US1975880A - Electrical discharge apparatus - Google Patents

Description

INVENTORS ATTORNEY Oct. 9, 1934. c. T. ULREY ET AL ELECTRICAL DI SCHARGE APPARATUS Filed Nov. 1, 1952 Patented Got. 9, 1934 ELECTRICAL DISCHARGE APPARATUS Clayton Tridle Ulrey, East Orange, and Norman I 0. Beese, Verona, N. J., assignors to Westinghouse Lamp Company, a corporation of- Pennv sylvania Application November 1, 1 932, Serial No. 640,632 .11 Claims. (01. 250-35 This invention relates to electric discharge devices embodying means adapted to indicate the condition and especially the thermal characteristic of some constituent thereof. In its more 5 specific aspect the invention is directed to an X-ray tubeembodying means adapted to apprize an operator thereof of the thermal condition of the anode and especially that portion. of the anode embodying the X -ray emanating target.-

Generally, electrical devices, such. as X-ray tubes, comprise an evacuated envelope having a plurality of oppositely disposed electrodes located therewithin. Qne of these electrodes, termedthe cathode, is commonly in the form of a filament. 'This filament has its terminals connectedto the secondary winding of a low voltage transformer frompwhich it obtains electrical energy which heats the filament to incandescence, and thermionically active temperature.

erally comprises a metallic rod, such as copper or The other electrode, termed the anode, genthe like, having embedded in theend thereof opposite the, cathode-a discv or plate of an X-ray emitting material, such as tungsten or the like.

When a voltage is applied between the cathode and the. anode theelectrons emitted at the ca thode due to its temperature are caused. to mi,- grate from the cathode andbe directed upon'the tungsten target with sufficient. velocity to cause X-ray emanations from. said target. The type of X-rays thatemanate from the target may be hard or soft X-rays depending upon the magnitude of the voltage applied between the electrodes;

. In practice it has been found ,thatthe target becomes heated due to the'electrons impinging thereon and that when some X-ray tubes are operated over an extended period of. time'that the target itself may become heated to such an extent and its temperature raised to such a degree that fusion thereof results;

Target heating and overheating with the consequent fusion thereof has heretofore been appreciated and known to thoseiskilled in the art. In order that overheating with the consequent fusion of the target might be obviated it is sometimes necessary that the voltage between the anodeand cathode be. removed. At such times when the operation ofan X-ray tube over an extended priod of time is-desired there is no clear, simple and infallible, visible or other mleans in an X.-ray apparatus which would indicate that,

the temperature of thetarget is in the vicinity of. its critical temperature, the fusion pointthereof.

might readily ascertained so that the necessary steps maybe takento obviate ,target'fusion it hasheretofore been proposed by Ulrey, in his Patent 1,704,267 issued -March 5, 1929 which. patent is assigned to the same assignee asthe present, invention, to employ in combination with. an X-ray tube'a thermo-couple comprisig a plu' ralityof conductors composed of dissimilar metals united at one end. This thermo-couple ex tends within the envelope of the X.-ray tube and has its-junction embedded in the anode at a position in the" vicinity: of the .target'embedd'ed saidanode. I. Although this heretofore proposed constructionhad admirably served the purpose for which it was intended, we have in the course; of our experimentations'in this field developed thepresent inventionwhich is a substantial improve-f ment over that hereinbefore briefly described.

Our invention contemplates the provision of an Xeray tube embodying a' thermo-co'uple which construction employs the anode as one of. the elements of a thermo-couple; which construction maybe readily, expeditiouslyand'inexpem sively manufactured; which construction is simpler and has fewer parts than the constructions heretofore proposed; which'construction is more attractivethanthose heretofore proposed 'and which construction in spite of having fewer'parts' at least as. sensitive and; enables one to obtain; as true an indication of the target temperature as'those heretofore'proposed for the same general purposes. a

