US1578045A - Autoelectronic device - Google Patents

Description

March 23 1926. 1,578,045

J. E. LILIENFELD AUTOELECTRONIC DEVICE Filed Jan. 28, 1922 c/u/z'us EdyarLilz'enfeZa INVENTOR BY Q v 2 ATTORNEY Patented Mar. 23, 1926.

UNITED STATES PATENT OFFICE.

JULIUS EDGAR LILIENFELD, OF WATERBURY, CONNECTICUT, ASSIGNOR OF ONE-HALF T0 WILLIAM H. BRISTOL, OF WATEBBURY, CONNECTICUT.

AUTOELEC'IBONIC DEVICE.

Application filed January 28, 1822. Serial No. 582,858.

and State of Connecticut, have invented certain newanduseful Improvements in Autoelectro'nio Devices, of which the following is a specification.

The invention relates to an electron releasin device, embodying an auto electronic efiect, that is to say a release of electrons due solely to an electric field, for .example, a device of the nature set forth in my co-pending U. S. application, Serial N 0. 364,215, filed the 8th day of March, 1920. In this application there is disclosed a sealed envelope or vessel, evacuated to such a high degree that ionization is substantially absent, said vessel enclosing also unheated electrodes separated by a gap sufficiently short to permit the starting of a discharge of electrons between said cold electrodes upon the application of a suitable potential. The present invention, however, relates to a novel form of the electron releasing cathode, particularly as to its shape and the metal comprising same, and to the method of producing such cathode. It has for its object in an autoelectronic device of this character, to provide an autocathode.or member releasing electrons solely under the influence of an electric field and of such special design and composition as to admit of employing much lower voltages than have heretofore been possible in the use of hi hly evacuated containers with cold electro e or electrodes. A very considerable reduction of the voltage may be obtained by makin the cathode of an extremely fine wire an providing a superfine point on itnot b mechanical means, however, but by chemical action. I have found that by employin for the cathode such metals. as are founf at the most electro-positive end of the scale, as the alkali metals and alkaline earth metals, the voltage necessary to cause current to pass between cold e ectrodes, in the absence of any substantial ionization and with predetermined gap, is greatly reduced. The degree of reduct1on appears to be eatest with the most electro-positive meta s-such as caesium, rubidium, otassium, sodium and lithium, while diminishing when approachthe alkaline earth metals. Moreover, an al- .loy of two or-more ofsa'id metals may be utilized for the production of a cathode. For example, in working with caesium, an admixture-of potassium, sodium or other metal of higher meltin point is useful to make the caesium liar er and reduce the pressure of its vapor.

Moreover, the mere presence within the highly evacuated container of the metals set forth, as in causing same to be deposited 1n any part of the container, has a beneficlal efiect for some of the metal eventually finds its way to the cathode.

The invention contemplates, furthermore, a novel method for preparing an autocathode from these metals, which normally are not suitable for exposure to the atmosphere, in forming such cathode in the envelope after evacuating it to a high degree.

The nature of the invention, however, will best be understood when described in connection with the accompanying drawings, in which- Fig. 1 represents a glass envelope, designed to be highly evacuated and provided with means for introducing metal.

Fi 2 and 3 illustrate similar vessels provided with diiferent means for introducing the metal. 1

Similar characters of reference designate corresponding parts thruout the several views.

Referring to the drawings, 10 designates a glass envelope or vessel which is designed to be evacuated, thru a suitable outlet which is subseguently sealed, as is well understood. Anano e 11 and a cathode 12 are provided in the vessel 10, to cooperate in manner set forth in my co-pending ap lication Serial No. 364,215, filed March 8t 1920; but in accordance with the present invention, the cathode is a superfine point and also comprises a metal such as is found at the most electro-positive end-of the scale.

Referring more particularly to Fig. 1, in addition to the two electrodes noted, there is further provided a pointed or sharp-edged blade member 15 in proximity to the anode and a similar member 16 in proximity to the cathode, said members being designed to provide bombarding electrons for their re'- a spective electrodes to heat up same and free them from occluded gases in the evacuation of the vessel.

The cathode 12 has been shown as a fine wire, about one-tenth of a millimeter, with a superfine point, that is to say a point which under a magnification of several hundred diameters, still appears as a point. In accordance with the invention, this wire is to be coated with a metal such as is found at the most electro-positive end of the scale, for example an alkali metal as caesium.

