US1906653A - Evacuation system - Google Patents

Description

M y 2 1933- P. L. SPENCER 1,9 6 653 EVACUATION SYSTEM Filed March 15, 1928 B6230 L.. p6iml" r Patented M 1 3 PIIBCY L; SPENCER, or" MEDFOBD, MASSACHUSETTS, ssIG CAMBRIDGE, MASSACHUSETTS, A coRroa 'rIoN or Non 'rro RAiTHEON inc; or 1.

MASSACHUSETTS I nvAcvArrorr sys'rmr 7 Application med March 1928. s erial m. 261,977.

The invention relates broadly to themanufacture of space current devices and in particular to an improved method of treating the electrodes.

5, Heretofore,

the evacuation process in .order'to remove gases, occluded m the metal either by passing a bombarding discharge between them or inducing a current in one or more of the metallic bodies by an externally located coil. For electrical bombardment, there has been employed direct current of polarity such as to impel the discharge toward the electrode of considerable 15 metal content, usually the positive member. While the anode treatment by direct current is satisfactory in case the cooperating electrode holds littleor no gas in occlusion, e; g.

a filamentary cathode, and for that reason requiring no preliminary heating, it fails to offer a double way bombardment in the event the cathode constitutes a nonthermionic 'member or has large mass. Moreover, in apparatus involving two; or more cathodes or anodes, prior art offers no automatic shift of bombarding ous combinations treatments of different degrees. I i a An object of my invention is to provide a simple, inexpensive and effective method of heat treating electrodes,and,,in general, to improve the manufacture and operation of gaseous conduction apparatus.

i In the drawing which illustrates a: preferred embodiment, numeral 1 designates the device undergoing'the process of .manufacture. This device may compriseanyform of space current apparatus; forconvenience, I 40 show a rectifier of the Raytheon type BH socalled such as described and claimed inihe applications of Smith, Serial No. 526,095 and it has been customary during S to heat the electrodes.

- heat each of theelectrodes and accordingly discharge between the vari.

of electrodes with the re-; sult that the elements are subjected to heat I impurities. The illustrated rectifier comprises an envelope 2 termin ting in reentrant stem 3 from which two glass] tubular members 4 proj ect; Fitting over the proj ections,"there are insulating thimbles ,5ioflava or the like having a relatively fine bore through which the anodes 6.6 of refractory wmetal extend. About'the latter, a hollow cathode? of re fractory metal is mounted, said cathodehaving a hemispherical, conical or other shape, and closed along the horizontal plane .by cover8,preferably of the same metal-as the cathode. As explained in the applications supra, a device such as described offers less impedance fo'rcurrent passing from the anode to the'cathode than vice versa and is adapted for ,rectifyingalternating current of relatively-low voltage,'=e. 'g. below 200 volts; During ,the evacuation process, I propose to provide a polyphase. source of current 9 of n'ections being,- had :with the electrodes through current limiting resistors l0rand wires 11,12. It will be. evident that the 7 current source produces an electrical dis- I charge between each pair of electrodes in succession, the electron or ion bombardment being suflicient to raise the temperature of the metallic bodies to a point where the occluded f relatively. high potential, e. g; 550 volts, congases escape and pass off to the evacuat ng pump.

Experience has shown that when using ly regulated by the current supply, accord- 1 ing uniformity of-treatment to ea ch elec-, trode and'also to the device as a whole. heat treatment and the evacuation ofoc eluded gases having been completed, a hy- 5 dr'ogen washmay be employed while on the m a The ;f

1. In the manufacture of a gas discharge I device of the type comprising an evacuated envelope enclosing a large-area cathode and,

a plurality of small-area anodes, and an atmosphere of an inert gas, the method of depriving said electrodes of occluded gases which comprises connecting said cathode and said anodes to the individual phases of a polyphase alternating current source and maintaining a polyphase space current discharge between said electrodes While simultaneously evacuating said envelope.-

2. In the manufacture of a gas discharge device of the type comprising a cathode having an extended discharge surface and a plurality of anodes, each of said anodes having a small discharge surface, said anodes and cathode being presented to a common discharge space, and an atmosphere of an inert gas in said discharge space, the meth- 0d of depriving said electrodes of occluded gases Which comprises connecting said cathode and said anodes to the individual phases of a polyphase alternating current source, and maintaining a 'polyphase space current discharge in said discharge space be tween said electrodes While simultaneously evacuating said envelope.

In testimony whereof, I have signed my name to this specification this 13th day of March, 1928.

PERCY L. SPENCER.

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