US2937303A

US2937303A - Electric discharge device

Info

Publication number: US2937303A
Application number: US683365A
Authority: US
Inventors: Kenneth J Germeshausen
Original assignee: Edgerton Germeshausen and Grier Inc
Current assignee: PerkinElmer Inc
Priority date: 1957-09-11
Filing date: 1957-09-11
Publication date: 1960-05-17
Anticipated expiration: 1977-05-17

Description

y 17, 1960 K. J. GERMESHAUSEN 2,937,303

su-zc'rmc visor-mas DEVICE Filed Sept. 11, 1957 .w mm m Es E N M R a m a r a A mm m M United States Patent ELECTRIC DISCHARGE DEVICE Kenneth J. Germeshausen, Newton Center, Mass., assignor to Edger-ton, Germeshausen & Grier, Inc., Boston, Mass., a corporation of Massachusetts 3 Application September 11, 1957, Serial No. 683,365

' 13 Claims. (Cl. 313-216) The present invention relatesto electric-discharge devices and, more particularly, to gaseous-discharge tubes, including high-voltage rectifiers.

There are decided advantages in employing hydrogenfilled rectifiers and the like in substitution for noble or other inert gaseous tubes or mercury-filled tubes that inherently possess a slow deionization time and are thus limited to relatively low-repetition frequency of operation. In such inert gas-filled devices, extreme anode sputtering occurs when the devices are operated at higher frequencies, markedly reducing the ability of the tubes to hold off inverse currents and resulting in rapid cleanup. While the fast deionization rate of hydrogen and the like, on the other hand, does not pose this same problem, there are, however, difiiculties in constructing hydrogenfi-lled rectifiers or clippers for use, for example, at repetition frequencies up to and exceeding 1000 cycles. While a higher tube drop results from the use of hydrogen gas,

this is not a serious objection for high-voltage rectifiers and the like, since the tube drop is a negligible portion of the supply and load voltages.

An object of the present invention is to provide a new and improved discharge-device construction that enables the employment of hydrogen gas and the like and hence provides a novel rectifier suitable for high-voltage operation and both low and high repetition frequency operation. This end is achieved through the use of a vane-type heated cathode and a cold anode disposed in close proximity to the free ends of the cathode vanes.

A further object is to provide a new and improved electric-discharge device.

Other and further objects will be explained hereinafter and will be more particularly pointed out in the appended claims.

The invention will now be described in connection with the accompanying drawing Fig. 1 of which is a longitudinal section of a discharge device constructed in accordance with a preferred'embodiment of the invention; and i Fig. 2 is a similar view of a modification.

The present invention is illustrated as embodied in an insulative cylindrical ceramic-walled housing 1 containing a cup-shaped anode elect-rode 3 and an inverted cupshaped cathode-electrode assembly 5, as of copper, each disposed with its lateral walls substantially vertical in close proximity to the housing walls 1 in order to provide long arc-discharge paths between the electrodes through the walls 1, as disclosed in my co-pending application, Serial No. 598,425, filed July 17, 1956, for Gaseous-Discharge Device. The cathode assembly 5 is provided with an opening 7 along its upper surface exposing a plurality of preferably planar substantially parallel conductive electron-emission-coated vane segments 13, 15, 17, etc., such as of concentric cylindrical configuration or other shape, as described, for example, in co-pending application, Serial No. 580,551, filed April 25, 1956, by Kenneth J. Germeshausen and Seymour Goldberg, for Electric-Discharge Device and Cathode.

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molybdenum and the inside wall of the anode cup 3 may be provided with a backing plate 19. In accordance with the invention, the anode surface 1 1 is disposed in close proximity to the exposed free edges or-tips of the cathode vanes 13, 15, 17, etc., overlapping and coextensive with the plane P formed by the said free edges, andspaced only a close distance S therefrom. The cathode vane segments maybe heated as by heating the base 9 through the use of heater strips 21 disposed within the base 9 and connected between a supporting strut 23 and supporting cup 25 connected to the cathode cup 5. Heater current-may be passed between an'external terminal 27, extending through the preferably ceramic bottom wall 29 of the housing, and an outwardly extending terminal flange 31 extending outside the housing Walls 1 and 29. Alternatively, a self-heated vane type cathode constructioncould be employed as described in co-pending application, Serial No. 660,592, filed May 21, 1957, by the said Seymour Goldberg, for Electric-Discharge Device and Cathode. Electrical connections to the anode 3 may be effected by means of the flanges 3' extending between the lateral walls 1 of the housing and the preferably employed ceramic backing ring 2. As explained'in the said co-pending application, Serial No. 598,425, the ceramic-to-electrode seals 4 and 6 'at the anode and cathode terminal flanges 3' and 31, respectively, may, as an illustration, comprise successive layers of silver and titanium hydride, nickel and eutectec'solder. I

