US3277327A

US3277327A - X-ray diffraction tube

Info

Publication number: US3277327A
Application number: US147948A
Authority: US
Inventors: Robert M Gager; Zed J Atlee; John T Perry
Original assignee: Dunlee Corp
Current assignee: Dunlee Corp
Priority date: 1961-10-26
Filing date: 1961-10-26
Publication date: 1966-10-04
Anticipated expiration: 1983-10-04

Description

Oct. 4, 1966 Y R. M. GAGER Em. 3,277,327 I XRAY DIFFRACTION TUBE Filed Oct. 26, 1961 l a Fig. I 1 so I24 2b n? no 122 I27 "J g as 28 88 i l I I 26 90 x 92 5 5 I28 I26 I29 I -/34 6 6 I50 Q d -3 1. 5

Q INVENTORS.

ROBERT M. GAGER ZED J. ATLEE JOHN T. PERRY B) BUCKHORN, CHEATHAM 8 BLORE ATTORNEYS United States Patent 3,277,327 X-RAY DIFFRACTION TUBE Robert M. Gager and Zed J. Atlee, Elmhurst, and John T. Perry, Melrose Park, Ill., assignors to Dunlee Corporation, Bellwood, 111., a corporation of Illinois.

Filed Oct. 26, 1961, Ser. No. 147,948 6 Claims. (Cl. 313-55) The present invention relates to X-ray tubes and more particulraly to a new and improved construction of a diffraction-type X-ray tube.

It is an object of the present invent-ion to provide a new and improved X-ray diffraction tube having improved operating characteristics.

More particularly it is an object of the invention to provide an X-ray tube having superior electrical stability over an extended period of life of the tube.

Still another object of the invention is to provide a difiraction tube having minimum exterior dimensions without sacrifice of the length of the focal spot.

These and other objects of the invention will become more apparent hereinafter.

In accordance with the illustrated embodiment the X-ray tube of the present invention comprises an anode target mounted in the end of an elongate supporting tube which forms the outer wall of the tube. anode is a filament mounted in the end of a cathode structure including an elongate supporting tube extending within and coaxial of the outer anode-supporting tube. The filament is mounted in a focusing cup formed in a cylindrical body which is secured within the end of the cathode-mounting tube by a unique arrangement which minimizes the possibility of electrical disturbances. Unique arrangements for mounting the getter and for connecting a source of power to the filament leads are also provided and which are described in further detail in the following description of the invention taken in conjunction with the accompanying drawings wherein:

FIG. 1 is an elevation partially in section of a diffraction tube made in accordance with the invention;

FIG. 2 is an enlarged fragmentary section showing the detail of the mounting of the windows in the tube envelope;

Referring to the drawings, the diffraction tube of the invention comprises an envelope including an outer tubular glass portion 20 having a reentrant inner portion 22. The tube portion 20 is connected through a glass-tometal seal 24 to a metal sleeve 26 which is suitably secured as by brazing to an annular ring structure 28 and by means of which the tube may be supported in a suitable housing. The ring 28 is brazed to a tubular metal housing 30, which in turn is connected at 3 2 by a lap-joint to a housing portion 64 square on its exterior surface but having a tubular bore and in the end of which is mounted an insert or target member 3 6 comprising a body of copper the face of which may be flat and serve as a target or which may have a target element 40 of a desired metal embedded therein.

The housing 34 is provided with a plurality of windows ,42 through which X-rays may be emitted from the target Facing the "ice Mounted on the end of the anode back of the insert 36 is a cap '50 having a bore 5 2 therethrough to which an inlet water line may be connected for admitting water to the back of the target member 36 which is recessed, as indicated at 54, to permit the water to flow across the back surface thereof. The edge of the insert 36 is cut away at one point to provide an escape path of the water to an annular recess 55 formed in the end surface of the anode portion '34 and thence to a discharge passage 56 in the cap '50.

