US2327586A - X-ray tube - Google Patents

Description

A118- 24, 1943- z.' J. ATLEE 2,327,586

X-RAY TUBE I Filed May 5, 1941 Zed/.Mike

Y My invention relates in general to stantially immune to the anode target Patented Aug. 24, 1943 K if: @am

` t X-RAYTUBE Y' Zed,J. Atlee, Elmhurst, Electric X-RayCorpor poration of New York Ill., assigner to General l ation," Chicago, EL, a cor- Application May 5, 1941, sei-iai No.' seien Y t y electronics and has more particular reference to the provision of an'improved X-ray generator. 1'

An important object of thepresent invention is to provide an X-ray generator having an envelope structure substantially immuneV to deterioration as a result of X-ray and electronicastion; a further object being to provide an X-ray tube in which all portions of the envelope normally exposed to X-ray and electronicaction during operation of the tube comprise metal subdeterioration; a still further object being to utilize a metal tube asY an envelope in an X-ray generator.

Another important object is to prevent metallic deposit, caused on the envelope by electrode deterioration during operation of the generator, from impairing the substantial transparency of Vthe envelope to X-rays; a further object beingf'to provide the envelope with a screen member shiftable progressively to present portions freeV of metallic deposit in position to transmit useful X- rays through theY being to provide aV windowed guard and Vco-operv ating screen in the generatonthe screen being movable in said Window to enable `deposit-free screen portions to be progressively presented at said Windowfin order to maintainX-ra'y transparency of the Window structure. Y t y Y These and numerous other important objects, advantages, and inherentfunctions ofthe invention will become apparent as Vthe-invention is more .fully understood from the following` Vcle-- scription, which, taken in conjunction with the accompanying drawing, disclosesY a preferred ein# bodiment of the invention. 1

Referring to the drawing:`

envelope; a stillfurtheij'object Y` dially thereof.

preferably'steel,envelope Il may Figure 1 is a` sectional View through anX-ra-yV generator embodying the present invent'iomfand Figure 2- is asectional View taken substantially along the line 2-2 in Figure 1.

To illustrate the invention, I have shownon the drawing an X-ray tubel l comprising'an anode I3 and acathode `l5*V enclosed ina"sealed envelope preferably comprising aseamlessstel tubeIL- The anode I3 comprises a'he'ad supporting a target. ls'opposite the cathode in position/to receive the impingement of electrons emitted by the' cathode during the operation ofthe device as fari -X-ray generator. VThe cathode Valso comprises a head in which may? be Vmounted affila- Ymetary element Vv2l adaptedV to be energized to form a source `of electrons forimpinge'ment"l upon i9. Theheads j of the v anode Y being` supported Vin Vanhermeticseal between the stem and the ends :ber '3 3. Each. seal-member Y of which is hermeticallyA Y established by the operation 11 oiaiins. (ci. 25o-ssi and cathode `are supported on stems V23 at the opposite ends of the generator, said stems 23 each an end seal structure forming ofthe envelope member Il. To this end, each stem 2S is formed With a seat 25, and each stem carriesa cup-shaped metallic seal element 29 formed with an' opening at one end to snugly receive the stem on which mounted, .themem- -bers29 beinghermetically sealed yeach on its carrying stem at the seat 25; LEach member 2! extends from its seat 25 and forms a skirt embracing Vthe stem" on which it'is mounted and forms an annular edge making a glass-to-#metal seal 3 i with a co-operatingf glass end seal mem- 33 comprises a glass disk. having a central neck forming thesea-l 3l and-fa marginal ange forming a glass-to-Inetal 'sea'lf With one end cfa rim 37,' the other end sealed on an annular ring member 3S. i The Vanode :andicathode electrodes are thus each supported on a ring mem- `ber t9, Whichiring-membrsare sealed to the opposite ends-301 the4 envelope member il preferablyV by V'means lof silver soldered joints 4l.

