US2043733A - High voltage vacuum discharge tube - Google Patents

Description

June 9, 1936. A. BRASCH ET A1.

HIGH VOLTAGE VACUUM DISCHARGE TUBE Original Filed March 25, 1931 2 Sheets-Sheet 1 TLFwdFLLL-LJLLWL JL-LHLFLL-LJHLL June 9, 1936. A. BRAscH ET Al.

HIGH VOLTAGE VACUUM DISCHARGE TUBE Original Filed March 25, 1931 2 Sheets-Sheet 2 Patented June 9, 1936 UNITED STATES PATENT OFFICE Arno Brasch and Fritz Lange, Berlin, Germany Renewal of application Serial No. 525,244, March 25, 1931. This application May 16, 1934, Serial No. 725,988. In Germany April 1, 1930k 13 Claims.

This invention relates to improvements permitting of the application of potentials of any desired strength to a vacuum space without the occurrence of unintentional self-discharge.

This forms a second application from Serial No. 525,244 led March 25, 1931, in accordance with section 4897 of revised statutes.

The invention affords great advantage with regard to the production of very rapid corpuscular rays of the particles of matter charged as positive or negative. The positive-charged particles may consist, for instance, of positive ions of gases (dia-cathode rays), while the negativecharged particles are formed by electrons (cathode rays).

Thus, for example, for the purpose of disintegrating atoms and the conversion of elements, it is necessary to accelerate corpuscles with potentials amounting to many millions of volts, and heretofore the construction of discharge tubes of a reliable nature for voltages of this extent has been confronted by insurmountable difficulties.

In the case of tubes produced according to the invention it has been readily possible to apply a potential amounting to 2,400,000 volts, and to create X-rays, the penetrative power of which approximately conforms to the gamma radiation of radium. It is naturally also possible to employ any desired higher potential, and to create rays considerably surpassing those of radium as regards hardness. Rays of the stated potential and approximately l milliampere intensity of current conform, however, according to calculation, to several hundred pounds of radium. The idea, therefore, is closely associated of employing these rays in lieu of radium for therapeutical purposes, more particularly for the treatment of cancer. An additional advantage resides in the fact that with the considerable intensities available the period of radiation may be out of all proportion short.

A vacuum space which is reliably free. from self-discharge under high potentials is furthermore capable of being successfully employed in conjunction with vacuum circuit breakers, in the case of which the object concerned is that of immediately interrupting arcs of high output and high voltage, or of preventing the formation thereof entirely.

In accordance with the invention, it is also possible to place considerably reduced requirements than have heretofore been usual on the degree of vacuum. The outgassing process essential for all high-voltage tubes has rendered it impossible to employ elastic, organic insulating v(Cl. Z50-27.5)

materials, such for example, as rubber, pertinax and cellon, or also porcelain, steatite and similar materials, While the use of cements for highvacuum tubes has also! been a diifcult matter.

It has been ascertained by experiment that in themselves potentials of such extent may be applied to a vacuum space that finally, with a given spacing, electrons are extracted from the electrode material even in the cold state.

The voltage limitation of roughly 300 kilovolts in the ordinary high-vacuum tubes ls due principally to sliding effects which originate chiefly at the inner wall of the tube bounding the vacuum space and then initiate a self-discharge.

We have already proposed in our Patent 2,005,- 021 of June 18, 1935 to suppress these sliding discharges by laminating the inner wall of the tube at frequent points in conductive or semi-conductive fashion, preferably with the use of metallic, resiliently tted annular structures resting against the wall. These rings were insulated against each other and the exterior, so that it was in no Way necessary to maintain the single rings at a defined potential. A particular Wall screening also proved to be Without object.

Even-With these arrangements it was possible to maintain at the tube potentials of more than 1,000,000 volts A. C., and to create very rapid cathode rays.

The experiments furthermore showed that sliding discharges might all the more readily be suppressed the greater the number of laminatlons, and above all it was found important, by reason of special measures, to increase greatly the slide- Ways from step to step with the lowest possible absolute spacing between the single lamellae. It was furthermore found to be of advantage to make the total arrangement inter-capacitative. Since this type of tube is more particularly intended for use under oil, and for the passage of f considerable amounts of energy, it was necessary to select a form of construction which, despite very numerous laminations, permits of a short and compact design.

