US2926278A - Arrangement in anode tubes for high voltage ionic valves - Google Patents

Description

Feb. 23, 1960 LAMM 2,926,278

ARRANGEMENT IN ANODE TUBES FOR HIGH VOLTAGE IONIC VALVES Filed May 29, 1956 2 Sheets-Sheet 1 I 30 l a 24 34 I a I L INVENTOR. U77QL 0mm Feb. 23, 1960 L 2,926,278

ARRANGEMENT IN ANODE TUBES FOR HIGH VOLTAGE IONIC VALVES Filed May 29, 1956 2 Sheets-Sheet 2 I N VEN TOR.

ARRANGEMENT IN ANODE TUBESFOR tuna VOLTAGE roNrc VALVES Uno Lamm, Lndv'ika, Sweden, assignor to Allmanna Svenska Elektriska Aktiebolaget, Vasteras, Sweden, a corporation of Sweden The present invention is a continuation-in-part of my application, Serial No. 236,757, filed July 14, 1951, now abandoned and relates to an anode tube for a high voltage ionic valve, and particularly to a method for mounting grading electrodes in such a tube.

One object of the invention is to provide a construction by which back-arcing is rendered more difficult.

Another object is to provide a construction by which the plasma layer in the anode tube most adjacent to the surrounding insulating Wall is divided into several electrically separated parts in order to prevent break-down between the anode and the cathode of the ionic valve in axial direction along the tube wall.

A further object is the provision of means for loosely supporting the grading electrodes without attachment at the tube wall.

Although general experience shows that contacts between metallic and ceramic bodies, such as porcelaintor the like, which are exposed to the conducting plasma may cause disturbances, and therefore should be avoided, it,

has been found that such contacts may be tolerated if the ionization of the adjacent plasma is very weak compared with that prevailing in the current paths during the nonconducting intervals, and the present invention is based on this finding. According to the invention the grading electrodes consist of two concentric parts, one central part provided with a number of holes for the passage of the arc, the peripheral portion of which is so arranged that only a very small diffusion of ions is permitted through the interstice between two adjacent grading electrodes, and one peripheral part forming a ring which rests against shoulders in the tube along practical their Whole periphery.

The rings resting against the shoulders may be integral with the discs in which case their introduction into the insulating tube may be effected, for instance, while cooling down the disc to a low temperature for permitting the introduction of the first introduced disc past the shoulders belonging to the later introduced discs, or the discs may be introduced past their own shoulders from beneath. As a rule it is, however, preferable to make the carrying rings loose with respect to the discs for facilitating the introduction into the insulating .tube. In such case each ring may preferably be provided with a slit for being introduced into a groove in the wall of the anode tube. At any rate, the rings should preferably be of essentially the same material as the discs. For such material preferably pure iron may be employed. Since this metal has a very low elastic limit, the rings must as a rule possess a very small radial width if they are slit at only one place and introduced by being pressed together in analogy with, for instance, piston packing rings. It may therefore be preferable to slit them at several places and to join them at these places by hinge bolts. At these slitting places it should at any rate be observed that the joints should not be butt joints but should be of such a form that the passage of possibly leaking ions is impeded by more or less labyrinth-shaped joints.

The contact surface between the ring and the insulating *tes Patent screened by the edge of the insulating material lying out side it.

The bushings for admit-ting current to the grading elec trodes preferably consist of separate, conical plugs of sub stantia-lly the same material as the tube wall, penetrating through the said wall and sealed there-against by a glaze layer. As these plugs may be turned or ground and as the holes may be bored, a finer precision of the placing of said plugs can be obtained than when using perforated projections, which are formed in advance, as has been previously proposed.

Outside the outer end of the plug there is placed a metal cap known per se, and this cap is provided at the inside with a central extension of substantially the same material, said extension traversing a hole in the plug and serving for the introduction of current. The sealing of the said cap to the plug may be effected before, simultaneously with or after the sealing of the plug into the tube Wall.

