US2339499A - Discharge device - Google Patents

Description

JUIL A13, ,1944. D. E. MARSHALL E-rm. 2339499 DISCHARGE DEVICE v original Filed sept. `26, 1940 INVENTORS D. E MHiE/HLZ hmz cn/06H55 ATTORNEY Patented Jan. 18, 1944 DISCHARGE DEVICE Donald E. Marshall, Allwood, and William J.

Knochel, Irvington, N. J., assignors to Westinghouse Electric & Manufacturing Company, East Pittsburgh, Pa., a corporation of Pennsylvania Original application September 26, 1940, Serial No. 358,474. Divided and this application April 18, 1942, Serial No. 439,575

v3 claims. (01; 25o-r7.5)

This invention is a division of our prior application directed to a metal-casing discharge device, Serial No. 358,474, filed September 26, 1940, which has become Patent No. 2,315,289 entitled Discharge device with water cooled baffle, the present invention likewise relating to discharge devices and to such devices utilizing metal casings. A

An object of the present invention is to provide an improved igniter tip lead-in structure.

A further object is to provide a lead-in structure for an igniter tip which is rigid and readily fabricated and which introduces no probabilities of rupture of the insulative portion or of any other part thereof.

A further object of the invention is to prevent mercury or other pool material from sputtering onto the insulative sealing portion of the lead-in structure.

Still further objects will appear both by direct recitation thereof and by implication from the context as the description progresses.

In the accompanying drawing wherein like numerals of reference indicate similar parts throughout the several views; K

Figure 1 is a view principally in cross section, of a discharge device embodying our invention.

Figure 2 is a cross section on line II-II of Figure 1; and

Figure 3 is a sectional View substantially on the line III-III of Figure 2.

In the specic embodiment of the invention illustrated in said drawing, there is shown a tubular inner casing I0, preferably of stainless steel, closed at its lower end by a dish-shaped plate or header I I, also of stainless or cold-rolled steel, having its downwardly-turned and peripheral flange I2 welded to the said casing Ill. The lower end of the casing III is flared outward just beyond the lower edge of said flange I2 and is welded to the said casing where the peripheral surface of the flange and the casing are in peripheral surface Contact. This structure permits securing an outer casing I3 to the lower flared periphery of the inner casing and provides a space I4 between the casings for passage of a cooling duid therebetween. The inner casing is closed and evacuated and has mounted therein toward its upper part an anode I5. A pool cathode I6 is situated upon the header II, and in operation a discharge from the said cathode to the said anode is obtained. In order to instigate le discharge, a starter tip or igniter I'I is employed the tip end of which as shown in Figure 3, dips into the mercury. Said starter tip is of high resistance material, preferably boron carbide, which does not amalgamate with the mercury. This starter tip requires support and requires a lead-iny connection and it is those parts which constitute important features of the pres- V2li unified therewith. It is pointed out, that the post and lead-in wire areA of appropriately conductive and relatively inexpensive metal'. The said aligned parts mayboth be ofthe same metal,

lsuch as copper, or if preferred, the post I9 which is within the evacuated casing, may be of steel whereas the lead-in wire 2I which is exposed to the outside atmosphere, may be of different material, such as copper. The purpose of the inverted cup member 20 is to obtain adequate support for the post I9 and also to obtain a vacuumtight seal. The structure accordingly contemplates utilization of a nickel-cobalt-iron alloy such as sold under the trade name of Kovar as the material used for said cup. The downwardly directed peripheral rim of the cup is sealed in the upper edge of a cylinder of borosilicate glass 22. At the lower edge of this glass cylinder is sealed the peripheral upper edge of the tubular portion 23 of a anged nipple, the flange 24 whereof is below the header II with the adjacent part of the tubular portion of the nipple projecting through a hole in said header. inasmuch as this nipple is likewise a nickelcobalt-iron alloy, or Kovar, the coefficients of expansion of said nipple, glass cylinder and cup will be substantially the same and there will accordingly be no probability of rupture occurring between the parts mentioned. The alloy is strong and will be able to resist deformation and differences in coeicients of expansion thereof and attached material parts. The flange of the nipple is peripherally welded or otherwise secured with a vacuum-tight joint to the header.

Around the portion of the nipple within the casing and around the superposed insulative cylinder, cup and post is a thimble-like metallic shield 25 the closed end of which is above the post and out of contact therewith. The lower edge of the thimble-like shield is welded or otherwise secured to the -uppersurface of header Il. The shield may be of molybdenum or of coldrolled steel. The shield 25 protects the insulating material or borosilicate glass 22 during heat treatment and during operation of the device. Mercury sputtering from the cathode spot instigated by the igniter tip, cannot coat the glass cylinder and short-circuit between the cup and nipple in View of the protection obtained by the shield. A vertical key-slotv 26 provides adequate clearance both for assemblyy purposes and for projection of arm I8 therethrough from the interior mounting on the post I9 to the exterior support of igniter tip I'l.

It is apparent that many modifications may be made in the preferred structurel illustrated and, accordingly, we desire only such limitations to be imposed upon our invention as are necessitated by the spirit and scope of the following claims.

We claim:

Y l. A discharge device comprising a metal envelope having a bottom, a pool cathode in said envelope on the bottom thereof, an anode in said envelope spaced above said cathode, means for initiating a discharge, said means being supported from a cup-shaped member the peripheral margin whereof is directed downwardly toward the bottom of said envelope, an insulative cylinder sealed at its upper yedge to the said downwardly directed margin of the cup-shaped member and sealed and supported at its lower edge above the said bottom of the envelope, and a shield around the said insulative cylinder, said shield extending upwardly from the said bottom of the envelope to a position above the level of said insulative cylinder, and said means for initiating the discharge being outside of and spaced to one side of said shield.

2. A discharge device comprising a metal envelope having a bottom, a pool cathode in said envelope on the bottom thereof, an anode in said envelope spaced above said cathode, means for initiating a discharge, said means being supported from a cup-shaped member the peripheral margin whereof is directed downwardly toward the bottom of said envelope, an insulative cylinder sealed at its upper edge to the said downwardly directed margin of the cup-shaped member and sealed and supported at its lower edge above the said bottom of the envelope, and a shield around the said insulative cylinder, said shield extending upwardly from the said bottom of the envelope to a position above the level of said insulative cylinder, said shield having a closed top above the said insulative cylinder, and said means for initiating the discharge being outside of and spaced to one side of said shield. 3. A discharge device comprising a metal envelope having a bottom, a pool cathode in said envelope on the bottom thereof, an anode in said envelope spaced above said cathode, means for initiating a discharge, said means being supported from a cup-shaped member the peripheral margin whereof is directed downwardly toward the bottom of said envelope, an insulative cylinder sealed at its upper edge to the said downwardly directed margin of the cup-shaped member and sealed and supported at its lower edge above the said bottom of the envelope, and a shield around the said insulative cylinder, said shield extending upwardly from the said bottom of the envelope to a position above the level of said insulative cylinder, said shield having a slot opening at one side thereof, and an arm projecting through said slot out of contact with the shield and constituting a support for the discharge initiating means, and a post from the said cup to and supporting said arm.

DONALD E. MARSHALL. WILLIAM J. KNOCHEL.

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