We have, therefore, constructed a discharge tube in the form of a series-connected condenser comprising very numerous sections. It is advisable to employ one section for every few thousand volts since, if the spacing is sufficiently small, sliding effects will occur even within these potential ranges.

The tube employed by us for 2,400,000 volts possessed, for example, With a total length of 84 cm., approximately 200 armatures. The absolute l distance apart amounted to .3 cm., and the slideway on the other hand to 6 cm.

In itself it is also possible to employ a smaller number of layers. We have discovered, however, that the greater the number of layers in the condenser arrangement the less is the consideration which requires to be paid toy outgassing of the materials employed.

The construction of an arrangement of this description is conceivable in numerous ways. It would be possible to furnish the inner wall of the tube with grooves and to it in these the single rings, or to employ any other method to ensure correct spacing.

To obtain a spacing as exact and as simple as possible with high capacity we have linked up, Without a particular holding means, alternate thin, ilat rings of metal and insulating material of a suitable specic inductive capacity. The inner diameters of the metallic rings will preferably be made smaller than those of the insulat ing rings, so that in the discharge passage metallic parts are preferably prominent and the insulating parts are arranged to be greatly covered.

By reason of this piling together a tubular structure is formed, the inner bounding faces of which form the discharge passage in accordance with the number of condenser layers. The outer bounding faces may be made vacuum tight in desired fashion by means of a rubber hose passed over the same and tting snugly at all points upon the evacuation, or by rltting into a special cylindrical cover, or by the use of moulding substances.

In order, in the event of intermediate layers of insulating material being employed, to obtain the largest possible slideways between the single metallic parts despite small absolute spacing of the plates, the insulating layers in the vicinity of the inner diameter may be slightly cut away on both sides, so that the metal does not lie against the insulating material in direct fashion at these points.

However, it is possible to obtain large slide- Ways in more simple fashion by employing in place of one insulating ring of certain thickness two or more correspondingly thinner rings which, however, possess different internal diameters, so that slideways of desired length may be obtained.

The tube employed for the experiments described above did not possess a special cylindrical cover. The vacuum closure was obtained by means of rubber rings and suitable insulating paper rings, which were arranged in each case between the single metallic rings and possessed a diameter such that the slideway from step to step amounted to 6 cm. The outer diameters of the insulating paper rings employed were larger than those of the metallic rings in order to render flash-over on the exterior more diicult. Beyond this the tube could be operated in oil. The tube Was situated in an insulating press to obtain a better packing on the part of the rubber rings; however, the surface pressure resulting upon the evacuation was mostly suiiicient to ensure that the rings tted tightly. In order to diminish the vapor pressure, more particularly of the rubber parts, we have contemplated the use of a construction more concisely referred to at a later point, whereby the rubber rings may be very narrow, and beyond this are also covered 01T to a great extent against the vacuum space by reason of the groove-like arrangement. In place of insulating paper it is naturally also possible to employ mica, glass, cellon or any other insulating material.

The rst and the last metallic plate may be constructed as electrodes, from which, in accordance with the polarity of the generated corpuscles, the negative or positive side of the arrangement is furnished with a suitable emission source.

Generally speaking, it is desirable to make the diameter of the discharge passage as large as possible for a given length to prevent the charge carriers from striking against the wall, as the point concerned is to allow as many charge carriers as possible to pass through the tube with full acceleration. On the other hand, however, it is important not to make the vacuum space larger than is absolutely essential. Since the charge carriers do not tend to dispersal to a considerable degree until relatively long distances have been covered, it is contemplated to adapt the form of the discharge tube to this dispersal tendency, i. e., to select a stepped, conical construction. It has already been stated that this invention enables, in place of ceramic insulators, elastic organic insulating substances also to be employed, as an outgassing of the material faces is not absolutely imperative. Since we contemplate selecting a large diameter for the tube and making the walls several centimetres in thickness, this fact is very important, as the walls or intermediate layers, in view of the dimensions concerned, can only be produced from glass With considerable trouble. To avoid damage to and carbonization of the organic substances when employing insulating materials sensitive to heat, it is proposed to coat these materials wholly or in part with an insulating but very resistible, non-decomposable substance, for example sulphur or glass.

