US1866624A - Vacuum discharge vessel - Google Patents

Description

July 1-2, 1932. w. DALLENBACH VACUUM DISCHARGE VESSEL Filed Feb. 24. 192

Patented July 12, 1932 wanrnnmitrnmmcn, or zuarcir, swirznnnann vacuum DISCHARGE VESSEL Application filed February 24, 1927, Serial No, 170,505, and in Switzerland March 4, 1926. i

My invention relates to vacuum discharge vessels of metal and has for its particular object to improve the leading-in connections.

In view of the high tension existing between I the vessel and the conductors discharges occur which will destroy the insulation resulting in leakage or short-circuits.

charges occur even at lowertensions, if the gas-pressure is increased, causing disturbances especially where gases or metal vapors participate in conveying current.

V The dangerous discharges occur especially at the places where the insulating material touches conducting portions, and the present invention aims to provide means for guarding against such. discharges.

As the insulator separates conducting parts of different electric voltage, there takes place across the surfaceof the insulator a drop of potential, which at that portion of the surface adjoining the rarefied gas will cause discharges. The .first consideration, therefore,

is to restrict this drop of potential to a nar-.

row zone which is small as compared with the mean free distance travelled by the electrons in the rarefied gas. This one can accomplish by covering the side of the insulator directed toward the vacuum with conducting parts slightly spaced apart, some of which conducting parts have the potential of the conductor, while others have the potential of the metal vessel. Without touching each other, the said conducting parts of different potential arearranged opposite to each other in a narrow zone. By such an arrangement the discharges are made much more diflicult,

the discharges being restricted in the gas space to a narrow zone in the direction of the electric field lines, so that a collision of the particles of the charge with the gas particles is not likely to occur. a

However, in many cases, this arrangement is not sufficient. The insulating material gensel of metal, E is the electrode, L the conducerally has a high emission of ions and electrons, which share in the discharge and are apt to considerably reduce the discharge tension. But this emission ofions and electrons can take place only, if the electric charges can be maintained Because of the poor electric conductivity, this is possible only at those Such dis:

material with conducting parts in the vacuum. I Of course, the distance of the zone from of the conductor isefiected. In this way, the I surface of the insulator inasfar as it adjoins the rarefied gas shall be protected. Moreover, insulating bodies. can be provided which I sions. V

Where very high tensions are present, it

tential is concentrated must betaken away from the points of contact of the insulating such points of contacts must be suificiently I I great andmust be at least several times greater than the width of the zone, so that in spite of-their high emission of ions and electrons, they can not contribute to a discharge in the rarefied gas. I

In the first place, this expedient is applied tothe insulator whereby thesealed leading-in lie entirely in the vacuum, and these must also be protected,ifthe introduction of the current shall be able to withstand higher tenmay become necessary to concentrate thedrop in potential instead of. one zone only, upon several narrow zones, which zones must be mutually separated'by spaces being a multiple of the width of the zone, since an eventual discharge in one zone must not interfere with U I the discharge tension in the others. Moreover, all said zones must have a sufficiently great distance from all the points of contact of the insulating material with the conducting parts, and these distances should be at least a multiple of the width of the zone.

In the drawing illustrating in a sectional view one embodiment of my invention:

G is the wall of the vacuum discharge vestor which carries the electric current and J the cylindrical insulator; Its surface where I it adjoins the vacuum is substantially covered by two metal projections F and F, forming with J a narrow gap W8. A similar gap is provided between F and F. Since F is electrically connected with the wall of the metal vessel and F with the electrode, the

drop in potential between G and E is concentrated on a narrow zone on the surface of the v 5 insulator at V. The width of said zone shall 1 claim:

correspond in size to or shall be small as compared with the length of the paths travelled by the electrons inthe rarefied gas. The zone at V is moreover removed about a 10 multiple of its width from the points of contact X and X between, the insulator and the 3 conducting parts in the vacuum. Furthermore, by this arrangement, the insulatin'gmaterial .is protected. against the discharges which normally start from the active surface of'the electrode, for the particles of the charge must diffuse through the narrow gap VS, before they can reach the surface of the insulator.

The insulatorJ need not serve as a sealing 7 medium for the vacuum as shown in the draw- .ing, for it mightbe located entirely in the vacuum and be used, for example, as a mechanical support.

In a vacuum discharge vessel of metal for -,containing a rarefied fluid, the combination of an electrode, an insulator sealing said elec- -trode in said vessel and slightly spaced conducting parts covering a portion of the surface of said insulator within thevessel, one of saidparts being electrically connected with said vessel and another of said parts' with said electrode, said conducting parts forminganarrow gap in which the dropin potential between said vessel and saidelectrode is l to be concentrated, said gap being located from the points of contact of said insulator a and conducting parts in the vacuum at a dis- 4 tance forming a multiple of its width, the

latter being small compared with the path traveled by the electrons in the rarefied fluid. 1

Signed at Berlin, Germany,this 9th day of I. I 7 February 1927. t r

R, WALTER "DALLENBAGH;

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