Means are provided for gettering the gases remaining within the envelope after exhaustion of the same. Mounted on the ring 28 is a sleeve or shield 60 which extends past the glass-to-metal seal 24. The shield is provided with a relatively wide annular groove 62 opposite the seal 24 so as to maintain clearance between the seal and the shield. The free end of the shield is provided with an outwardly turned flange '64 and immediately adjacent thereto the outer surface of the shield is provided wit-h a further groove 66. Referring to FIG. 3, this latter groove is adapted to retain a wirelike getter element 68 comprising a length of tubular wire dined with a suitable gettering material, such as barium, magnesium or a mixture of such materials. One side of the wire is ground away to provide a thin wall section 69 through which the getter may escape when vaporized. After the envelope has been exhausted by mechanical means of as much air as possible, the getter element 68 is flashed by inductively heating the shield 60 with a coil arranged externally of the envelope. The heat from the shield 60 will transfer to the gettering element, causing the gettering material to vaporize and escape through the thin wall portion 69. The escaping gettering material will tend to deposit upon the adjacent cooler surfaces of the glass-to-metal seal 24, sleeve 26 and envelope 20, thus providing a conductive coating 70 over the seal which, during operation of the tube, lessens the electrical stress to which the seal may otherwise be imposed. It will be observed that while the flange 64 confines the gettering material to the area opposite the shield 60, the gettering material is relatively in the open so that any residual gases within the envelope or escaping occluded gases may readily contact and be absorbed by the gettering material. It is, furthermore, readily visible so that it can readily be determined whether or not a successful flash has been made.

The external surface of the glass-to-metal seal 24, the sleeve 26 and envelope 20 in the vicinity of the glassto-metal seal preferably are coated with graphite or a similar conductive coating 71 to equalize potentials thereover and minimize spitting. The remainder of the enevlope 20 may be provided with a coating 72 of a ceramic material, to protect the envelope from puncture from discharge between the envelope and the housing (not shown) in which the tube is mounted.

Turning now to the cathode structure of the tube, the cathode comprises an elongate mounting tube secured at one end to the reentrant portion 22 of the glass envelope portion 20. As will be noted in FIG. 1, at its internal end the reentrant portion 22 is necked down to a smaller diameter and is connected by a glass-to-metal seal 82 to a metal sleeve 84. The sleeve 84 is brazed to a cylindrical header 86 to which the tube 80 is secured in vacuum tight relation. The sleeve 84 and the tube 80 are spaced a slight distance apart so as to define -a peripheral groove 88 between them. Surrounding the end of the tube 80 adjacent the sleeve 86 is a shield 90 having a portion 92 spaced from, but surrounding the glass-to-metal seal 82, to protect the same from stray electrons. The shield 90 is secured in place by peening the portion overlying the groove 88 as indicated at 94, so that such portion extends into the groove.

Mounted in the opposite end of the tube 80 is a cathode cup 100 comprising a snugly fitting cylindrical body preferably of titanium to minimize contamination of the target. The body 100 is formed with a peripheral groove 101 (FIG. 4) into which the tube 80 is'peened to secure the body in place. The :peening method of securing the cathode cup within the tube 80 eliminates the need for screws as used heretofore and which, because of their sharp edges, are a source of contamination because of the initiation of cold cathode discharge therefrom and resultant sputtering of metal during tube operation. The cup 100 is provided on the face adjacent the anode 36 with a transverse recess 102 in which is mounted a filament 104. The cup 100 is also provided with a transverse bore 106 which extends parallel to the recess 102. The opposite ends of the filament 104 are connected to

leads

108, 110 which extend through openings 112 into the bore 106. The openings 112 are spaced equidistantly on opposite sides of the axis of the body 100 in close proximity to the periphery of the body so that the filament 104 is of maximum length relative to the diameter of the tube 80. In bore 106, the

leads

108, 110 are bent towards each other and then pass through a pair of openings 114 extending between the bore 106 and the opposite end of the body and which openings are spaced equidistantly on opposite sides of the axis of the body 100, but at a lesser distance than openings 112. -

Insulators

116, 118 may be provided within the openings 112, 114, respectively. From the body 100 the

leads

108, 110 extend to the header 86. Bead insulators 120 preferably are placed upon the leads to prevent their engagement in the event of sagging and also to prevent their accidental shorting against the tube 80. The leads are carried outwardly of the sealed portion of the envelope through seals 122.

Means are provided for connecting the

leads

108, 110 to a suitable source of electrical energy. Referring again to FIG. 1, extending from the header 86 is a coaxial post 124- having a threaded coaxial opening 126 in the distal end thereof. The post 124 is provided with a slot 127 through which the end of the lead 110 extends into the opening 126, as shown in FIG. 5, the lead being clamped against the bottom of such opening by a setscrew 128. Into the opening 126 is threaded a rodlike base portion 129 of an electrical jack 130 which includes a cup-like portion 131 for receiving the mating prong 132 of a cooperatively formed electrical connector.

