US1715151A

US1715151A - Composite anode for x-ray tubes

Info

Publication number: US1715151A
Application number: US57271A
Authority: US
Inventors: Ulrey Clayton Tridle; Louis F Ehrke
Original assignee: Westinghouse Lamp Co
Current assignee: Westinghouse Lamp Co
Priority date: 1925-09-19
Filing date: 1925-09-19
Publication date: 1929-05-28
Anticipated expiration: 1946-05-28

Description

May 28, V1929. Q T ULREY ET AL 1,715,151

COMPOSITE ANODE FOR X-RAY TUBES Filed Sept. 19, 1.925

lupon the X-ray tube Patented May 28, 1929.

UNITED :STATES PATENT oFFic-E.

CLAYTON VlItIIlrLE ULREY, F EAST ORANGE, AND vLQUIS E. EHR-KE, "0F NEWARK, NEW JERSEY, ASSIGNORS T0 WESTINGHOUSE LAMP COMPANY, A .CORPORATION I 0F PENNSYLVANIA.

COMPOSIAlTE ANODE FOR X-RAY TUBES.

Application led September 19, 1925. Serial No. 57,271.

rllhis invention relates to X-ray tubes and lmore particularly to suoli tubes adapted for diagnostic purposes.

The present invention is an improvement shown in co-pending application, Serial No. 38,395, iiled Junel 20, 1925, assigned to the present assignee and to the X-.ray tubes disclosed by the other applications referred to in said co-pending application.

Our invention and improvement relates 'to the provision in an X-ray tube of the type disclosed in said co-pending applications of means for external coolingand 'more specili- Ically to the construction ofthe anode .unit for securing good heat conduction whereby a greater energy input may be utilized with advantageous results.

In view of the foregoing it is an object of the present invention to provide an X-ray tube of the type disclosed in said co-pending application Tvith external cooling means.

Another object of the invention 1s to provvide 'an anode construction enabling the expeditious assembly and sealing thereof in the envelope-or container of an X-ray tube.

A further .and more specific object of our invention is to provide an anode consisting of a plurality of parts certain of which are of ldifferent metals and Which are so united and assembled that good head conduction is obtained from the target end of the anodefto the other or radiator end.

@ther vobjec-tsof the invention will be apparent as the following description of the in- ,vention is read.

A better understandingvof the invention may be obtained by lreferring to the accompanying draiving in which:

Fig. 1 is a cross-sectional view of an -ray vtube embodying the invention and Fig. 2 is a detailed vieu1 of the anode assembly.

Referring to Fig. 1 of thevdraiving an X- ray tube embodying our invention may comprise a glass envelope 3 of cylindrical'shape to which is sealed at 4 avreentrant tube Which has its end 6 extending in close proximity to tlieend of the container or envelope 3. Enclosing the end 6 of the reentrant tube 5 and supported vthereby is an'inverted cup-shaped metallic screen member 8, said member having a relativelysmall opening 9 in the-end IThe body l12 has Wall Wall 11 thereof. The end G of the reentrant ltube supports a cup-shaped body 12 of insulating material by means of an outwardly projecting fiange 13 integral with said body.

le having small circular opening 15 therein, said opening being in line with the longitudinal anis of the X-ray tube` Disposed Within the insulating body 12 is a filament or electron-emitting cathode 16 b ent in the form of a spiral having a centrally disposed opening 17 which opening is also in axial alignment with the longitudinal axis of the X-ray tube. The ends 18 and 19 of the iilamentary cathode pass throrgh apertures 21 and 22, respectively, in a mica disk 23 and through opening 241 and 25, respectively, in the Wall 11 of the metallic member or screen 18. The mica disl 23 has a central opening 26 therethrouglralso in axial alignment With the longitudinal axis ofthe tube.

