US1192706A - X-ray tube. - Google Patents

Description

E. THOMSON.

X-RAY TUBE.

APPLICATION FILED SEPT. 14, 1914.

l 1 9%,?6, Patented Jul 25, 1916.

Witnesses: lnvehtor; fggg 46% b Elihu Thomsop ELIH'U THOMSON, Q1 LYNN, MASSACHUSETTS, ASSIGNOR T GEHEEMQFQELEGTH-IO CGMPANY, CGEPQRA'IION OF NEW YORK.

X-nsr time.

1,192,?(36, specification To all whom it may concern:

Be it known that l, Enrrro TiioMsoN, e citizen of the United States, residing at Lynn, county of Essex, State of Massachusetts, have invented certain new and useful Improvements in Iii-Rey Tubes, of which the following is a description.

The present invention relates to K rey devicesand its object is to prevent locel overheetin end melting of the metal on the surface or e terget or electrode subjected to the bombardment of cathode rays in accordance with my invention overheating of focal spot, the port of the surface of the target or unticetiiode subjected to the borr nrdnient of the cathode rays is prevented by successively renewing the terget surfece during the operation of the tube,'for exempie, by making the ter et in the shape of t'lleti or disk and rotating the same any W y, for example, by externel means or by the reaction of the rays striking *1 mm of the tar tangentially. The of y invention are pointed on particularity in the epper inv reference in conneo ings in Wli Figure I. a, rotatable the cetliode with greet claims derstood by e foliowing description taken :2 accompanying drewolved by the impact of 2 is e deteii pien View of the rote .et; 3 is side elevetion of Le terg-et partly in section; Fina 4c is e deti form of et; Fig, 5 shows in outline an X-rey tube w ing the erg-st roteted by externei. men and Fig. is o deteii sectional view of e cetnode operebie at incendescence in a highly evacuated tube in "which. the cathode or bets rays ere produced by pure electron emission The iii-ray tube shown in Fig. 1 consists as'usuel 2, glass envelop 1 having side arms 2, 3, into the stem 4, 5 of which are respectively sealed the cathode conductor 6 end the anode conductor 7. The cathode 8 which may consist of aluminum is of the usuei concuve or dished type proportioned to focus the cathode rays upon limited surface area of the target. The tergetfi is fashioned in the shape of ewbeel so posi= tioned by means of the carriers 10 that the es cathode rays Will be directed tengentielly to tube containing ed sectionel View of e modified I to rotate the target I may, as shown Y ofletfirs Patent Eetented July 25, idltdo Application filed eeptember 14, 191%. Serial No. 881,519. I

its surface so as to produce rotation in the .d rection of the arrow. Although the sotwo surface upon which the cathode rays are received is thereby continuously renewed the X-rays as shown by dotted lines are continuously directed downwardly es the relative position-of the cbtbode spot remains the same. As the surface of the terget has a regularlcontour, as indicated in the drawing, the position of the cathode spot remains substentieily fixed in space and, therefore, the X-reys are continuously emitted and the direction of the rays with respect to the object to be treated or exemined remains substantially the some.

The Wheel 9, as shown in Figs 2 and 3, may consist of a frame Work of copper or like metal of good beet conductivity comprising a hub 11 and outwardly extending spoxes 12 between the flared ends of which are is-pinched or otherwise joined a perip ierui band 13 of tungsten, or other ii refrestory metal. The shaft i ire & liite bearings 15 so as to give iubricen and enable the Wheel when carefully beienced to be easily ro' ed anothe co struction, shown in i, e eripheral merit-13 of tungsten or the like is inc by tWo thin disks 16, 16, of Copper 0'; law metal, these disks beii eld toge her smell rivets 17 as indies e The tungsten or refractory 331% in Figs. 3 4 need not be e; comp etout to ailow for expansion on been it can be composed llnsteed of depending upon a component of the repulsive of the cathode 5, rotate the target by me netic zneens, target 9 is connected Wi e inetel supported by one end on the same bearing" es the target and ot the other end upon beering 20 in a, side arm 21 of the tube. Upon this rod 19 in tire side is mounted a magnetic member 22 which it the simpiest form may be e small red iron. Immediately outside of the side '21 is a rotating magnet 23, the poles 2e, 25

of which are closely adj ecentto the megnetio member 22. By roteting thismegnetupon 'a shaft 26 in any convenient manner the target 9 may be rotated at anydesired speed. Of course instead of using a rotating magnet, a rotating magnetic field may be pro duced by other convenient means. Both Figs. 1 and 5 show an X-ray tube having an unheated target and therefore contain a small amount of gas and operate by positive ionization, but my invention is easily applicable to a tube containing an incandescent cathode 27, as shown in Fig. 6, surrounded by focusing member 28, the

' vacuum in the tube being so high that positive ionization is substantially absent and the cathode rays being produced by substantially pure electron emission from the heated cathode.

What I claim as new and desire to secure by Letters Patent of the United States, is 1. Themethod of increasing the capacity 7 of an X-ray tube which consists in directing cathode rays upon a limited area of the surface of a refractory target and renewing 4. An X-ray tube comprising an envelop,

means for generating cathode rays and a rotatable anti-cathode comprising a circular band of tungsten.

5. In an X-ray device, the combination of means for producing cathode rays, a target comprising a band of refractoryv metal upon which said rays impinge, and means movably supfporting said target to permit a change 0 surface subjected tothe bombardment of the cathode rays.

6. In an X-ray device the combination of means for producing a converging bundle of cathode rays, a refractory target of regular contour located near the focus of said rays, and means movably supporting said target in a position to permit motion of said target by the impact of said cathode rays. 7. In an X-ray device, the combination of a rotatable refractory target of regular contour, a mounting therefor, and means for directing a stream of cathode rays tangentially upon said target.

8. An X-ray device, comprising the combination of means for generating cathode rays, a target surface located in the path of Said rays and means for changing the target surface receiving said rays while said rays are impinging on said target.

In witness whereof, I have hereunto set my hand this eighth day of September, 1914.

ELIHU THOMSON.

. Witnesses:v

JOHN. A. MoMANUs, 'Jr., FRANK Gr. HAT'IIE.

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