4.X-rays generated atthe anode are emitted ragenerally in theldirection, of` the inclination Aat rays passing outwardly of the y'envelope'opposite 'the 'endof theianode electrodei'if desired, the be' formed with a Window openingrl opposite thetarget I3, and aV pane ofvv material 45, which is substantially transparent to Xfrays, may be *sealed on the envelope atv saidopening. 'I prefer to utilize a beryllium window-pane :i5 for this purpose, since beryllium is substantially transparent to X-rays. i

The beryllium Window-pane may be applied by soldering'it in a ring of coldrolledsteel 4l by meansrof a suitable solder1 '49, 4Which may comprise .an alloy of silver and copper in substantially equal quantities of each, the preferably steel ring lbbeing brazed, soldered. or Welded to the steel `tube l l iin any suitable'or preferred vacuum-tight fashion. r

VIt should be understood that X-ray generators 'function to produce X-rays in? response to `the activation of the anode electronic actioni consisting of theimpingement ofielectrons emitted by the cathode upon the Y anode target. I9.

t Electronic impingement on the target results in the 'generation of relatively large-quantities of'heat atthe target, lWhich is dissipated thencelthrough the-body of Vthe anwhich the target is mounted, useful by electronic action V of the cathode, said meansVV for eliminating metallic deposit, and to this end' Iprovide,

. material' secured 'at the target vat operating temperature results in the evaporation of the material oi the target;

andthe material of the cathode and itsv fila Y ment may also be gradually ration during the operating life of the generator'. The metallic material of the anode 'and cathode, thus vaporized and dissipated during operation, becomes deposited upon the envelope, particularly in the zone radially of the facingends of the electrodes. Incourse of time during -theoperation of thus deposited may build up to suicient thickness to `appreciably impair the Xeray Atransparencyof the*v envelope, 4and particularly of the window, and thus` impair the efliciency of the device-as a source of useful X-rays.V

Inorder to maintain the eciencyof the generator as*V a source of useful X-rays, I propose Within the envelope .ITL an annular sleeve or shield 5l" disposed withinthe envelope member l1, said dissipated by evapo- Y the interior surfaces ofl the device, the lm the deleterious eiects of.

through a distance sufiicient'to movethe shutter into position presenting a fresh shutter sure Y V l face, uncoatedby metallic deposit, in the-opening 55. Alternately and preferably,

shown at 6l, withinl a cham the glass seal member derstoodffrom the foregoing description, and it y is Vobvious that numerous changesr may .be made the. several parts without departing from the shield 5I comprising preferably a steel tube'oi n a size to fit'within the tubularv memberl1 and provided with a rim'53 at'one endofthel tube 5I, by meansorwhich it may be secured, as by spotwelding or otherwise, to and'within the member -I'l `in position embracing the facingendsA of'theelectrodes'lS and l5.:.The tube 5|'is provided with an opening 55 in line withthe;

X-ray'tranrslucent envelope portion 45;

j- It'will be noted that the sleeve 5l defines an annular channelwith'the envelope i1 outwardly of the shield 5I, and-within. this-'annular channel,I dispose a preferablyv cylindrical shutter 51 of anyy suitable material whichissubstantially transparent to X-r'ays.l The-shutter51 formed-.with an opening -tween said shutter means and saidelectrode` f 'convenientlymay be formed ofaluminum which,

. in addition'to being substantiallyv transparent to X-rays, is light in weight.Y YAs thegenerator is operated in service, thef.imiter-surfaces of the screen 5l will receive theV metallicdeposit resulting from vaporization of the electrodernaterials but will screen the .shutter 51 against metallic deposit thereon, .except at the shutter portions exposedV in theopening'. After such exposed portions', however, have received a metallic deposit to a tickness materiallyim.- pairing the efliciency ofthe device as a source of effective X-rays passing through the window 35, the shutter l'may be turned in orderto presentan uncoated portion thereof at the open-v ingK 55, thereby` completely restoring the: efliciency of thegenerator Yas' `a source; oi"V X-rays delivered through the opening 55 and thewinvAny suitable means may be employed for .turning" theoshutter 51, and variet vcomprising lafbar of suitable magnetic thenl shifted'circumferentially of .the shell l1 I have shown a magnetic the edge ofthe' shutter in position-to; be actuated by a magnetoperated spirit orzscope of the invention, .or sacrificing any ofvits attendant advantages, the' form here-v in disclosed being'a preferredl embodiment for the purpose 'of' illustrating' the' invention. g Y,

-The invention is hereby claimed as follows?V l. A deviceiof the class described, comprising an envelope, electrode* means"k within said en-V velope, overlapping shield and shutter means rial vaporized as a `result vaporized material kat said opening.

