US2141655A - Radiation sensitive device - Google Patents

Description

Dec. 27, 1938. H. KoTT RADIATION SENSITlVE DEVICE Filed Dec. 16, 1933 ATT() R N E "(5 ,was

RADIATION SENSITIVE DEVICE Application December 16, 1933, Serial No. 702,827

. 4 Claims.

This invention relates to radiation sensitive dev vices and more particularly to radiation sensitive devices adapted to be utilized in combination with relay devices utilizing the current flow in such radiation sensitive devices as a means for energizing the same.

One of the objects of the present invention is to provide an improved radiation sensitive device.

Another object of the present invention is to provide a radiation sensitive device which is responsive to all wave lengths of radiation and which may be rendered selectively sensitiveto such radiation.

These and other objects of the present invention will become apparent as the invention is further disclosed.

I'his current iow through the device is believed to be fundamentally what may be termed a leakage current between the' electrodes and it appears to vary directly with the degree of ionization of the lling of ionizable gas contained within the radiation permeable envelop at any given voltage across the electrodes. It is also materially varied by the specic electrode composition and it appears that with electrodes having a relatively low threshold potential of electron emissivity a greater leakage current flow will be obtained at any given voltage. It is also materially varied by the photo-sensitivity of the electrode and a greater current flow with increase in photo-sensitivity of the electrodes will be obtained.

However, with an electrode composition of negative photo-sensitivity and of a determined threshold potential of electron emissivity, I have discovered that the leakage current flow between the spaced electrodes may be varied by varying the degree of ionization of the ionizable gas present within the enclosing envelop. I have further discovered that this variation in the degree of ionization of the gas may be effected either by varying the temperature or pressure of the said gas or by exposing or subjecting the gas to radiation. The radiation employed may be radiation of any wave length or band of wave lengths, such as heat, light, infra-red, red,l ultraviolet, X-radiation and even'cathode radiation. The extent or degree of increase inionization that is obtainable in the gas by exposing the same to radiation is a function of the quantity of radiation employed as well as the specic Wave length of radiation employed. It is also a function of gas pressure and of gas composition and electrode spacing. All of these yfactors however may be adjusted with respect to each other andthe objective in view to obtain the desired result, namely (Cl. Z50-171) a variation in the leakage current between two spaced electrodes enclosed within an envelop containing a filling of an ionizable gas. The pressure of the gas filling may be varied widely within the range of atmospheric pressure down to a pressure aproximating but above that which produces a substantially non-striking vacuum.

As a specificv embodiment of the practice of the present invention but not as a. limitation thereof I will disclose the adaptation of the same producing a light radiation sensitive device designed to be utilized in combination with a relay device to actuate the same. In connection with the following description reference should be madev to the accompanying drawing wherein:

. Fig. 1 is a side elevation in section illustrating one form of the present invention; Fig. 2 is a section along plane 2 2 of the same; Fig. 3 is a side elevation in section illustrating a second form of the present invention; Fig. 4 is a section along plane 8 4 of the same; Fig. 5 is an enlarged sectional view illustrating one feature of the same; Fig. 6 is a side elevation in section illustrating another form of the present invention; Fig. '7 is a side elevation in section illustrating still another form of the present invention; Fig. 8 is a section along plane 8 8 of Fig. 7 and Fig. 9 is a side elevation in section oi. still another form of the present invention.

Referring to the drawing, Figs. l and 2, the radiation sensitive device of the present invention (Fig. 1) comprises a radiation permeable envelop I, cold electrodes 2 and 3 sealed therethrough, and a pressure of ionizable gas fl disposed therein.

Electrodes 2 and 3 are spaced apart aproximately 3 millimeters and are comprised of metal such. as nickel, iron or nickel-iron' alloy. configuration they are round wires of approxi mately .5 millimeter.