Mounted on the base port-ion 129 of the jack 130 are a pair of ring-

like insulators

133, 134 which support a second cylindrical electrical jack 140 in concentric relation to the jack 130. The jack 140 is adapted to be engaged by surrounding prongs 142 of an electrical connector which includes an annular insulator portion 144 which fits within the annular space between the

jacks

130, 140. The lead 108 is connected to the base portion of the jack 140 by a screw 146. The

jacks

130, 140 preferably are of brass or similar good conductor and are provided with a coating of gold to assure a clean surface and good contact with the connectors in engagement therewith.

The construction of the cathode described and shown with the convergence of the filament leads at the opposite ends of the tube 80 permits the diameter of the tube 80 to be held at a minimum, thus enabling the diameter of this sleeve 30 and housing 32 to be held to a minimum without sacrificing filament length or anode-to-cathode spacing.

Having illustrated and described a preferred embodiment of the invention it should be apparent that the same permits of modification in arrangement and detail. We claim all such modifications as come within the scope and purview of the attached claims.

We claim:

1. In an X-ray tube a cathode comprising (a) an elongate metal tube,

(b) a right cylindrical body secured within said tube,

adjacent one end thereof,

(c) said body having a transverse recess on the face thereof nearest said tube one end and a transverse bore substantially medially between the opposite ends thereof axially parallel to said recess,

(d) said body having a first pair of circular openings extending between said recess and said bore, said openings being spaced substantially equidistantly on opposite sides of and being parallel to the cylindrical axis of said body, and in close proximity to the periphery of said body,

(e) said body having a second pair of circular openings extending between said bore and the opposite end of said body, said second openings being spaced substantially equidistantly on opposite sides of and being parallel to the cylindrical axis of said body, the spacing between said second pair of openings being less than that between said first pair of openings,

(f) a filament positioned in said recess and extending lengthwise thereof, and

(g) a pair of electrical leads connected to the opposite ends of said filament, said leads extending one through each of said first pair of openings and thence one through each of said second pair of openings.

2. In an X-ray tube a cathode comprising (a) an elongate metal tube,

(b) a right cylindrical body of titanium fitted snugly within said tube, adjacent one end thereof, said body having a peripherally extending groove therein,

(c) said tube being deformed to extend into said groove thus to secure said body against movement longitudinally of said tube,

(d) said body having a transverse recess on the face thereof nearest said tube one end and a transverse bore substantially medially between the opposite ends thereof axially parallel to said groove,

(e) said body having a first pair of circular openings extending between said recess and said bore, said openings being spaced substantially equidistantly on opposite sides of and being parallel to the cylindrical axis of said body, and in close proximity to the periphery of said body,

(f) said body having a second pair of circular openings extending between said bore and the opposite end of said body, said second openings being spaced substantially equidistantly on opposite sides of and being parallel to the cylindrical axis of said body, the spacing between said second pair of openings being less than that between said first pair of openings,

g) a filament positioned in said recess and extending lengthwise thereof,

(h) a pair of electrical leads connected to the opposite ends of said filament, said leads extending one through each of said first pair of openings and thence one through each of said second pair of openings, said leads being parallel to the axis of said body in said openings.

3. An X-ray diffraction tube comprising (a) an outer metal tubular portion,

(b) an anode target mounted at one end of said metal tubular portion,

(c) a tubular glass portion connected by a glass-tometal seal to the opposite end of said metal tubular portion, said glass portion including an elongate, inner, tubular reentrant portion, the inner end of said reentrant portion being necked down to a smaller diameter than the remainder thereof,

(d) an inner metal tubular portion coaxial with said outer portion,

(e) means connecting one end of said inner metal tubular portion to the end of said reentrant portion,

(f) a cylindrical member mounted in said inner metal tubular portion adjacent said one end, said member being secured to the inner surface of said tube in vacuum tight relation therewith, said member having a pair of diametrically positioned, axially parallel openings therethrough,

(g) a post extending coaxially from said member toward said glass portion,

(h) a first electrical jack mounted on the end of said post, said jack comprising an elongate rod-like base portion and a cup-like portion for receiving a mating prong of a cooperative electrical connector,

(i) a second electrical jack comprising a tubular element,

(j) means mounting said second jack in concentric relation to said first jack, said jacks being positioned beyond the said necked down portion of said reentrant portion but within said reentrant portion,

(k) a pair of electrical leads electrically connected one to each of said jacks,

(1) said leads extending one through each of said openungs,

(m) seal means forming a vacuum tight seal between said leads and said member,

(11) a filament mounted in the end of said inner tube opposite said one end, said leads extending through said tube and being connected to said filament.

