US1678870A - Vacuum-tube device - Google Patents

Description

July 31, 1928.

I. E. MOUROMTSEFF VACUUM TUBE'DEVICE Filed April 28, 1925 INVENTOR llllll l- (lllilllllll.

WITNESSES:

Patented July 31, 1928.

UNITED STATES PATENT OFFICE.

ILIA EMMANUEL MOUROMTSEEF, OF WILKINSBURG,.IPENNSYLVANIA, ASSIGNOR TO I WESTINGHOUSE ELECTRIC & MANUFACTURING COMPANY, A CORPORATION 01' PENNSYLVANIA.

VACUUM-TUBE DEVICE.

Application filed April 28, 1925.; Serial No. 26,338.

My invention relates to vacuum-tube devices and more particularly to vacuum-tube devices of the exterior anode type.

An object of my invention is to provide a 5 vacuum-tube device, having a light-weight metallic shell.

Another object of my invention-is to provide a high-vacuum device with a light metal shell container.

Another object of my invention is to provide a metal shell vacuumtube device having a pressure therein less than one one-hundredth of a millimeter of mercury.

Another object of my invention is to provide a metal shell vacuum-tube device with reinforcing means cooperating therewith,

whereby the device can be baked out during the evacuation thereof without danger of collapse of the shell.

It was early practice to construct vacuum tubes having a container entirely of glass. The ability of the glass to pass heat through its body imposed limitations upon the amountof energy which could be translated, and it was desirable, therefore, that a portion of the container be of metal to serve as one of the electrodes. This construction providod means for applying fluid in contact with the outer surface for cooling purposes. It was found necessary, of course, to make a seal between the glass insulating portion and the metal shell portion. This seal was necessarily made between glass and a very thin metal edge making it desirable that the metal shell also be very thin. It was likewise found necessary that such device be very thoroughly baked out at an elevated temperature in order toobtain a sufliciently high vacuum.

The temperature at which the copper shell must be baked out in order to remove occluded gases is at or ,above a dull red heat, and atthat temperature great difiiculty has been experienced in constructing a metal 4 shell portion which would be thin enough to permit of the construction. of a glass to metal seal and which would not collapse under the atmospheric pressure surrounding it.

My invention provides means wherebya thin metal shell portion can be reinforced.

during the exhausting operation whereby its shape is maintained against the atmospheric pressure.

By this means I am enabled to provide a vacuum-tube device having a thin metal shell portion and a very high vacuum therein.

Other objects and structural details of my invention will be apparent from the following description, when read in connection with the accompanying drawing, wherein Figure 1 is a view in vertical elevation of a typical vacuum-tube device of the thermionic discharge type with the reinforcing device of an embodiment of my invention positioned thereon;

Fig. 2 is an alternative embodiment of my invention, and;

Fig. '3 is a plan view of a detail of the embodiment. v I

Referring to the figures, a vacuum-tube device has a glass portion 1 and a metal portion 2with an edge seal 3 connecting them. I Suitable internal structure is provided, suchas a grid 4, and a cathode struc ture 5, which are mounted upon a press 6 and a re-entrant portion 7 of the glass structure.

A tubulation 8 for connection to the exhaust pump is connected .to the lower portion of the device. A temporary cylindrical metal jacket 9 of substantial thickness is adapted to surround the metal portion 2 in contact therewith. The jacket 9 is split vertically at point 11 and is surrounded by a plurality 5 of binding wires 12, 14.- and 15.. In the alternative embodiment shown in Fig. 2, a metal spiral 16 surrounds the metal shell 2 and exerts a pressure thereon. In each embodiment, a shielding collar 17 is positioned upon the metal shell 2 and closely adjacent to the seal portion 3. 4' In the operation of my invention, the vacuum-tube device is assembled in the manner well known in the prior art and pre 5 pared for evacuation.

The reinforcing means 9 or 16 of my invention may then be slipped over the metal shell portion of the device and held firmly in contact with the shell. If the split sleeve embodiment is used, it is firmly held by the wrapping-wires12, 14 and 15. If the spiral to a pressure of a millimeter or less of mercury. The backing pumpis followed in. turn by a diffusion pump which is capable of evacuating the device to pressures less'than one one-hundredth of a millimeter of mercury.

The vacuum-tube device having been con 'nected" to the pump, manifold and exhausted by the rough pump','a heating oven is ..positioned around it and heat is applied to the device. Evacuation by the rough pump may be completed in a ver few minutes and it may then be followed y the backing pump which may require a some- What longer time. During this period, the temperature of the device as a whole may be raised.

When evacuation by the backing pump is complete, the difiusion pump, in turn, is applied to the device and exhaustion continued by its agency. Simultaneously, the temperature of the device is being raised by the oven.

The heating and evacuation are'continued for a substantial period of time during which the temperature of the metal shell portion 2 may be raised to a dull red heat which may be attained partially by the heat of the oven and partially by electron bombardment of electrons obtained by the application ofcurrent to' the filament 5 and etween the filament and shell 2.

It has been found necessary to attain a temperature of a dull redheat to drive out of the metal all of the occluded gases. At this temperature a copper shell havin a diameter of 1 and a thickness of less than ninety/one-thousandths of an inch will collapse because of the pressure of the atmosphere upon itsouter' surface. In this collapse, however, there' is a spreading of portions of the shell. Such spreading is prevented bythe device of my invention when applied to the metal shell and, there- Y fore, the shape of the shell is maintained at the elevatedtem erature. The presence of v the metal shell 0 m invention permits the shell portion 2? of e vacuum tube device to-be made as thin as forty/one-thousandths inch or less and further permits the shell portion to be drawn or spun of soft metal such as copper andto retain its shape during the necessary heating and evacuatlon. By this means, I am enabled produce a vacuum-tube device having a thin copper shell portion as a part of the contalner thereof and having therein a vacuum showing a pressure less than one one-hundredths of a millimeter of mercury.

While I have shown-but two embodiments of my invention, it is capable of other changes and out departing is desired, therefore, that only-"such limitations shall be imposed thereon as are reuired by the prior art or by the appended c aims.

I claim as my invention: 1. A space-current device, comprising a plurality of electrodes, and aconta1ner therefor, comprising a metal portion and a glass portion, and means for preventing the collapse of said metal portion thereof during evacuation comprising a metal reinforcing jacket therearound.

2. A vacuum-tube device, comprislng a metal shell adapted to be heated, and means adapted to prevent collapse thereof during said heating, comprising a metal jacket adapted to fit over said shell.

3. A vacuum-tube device, comprising a cylindrical metal shell adapted to be heated, and means adapted to prevent collapse thereof duringsaid heating, comprisin a with a reinforcement.

5.I n the manufacture of a vacuum elec tr1c-d1scharge device having a wall of in-;

suflicient strength to withstand pressure when heated to an elevated temperature, the 1 steps of applying an external reinforcement to the weak portion, heating said weak portion, exhausting the device, and removing the reinforcement.

' In testimony whereof, I have hereunto iubsc ribed my name this 22nd day of April,

ILIA E. MOUROMTSEFF.

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