Such superfine points may be obtained of fine wire which has been employed as an anode in an electrolytic process, or has been dipped into a suitable solvent until reduced to the necessary degree of fineness. If tungsten be used to receive the cathode coating,

the tungsten wire may be dipped into poin proximity to the cathode.

tassium nitrite. In the case of a glass or quartz support for the cathode coating, fluoric acid may be used to point the glass. Other means for obtaining fine points of the wire consist in utilizing same as an electrode for a gas discharge, are discharge, spark discharge, etc. a

To effect the introduction of the cathode metal, which is subject to immediate oxidation, into the vessel 10 and its deposition on the cathode 12, cathode metal 20, as caesium or for example another of the more volatile metals such as rubidium, potassium and sodium, or an alloy thereof, is placed in the outermost bulb of a series of connected bulbs 21. These bulbs terminate in the vessel 10 thru a tube 22 havin its outlet T e metal is successively distilled from one bulb to the next, while sealing off the last empty bulb so'that, finally, a metallic deposit in a high state of purification and free of gases, Will be produced within thevessel 10 and upon a portion of the cathode support 12, forming a coating thereon of caesium or of another metal found at the most electro-positive end of the scale and from which electrons may be projected at much lower voltages than have been heretofore-possible.

Another means of introducing the cathode metalto form'the autoelectronic cathode is illustrated in Fig. 2. The metal '30, in this instance, as in the former case is successively distilled thru a series of-bulbs 31 into a tube 32 surrounding the cathode support 33 and deposited thereon to form a suitable coating. Or, when the character of the metal will permit ofso' doing, itmay be melted andcaused to run down thru the tube and-over the cathode support, subseuently cooling and forming a solid coating.

t ereon. A further expedient is set forth in Fig. 3,

port passes. The cap member 36 is desi ed to retain a capsule or disk of the cat ode metal 37 and the member is then heated to volatile metalssuchas calcium, strontium,

barium and lithium' and the heating is effected by means of bombarding electrons discharged from an electrode 38 mounted in the vessel in proximity to the cap, said bombardment serving also to drive out any occluded gases therein. By this expedient, only a slight amount of the cathode metal condenses outside of the cathode point. This is a decided advantage as. the electronic discharge will then not find a metallic coating from which gases would be set free thereby and affect the degree of vacuum and consequently the electron releasing effect. In the use of the metals for cathodes as hereinbefore set forth, it has been possible to reduce the voltage required to such an extent so that the device becomes suitable for use as a detector or transmitter of electro-magnetic waves and for amplification purposes.

I claim 1. An autoelectronic device, comprising a sealed envelope evacuated to such a high degree that ionization is substantially prevented, and containing a metal found at the most electro-positive end of the scale, and un heated electrodes therein, separated by a gap sufficiently short to permit of starting the discharge therebetween upon the application of a suitable potential.

2. An autoelectronic device, comprising a sealed envelope evacuated to such a high degree that ionization is substantially prevented, and unheated electrodes therein, one of which comprises a metal found at the most electroositive end of the scale, said electrodes being separated by a gap sufiiciently short to permit of starting the discharge therebetween upon the application of a suitable potential. v

3. An autoelectronic device, comprising a sealed envelope evacuated to'such a high degree that ionization is substantially prevented, and unheated electrodes therein, one of which consists of an alkali metal, said electrodes being separated by a gap sufliciently short to permit of starting the discharge therebetween upon the application of a suitable potential.

4. An autoelectronic device, comprising a sealed envelope evacuated to such a high degree that ionization is substantially pre vented,- and unheated electrodes therein, one of which comprises caesium, said electrodes being separated by a gap sufficiently short to permit of the discharge therebetween upon the application of a suitable. potential. 5. n autoelectroni'c device, comprising a sealed envelope evacuated to such a. high degree that ionization is substantially prevented, and unheated electrodes therein, one.

' of-which consists of a support coated with caesium,- said-electrodes being separated by; ,a gap sufliciently short to permit of starting separated by a gap 'sufliciently short to 'permit of starting the discharge therebetween upon the application of a suitable potential.

7. An autoelectronic device, comprising a sealed envelope evacuated to such a high degree that ionization is substantially prevented, and unheated'electrodes therein, one of which consists of a superfine support coated with a metal found at the most electro-positive end of the scale, said electrodes being separated by a gap sufliciently short to permit of starting the discharge therebetween upon the application of a suitable potential.

8. Anautoelectronic device, comprising a sealed envelo evacuated to such a high degree that ionization is substantially prevented, and unheated electrodes therein, one of which consists of a superfine support coa with caesium, said electrodes being separated by a gap sufliciently short to permit of starting the discharge therebetween upon the application of a suitable potential.

9. An autoelectronic device, comprisin a sealed envelope evacuated to such a high egree that ionization is substantially prevented, and unheated electrodes therein, one of which consists of a superfine support "coated with an alloy of'ceesium-and potassium, said electrodes being separated by a gap sufliciently short to permit of starting the discharge therebetween upon the application of a suitable potential.

10. An autoelectronic device, comprisin a sealed envelope evacuated to such a'hig degree that ionization is substantially pre vented, and unheated electrodes therein, one of which consists of a superfine .support coated with an alloy. of caesium, potassium and sodium, said electrodes being separated by a ap sutficiently short to permit of starting the discharge therebetween upon the apphcation of a suitable potential.

Signed at Waterbury, in the county of New Haven and State of Connecticut, this 26th day of January, A. D. 1922,

JULIUS EDGAR LILIENFELD.

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