US2005021A

US2005021A - Vacuum tube

Info

Publication number: US2005021A
Application number: US481654A
Authority: US
Inventors: Brasch Arno; Lange Fritz
Original assignee: Individual
Current assignee: Owens Corning Intellectual Capital LLC
Priority date: 1929-07-23
Filing date: 1930-09-13
Publication date: 1935-06-18
Anticipated expiration: 1952-06-18
Also published as: FR365609A; GB365609A

Description

June 18, 1935. A. BRASCH ET AL VACUUM TUBE Filed Sept. 13, 1930 2 Sheets-Sheet l ifig i.

VACUUM TUBE Filed Sept. 15, 1930 2 Sheets-Sheet 2 Patented June 18, 1935 UNITED STATES PATENT OFFICE VACUUM TUBE Arno Brasch and Fritz Lange, Berlin, Germany 10 Claims.

The present invention relates to improvements in vacuum tubes and particularly to vacuum tubes for generating very rapid corpuscular rays, both of a positive as well as a negative kind,

with a more specific object of creating very hard X-rays.

The arrangement described in the following furthermore enables the voltage at the tube to be increased to such extent that a conversion of elements may be performed by means of the corpuscular rays accelerated therein.

Generally speaking, it is impossible to operate a single-stage discharge tube with voltages much in excess of 200,000 volts, as rupture of the walls will then take place.

We have ascertained by experiment that it is possible to operate single-stage discharge tubes with voltages much in excess of 1 million volts without employing an actual guard for the walls such as heretofore variously proposed and also employed in practice.

In the course of our experiments we have discovered that the occurrence of independent discharge is apparently initiated by a kind of sliding discharge taking place along the inner wall of the tube. lamination of the total inner wall of the tube along the discharge passage by means of more or less conductive annular structures absolute freedom of independent discharge could be-observed even with the use of alternate current of 50 periods and a voltage of 1,300,000 volts. A particularly remarkable feature associated with the invention consists in the fact that particular claims of any kind do'not require to be placed on the quality of the vacuum-employed, so that for the construction of the tube it is even possible to employ organic materials which, as well known, always possess a certain pressure.

By sufliciently fine divisioning or lamination of the discharge passage, operations may be performed even with the most extreme voltages with a vacuum not exceeding more than 1/1000 mm. Hg. This fact is particularly important in the generation of extremely rapid passage rays.

The annular laminations may .be applied in various different ways. Since it is important to make the slideway between the individual laminations as large as possible, whereas on the other hand it is also desirable to provide as many divisions as possible over a given space, the arrangement is preferably such that the portions of the insulating wall situated between the individual laminations are formed to provide pro- By extremely fine divisioning orjections or grooves. The divisioning may then be performed in these grooves which serve simultaneously for mounting the annular laminations and to increase the insulation between them.

In the particular arrangement employed for 5 the experiments the vacuum tube consisted of thick-walled porcelain (2 centimeters) 8 centi- I meters in diameter, which was particularly safe against rupture. The total length of the tube amounted toapproximately 2 meters. The lami- 10 nations consisted of approximately200 metal rings fitted at equal distances. apart. Since the rings consisted of a resilient metal (nickel) it was possible to dispense with any particular holding means for the same. Expulsion of the gas from 15 the various materials employed was also unnecessary. The electrode feed was performed by means of metallic caps, which were cemented on. Inwardly projecting electrodes were not employed, as these would have been detrimental to 20 the effect of the laminations.

The invention is shown byway of example in the accompanying drawings.

Figures 1 to 6 represent diagrammatically different constructional forms of the vacuum (118- 25 charge tube, Fig. l being a longitudinal section; Fig. 2 a fragmentary perspective cross section of Fig. 1; in Fig. 3--is shown a modification of Fig. 1 and Figs. 4, 5 and 6 are similar views to P18.

