube suitable for electric uid is normally utilized, such as hydrocontinuous Operation wherein an ,anode is procarbon oils, but even such uid requires special vided through which a cooling and insulating treatment t0 DIOPBTIY adapt them OI anode C001- material, suchas oil circulates, at high velocity `:i0 ing pUIDOSeS. thereby increasing the eiiciency of :heat trans- In the utilization of any cooling mediumA one of :fer from the heated surfaces to themedium. the mOSt important faCtOlS iS tluloulerlli or hy- Another object of my invention is the provision draulic iiow, which is absolutely necessary to of an X-ray tubehaving an anode which beecelt heat eXChalge in that there iS always comes heated during operation of the tube and v45 a film of the medium in contact with the walls wherein a cooling and insulatingY medium of of the passage through which it flows. The heat khigher viscosity than water is caused to circulate from the body to be cooled must be transmitted therethrough at a high velocity thus reducing through this lmto the turbulent body of a well :thetendency of the mediumto film. mixed cooling fluid. When cooling and insulat- A further object of my present invention is the .50 ing materials, such as hydrocarbon oils and the provision of an X-.ray tube `having an anode like, are employed for cooling purposes there is a which becomes heated during operation of the greater tendency for the same to film overthe tube and wherein a cooling and insulating Vmasurface due to its high viscosity and,'because of terialof ycomparatively high viscosity circulates its 10W thermal conductivity. about 99% oi the Atheretlm)ugh at high velocity and turbulence thusre increasing the eiiiciency of heat transfer and substantially eliminating the probability of carbonizing of the medium at pointsrof greatest heat.

Still further objects of my present invention Will become obvious to those skilled in the art by reference to the accompanying drawing wherein:

Figure 1 is a side view of an X-ray tube constructed in accordance with my present invention,

Fig. 2 is a longitudinal sectional view of the anode construction of my tube,

Fig. -3 is a sectional View taken on the line III-III of Fig. 2 looking in the direction of the arrows, and Y Fig. 4 is a sectional view takenY on fthe line IV-IV of Fig. 2 looking in the direction indicated by the arrows. a

Referring now to the drawing shown in Fig. 1 an X-ray tube comprising an evacuated envelope 5 having a reentrant sleeve Y6 forming an inner fold extending a substantial distance longitudinally of the envelope to well of this reentrant sleeve l.

A further reentrant stern I2 extendsinwardly of the envelope and has sealed thereto the anode electrode I3 which receives energy through a con- Y ductor I4. By reference more particularly to Fig. 2 this anode comprises a hollow metallic member I5, such as spun copper or the like, sealed to this reentrant portion of the envelope.V

A head or back plate I6 of good heat conducting material, such as copper or the like, is molecularly secured to the member I5 and this head in turn is provided with a target face I'I of a refractory metal, such as tungsten, secured thereto adjacent the cathode which Vreceives the electron bombardment during operation of the tube.

This electron bombardment being more orV less concentrated upon the target I'l, causes the generation `of considerable heat particularly when the tube is continuously operated for long periods of time as in the administration of therapeutic treatments. This heat is in turn transmitted to the copper head or back plate I6 and in order to transfer this heat and maintain the temperature of the entire anode substantiallyv uniform I provide a structure for circulating an insulating Yand cooling medium through the anode stem.

The interior of the hollow member or anode stemV I5 has suitably secured thereto an annular threaded ring or the like I8 and an elongated thimble like member I9 is arranged to threadedly engage this ring I8 being screwed in place by a suitable tool engaging recessesv 20 provided in the thimble. rlhe thimble I9 is provided with a shoulder portion 22 of increased diameter'with its outer periphery spaced closely to the interior of the member I5 and the endV of this thimble I9 is provided with a concave surface or face 23 spaced a Short Ydistance from the end of the member I5 to which the copper head I 6 is secured. While I have-shown the member I5 as having a closed end to provide more surface area for the purpose of molecularly Vsecuring the back in detail I have plate I t thereto and to facilitate ease of construction, it is to be understood that this may be open ended thus allowing the face 23 to be spaced a short distance directly in the rear of the back plate I5.