Brieflystated our invention contemplates the provision of a single'additional wire'as one of the elements of a thermo-couple within the envelope' of an ordinaryiX-ray tube, and the utilization of the anode'per se and the anode extension as the other element of the thermo-couple. Thus the anode and anode extension perform dual functions. They together serve as an element of the X-ray tube and simultaneously as 'an' element of the thermo-couple. Across-said anode' extension and said single wire is'electrically connected any suitably: calibrated indicating device'- which may'indicate the temperature of the target so' that the operatormay be informed as to its thermal condition. The indicator clevice'may consist of any standard form-of any-appropriately calibrated 'millivoltmeter or galvan'ometer, the. constructional andxfunctionalfeatures of which arewell" known andform no part of the present invention; 1 :1 r r i r One'of the objects oflour invention is to provid'e an electric discharge device' embodying a;

thermo-couple which combination may be relatively readily, expeditiously and inexpensively manufactured.

Another object of our invention is. to provide an electric discharge device embodying a thermocouple thecombination of which is relatively simple and attractive and consists of relatively few parts.

A still further object of our invention is to provide a relatively simple and attractive X-ray tube having a thermc-couple associated therewith, which combination performs the function of an X-ray tube and has a relatively sensitive thermogouple associated therewith.

Our invention finds application in a number of different types of electric discharges devices, but for the sake of. simplicity and conciseness, and

further, so that .the advantages attendant therer to may be readily apparent, we will describe it as 20 .7

applied to an X-ray tube. Although the invention is applicable to most, if not all of the X-ray tubes, we will hereinafter describe its application to the type of construction disclosed in the patent application of Nelson H. Stewart, Serial No. 578,244, filed December 1, 1931, and assigned to the same assignee as the present invention. The illustrative embodiment of the invention hereinafter described is to be taken by no meansin the way of limitation, but merely in a manner of illustration. n

A clear understanding of our invention may be obtained from the following description and appended drawing wherein;

Figure .1 represents an elevational view with some of the parts in section of an X-ray device embodying our invention;

Figure 2 is a cross section of Figure 1 along lines IIII of Figure 1 in the direction of the arrows;

Figure 3 is similar to Figure 2 and represents a cross sectional view of a modification of Figure 1; and

Figure 4 represents a modification of the anode and thermo-oouple construction illustrated in Figure '1.

As shown in Figure 1 the X-ray tube therein illustrated may consist of a glass envelope having a body portion 11 of generally cylindrical form, with a hemispherical upper portion 12 at one end and a reentrant tube 13 at its other end.

This reentrant tube 13 extends upwardly into the' body portion and has a major portion thereof spaced therefrom. To the upper end of said reentrant tube 13 is hermetically sealed a metallic tubular and preferably copper sleeve or support coupling 14. Secured to the upper end of said support coupling 14 is an anode 16 measuring about one and one eighth inches in diameter and composed of copper or the like.

The support sleeve or coupling has means, and as shown a threaded recess, in which is screwed a metallic and preferably a copper rod 15 also about one inch in diameter, which ordinarily functions as a heat and electrical conducting element of the common X-ray tube.

The anode 16 and the anode extension 15'are in axial alignment, with the anode 16 being located in the evacuated spacewithin the envelope, and the anode extension 15 being located outside of said envelope and extending substantially beyond the lower limit of the envelope.

' On to the free end of said anode extension 15 is secured by means of a stud bolt or other advisable means a radiator 18 which as shown consists of a plurality of aluminum fins. The upper or free sten or the like, serving as an X-ray emitting.

mamrial upon bombardment thereof by the electrons from a suitable electron emitting filamentary cathode, (not shown).

Disposed around andhaving its interior wall 7 spaced from the free or target end of the anode 16 is an X-ray screen 20 composed of nickel-iron or the like. This X-ray screen houses both the cathode and a focusing cup (both not shown). The cathode is electrically connected to a plural ity of conductors 21 and 22 which are hermetically sealed to the envelope 10, and electrically secured to contact caps 23 and 24 respectively located on the exterior of the envelope near the hemispherical end thereof.

