US2245998A - Grid-controlled gas or vapor-filled discharge vessel for high operating voltages - Google Patents

Description

s w T 'June 17, 1941. 2,245,998

GRID-CONTROLLED R VAPOR-FILLED DISCHARGE VESSEL ,FOR HIGH OPERATING VOLTAGES INVENTOR HE/EBf/FT F/f/IFC 24x91 mm ATTORNEY Patented June 17, 1941 TENT oFF cs- GRID-CONTROLLED GAS R VAPOR-FILLED DISCHARGE VESSEL FOR HIGH OPERAT- ING VOLTAGES Herbert Pietsch, Berlin-Siemensstadt, Germany,

assignor to Fides Gesellschaft fiir die Verwaltung und Verwertung von gewerblichen Schutzrechten mit beschrankter Haftung, Berlin, Germany, a corporation of Germany Application June 28, 1939, Serial No. 281,577 In Germany July 15, 1938 2 Claims.

The invention relates to a gaseous discharge device and especially a grid-controlled gaseous discharge device.

An object of the invention is to prevent the occurrence of any discharge between the anode and cathode outside of the space occupied by the grid electrode.

Another object is to provide blocking discharge rneans between the control electrode and the container wall that will not readily conduct heat to the container wall.

Other objects and advantages of the invention will be apparent from the following description and drawing, in which the figure is a view, mainly in cross-section, of a'discharge device illustrating a preferred embodiment of the invention.

In gaseous discharge devices, the cathode and anode are spaced from one another with generally a grid in the space between the two. It occasionally happens, however, that because of the ionization of the gaseous atmosphere, a discharge may occasionally find an easy path from the cathode around the side of the control electrode to the anode. These occasional discharges will, of course. cause trouble because the occurrence will be at a time when the grid is supposed to prevent the breakdown of the tube. The main purpose of the invention is to prevent such a discharge occurring.

A large proportion of the discharge devices that are utilized for industrial control have glass walls. The control grids in such discharge devices that are being actively and frequently utilized, will generally have a high temperature because of the heat of the discharge. It is another object of my invention that the means preventing discharges around the control electrodes will not directly and rapidly transfer the heat of the control electrode in operation to the glass wall of the container and damage it.

In the figure is disclosed a typical gaseous discharge device used for control purposes. This device in its specific form, is to be taken for purposes of illustration and notin a limiting sense. The device includes a cathode I that is preferably of the so-called hot type, either directly or indirectly heated.

Th anode 2 may be of any desired shape. The control electrode 3 is illustrated as having preferably an H-shaped cross-section with the cathode l illustrated in the lower portion of the H and the anode 2 projecting into the upper portion of the H, and a perforated central partition 4 for the passage of the discharge therethrough under the control of the grid. The control grid i preferably supported by the wire 5 fastened in the press, which also supports the cathode. The glass vessel or container 6 has preferably a constriction 1 for providing a narrow circular gap between the control electrode 3 and the vessel Wall 6. This constriction is preferably at the upper portion of the tube 'as illustrated, although it may be located at other places in the device. A ring 8 is utilized toblock the space between the control electrode 3 and the container wall 6. This ring is preferably held by a U-shaped metal ring 9, fastened to the control grid 3.

This ring 8 is preferably of flexible material, having a low thermal conductivity. In order to obtain suflicient high thermal resistance, thin foils or metal of low thermal conductivity may be used. Of the non-metallic materials, mica is especially adapted for use as a ring, in view of its high thermal resistance. The ring, if constructed of mica or other non-conducting material, may be provided with a conducting coating, as for example, a graphite coating. This conductive coating may only cover the zone of the flexible ring which is in contact with the glass wall, or the entire surface of the flexible ring may be made conductive with such a coating. The coating is generally in the form of a thin film on the mica. This conductive coating will prevent charges accumulating on the glass or mica, and will also aid in preventing any discharge not under the influence of the control electrode. The graphite coating is designated by the numeral l 0 on the drawing.

If the field of the anode terminates in the region of the flexible ring, it is advisable that the ring have no sharp edges or points which would create field emission. If wire gauze is used for the circular gap between the vessel wall and the control part, then this gauze should be screened adequately at the position opposite the anode by the control body.

When flexible mica is utilized for the ring, the mica will absorb or cushion any jolts or jars given to the outer casing and will prevent thetransfer of such shocks to the inner electrodes. If the ring were made of any unyielding material, such as glass, these shocks would be transmitted or, if the glass were thin, the glass would crack.

Although I have shown and described a specific embodiment of my invention, I do not desire to be limited thereto, as various other modifications of the same may be made without departing from the spirit and scope of the appended claims.

I claim:

a thin layer of electrical conducting material thereon.

2. A gaseous discharge device comprising a container, a cylindrical control electrode therein 1. A gaseous discharge device comprising a 5 having a perforated partition therein, an anode container, a cylindrical control electrode therein having a perforated partition therein, an anode on one side of said partition, a cathode on the other side of said partition, and a flexible ring of low thermal conductivity attached to the outer portion of said control electrode and extending to the wall of said container, said ring having on one side of said partition, a cathode on the other side of said partition and a flexible ring of mica attached to the outer portion of said control electrode and extending to the wall of said container, said ring having a thin layer of electrical conducting material thereon.

HERBERT PIETSCH.

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