4. An X-ray diffraction tube comprising (a) an outer metal tubular portion,

(b) an anode target mounted at one end of said metal tubular portion,

(c) a tubular glass portion connected by a glass-tometal seal to the opposite end of said metal tubular portion, said glass portion including an elongate, inner, tubular reentrant portion,

(d) an inner metal tubular portion coaxial with said outer portion,

(f) a cylindrical member mounted in said inner metal tubular portion adjacent said one end, said member being secured to the inner surface of said inner metal tubular portion in vacuum tight relation therewith, said member having a pair of diametrically positioned, axially parallel openings therethrough,

(g) a post extending coaxially from said member toward said glass portion,

(-h) a first electrical jack mounted on the end of said post, said jack comprising an elongate rod-like base portion and a cup-like portion for receiving a mating prong of a cooperative electrical connector,

(i) a pair of annular electrical insulators secured to said base portion in longitudinally spaced relation, said insulators having a greater diameter than said cup portion,

(j) a second electrical jack comprising a tubular element mounted on said insulators and extending in coaxial relation to said first jack, said jacks being positioned within said reentrant portion,

(1) said leads extending one through each of said openll'lgS,

(m) seal means forming a vacum tight seal between said leads and said member,

(11) a filament mounted in the end of said inner tube opposite said one end, said leads extending through said tube .and being connected to said filament.

5. In an X-ray diffraction tube an envelope comprising (a) an outer tubular metal wall portion,

(b) an outer tubular glass wall portion,

(c) a glass-to-metal seal joining said wall portions,

(d) a metal sleeve connected at one end to said metal Wall portion and extending within said glass wall portion in spaced, overlapping relation to said glassto-metal seal,

(e) said sleeve having an outwardly facing flange on the free end thereof,

(f) a getter element comprising an annular wire-like metal sheath containing a gettering material mounted on the outer surface of said sleeve in proximity of said glass-to-metal seal whereby upon flashing of said element said gettering material will deposit upon said glass-to-metal seal and will overlap upon both said wall portions to provide an electrically conductive coating over said seal.

6. In an X-ray dififraction tube an envelope comprising (a) an outer tubular metal wall portion,

(b) an outer tubular glass wall portion,

(c) a glass-to-metal seal joining said wall portions,

(d) a metal sleeve connected at one end to said metal wall portion and extending within said glass wall portion in overlapping relation to said glass-to-metal seal,

(e) a getter element comprising an annular wire-like metal sheath containing a gettering material mounted on the outer surface of said sleeve in proximity of said glass-to-metal seal whereby upon flashing of said element said gettering material will deposit upon said glass-to-metal seal and will overlap upon both said wall portions to provide an electrically conductive coating over said seal.

References Cited by the Examiner UNITED STATES PATENTS 2,215,426 9/1940 Machlett 313-56 2,310,567 2/1943 Atlee et al. 313-59 2,445,993 7/1948 Beggs 313174 2,446,270 8/1948 Eitel et al. 3l3318 2,502,070 3/1950 Atlee et al. 31355 2,535,708 12/1950 Vlach 3 l357 2,582,454 1/1952 Pohle 3 l383 2,686,884 8/1954 Atlee 31357 2,836,747 5/1958 Atlee 3 l357 2,836,748 5/1958 Atlee 3 l358 JAMES W. LAWRENCE, Primary Examiner.

RALPH G. NILSON, GEORGE N. WEST BY,

Examiners.

60 W. F. LINDQUIST, P. C. DEMEO,

Assistant Examiners.

Claims

6. IN AN X-RAY DIFFRACTION TUBE AN ENVELOPE COMPRISING (A) AN OUTER TUBULAR METAL WALL PORTION, (B) AN OUTER TUBULAR GLASS WALL PORTION, (C) A GLASS-TO-METAL SEAL JOINING SAID WALL PORTIONS, (D) A METAL SLEEVE CONNECTED AT ONE END TO SAID METAL WALL PORTION AND EXTENDING WITHIN SAID GLASS WALL PORTION IN OVERLAPPING RELATION TO SAID GLASS-TO-METAL SEAL, (E) A GETTER ELEMENT COMPRISING AN ANNULAR WIRE-LIKE METAL SHEATH CONTAINING A GETTERING MATERIAL MOUNTED ON THE OUTER SURFACE OF SAID SLEEVE IN PROXIMITY OF SAID GLASS-TO-METAL SEAL WHEREBY UPON FLASHING OF