The central leading-in conductor is preferably tubular in order to facilitate the connection to thepotential distributor in the manner to be described more in detail below.

It should either have a smaller outer diameter than the diameter of the plug hole or terminate at a certain distance inside the inner end of the plug, in order that a possible contact between the metal and the insulating wall shall be well screened in relation to the active parts ofthe in;

terior of the anode tube.

7 By the precision obtained in a leading-in bushingthe type now described, the use of a very she-rt flexible conductor for connecting to the corresponding voltage distributor is permitted, it being possible to screen the said 7 conductor as well as the leading-in conductor. The.

former may, for instance, take the form of a contact brush composed of a plurality of Wires, which is introduced into the hollow conductor. Possibly a brushshaped conductor may instead be secured tothe cap and between a grading electrode and the insulating Wall. Fig.

3 shows in a plan view a joint of a divided ring and Fig.

4 is a corresponding side view. Fig. 5 shows a side viewand Fig. 6 a cross section of the ring at the place of aof bayonet joint. Fig. 7 shows a detail sectionm view a leading-in bushing for the discs. I In the form shown in Fig. 1, the anode tube 3 has a number of identical grading electrodes 19 containedtherein, each of said electrodes comprising a central part 26 and a peripheral part 1; The central part of the grading electrodes may for instance consist of a central box-shaped construction 27 provided with a number of holes 28 for'the passage of the arc and an outer single portion 29 of conical shape ending with a bent portion 30 which is joined with the outer part1. Said outerpart 1 may consist of a ring preferably made from-the same material as the central part 26 and either being in one piece or in several pieces which may be joined together. The conical portion 29 of the central part 26 should have such an extension that the interstices against adjacent electrodes have a length which is many times the space between adjacent electrodes for the purpose of preventing diffusion of ions from the central portion of the part 26 to the inner periphery of the anode tube 3. Along the anode tube a resistor 20 is shown which has one of its ends connected to the anode bolt 21 which is PatentedFeh- 23,

Of course other connected to the anode body 31 by means of a conductor 32 and a screw 33, while the other end of the resistor is intended to be connected to the cathode of the ionic valve, not shown. The resistor 20 serves as the potential distributor while leads 22 and 23 connect tappings on said resistor with the cap 14 and 14'', respectively of the leading-in conductors for the grading electrodes. As these leading-in conductors are divided around the circumference of the anode tube as shown in the left hand half of the figure, only two of such conductors are shown on the right hand portion of the drawing. The bottom leading-in conductor 24 is intended to be connected to a grid control device as it belongs to the grid 25 of the tube, said grid is preferably mounted according to the same principle as the grading electrodes 26 and for this purpose a ring 34 is shown to be inserted in a peripheral groove. The anode tube is joined with the portion 35 of the ionic valve vessel.

From the enlargement, shown in Fig. 2, it will be clear that the ring 1 rests in a groove at the inside of the insulating anode tube 3 and that the borders of the grooves form shoulders 2 at the inside surface. Preferably the grooves are ground into the insulating wall for effecting the necessary precision and the shoulders serve for reinforcing this wall. The ring is, on the other hand, preferably provided with a circumferential recess 4 which leaves the inner edge of the shoulder in the insulating wall 3 free and to a certain extent screens the inner limiting line for the bearing of the ring against the insulating wall. Especially if the height of the ring is equal to the height of the groove in the insulating wall so that the ring will rest against the insulating material at the upper side, this upper side of the ring preferably is provided with a corresponding recess for the same purpose.

If the ring is sufficiently elastic to be bent inwardly and then expand again, so as to fit into the groove in the insulating wall, it may be sufiicient to slit it at one place. If it is made from pure iron, its elasticity is usually insufiicient for the above purpose, and the ring must be cut into several portions of equal or unequal length and said portions are preferably joined together by hinges at all places but one. Fig. 3 shows such a hinge joint in plan view and Fig. 4 the same joint in a side view in the most simple arrangement having oblique joint surfaces, but the surfaces may of course also be graduated or shaped in another manner. The hinge bolt is designated by 6. At one place the sections should be free from each other during the introduction, but they may preferably be joined there by a bolt after the introduction.