Surrounding this metallic screen and functioning to provide a screen supporting and shock absorbing means are a plurality of resilient plates 25 which bear against the outer surface of saidscreen and the interior wall of the envelope.

Located within the envelope and extending upwardly therewithin is a second reentrant tube 26 surrounding and spaced from the tubular sleeve 14 and the anode 16. This reentrant tube is of a material length and has its lower edge fusibly united with the envelope.

Secured to said anode may be a resilient sleeve such as that disclosed in the patent to Ulrey No. 1,715,152 issued May 28, 1929 and assigned to the same assignee as the present invention, or as shown, resilient plates or spring means 45 such as those described by Blakeman in United States patent application Serial No. 560,738, filed September 2, 1931 and assigned to the same assignee as the present invention.

An inverted cup shaped shielding means'27, M composed of copper or the like, has its base resting upon the upper shoulder of the tubular mem ber 14' and has a portion thereof located therebetween and the lower end of the anode 16. The cylindrical portion of this shield extends downwardly, surrounds and is spaced from the tubular sleeve 14, the seal and the upper portion of the reentrant tube portion 13.

According to our invention and as shown in Figures 1 and 2, We provide a simplified structure wherein the anode 1.6 serves as an electrode and a heat radiating means for the X-ray tube, and also as one of the elements of an indicating means, and specifically a thermo-couple.

As illustrated the anode 16, at a position below and substantially inthe vicinity of the target 19 is bored to provide a small diameter recess 28 located adjacent said target. Extending longitudinally of the anode from the lower end thereof up to said recess 28 is a shallow, relatively narrow groove 29 adapted to accommodate an element 30, which together therewith forms a thermo-couple, and adapted to receive also an insulating sleeve 31 of quartz or the like, surrounding said element 30. The groove 29 may be readily formed by a simple milling operation.

The single wire 30 may be composed of any metal or alloy other than copper, as for example nickel, nickel alloy and the like, having the desired thermo-couple properties. The thermocouple wire 30 has a relatively short bent portion lid 33 extending about normal to the major portion thereof and located in the recess 28. The remaining length of wire contiguous therewith extends along the longitudinal groove, along the shield 27 and over to and through one side of the envelope near the lower portion thereof, wherein it forms an air tight seal therewith, with a portion thereof extending outside of the envelope.

This small portion of thethermo-couple wire extending outsidetheenvelope is elctricallyse cured to a metallic cap 34 located on the exterior of said envelope. In order that the bent portion extending within the recess maybe in close contact with the anode 16 and on that side of'the re-. cess closest to the plane of the target there is provided a plug, peg or wedge 35 composed of the.

same-material as the anode, asfor'example copper.. This plug, pegor wedge maybe driven into the recess containing said bent portion of the thermo-couple wire and serves tofirmly locate one end of said wire and to force said. bent portion into good contact relation with-the anode to form a good thermo-junction. Any other desirable method or means of forming a good thermojunction between the anode 16 and the end 33 of. the thermo-couple wire 30 may be employed. The plug, peg or wedge 35 we regard as part of the anode; f In orderthat the anode and the thermo-couple wire may efiiciently function as a thermo-couple and to provide an attractive structure, there is provided over the thermo-couple wire the di-electrio sleeve 31, as for example quartz or the like.

This di-electric sleeve 31- totally surrounds that portion of the wire extending from the upper end of the groove andbelow the free end of the shield. As shown this (ii-electric shield has a bore of sufficient' diameter adapted to accommodate the thermo-couple wire '30 and an outside diameter of such dimension as to fit snugly in said groove 29.

The thermo-couple wire 30, together with its dielectric sleeve 31, may be readily fixed in the groove 29 of said anode 1-6 by any appropriate means and one means, as shown in Figure 1, comprises providing the anode along appropriate lengths thereof with circular shallow grooves 36. Tie wires 37 of copper or the like are located in these grooves so as to fixedly secure said thermo couple wire 30 togetherwith insulation 31 to the anode and thus prevent any liability of insulation fracture. Further, a tie wire 32 fixedly secures the insulated thermocouple wire to the shield 27, as shown in Figures- 1 and 4.

