US2653265A - Gas-filled grid controlled electronic tube - Google Patents

Description

Sept. 22, 1953 A. w. COOLIDGE, JR

GAS-FILLED GRID CONTROLLED ELECTRONIC TUBE Filed March 23; 1951 Inventor-z e o w m M 5 O c. M W. .6 w H m M W Patented Sept. 22, 1953 GAS -FILLED GRID CONTROLLED ELECTRONIC TUBE Arthur w. Coolidge, Jr., Scotia, N. Y., asslgnor to General Electric Company, a. corporation of New York Application March 23, 1951, Serial No. 217.262,

' 1 Claim. 1

The present invention relates to electric dis- Y charge devices of the gas or vapor-filledtype, and

particularly to improved devices of this character with respect to the ability of the device to conduct large currents and withstand severe commutation duty.

In electric discharge devices of the gaseous type,

it is a. problem to provide constructions which function properly under certain electrical conditions. For example, to be commercially satisfactory, the control electrode must operate consistently to permit initiation of conduction at the same instant in the anode voltage Wave for a given voltage of control electrode. Also, the tube must be able to prevent the establishment of a discharge during the inverse voltage cycle. A measure of the ability of a gaseous tube to remain nonconducting immediately following a period of normal conduction is provided by th commutatation factor of the tube. The commutation factor of a tube has been defined as the product of the rate of current decay in amperes per microsecond just prior to the end of the commutation period, and the rate of inverse voltage rise in volts per microsecond just after commutation is complete.

Recently gas or vapor electric discharge devices, particularly those employing a rare gas filling, have been designed to provide rather complete shielding of the anode in order to protect th anode from positive ion bombardment during the inverse voltage cycle. Close spacing between the grid and the anode and between these electrodes in the shielding has also been provided to limit the number of ions alfected by the anode field at the end of a period of conduction, and to limit the volume of ions inthe grid anode region.

While these improvements have resulted in good electrical characteristics of the tubes, they. have from a manufacturing point of view been rather expensive and have required a large number of metal parts for the shielding function. The support of thes parts also renders the resultin mount somewhat complicated to assemble and less rigid from a mechanical point of View than would be desirable.

It is an important object of the present invention, therefore, to provide an improved gaseous type of electric discharge device which i simple and rugged in construction and which is capable of carrying large currents and exhibits satisfactory electrical characteristics, even in circuits subjecting the devices to severe commutation duty.

Further objects and advantages of my invention will become apparent as the following description proceeds, referencebeing had to the accompanying drawing in which the single figure is an elevational view in section of a gaseous electric discharge device embodying my invention.

The electric discharge device there illustrated includes a pair of generally cylindrical envelope sections l and 2 of glass or other insulating material, having open ends joined together in hermeticaily sealed relation by the oppositely extending flanges 3 and 4 of a. grid structure designated generally by the numeral 5. The grid structure may to advantage be fabricated from a pair of cup-shaped members brazed together in back-to-back relationship, and including central planar portions 6 and l in addition to the flanges 3 and 4. The planar central portions 6 and I are provided with suitable slots 8, through which the electric discharge may take place. A suitable grid terminal 5a is joined to the flanges 3 and 4 of the grid members.

The lower end of the envelope I is provided with a pair of circular bosses 9, to which suitable metal closure members In and l l are sealed. These closure members are of cup shape and are preferably formed of an alloy having temperature expansion characteristics matching those of glass, such as one of the well-known iron-nickel cobalt alloys. The cathode structure, designated generally by the numeral I2, is supported from the terminals It and H by a pair of conductors l3 and I4, which are suitably bonded to the members I0 and H. The external terminal connections for the cathode are provided by a pair of strap terminals I5 and I6 secured to the members l0 and II.

The anode is sealed to and supported from the other end of the insulating envelope section 2. As illustrated, th anode includes a generally planar and circular action portion ll, formed integrally With a cylindrical supporting portion [8, the outer end of which is joined to the envelope section 2 by a sealing ring 19, preferably formed of an ironnickel-oobalt alloy. The planar portion of the anode is reinforced by a heavy circular plate 20, brazed or otherwise secured to the outer surface of the planar portion ll of the anode, and a terminal connector is provided by a heavy conducting strap 2|.

As will be apparent from an inspection of the drawing, the diameter of the supporting portion of the anode is only slightly smaller than the internal diameter of the flange 4 of the grid, and the envelope portion 2. The length of the supporting portion is also sufiicient to space the active anode surface very closely with respect to a minimum. The construction is much simpler than the internally shielded gaseous tubes which have been employed in the past. The large exteriorly exposed anode surface and the exteriorly exposed grid surfaces facilitate the conduction of a large amount of heat away from these elements.

While I have described a particular embodiment of my invention, it will be apparent to those skilled in the art that changes and modifications may be made without departing from the true spirit and scope of my invention in its broader aspects, and I aim, therefore, in the appended claim, to cover all such changes and modifications as fall within the true scope and spirit of my invention.

What I claim as new and desire to secure by Letters Patent of the United States is:

An electric discharge device of the gaseous discharge type, comprising a generally planar grid structure, having a pair of circular flanges extending in opposite directions from the outer edge of said grid structure, a cylindrical envelope sec- 4 tion of insulating material sealed at one end to one of said flanges, an anode structure including a generally planar active surface and a cylindrical supporting structure joined at one end to the outer edge of said active surface and sealed at the other end to said envelope section, said cylindrical supporting portion extending within said envelope section and supporting said anode in closely spaced relation with respect to the planar surface of said grid and the diameter of said supporting portion being only slightly smaller than the internal diameter of said envelope section and the flange on said grid to enclose a minimum volume of gas between said anode and grid, a second cylindrical envelope section of insulating material sealed to the other flange of said structure of said envelope section and a cathode supported within said other envelope section.

ARTHUR W. COOLIDGE, JR.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 2,179,601 Smith Nov. 14, 1939 2,367,331 Bondley Jan. 18, 1945 FOREIGN PATENTS Number Country Date 492,464 Italy Mar. 10, 1943

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