After the ring has been put in place the inner part of the grading electrode is introduced, only the peripheral portion ofsaid inner part being shown in Figs. 2, 6, 7, and the inner part is secured to the ring preferably only at a small number of places, for instance, by some kind of bayonet joint. Fig. 5 shows the slot in the ring serving this purpose as seen from its inside, and Fig. 6 shows a corresponding cross section. The slot in the ring consists of an axially extending portion 7, which serves to admit the pin 9 extending'from the inner part 18 which should pass the aforesaid ring to be secured into another ring. Theslot has further an off-set portion 8, through which the pin belonging to the gradingelectrode which the said ring shall form a part of shall be introduced from the side, whereupon it should pass into the 4 lowest portion of the off-set slot and rest there, the pin and slot there forming a bayonet joint.

In Fig. 7 the tube wall 3 is provided with a conical hole into which a conical plug 12, preferably of the same material as the tube wall 3 is inserted and sealed by a glaze. This plug has a penetrating hole 13, which however, at the outer end of the plug is covered by a cap 14 sealed by glaze. The cap carries a tubular conductor 15, which preferably runs freely through the hole 13 of the plug and into said conductor 15 there may be intro duced an elastic, preferably brush-shaped contact 16, which may be screwed into a part 17 secured to the inner part of a grading electrode 18 after part 17 has been secured in place. As aforesaid, several other elastic contact types may be employed. Characteristic to the arrangement is that in any case, on account of the precision of the position of the bushing, no long flexible conductor is needed for the connection. Instead of a glaze, other sealing means may be employed, for instance a lacquer.

I claim as my invention:

1. In an anode tube for high voltage ionic valves a continuous insulating wall of ceramic material, an anode body, a number of similarly shaped and positioned grading electrodes, means to keep said electrodes continuously under different potentials, said electrodes each consisting of two parts, one central part, means for the detachable connection of the said central part to the said peripheral part and one peripheral part, said central part being provided with holes for the passage of the arc, the outer portion of said central part having conical shape so that it forms, with the corresponding parts of adjacent electrodes, interstices having lengths many times the space between two adjacent conical parts, said peripheral part forming a ring, and peripheral grooves accommodating said peripheral ring parts and limited-by shoulders in the inner surface of said insulating wall to a number of grooves corresponding to the number of the grading electrodes.

2. Grading electrodes according to claim 1 comprising detachable joints between their central part and their peripheral part for the attachment of the said central parts to the said peripheral parts after the assembly of the peripheral parts on the said shoulders on the internal surface of the insulating wall.

3. Grading electrodes according to claim 1 in which the peripheral parts consist of rings, each split at at least two points along their periphery.

4. In an anode tube according to claim 1 said means to keep the grading electrodes under different potentials, consisting of a potential divider connected between anode and cathode potential, plugs of insulating material penetrating through said insulating wall, caps sealing holes through said plugs at their outer ends and leading-in conductors for said grading electrodes contained in said holes, leads connecting tappings on said potential divider with said caps.

References Cited in the file of this patent 'UNITED STATES PATENTS 2,182,185 Trump Dec. 5, 1939 2,446,600 Lamm Aug. 10, 1948 2,629,066 Eitel Feb. 17, 1953 2,812,466 Murdock Nov. 5, 1957 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent N00 2,926 278 February 23 1960 Uno Lamm It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

Column 4, line 29 strike out "and one peripheral part" and insert the same after "part" in line 27, same column,

Signed and sealed this 6th day of September 1960 SEAL) Atest:

ERNEST W, SWIDER ROBERT C. WATSON Afiesting Officer Commissioner of Patents

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