2. -A device of .the Classdescribed,A comprising an envelope,`electrode means within said. elivelope, .overlapping shield and shutter means within said envelope in" position to-receive', ma-

terialvaporizedf as aresult oijtlieactuationot 'the-"electrodemeans; said shield meanslboing. and being disposedber j means, whereby to yuncover a portion ofeth'e shut'- termeans at said opening, :said/shield and/shut- .ter means beingrelatively movable topresent'rre# mote portions of thershuttermeans in position v toreceive said vaporized materialfat saidfopening, and magnetic meansfor,v relatively Vmoving' saidv shield and `shutter means.

3. Adevioe ofltherclass,descr1bed,c0mprising any envelope, electrodemeans within .saiden-y velope, overlapping 'shieldgand shutter means: within said venvelope in position. to receive Ina-1.V terial vaporized as aresult of the-actuation of the ,electrodemeans said shield; means being formed with an' openingandbeing disposed bei.

tween said shutter means yan ter means being relatively movablev to present to Vreceive Vsaid 4.v Adevicebf the class desribedfcomprisfing an envelope, Aelectrode means within, said'l en'" velope, 'concentrically disposed-,shield and shut4 termeans within, said envelopejin' circlingjthe electrode means, saidshieldfmeans being formed with'an opening and`A beingdiSF,V posed between saidshutter means andsad'elecgf; f gf" dv sadj: electrode -Y n A means, whereby to uncover a portion of theA shutvter means at said opening, said shield -andshut- Vmote portions of the shutter means` in exposed y position at said opening.

5. A device of the class described, comprising an envelope, electrode means Within said envelope, an annular shield within said envelope' and formed with a Window opposite said electrode means, and a cylindrical shutter encircling said shield Within saidv envelope, said shutter being turnable with respect to said shield whereby to present'remote portions of the shutter in position exposed atvsaid Window.

6.V A device of the class described, comprising electrode means, means forming an envelope enclosing the electrode means and providing a shield formed with an opening opposite said electrode means and a movable shutter co-operatively associated with said Vshield and operable to present remote portions of said shutter in said opening.

'7. A device of the class described, comprising an envelop-e, electrode means Within said envelope and including an anode adapted to be energized to constitute a source of X-rays, a shield in said envelope adjacent said anode, said shield being formed with an opening in the path of useful X-rays emanating from said anode, and

a shutter of material substantially transparent to `X-rays disposed in said envelope outwardly of said shield, said shield and shutter being relative-V ly movable to present remote portions of the shutter in position exposed at said opening.

8. A device of the class described, comprising an envelope, said envelope comprising a tubular metallic member and end seals on said member, electrode means in said envelope and supported on said end seals, means on said envelope forming a shield spaced from and'. having an open--v ing opposite said electrode means, and a shutter on the side of said shield remotey from said electrode means and movable with respect to the shield to present rem te portions of the shutter at said opening.

9. A device of the class described, comprising anrenvelope, said envelope comprising a tubular metallic member and end seals on said member,v

electrode means in said envelope and supported on said end seals, means on said envelope forming a shield spaced from andrhaving an opening opposite said Velectrode means, and a shutter on the side of said shield remote from said elec-A trode means and movable with respect to the shield to present remote portions of the shutter at said opening, said shutter comprising material substantially transparent to X-rays.

10. A device of the class described, comprising an envelope, said envelope comprising a tubular metallic-member and end seals on said member,

on said end seals, meanson said envelope forming a shield spaced from and having anvopening opposite said electrode means, and a shutter on the side of said shield remote from said electrode means and movable with respect to the shield to present remote portions of the shutter at said opening, said shutter comprising aluminum.

. an envelope,

11. A device of the class described, comprising said envelope comprising a tubular metallic member and end seals on said member, electrode means in said envelope yand supported on said end seals, means on said envelope forming a shield spaced from and having an opening opposite said electrode means, and a shutter on the side of said shield remote from said electrode means and movable Withfrespect to the shield to present remote portions 'of the shutter at said opening, said shutter comprising material substantiallyrtransparent to X-rays and having an edge portion extending adjacent one of said end seals, and means on said edge in position to be inuenced by forces applied through said end seal for moving said shutter.

ZEDJ. ATLEE.

means in said envelope and supported Y

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