The ends 18 and 19 of the lilamentary cathode are Welded or otherwise secured to leading-in Wires 27 and 28, respectively, said Wires being vhermetically sealed in the glass Walls of the envelope 3 or else in presses' 29 and 31 of

stems

32 and 33 fused 'to the Walls of the envelope 3. The leading-in Wires 27 and 28 maybe secured to contact caps 2T and 28 respectively.

The above described structure is fully disclosed and claimed in the co-pending applications referred to heretofore and forms no Vpart of the present invention except where claimed in combination with features subsequently to 'be'disclosed rlhe present invention, as stated heretofore, relates more particularly to constructing the anode in such manner as to provide for external cooling and also to simplify as Well as to reduce the cost of assembly of the component parts of the tube.

The anode as aWhole is designated by the numeral 34 and comprises essentially three parts, namely,-the target portion 35, the seal portion 36 and the radiator portion 37.

The tarlret portion consists of a solid rod or copper or other good heating-conducting moterial which 'has a head portion 38 having a rounded end 39 in which is secured by threading or otherwise a target l1 of good ray-radiating material, such thorium and the like.v A reduced shank 12 extends from the head portion, said shank having a.

Y the target portion to the seal portion 36.

' a pressure the saine,

CII

v tion 47 The seal portion 36 may consistof a rod 'ofcopperlhaving av threaded aperture or recess 46 in one end for receivingthe threaded end 44 of the target portion and an enlarged portion at the opposite end which also has a threaded recess for securing the seal portion to the radiator portion 37. The enlargedpor has an annular iange '49 extending therefrom, said flange being sufficiently thin so that it will stretch and will not exert such upon the glass as tosliear. or break inches has proven satisfactory. It is well known that copper or its'oside will wet glass as to form an hermetic seal therewith.

rIhe radiator portion 37 comprises a` shank 510il aluminum having` a threaded end.A 52 for engaging the threaded recess 48 and having the other end 53reduced in 4cross-section. A brass sleeve 54 is forcedover the reduced end 53 ofthe shank and supports a plurality of radiating vanos or fins 55 of disk-shape spaced apart by washers 56 which latter are clamped to brass sleeve 54 between flanges 5T integral with the latter. The end 58 of the brass sleeve 54 engages ashoulder 59 on the shank 5l. ployed to more firmly securev the radiator on .the shank. The radiator portion 37 may, if

desired, be cast in one piece and be made of aluminum. K Y Y Y The advantages secured by constructing the anode in three parts areas follows:

It is desirable to make the seal portion 36 as a separate unit as it prevents injury Y through oxidation of the target since in seal- Ving the seal portion 36 to glass it is necessary to" heat the copper to aliigh temperature. lllhere the target portion is separate at the time such operation is performed, the heat thus necessary to affect the sealing can not reach the target inasmuch as such operation Vcan be made while the two parts are separated. It is also advantageous to make the seal portion separate from the'standpoint of economy, since in the event of afaulty or damaged seal the main part of the target is Y not lost. ln addition the seals may be made separately and tested before assembling the parts of the anode.

It is of advantage to make the radiator porl tion separate from the seal portion in order to facilitate the construction and to save material and labor in case of a faulty oi damaged seal. l

rlhe heat conduction from the target to the radiator during operation of an X-ray tube embodying the present anode construction is not materially impaired by such construction as the threaded unions between the parts are VVso constructed that the thermal contact iin- Y proves with rise 1n temperature. As will VA thickness of from .008 to .O12V

A washer 61 and screw 62 may be embecomes heated through electronic impact upon the target 41, the copper rod 42 expands and since the heat` is flowing from this portion toward theradiator it is obvious; that said portion will be at a more elevated temperature than the seal portion 36, owing to this difference intemperature and the disposition of the end of 44 of the target portion'in the recess 46 of the seal portion it is obvious that the threaded end of the rod will expand into firm contact with the threads of the recess 46, thus providing forgood heat conduction through this connection.