In accordance with the present invention, the design of the anodecathode interaction spaces must be such as to permit hold-01f of high inverse voltages while, at the sameti-me, permitting starting at quite low forward voltages. 9 The device of Fig. 1 depends for its high inverse hold-off characteristic upon the very close spacing S between the anode surface 11 and the adjacent plane P of the cathode vane edges or tips, which it overlaps. The use of this structure requires that the anode 3 11 remain colds'ince cathode material from the coated vanes 13, 15, '17, etc. will become deposited upon the anode surface 11 and could thus cause thermionic emission from the anode surface 11 if it were hot. Low anode temperatures are assured through the use of the before-mentioned anode cup construction which serves as the upper external wall of the housing of the device and hence an effective heat radiator. The cathode vanes 13, 15, 17, etc., moreover, are sufficiently closely spaced so that the inverse voltage fields rapidly attenuate along their height. "Further, any electrons originating at the, anode 3 will tend to be focused to the cathode vane edges or tips and will thus traverse the shortest path. The spacings and pressure, however, must be such that negligible ionization occurs along this path. For a-spacing S in a'hydrogen medium of about Arinch, a pressure in the order of 300 microns I may be used. More generally, in a. pressure range of from substantially 300 to 400 microns, a spacing Sof from substantially 0.08 to 0.20 inch between the jfreecdges of the cathode vane segments 13, 15, 17, etc. and the anode surface 1 1 may be employed. I

An important advantage of this structure resides'in the fact that through the omission of any'b'afile between the plane P- of the cathode vane edges or tips and the anode surface 11, the very lowest tube drop may be obtained, thereby reducing tube dissipation. Very w forward starting voltages are also therebyassured, The deioniza tion time constant'of' thisstructure, moreover, wil not exceed several microseconds. Thus, at 1,000 cycles repetition frequency of operation of the rectifier of Fig. l, in the order of 50 or 100 time constants will elapsebetween the time forward conduction ceases and appreciable inverse voltage appears.

In the modified design shown in Fig. 2, the upper end of the cathode cup 5 is provided with an apertured bafiie to provide a plurality of openings 7 between the emitting vanes 13, 15, 17, etc. and the anode 3-11. The apertures or openings 7 are made sufficiently large to achieve the desired forward starting voltage. The free edges of the cathode vanes 13, 15, 17, etc. are again located close to the openings 7' to reduce the effective spacing for inverse electrons, with the bafiie regions between the apertures 7 shielding the free edges of at least some of the vanes from the corresponding oppositely disposed portions of the anode 311. This design will result in somewhat greater tube dissipation than the design of Fig. 1 due to the voltage drop through the plurality of Openings 7, but it has an advantage in that reduced deposition of cathode material on the anode surface 11 will result.

Further modifications will occur to those skilled in the art and all such a-reconsidered to fall within the spirit and scope of the invention as defined in the appended claims.

What is claimed is:

1. In an electric-discharge device, a first electrode comprising a plurality of co-extensive vane segments adjacent free edges of which. terminate along a predetermined plane, and a second electrode having a substantially planar surface extending substantially parallel to the predetermined'plane and disposed in close proximity to the same.

2. In a gaseous-discharge device, a cathode comprising a plurality of co-extensive vane segments adjacent free edges of which terminate along a predetermined plane, and an anode having a substantially planar surface extending substantially parallel to the predetermined plane and disposed in close proximity to the same.

3. In a hydrogen-discharge device operating in a pressure range of from substantially 300 to 400 microns, a cathode comprising a plurality of co-extensive vane segments adjacent free edges of which terminate along a predetermined plane, and an anode having a substantially planar surface extending substantially parallel to the predetermined plane and disposed at ,a spacing of from substantially 0.08 to 0.20 of an inch there-from.

4. In a gaseous-discharge device, a cathode comprising a plurality of co-extensive substantially parallel vane segments adjacent free edges of which terminate along a predetermined plane substantially normal to the vane segments, and an anode having a substantially planar surface extending substantially parallel to the predetermined plane and disposed in close proximity to the same.

5. In a gaseous-discharge device, an inverted cupshaped cathode having an opening at its upper surface exposing aplurality of co-extensive vane segments adjacent free edges of which terminate along a predetermined plane adjacent the said opening, and an anode having a surface substantially parallel to the predetermined plane and disposed in close proximity to the opening.