1 of still other modifications of the invention. 30

Referring to Figure 1, the tube is made of insulating material and is closed by two metal end caps 2 and 3. The glow-cathode 4 extends suitably insula'ted through the cap 3 while the watercooled anticathode 5 is mounted on the cap I. 35 The subdivision or lamination of the inner wall of the tube I is effected, as shown in Figure 1, by closely adjacent rings 8 of more or less conductive material. The position of the rings is shown diagrammatically in Figure 2.

The annular laminating structures or rings are closely spaced along the walls, the spacing being such that, conforming with the corresponding distribution of the potential, the difference in potential between any two neighboring rings will 5 be smaller than the minimum necessitated by the vacuum and the form and material of the tube to initiate the sliding discharge between rings.

In Figure 3, the sliding path is enlarged by suit- 50 able grooves I l between the rings. For this purpose, the inner lining of the tube l is grooved or corrugated and the rings 6 are diagrammatically indicated as supported bythe projecting portions of the corrugations while the discharge 55 tube I is closed by the caps 2 and 3 in the usual manner, these caps bearing the anti-cathode 5 and the cathode 4 respectively.

Figure 4 shows\a further constructional form wherein the means for distributing the potential difference along the walls of the tube to prevent sliding discharges is in the form of a helix 9 inserted in the smooth interior of the tube I so that a helix connection with great induction is formed for current impulses and alternating voltage. This helix corresponds to the laminations G in Figs. 1 to 3.

Fig. 5 shows a further constructional form wherein the envelope comprises the internally corrugated tubular portion l' of insulating material and the end cap members 2' and 3'. The cathode, diagrammatically shown at l, is carried by the end cap 2', and the anode or anticathode 5' is carried by the end cap 3'. The annular structures diagrammatically indicated at 6' for dividing the potential diiference along the walls of the tube are shown mounted in the grooves.

Fig. 6 shows a further constructional form in which the internally corrugated tubular portion I of insulating material having the divisioning means 6', is provided with one end cap 2 carrying a suitable cathode 4", and in whichthe means providing the anode 5" serves as the cap for the other end of the tubular insulating portion.

It the tubes are operated in a special insulating medium, for example oil, it will naturally be desirable to reduce the length as far as compatible, in order to be able to pass high emissional outputs through the tube without obstruction. With suillciently small dimensioning of the laminations it is also possible to provide several hundred laminations over a length of tube amounting to only between 30 and 40 centimeters. Any emissional arrangement of the known kind may be employed for generating passage or cathode rays. The experiments made have shown that any desired voltage may be applied to a vacuum chamber up to the occurrence of the so-called Lilienfeld eifect (10 to 10" volt-cm), and that the voltage limitation hitherto observed at approximately between 300,000 and 400,000 volts in connection with single-stage tubes is merely occasioned by certain sliding efiects along the inner wall without, as hitherto assumed, the quality of the vacuum constituting a governing factor.

What we claim as new and desire to secure by Letters Patent is:

1. A vacuum discharge tube comprising an envelope,- a cathode and an anode mounted therein and spaced to form a relatively long dischargepath therebetween for the desired discharge between cathode and anode, a plurality of closely spaced, electrically conductive rings within the envelope, said rings extending along said entire discharge-path and being electrically insulated from each other and from the exterior of said envelope.

2. A vacuum discharge tube comprising an envelope, a cathode and an anode mounted therein and spaced to form a discharge-path therebetween for the desired discharge between cathode and anode, a plurality of closely spaced electrically conductive rings within the envelope, said rings extending along said discharge-path and being electrically insulated from the exterior of said envelope; said' envelope being internally corrugated to form seats for said conductive rings and increase the insulation against sliding discharges between rings.

3. A vacuum discharge tube comprising an envelope, a cathode and an anode mounted therein and spaced to form a discharge-path therebetween for the desired discharge between cathode and anode, a plurality of closely spaced, electrically conductive rings within the envelope, said rings extending along said discharge-path and being electrically insulated from the exterior oi said envelope; said envelope being internally corrugated to provide a large surface between each of two neighboring conductive rings to insulate against the initiation of sliding discharges.