One other means that we have found suited for the purpose of fixing the thermo-couple wire 30 together with its insulation 31 to the anode is disclosed in Figure 3. As therein disclosed there is obviated the necessity of providing spacedcircular grooves on the surface of the anode to accommodate tie wires and also the tie wires themselves.

'As shown, for this purpose we may'provide a plurality of grooves 38 and 39, forming a groove of dovetail form. The grooves 38 ing to our invention may replace the groove 29 illustrated in Figures 1 and2. The groove 38-extends longitudinally along the anode. U

Below said groove-38 and having its upper limit contiguous with the lower portion of the groove 38 is a shallow groove 39 of the same general dimensions as the-groove 29'heretofore described in connection with Figures 1 and 2. In this con struction the thermo-couple wire 30 together with its insulating sleeve 31 is located substantially within the lower groove 39.

A key 40, composed of a material preferably the same as that of the anode 16 and being of such a configuration and dimensions that it may be sliddisplacement thereof and and 39 accord ably mounted in the; dovetail groove38, is located in said groove 38 so that the anode appears to be a substantially unitary, homogeneous structure. The key 40, assembled insaid groove 38, frictionallyengages the outer surface ofv said insulating material 31 so as to holdor fix the same together with the thermo-couple wire, 30 ina relatively permanent position.

Although we; have described means, such as a key, 4001 thetie wires 3'7 for fixing the thermocouple wire and insulating sleeve to the anode it is within the scope of this invention to include any means for holding said thermo-couple wire and insulator to said anode. The invention'also contemplates forthis same general purpose the utilization of only the springmeans 45. This spring means may be located between the anode 16 and the second reentrant stem 26 sothat they are in frictionalengagement with a portionv of the anode, the insulating covering 31 and the inner surface of the reentrant tube. Another embodiment of our invention is illustrated in Figure 4 andis essentially a-modification of the construction shown in Figure 1. As shown the anode thermo-couple construction comprises an-anodesimilar to that illustrated in Figure 1, except that the-anode shown in Figure 4 has a small bore elongated opening 50 extending I through approximately the center thereof with A thermo-couple wire 54 extending through a copperplug '56 whose external diameter is about the same diameter as that of the .bore 50 has one end thereof welded to said copper plug as at. 57,

which copper plug is firmly securedinthe closed end of the boret50 by any. appropriate pressure means.-- x

The copper plug 56 or other appropriate means for. forming agood thermal contact between the anode. proper and the wire 56 we regard as. part of the anode 16. The thermo-couplewire extends throughthe bore. 50, the. large bore '52: and.

the side bore 53.. Surrounding saidthermo-couple wire are a plurality of quartz lengths of tubing'55' which insulates from the anode that portion. of

the thermo-couplev wire beyond thejunction.

It. has been found thata construction embodying the features hereinbefore described may readily be associated with an appropriate indicating means so that the operator'maybecome cognizant of the temperature ofthe target, at any time during the operation of said tube. The general hookup involved in associating an indicating device therewith is illustrated in Figure 1 andcomprises an electrical conductor connection 41 between an appropriate terminal of the appropriately .calibrated and shielded corona proof millivoltmeter 42.and the radiator 18, and an electrical connection 43 between the other terminal of said meter to the cap 34. The shielded case is electrically connected to the conductor 41 by a suitable conductor.

Although we have described with particularity our invention together with its associated parts, it has been done only so that the invention may be readily practiced. The scope of the invention is to be limited only by the prior art.

What is claimed is: I

1. The combination of a thermo-couple and an electrical discharge device including an envelope, a plurality of electrodes therein, one of said electrodes being an element of the thermo-couple and having a groove in the surface thereof, an electrical conducting element, difiering in composition from that of said one of said electrodes,

secured to said one of said electrodes, and insu-' lating means in said groove between said ele-- ment and said one of said electrodes, a'thermojunction consisting of said one of said electrodes and said element, said one of said electrodes be ing the other element of the thermo-couple.