There is also the possibility of making the Walls or intermediate insulating layers wholly or partially of quartz or quartz material, porcelain, steatlte, etc.

Vacuum tubes produced according to the invention may be successfully operated by short high-voltage impulses, such as supplied, for example, by technical impulse testing systems. The duration of these impulses is situated approximately within the range of 10-3 and 10-6 seconds, it being characteristic that the interval between two impulses is long in comparison with the duration of the impulse itself. Since a discharge can only take place when electricity carriers of both polarities are present, and are furnished with the opportunity of eiectively impacting, it is possible in the case of sub--divided tubes of this nature, the rapidly occurring sliding discharges along the wall having been overcome, to utilize the lower degree of movement of the ions and, owing to the retardation, to apply much higher potentials to the tube than would conform to the prevailing gas pressure. For example, it was possible to employ these tubes up to 2,400,000 volts as ion tubes. The generation of hydrogen passage rays was also successful, and up to the present has been performed to the extent of 1,000,000 volts. It is important that the increase of potential occurs with suicient rapidity. A great advantage of this arrangement resides in the fact that practically unlimited intensities may be obtained in a very short time. This fact is very important when using the tube for medicinal purposes. It has been found when using X- rays that the useful effect of the X-rays is frequently nullied by the detrimental effect of the secondary radiation. These drawbacks are ob viated when using cathode rays, which are only at rest at a certain place in the interior of the body where they produce the required medicinal effect.

The invention is illustrated by Way of example in the accompanying drawings.

Fig. 1 is a longitudinal section through a form of embodiment of the discharge tube.

Fig. 2 is a View of part of a further embodiment of the discharge tube, partly in section.

Fig. 3 is a longitudinal section through an additional embodiment, employing rubber rings which are substantially circular in cross-section.

Fig. 4 is the View of a still further form of embodiment of the tube, in which the discharge space is increased towards the anode.

With regard to Fig. 1, I and 2 designate two plates or rings, which at the same time act as supports for the cathode indicated at 3 and the anode indicated at 4. The tube wall between these two plates is composed of metal rings 5, rubber rings 6 and insulating rings 1. As shown in Fig. 1, these rings are superimposed in alternate fashion and in such a manner that the edges of the holes in the metallic rings 5 project beyond the corresponding edges of the insulating rings 1, in order to sub-divide the wall of the tube in the manner above described. The rubber rings 6 serve to Seal the inner space of the tube against atmosphere.

In the embodiment according to Fig. 2 the outer peripheral edges of the insulating rings 1 project only to a slight extent beyond the outer edges of the metallic rings 5. The sealing of the tube against the exterior is performed, however, by means of a rubber sleeve or the like 8, which under the action of the outer atmospheric pressure moves into the grooves formed between the metal rings and the insulating rings. The attachment of the sleeve 8 to the end plate I may be performed in any appropriate fashion, for example by means of a clip.

In the form of embodiment according to Fig. 3 the rubber rings 6 shown in Fig. 1 are replaced by rubber rings 9. These rings, in the manner described above, may be fitted in special grooves in the insulating discs 1, or, as shown in Fig. 3, there may be provided on the insulating rings 1 insulating rings I0 and Il disposed concentrically to each other .on both sides, so that the annular space between these rings may be employed for location of the rubber ring 8. Upon the application of the metal rings 5 and upon assembly of the complete wall of the tube the rubber rings 9, as disclosed by the drawings, are somewhat compressed, and serve as a packing in a similar manner to the rubber rings 6 in Fig. 1.

Fig. 4 shows an embodiment in which packs of rings in relatively step-like fashion are so arranged that the discharge space between the cathode and the anode (designated K and A respectively in Fig. 4) is widened out. The single packs may be composed as in the embodiments according to Figs. 1-3. The packs in Fig. 4 are designated P.