Moreover, this end of the member I5 is more or less integrally united with the back plate IB and for all intents and purposes may be considered as a part thereof. Accordingly throughout my specication and claims I shall refer to the back plate as being spaced directly from the face 23 of the thimble I9 and directly contacted by the cooling and insulating material. 'I'he opposite end of the thimble is likewise provided with a shoulder portion 24 and a series Vof spacer Washers 25 are disposed between this shoulder portion 24 and the annular ring I8 for the purpose of adjusting the spacing between the concave end surface of the thimble and the adjacent surface of the back plate I6.

A longitudinal opening having a reduced diameter portion 26 and a portion'ZI of larger diameterv Yextends through the thimble I 9 from the center of the concave face 23. An inlet conduit 28 of suitable insulating material, such as hard rubber or a phenolic condensation product, threadedly engages tiie reduced diameter portion 2E and projects' beyond the envelope for connection to a suitable oil reservoir. Y

In a similar manner a concentrically disposed outlet conduit 29 surrounds the inlet conduit which is formed of the same insulating material and threadedly engages the thimble I9 at its increased diameter portion 2'I. A plurality of radi- 'ally disposed passagesY V30, as shown more clearly vtion of Louis F. Ehrke, Serial No. 754,231 filed November 22, 1934 and assigned to the same assignee as the present invention, and also to the thimble I5 to prevent clinging of the cooling and insulating material with the formation of an undesirable deposit as hereinafter more fully described. v

In the operation of the tube a cooling and insulating material, such as a high grade hydrocarbon oil, is caused to flow from a suitable reservoir through the inlet conduit 28 toV the concave face 23 of the thimble I9. Due to the spacing between this end of the thimble and the rear surface of the back plate I6, which is the point of greatest heat, as well as the configuration of the thimble surface 23 a high turbulence of the oil results with an attendant high velocity in the flow thereof. This accordingly prevents too great a illming of the oil at the point or surface of greatest heat with a rapid flow of sufficient volume 0fV the fluid to transfer the generated heat thereto. The oil then circulates around the periphery of the shoulder portion 22 into the annular passage formed by the latter and the ring I3 after which it enters the outlet conduit 29 throughV the radial openings 3) and returns to the reservoir for cooling.

Y prevents, too great a filming of the oil witha concentration of heat transfer at the surface of greatest heat, but likewise eliminates the pcssi- Y 'bility of the oil carbonizing by leaving deposits which would ordinarily occur offering an impediment to the flow thereof, as well as acting as a heat insulator. This is further augmented by the coating of nickel or other metal upon the greater portion of the surface of the copper thimble I9 and the adjacent surface of the member l5, which is contacted by the oil when at its highest temperature. The possibility of the cil forming a chemical deposit with the copper is eliminated by this metallic coating which has a polished surface offering less resistance to the flow of the heated oil as well as the fact that the particular metal employed has a less anity for the various elements composing the oil than would copper. This latter feature of providing the coating 32 upon the inner surface of the hollow anode stem l5, however, forms no part per se of my present invention but is specifically shown and claimed in the aforenoted copending application.

It thus becomes obvious to those skilled in the art that I have provided an X-ray tube suitable for `continuous operation for therapeutical purposes wherein an anode is provided through which a cooling and insulating material circulates for transferring the heat generated during operation of the tube. By increasing the turbulence and maintaining a constant velocity of iiow at the surface of greatest heat an increase in the efficiency of heat transfer is obtained. Moreover, by increasing the velocity of flow at the critical area or region where high turbulence is needed and low viscosity is available through high temperature, resistance to the flow of oil in this region is reduced to a minimum, and the maximum amount of oil surface is presented in the path of heat flow immediately in back of the target without possibility of resulting carbonization of the oil.

Although I have shown and described one specific embodiment of my invention I do not desire to be limited thereto as various other modifications thereof may be made without departing from the spirit and scope of the appended claims.

What is claimed:

l. An X-ray tube comprising an envelope, a cathode, an anode including a refractory metal target which becomes heated during operation by electron bombardment, a back plate of good heatI conducting material for supporting said target and a hollow anode stem for supporting said back plate, and means for uniformly circulating a cooling and insulating material over the maximum surface area of said back plate rearwardly of said target including a member disposed interiorly of said anode stem having passages for the ingress and egress of a cooling and insulating material, and said member being of such size relative to said back plate and having a concave surface spaced a short distance from the adjacent rear surface of said back plate so as to impart a, high turbulence and high velocity to said cooling and insulating material at all points of greatest heat to enable said material to flow over the surface of said back plate without lming and to effect maximum heat transfer from said anode to said cooling and insulating material.