2. The combination of a thermo-oouple and an electrical discharge device comprising an envelope, a plurality of electrodes therein, one of said electrodes having a recess therein and a groove extending along the surface thereof, and an ele ment differing in composition from that of said one of said electrodes, said element having a portion thereof in said recess and contiguous with said one of said electrodes and insulating means in the groove between'said one of said electrodesand said element, said one of said electrodes and said element forming 'a' therino-jun'ction at the contiguous areas of said one of said electrodes and said element, said one of said electrodes and the elements of a thermoa portion thereof contiguous witha portion of said element and forming a thermo-junction therewith, another portion of said element located in said groove, insulating means between the surface of the groove and said element lying there-' Within; said anode and said element being elements of the thermo-couple.

a. The combination of a thermo-couple and.

an electrical.discharge-device comprising an en-- closing envelope, an anode, a cathode, and an element therein, the =thermo-junctio-n of said thermo-couple consisting of a portion of said element contiguous with said anode,'a groove in said anode, another portion of said element in said groove, insulatingmeans between said element and the surface of said groove'and means maintaining said element in said groove.

5. The combination of a thermo-couple and an X-ray, device'comprising an enclosing envelope including an anode, a' cathode and an element of a composition other than that of the anode located therewithin, said anode and a por-' tion of said element being contiguous to form a thermo-junction, said element and said anode be? ing elements of the thermo-couple.

6. The combination of a thermo-couple and an X-ray tube comprising an enclosing envelope including a cathode, an anode and an element, said element being a metallic composition other than that of said anode, said anode having a target portion, the thermo-junction of said thermocouple consisting of a portion'of said element contiguous with a portion of said anode other than the target portion, said anode and said element being elementsof the thermo-couple.

7; The combination of a thermo-couple and an X-ray device comprising an enclosing envelope including an anode, a cathode and an element therewithin, thecomposition of said element differing from that of said anode, .said anode having a target portion the thermo-junction of said thermo-couple consisting of a portion of said element contiguous with said anode at a position relatively close to said target, another portion of said element insulated from said anode, said anode and said element being elements of the thermo-couple; 8. The combination of a thermo-couple and an X-ray tube comprising an enclosing envelope including an anode, a cathode and an electrical conducting element, said element being of a composition other than that of the anode, said anode having a groove therein, a portion of said element being contiguous with said anode to form a thermo-junction, another portion of said element located in said groove, an insulating sleeve on said element and in said groove, said element and said anode being elements of the thermo-couple.

-9. The combination of a therrno-couple and an Xray tube, comprising anienclosing envelope, an anode,.a cathode and an element therewithin, said element being of a metallic composition other than that of the anode, saidpanode.

having a longitudinal groove in the face thereof, the thermo-junction of said thermo-couple consisting of a portion of said element contiguous with said anode, another portion of said element located in said groove and insulated thereat from the anode and means maintaining said element in position, said anode and said element being elements of the thermo-couple.

10. The combination of a thermo-couple and an X-ray tube comprising an envelope, an anode, a cathode, and an element, said element being of a metallic composition other than that of said anode, said anode having a groove in the face thereof, said element having a portion thereof contiguous with the anode to form a thermoiunction therewith, another portion of said element surrounded by refractory insulating sleeve located'in said groove, said anode and said element being elements of the thermo-oouple.

ll. The combination of a thermo-couple and anX-ray tube comprising an envelope having an anode, a cathode and an element therein, saidelement composed of a material other than that of said anode, said element having a portion thereof contiguous with said anode, a longitudinal groove extending along said anode, a refractory insulating sleeve surrounding another portion of said element and located in said groove, and still another portion of said-element sealed to said envelope, and a keyin the groove of said anode fixing the element and insulating sleeve therefor therewithin, said anode and-said element being elements of the thermo--couple.

v CLAYTON TRIDLE ULREY.

NORMAN C. BEESE.

Images