US1596405A - Rontgen tube - Google Patents

Description

ugo 17 192%,

H. V. DECHEND RNTGEN TUBE Filed August 27, 1921 LWN- Patented Aug. 17, 1926.

HERMANN v. DECHEND, OF HAMBURG, GERMANY.

RNTGEN TUBE.

Application led August 27, 1921, Serial No. 495,910, and in Germany April 19, '1920.

My invention relates to improvements in Rntgen tubes, and more particularlv in:

tube's having incandescent cathodes. 1f the rays of a Rntgen tube are to be used for producing imagesI it is necessary to have a nearly point-like focal spot. but. if the rays are to be used for therapeutic purposes a focal surface in the forni of a sharp spot may be dispensed with. Heretofore thes-e facts have not been availed of in the manufacture of Rntgen tubes for constructing therapeutic tubes and tubes for producingimages on dii'erent principles, and the elec` trodes of tubes of both types have been constructed on the same principles. The stream of cathode rays is always comparatively small and the portion of the anticathode which can be put to use is not more than a 'few square centimeters. In therapeutic tubes a larger part of the surface. of the cathode has been availed of for therapeutic purposes by changing the relative distance between the cathode and the anticathode, or by changing the curvature of the concave cathode, the object being to reduce the speciiic load on the focal spot, yet also in this case the whole energy of the stream of cathode rays is concentrated on a comparatively small surface of the anticathode, which therefore is highly heated because most of the energy is transform-ed into heat. To carry away the large amount of heat from the inaccessible anticathode is difficult in practice, so that the tube can not be charged beyond a certain limit.

The object of the improvements is to provide a Rntgen tube having an incandescent cathode which is entirely different in construction from constructions now in use and which permits an almost unlimited increase of the capacity of the tube. IVith this object in view my invention consists in providing large sources for electrons by equipping the tube with an incandescent cathode of increased length and one or more anodes of large Surfaces located at the side of the cathode. In the manufacture of Rntgen tubes of this type and more particularly with reference to the location of the electrodes and the material from which they are made, due regard must be paid to the principles known in the manufacture of highly charged oscillation tubes. Therefore the anodes are made from metals of high atomic weight, such for example as tantalum, tungsten, uranium, platinum,

gold, and the like, and the electrodes are located so as not to interfere with the discharge of the rays, and finally the terminals of the supply conductors to the electrodes must be disposed the proper distance apart, depending upon the voltage applied thereto.

In order that the invention maybe more clearly understood two examples embodying the same have been shown in the accompanying drawing, in which the same reference characters have been used in all the views to indicate corresponding parts. In said drawing,-

F ig. l is a Vertical section of a Rntgen tube provided with an incandescent cathode.

Fig. 2 is a section taken on the line A-B of Fig. l, and

Fig. 3 is a sectional ication.

In the example shown in Figs. l and 2, the incandescent cathode l is in the form of a bifurcated wire suspended with its middle portion from a coiled spring 3 secured to carriers 2 in the form of wires. The lower ends of the cathode are connected to terminals 4 and 5. On the wires 2 a wire net 6 is coiled which has the function to keep from the incandescent wire l the strong forces of electric attraction connected with View showing' a modithe operation at high volt-age. The wire netl 6 constitutes a grid, and through the Carrier wires 2 and spring 3 this grid is in conducting connection with the cathode or filament l, so that the latter and the grid 6 will be at the same potential, thus preventing the high-voltage charges from deforming said filament. As indicated in F ig. 2, there are four upright carrier wire. portions 2, but for the sake of clearness, the upper portions of only two carrier wires 2 have been shown in Figs. 1 and 3. The lower ends of the carriers are secured to arms 7 lixed to the upper end of a metallic sleeve 8 placed on a glass tube 9 fused to the body of the Rntgen tube. The leading-in wires 4 and 5 are passed through the upper thickened end 10 of the tube 9, and they are spaced the required distance apart to provide suiicient insulation.

At opposite sides of the incandescent wire l and in the direction of its length two spaced anodes 1l (Figs. l and 2) in the form of sheet metal strips are provided, which are made from a suitable metal of high melting temperature and high atomic weight. Said anodes or anti-cathodes are secured with their upper ends to arms 12 provided on a metallic sleeve 14 mounted on a glass tube 13. The leading-in wire 16 connected with the sleeve 14 is passed through the thickened lower end 15 of' the tube 13.

The leading-in wires 4 and 5 of the incandescent wire 1 are connected with the terminals of a heating battery 17. Between the leading-in wires 4 and 5 and the lead` ing-in wire 16 a high-Voltage generator 18 of any suitable construction is interposed.

The plate-like anodes 11 are disposed with their surfaces at au angle relatively to each other, so that the space confined between them is broadened or fiares in the-direction of the object on which the rays are thrown, as is Shown in Fig. 2.

In the modification shown in Fig. 3 the anode 19 is in the form of a truncated hollow cone made from sheet metal having a high melting point and a -high atomic weight, and the said cone is spaced from the incandescent wire 20 and encloses it in substantially the same manner as described above, that is, the filament is located between flaring surfaces, or within a flaring space, and the two branches or legs of such filament are disposed in a plane transverse to the converging anode or anticathode portions which bound said space. The rays are emitted in the direction of the axis of the cone and through the base thereof. The anode 19 is supported on a transverse rod 21 disposed within a lateral extension 22 of the tube and connected with the leadingin wire 23.

In the constructions of the Rntgen tube described herein anodes of considerable dimensions can be used, for example anodes having a radiating surface of or 100 square centimeters, without interfering with a reliable operation. At a temperature of 2000o C. each square centimeterl is adapted to emit 40 watts. Therefore the capacity of the anode is as high as from one to four kilowatts.

Furthermore it is not necessary in my improved tube to keep the cathode rays together by collecting means, because-,owing to the arrangement of the incandescent wire within the space bounded by the anode or anodes the cathode rays can not be dispersed.

I claim:

1. A Rntgen tube comprising a cathode element adapted to be heated to incandescence by the passage of an electric current, and an anode element having portions located on opposite sides of said cathode clement andv at an Aangle to each other to form a flaring space within which-said cathode is located, said space being open at the wide portion for the escape of Rntgen rays.

2.. A Rntgen tube'comprising al Cathode filament adapted to be heated to incandescence, and an anticathodeclement'having converging portions located on opposite sides of said filament, the space between said converging portions 4being open, Where such converging portions are farthest apart, for

the escape of Rntgen rays.

3. A Rntgen tube comprising an anticathode element having converging portions which bound a flaring space open at those points--where said converging portions are farthest apart, and an arched cathode filament adapted to be heated to incandescence yand having its side members within said space in a plane which intersects said converging portions.

4. A Rntgen tube comprising a cathode filament, a carrier wire therefor, a spring connecting said Wire with the filament, a grid coiled on said wire, and an anticathode associated with said filament.

5. A Rntgen tube comprising a cathode filament, a grid coiled around the cathode si gnature. v

HERMANN v. DECHEND.

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