2. An X-ray tube comprising an envelope, a cathode, an anode including a refractory metal target which becomes heated during operation by electron bombardment, a back plate of good heat conducting material for supporting said target and a hollow anode stem for supporting said back plate; and means for uniformly circulating a cooling and insulating' material over the maximum surface area of said back plate rearwardly of said target including a member threadedly engaging the interior of said anode stem provided with a concave surface spaced from the adjacent rear surface of said back plate and having a smooth polished coating of a metal offering a negligible resistance to the flow of a cooling and insulating material, and inlet and outlet passages provided in said member for the circulation cf a cooling and insulating material interiorly of said anode stem and in Contact with said back plate, said inlet passage terminating coaxially with the concave surface of said member whereby a high turbulence and high velocity is imparted by said concave surface to said cooling and insulating material at points of greatest heat to cause flow thereof over the maximum surface area of said back plate with substantially no resistance thereto and maximum heat exchange is effected between said anode and said cooling and insulating material.

3. An X-ray tube comprising an envelope, a cathode, an anode including a refractory metal target which becomes heated during operation by electron bombardment, and means disposed interiorly of said anode for circulating a cooling and insulating material at a high constant velocity interiorly of said anode, said means being spaced in close proximity to the rear surface of said anode immediately in back of said target and having a surface of a diameter slightly less than the internal diameter of said anode, and said surface being angularly disposed relative to the rear surface of said anode so as to impart a high turbulence to said material to cause a rapid flow thereof over the maximum surface of greatest concentration and to effect efcient heat transfer from said anode to said material without the formation of a heat-absorbing film impeding the uniform flow of said material.

4. An X-ray tube comprising an envelope, a cathode, an anode including a refractory metal target which becomes heated during operation by electron bombardment and a back plate of good heat conducting material for supporting said target, and means disposed interiorly of said anode for circulating a cooling and insulating material Vat a high constant velocity immediately in back of said back plate, said means being spaced in close proximity to the surface of said back plate and having a surface of a diameter slightly less than the internal diameter of said anode, and said surface being angularly disposed relative to the surface of said back plate so as to impart a high turbulence to said material to cause a rapid flow thereof over the maximum surface of greatest heat concentration of said back plate and to effect efficient heat transfer from said anode to said material without the formation of a heatabsorbing film impeding the uniform flow of said material.

5. An X-ray tube comprising an envelope, a cathode, an anode including a refractory metal target which becomes heated during operation by electron bombardment and a back plate of good heat conducting material for supporting said target, and means for uniformly circulating a cooling and insulating medium over the maximum surface area of said back plate including a member spaced from said back plate having passages for the ingress and the egress of a cooling and insulating material, and said member having a surface adjacent to said back plate spaced in close proximity thereto and of a diameter slightly less than the internal diameter of said anode in order to impart a high turbulence and a high velocity to said cooling and insulating material immediately in back of said back plate to enable the material to ow uniformly over the entire surface of said back plate of greatest heat concentration and to eect maximum heat transfer from said anode to said Vcooling and insulating material.

6. An X-ray tube comprising an envelope, a cathode, an anode including a refractory metal target which becomes heated during operation by electron bombardment and a back plate of good heat conducting material for supporting said target, and means for uniformly circulating a cooling and insulating material of comparatively high viscosity over the maximum surface area of said back plate rearwardly of said target including a member spaced from said back plate have ing passages for the ingress and the egress of a cooling and insulating material, said member having a surface adjacent to said back .plate in close proximity thereto and of a diameter slightly less than the internal diameter of said anode in'order to impart a high turbulence and a high velocity to said cooling and insulating material immediately in back of said back plate and to cause the material to iiow uniformly over the entire surface of said back plate Without forming an impediment to the iiow thereof, torpresent maximum amount of cooling and insulating ma'- terial surface in the path of greatest heat flow Vto effect maximum heat exchange between said anode and said cooling and insulating material.

D. GORDON SHARP.