4. A vacuum discharge tube for very high voltages having cathode and anti-cathode members, comprising an open ended tubular member or insulating material, a plurality of conductive laminations uniformly spaced within said tubular member, a cap secured on each end of the tubular member forming respectively seats for said cathode and anti-cathode members, said tubular member being provided with internal corrugations having the same spacing as said laminations and the apices of the corrugations iorming seats for the laminations.

5. A vacuum discharge tube comprising an envelope having a substantially cylindrical insulating portion, electrodes mounted therein adjacent the ends thereof and spaced to form a dischargepath, a plurality of electrically conductive loops within the envelope, said loops extending along said discharge-path and having an exterior diameter substantially the same as the interior diameter of said envelope and being electrically insulated from the exterior of said envelope; said loops being interconnected.

6. A vacuum discharge tube comprising an envelope, an emissional cathode and an anode mounted therein and spaced to form a relatively long discharge-path therebetween for the desired discharge from the cathode to the anode, a plurality of electrically conductive loop-like members within the envelope, said loop-like members extending along said entire discharge-path and having substantially the same exterior diameter as the interior diameter of said envelope and being electrically insulated from the exterior of said envelope.

7. A vacuum discharge tube comprising an envelope, electrodes mounted therein and spaced to form a relatively long discharge-path for the desired discharge between said electrodes, a plurality of electrically conductive loop-like members within the envelope, said loop-like members extending along said discharge-path and having substantially the same exterior diameter as the interior diameter of said envelope and being electrically insulated from the exterior of said envelope; said loop-like members together forming k a helically wound wire.

8. A vacuum discharge tube comprising an envelope having a tubular portion of insulating material, means providing an emissionalcathode at one end of said tubular portion, and means providing an anode at the other end of said tubular portion, said means comprising members constituting caps closing the respective ends of said tubular portion or the envelope, a plurality of conductive, annular laminations within said tubular portion and spaced along the inner wall thereof and electrically insulated from any external source of potential, said tubular portion being internally corrugated to provide means for mounting said laminations and to increase the length of insulating surface between adiacent laminations, the spacing between said laminations being such that, conforming with the corresponding distribution of the potential, the diiierence in potential between two adjacent laminations will be smaller than the minimum value necessitated by the vacuum to initiate a sliding discharge between laminations.

9. A vacuum discharge tube comprising an envelope having a tubular portion of insulating material and end caps carrying respectively an emissional cathode and an anode, said cathode and anode being spaced apart to provide a relatively long discharge-path therebetween for the desired discharge from cathode to anode, means electrically insulated from any external source of potential comprising a plurality of electrically conductive loop-like members supported by the inner wall of said tubular portion and extending along said entire discharge-path acting when the potential difference to produce the desired discharge between cathode and anode is applied to the tube to divide the potential difierences along the walls of the tubular portion between adjacent portions of said loop-like members to such small values that the length of the paths along the walls of the tubular portion between such adjacent portions of the loop-like members will be sufllcient to prevent the initiation of sliding discharges between said loop-like members.

10. A vacuum discharge tube comprising an envelope having a tubular portion of insulating material, the inner wall or said tubular portion being provided with closely spaced grooves providing annular projections therebetween, metallic end caps for said tubular portion carrying respectively a cathode and an anode, and means for dividing the potential diflerence along said inner wall comprising closely spaced annular laminations electrically insulated from any external source of potential, the spacing between said laminations being such that conforming with the corresponding distribution of the potential, the difierence in potential between two adjacent laminations will be smaller than the minimum value necessitated by the vacuum to initiate a sliding discharge between laminations, said grooves and projections constituting means whereby said laminations are held in place on said inner wall and whereby the length of insulating surface to prevent such sliding discharges is increased.

ARNO BRASCH. FRITZ LANGE.