US2189593A - Gas or vapor filled discharge tube - Google Patents

Description

Feb. 6, 1940. A. PUfZER GAS OR VAPOR FILL ED DISCHARGE TUBE Filed Oct. 27, 1937 INVENTOR A/fraaPdZZer ATTORNE WITN ESSES.

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Patented Feb. 6, 1940 PATENT OFFICE GAS on VAPOR. FILLED DISCHARGE TUBE Alfred Piitzer, BerlineS'panda'u, Germany, assignor to Siemens & Halske Aktiengesellschaft Siemensstadt, near Berlin, Germany, a corporation of Germany Application October 27, 1937 Serial No. 171,329

. In Germany October 1, 1936' 2 Claims.

The invention relates to an electrical discharge device and especially one with a plurality of anodes. v

An object of the inventionis to prevent undesired d1scharges between electrodes in a device having a plurality of current paths therein.

In devices having a plurality of current paths, such as the tubes having a plurality of anodes, and possibly a'plurality of auxiliary electrodes,

. with a common cathode, there is a comparative- 1y great danger of undesired discharges These discharges may be either a backfire or 'a forward-fire to an electrode" in another current ,path than that desired. The safety protection against this undesirable ignition phenomena is not sufficient as it should bein tubes of this type of the prior'art, unless the tubes are constructed with a comparatively complicated structure. v ,The construction of such discharge tubes is rendered more diflicult because of the stresses which arise as a result of the utilization of high power and by the requirement that distances between electrodes be accurately maintained. An object of the present inventionis a discharge device whichcombines great operating safety and simple mechanical construction.

Other objects and advantages of the invention will be apparent from the followingdescription and drawing in which Figure l is a top crossthe invention. Fig. 2 is a perspective'view of the device similar to Fig. 1- with parts broken away and the curved parts elliptical instead of cylindrical; and Figs. 3, 4, 5, 6 and 'l are topcrosssectional Views illustrating various modifications of Fig. 1.

Fig. 1 shows schematically the structure of two-anode grid control discharge device accord ing to the invention. Thecathode I is prefer- 4 ably centrally placed therein. This cathode is preferably of the hot cathode type and constructed asa spiral. Inthis construction the auxiliary electrode 3 is preferably utilized as a cylindrical grid, which is common for the two-,

current paths described in the device. The grid has preferably slots 5 on two opposite sides of the v cathode for the penetration of the discharge to.

sectional View of electrode structure embodying .lic screen I. I

In Fig." 2 is perspectively illustrated the elements mentioned in connection with Fig. 1 except that'the parts 2, 3 and l are elliptical in cross-section. This assembly may be placed in any suitable, glass or other type container which will be filled with a metallic vapor or noble gas. This figure illustrates the preferred structure, of the metallic screen I which'has two covers 9 and H for theends of portion 1. Theupper cover i H is preferably constructed as a network in order that the structure maybe properly pumped out preparatory-to the introduction of the desired gas or vapor into the discharge valve. The elec-' trode system is connected by current conducting leads extending through small insulating tubes H] from the usual press through the bottom plate 9. The current conducting lead l3 to the oath ode preferably passes through the plate 9 and the, return; of the heat currentis preferably through the upper cover I l and the metal screen 7 'i to the wire [4. 1

As illustrated in these two figures the anodes of the discharge device form a unit enclosing a'cathode and these anodes are electrically sep-' arated from each other by longitudinal joints with insulation inserts. The anodes and control electrodes are of cylindrical contour although other curved or straight-sided sheet material may be utilized. These anodes and control electrodes form a mutually suporting unit with fixed distancesmaintained between the elements. The distances of the screen I from the electrode surface as well as the covers ofthe screen are preferably that of the mean free path of an electron of the gaseous medium of the discharge device. The discharge between the exterior "surfaces of the anodes" are thus avoided and undesirable dis- 45 charges between the interior surfaces or the anodes are prevented by the separation provided I by the control electrode. The protective cylinder offers .injaddition the further advantages that by reason of its presence, disturbances because of wall charges, are avoided.

gitudinally of the anodes and by the insertion of intermediate layers of insulating material. Ihe radial projection surfaces of the control electrode: or electrodes are preferably so constructed that they penetrate betwee' the flanges forming the connection between the two anodes and are held rigidly insulated therebetween. The flange connection is preferably carried out by insulating screw couplin Under certain circumstances the flange shaped projection of the auxiliary electrode may be projected between the flanges of the anodes to the outer cylindrical screen either with or without the insertion of insulating material between the auxiliary electrode and the screen. These flange shaped projections from the auxiliary electrode to the outer screen are illustrated in Fig. 3. The inserts of insulating material may be superfluous when no control eiTect is to be exerted and only a separation of the discharge spaces and possibly a partial screen of the cathode is desired as for example in rectifier tubes. The flange projections are in that case brought through the anodes by insulation and are fastened directly to the outer cylindrical metallic screen. This arrangement is particularly for use when-a suitable potential, for example, cathode potential, is to be applied to the metallic screen. In Fig. 3 the electrode 3 would serve not for control purposes, but together with those projecting surfaces fulfill the task of separating the discharge spaces and of screening the cathode. The projecting parts 4 are both insulated from the anodefi but are fastened to the screen 1 directly so that they together with the electrode part 3 take on the potential of the cathode terminal.

Fig. 4 shows the invention applied Z-phase rectifier. The anode structure comprises three separate insulated anodes 2. In this case the openings in the auzn'liary electrodes, which may be used for screening or control, are arranged in a manner corresponding in direction with the anode with which they cooperate.

Fig. 5 discloses 3-phase discharge device with a common grid which basically corresponds in its structural features to the rectifier according to Fig. 3.

In Fig. 6 a B-phase control vessel with separate grids differs from that illustrated in Fig. 5 by the insulating intermediate layers l2 between the projecting parts t of the control electrodes.

Fig. 7 discloses the invention as applied to a discharge device that is especially adapted to be an inverter with two anodes. In this case the grid electrodes are again separated from each other by insulation l 5 while the remainder of the construction corresponds to the discharge device illustrated in Fig. 1.

The arrangement of the electrode system as described not only has the advantage of a complete protection against undesired discharges but also there is a high resistance against all mechanical and thermic stresses. The mutual support of the anodes and auxiliary electrodes maintain the electrode distances completely constant and this is or great importance in maintaining the tube characteristics constant. Either or both the auxiliary electrode and anode current leads or the tubes are made sufficiently rigid to support the structure.

t is clear that this simple construction oilers many application possibilities in particular as regards the number and arrangement and functioning of the electrodes. Thus it is possible to construct the tube as a full-wave rectifier, a fullwave valve or a S-phase valve, etc. By proper arrangement of the insulation it is possible to maintain the control electrodes influencing the individual discharge paths either separate or common. From this possibility a number of structural forms may evolve of which the forms described on the drawing are only examples. Accordingly, it is desired that only such limitations be imposed on the following claims as are necessitated by the prior art.

I claim as my invention:

1. An electrical discharge device comprising a cathode and a plurality of anodes and control electrodes, said control electrodes cooperating to form an enclosure about said cathode and having solid insulating means between the various control electrodes, and said anodes cooperating to form an enclosure about said cathode and control electrodes and having insulation means between the various anodes.

2. An electrical device comprising a cathode, a plurality of curved conductive members enclosing said cathode and having openings therein, a plurality of flanges from said members, a plurality of curved conductive members enclosing said cathode and said first curved conductive members and inst-dating means joining said last mentioned curved members to the flanges on said first mentioned curved members.

ALFRED PiiTzER.

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