6 In a gaseousdischarge device, an inverted cupshaped cathode having an opening at its upper surface exposing a plurality of co-extensive vane segments adjacent free edges of which terminate along a predetermined plane adjacent the said opening, an anode having a surface substantially parallel to the predetermined plane and disposed in close proximity to the opening and overlapping the same.

7. In a gaseous-discharge device contained within the insulative walls of a housing, an inverted cup-shaped cathode having an opening at its upper surface exposing a plurality of co-extensive vane segments adjacent free edges 'of which terminate along a predetermined plane adjacent the said opening, the lateral walls of the cup being disposed in close proximity to the said insulative walls, and an anode having a surface substantially parallel to the predetermined plane and disposed in close proximity to the opening.

8. In a gaseousdischarge device contained Within the insulative walls of a housing, an inverted cup-shaped cathode having an opening at its upper surface exposing a plurality of co-extensive vane segments adjacent free edges of which terminate along a predetermined plane adjacent the said opening, the lateral walls of the cup being disposed in close proximity to said insulative walls, and a cup-shaped anode the lateral walls of which are disposed in close proximity to the said insulative walls and the bottom surface of which extends substantially parallel to the predetermined plane and is disposed in close proximity to the said opening, overlapping the same.

9. In a gaseous-discharge device contained within the insulative walls of a housing, an inverted cup-shaped cathode having an opening at its upper surface exposing a plurality of co-extensive vane segments adjacent free edges of which terminate along a predetermined plane adjacent the said opening, the lateral walls of the cup being disposed in close proximity to the said insulative walls, and a cup-shaped anode the lateral walls of which are disposed in close proximity to the said insulative walls and the bottom surface of which extends substantially parallelto the predetermined plane and is disposed in close proximity to the said opening, overlapping the same, the cup-shaped anode and cathode having terminal flanges extending outside the said walls of the housing.

10. In a gaseous-discharge device contained within the insulative walls of a housing, an inverted cup-shaped cathode having an opening at its upper surface exposing a plurality of vane segments extending co-extensively along a direction substantially parallel to the lateral walls of the cup from a base disposed within the cup, the free edges of the vane segments terminating along a predetermined plane adjacent the saidopening and substantially normal to the said direction and the said lateral walls of the cup being disposed in close proximity to the said insulative Walls, and a cup-shaped anode the lateral walls of which-are disposed in close proximity to the said insula'tive walls and the bottom surface of which extends substantially parallel to the predetermined plane and is disposed in close proximity to the said opening, overlapping the sarne.

11. In a hydrogen gaseousadischarge device contained within the insulative walls of a housing, an inverted cupshaped cathode having an opening at its upper surface exposing a plurality of v-ane segments extending coextensively along a direction substantially parallel to the lateral walls of the cup from a base disposed within the cup, the free edges of the vane segments terminating along a predetermined plane adjacent the said opening and substantially normal to the said direction and the said lateral walls of the cup being disposed in close proximity to the said insulative walls, and a cup-shaped anode the lateral walls of which are disposed in close proximity to the said insulative walls and the bottom surface of which extends substantially parallel to the predetermined plane and is disposed in close proximity to the said opening, overlapping the same, the cup-shaped anode and cathode having terminal flanges extending outside the said walls of the housing.

12. An electric discharge device having a first electrode comprising a plurality of co-extensive vane segments adjacent free edges of which terminate along a predetermined surface, and a second electrode having a surface substantially co-extensive with the said predetermined surface and disposed in close proximity to the same, and in which there is provided means interposed between the said predetermined surface and the second electrode, shielding the free edges of at least some of the vanes from the corresponding oppositely disposed portions of the said surface of the second electrode.

13. An electric discharge device as claimed in claim 12 and in which the said shielding means comprises an apertured conductive member. I

References Cited in the file of this patent 5 UNITED STATES PATENTS I 1,874,753 Hull Aug. 30, 1932 1,968,839 Lederer Aug. 7, '1934 1,999,806 Eitel et a1. Apr. 30, 1935 10 2,458,693 Drieschman Jan. 11, 1949 6 Knochel Dec. 27, 1949 Sloan Dec. 27, 1949 Baker Jan. 20, 1950 Rothstein Oct. 25, 1951 White Apr. 1, 1952 Schneider June 3, 1952 Watrous Sept. 1, 1953 Coolidge; Sept. 22, 1953 White Mar. 25, 1955 Germeshausen et a1. Feb. 25, 1958 Price June24, 1958