Conduction of the heat between the 'seal portion 36 and the radiator portion 37 is facilitated by making the portion 5l of the latter o-f aluminum. Owing tov aluminumV having a greater coefficient of expansion than that of copper of which the seal portion is made, it is obvious that contact between the threaded end 52 and threaded recess 43 iinproves as the temperature rises, VA .further advantage in the use of aluminum is that on account of its low density thestress on the seals, due Ato the weight of the radiator, is consideably less than if copper or a heavier metal were used. Y

The anode 34 may be supported within the envelope by means of af sleeve 63 of metal which may have an interiorly threaded collar 64 integral therewith for connection to the threaded portion 43 on the target portion V35. The sleeve 63 is of such size as to frictionally lengage the inner surface of the reentrant tubeV Theseal portion 36 through the thin annul lar flange 49 may be hermetically sealed-at 6T to a flare 68 which in turn may be fused tof the envelope 3 at 69. i Y

As set forth more fully in the co-pending application above identified, the tube may be evacuated in any suitable manner and thereafter mercury vapor orl an inert gas admitted thereto at about one micron pressure. In addition the spacing of the electrodes with respect to each other and the distance between the anode and inner `wall of the reentrant tube .5 should be such thatno appreciable gaseous ionization occurs. The functions of the variousparts of the' device except the anodestructure and the manner in which'the same operates -isl more fully set forth inthe co-pendingV applications heretofore referred to and inasmuch as these form no part of the present invention no detailed explanation is essential 'to a full understanding thereof. It will also be noted that by reason ofthe construction described X-rays generated are taken outvof the tube along its longitudinal axis.

Modicationsof the invention Willroccur to those skilled in the art, however' such modiiications are contemplated as come Within the spirit and scope of the invention as defined by the appended claims.

7hat is claimed is:

l. An anode for an X-ray tube of the character described comprising a` target portion, a seal portion removably secured to said target portion, and a radiator portion, said seal and target portion being composed of the same material and the former having an opening in which said target portion is itted.

2. An anode for an X-ray tube of the character described comprising a target portion of copper, a seal portion of copper and a radiator portion of aluminum, said target and radiator portions being secured in said seal portion, and said seal portion having an opening in which said target portion is fitted.

3. An anode for X-ray tubes and the -like comprising a rod of copper, a seal portion of copper having a recess for receiving the end of said rod, and a radiator portion of aluminum secured to said seal portion.

4:. An anode for an X-ray tube comprising a rod of copper having a target in one end thereof and being threaded at the other end, a seal portion consisting of a threaded recess at one end for receiving the threaded end of said rod, a sea-ling iiange` extending from the other end of said seal portion, and an aluminum rod secured in the last-mentioned end of said seal portion, said aluminum rod having a radiator secured thereto;

5. An anode for an X-ray tube comprising three parts, one part consisting of a rod of copper having a rounded end with a target inserted therein and the other end being threaded, and a threaded portion intermediate the ends of said rod, another part of said anode consisting of a rod of copper having a recess in each end thereof and an annular flange extending from one end, said iange being relatively thin and serving to forni a seal with glass, and the third part of said anode consisting of a rod having one end threaded and having a radiator secured to the other end.

6. An X-ray tube comprising an envelope, a reentrant tube therein and fused at one end thereto, an anode housed Within said tube, Said anode comprising an anode-portion having a target in one end thereof and means for supporting said anode upon the inner side of said tube, and a seal portion secured to said anode portion, said seal portion having a flange for hermetically sealing said envelope to said seal portion.

7. An X-ray tube comprising an envelope, a cathode and an anode therein, focusing means adjacent said anode and cathode, said anode comprising a rod of good heat conducting material, a sealing portion threadedly engaging the end of said rod, and a radiator portion threadedly engaging said sealing portion and means on said rod for supporting the same Within said envelope.

In testimony whereof, We have hereunto subscribed our names this eighteenth day of September, 1925.

CLAYTON TRIDLE ULREY. LOUIS F. EHRKE.