It will be understood that no restriction is made to the specific forms of embodiment shown, and that various modifications are quite possible within the meaning of the above description and the annexed claims Without departing from the spirit of the invention.

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

1. An ultrahigh-voltage vacuum discharge tube comprising end plates with electrodes and a series of contiguous unit condenser sections forming with said end plates an evacuated enclosure, each of said unit condenser sections comprising first a sealing insulating ring, then a metal ring, then another sealing insulating ring, then a main insulating ring, each of said rings abutting the next in the order named, to form a hermetically sealed envelope.

2. An ultrahigh-voltage vacuum discharge tube comprising end plates and a series of contiguous annular unit condenser sections, each of said sections abutting against the next to form a substantially tubular surface between said end plates,

electrodes supported by said end plates to provide a discharge path centrally of said space, said space being evacuated.

3. An ultrahigh-voltage vacuum discharge tube comprising end plates embodying electrodes and i) a ser1es of cont1guous umt condenser sections a series of contiguous unit condenser sections diameter of the said metal rings is less than Y the inner diameter of said insulating rings.

6. An ultrahigh-voltage vacuum discharge tube as claimed in claim 1, in which the inner diameter of said metal rings is less than the inner diameter of said insulating rings, said sealing insulating rings being composed of elastic or-l ganic material and having an inner diameter greater than the inner diameter of said mail insulating rings, to provide a long inside 1eak` age path.

7. An ultrahigh-voltage vacuum discharge tube as claimed in claim l, the inner diameters of said metal rings and said main insulating rings of a unit being different from each other, and the corresponding rings of different units having the same inner diameter.

8. An ultrahigh-voltage vacuum discharge tube as claimed in claim 1, wherein the outer diameters of said insulating rings are greater than the outer diameters of said metal rings.

9. An ultrahigh-voltage vacuum discharge tube as claimed in claim 1, wherein the outer diameters of said insulating rings are greater than the outer diameters of said metal rings, and wherein the inner diameters of said metal rings are less than the inner diameters of said insulating rings.

10. An ultrahigh-voltage vacuum discharge tube as claimed in claim l, said rings gradually increasing in size from the cathode end towards the anode end of the tube.

l1. An ultrahigh-Voltage vacuum discharge tube as claimed in claim 1, wherein said insulating parts are coated with a heat-resistant, nondecomposable insulating substance.

12. An ultrahigh-voltage vacuum discharge tube as claimed in claim 1, wherein said insulating parts are coated with sulphur.

13. An ultrahigh-voltage Vacuum discharge tube comprising end plates, a series of contiguous unit condenser sections of relatively high capacity and constituting with said end plates the Wall of the said tube and forming an evacuated sealed envelope, the said Wall being noneconductive in respect of the highest potential applied and each of said unit condenser sections comprising alternate rings of metal and insulating material, electrodes supported centrally of said end plates between which electrodes the discharge is adapted to pass centrally of said discharge tube.

ARNO BRASCH. FRITZ LANGE.

CERTIFICATE OF CORRECTION.

Patent No. 2,043,733. June 9, 1956.

ARNO BRASCH, ET AL.

It is hereby Certified that error appears in the printed specification of the above numbered patent requirig Correction as follows: Page 5, second column, line 14, claim 2, for the Word "surface" read space; and line 38, Claim 4, insert a comma after ringH second occurrence; and that the said Letters Patent should be read with these corrections therein that the same may conform to the record of the case in the Patent Office.

Signed and Sealed this 15th day of September, A. D. 1936.

Henry Van Arsdale LSeal) Acting Commiesioner or Patents.

CERTIFICATE OF CORRECTION.

' Patent No. 2,045, 753. June 9, 1956.

ARNO BRASCH, ET AL.

It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction as follows: Page 3, second column, line 14, claim 2, for the Word "surface" read space; and line 38, claim 4, insert a comme. after "ring" second occurrence; and that the said Letters Patent should be read With these corrections therein that the same may conform to the record of the case in the Patent Office.

vSigned, and sealed this 15th day of September, A. D. 1956.

Henry Van Arsdale tseal) Acting Commissioner of Patents.

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