'Ihe electrodes are comprised of materials of substantially negative photo-sensitivity and of relatively high threshold voltages of electron emissivity. However, it isnot to be construed that I am limited thereby. To obtain greater responsivity to radiation of all types I may comprise electrodes 2 and 3 oi' photo-sensitive materials or of materials having relatively lower threshold voltages oi' electron emissivity or surface the same with such materials. By a proper selection of such photo-sensitive materials and materials of relatively lower threshold voltages of electron emissivity, I may render the device selectivelyresponsive to preferred" ranges of radiation as measured in Angstrom units. Photo-sensitive 1 v comprised of a disc, if desired. The precise shape.

materials and materials of relatively lower threshold voltages of emission useful in the present invention comprise selenium, tellurium, the alkali and alkaline earth metals, .the rare earth metals, and the so-called rare metals, zirconium, titanium, thorium, uranium, tungsten, molybdenum, tantalum, vanadium and the like metals or alloys of the same with one or more of the base metals iron, nickel, copper, aluminum and the like.

The size, shape and configuration of electrodes 2 and 3 may be widely varied without departing from the nature and scope of the present invention. The specific size, shape and configuration of electrodes 2 and 3 will depend upon contemplated service conditions and requirements, and in Figs. 3 to 9 inclusive I have indicated some contemplated modifications thereof.

Figs. l and 2 show electrodes 2 and 3 as concentric loop electrodes preferably disposed in the same plane and with the lead Wires extending thereto through the press 20 electrically insulated from each other by means of dielectric insulating sleeve members 2| preferably comprised of glass. Alternatively, round wire electrodes 2 and 3 in this modification may be flattened to strip or ribbon form without departing from the present invention or the central electrode may be and configuration of electrodes 2 and 3 is determined by the electrical characteristics desired, and the contemplated application of the same in special fields such as sound and radiation record-- ing, transmission, receiving, television and the like.

In the modification illustrated in Figs. 3`to 5 inclusive I employ a grid type electrode wherein the electrodes 2 and 3 are located upon the face of a dielectric insulator 22. Dielectric insulator 22 is preferably comprised of glass of high dielecf tric insulating characteristics and is also preferably plate shaped. Along opposite sides of ,one face of the plate 22 I dispose electrodes 2 and 3 respectively and from each electrode I extend a plurality of arms 2 and 3 frpm each electrode 2 and 3 towards the other or opposite electrode with arms 2' and 3' in parallel spaced' relationship along the lengths of electrodes 2 and 3 thereby bringing electrodes 2 and 3 in a desired close spaced relationship over a relatively large surface area. Thereafter the electrodes 2 and 3 may be mounted upon leading-in and support wires 24 and 25 extending through press 20 in any convenient or desired manner.

Dielectric insulator 22 performs an additional function in that due to its property of forming adsorbed surface lms of gases the leakage of current between grid electrodes 2 and 3 is greatly facilitated. This method of mounting electrodes 2 and 3 also provides a means for obtaining a desired relative close spacing of the electrodes which is controllable, reproducible and substantially permanent, thereby providing a means to reduce the internal resistance of the gaseous conduction discharge device to a desired minimum.

In Fig. 6 I have shown still another contemplated modication wherein electrodes 2 and 3 are concavo-'convex in shape and are mounted upon the leading-in conductors 24 and 25 with the convex surfaces of each in close spaced faced relationship. If desired and to lower the electrical resistance of the gas path between electrodes 2 and 3 a proportion of a metal vapor such as mercury vapor from mercury 26 may beincorpO- rated.

.is a radiation permeable envelop.

A further modification is disclosed in Figs. 7 and 8, wherein-one of the electrodes 2 and 3 is shown cylindrical in shape and surrounding the other electrode 3 and 2 concentrically disposed therein. In such an arrangement of electrodes in one instance the cylindrical electrode may be utilized as the negative or cathode electrode and the center concentric electrode the positive or anode electrode or vice versa. and one or the other of the electrodes may be comprised or surfaced with materials having relatively low threshold voltage of electron emissivlty or of photosensitive materials.

In Fig. 9 I have schematically illustrated an arrangement of electrodes wherein electrode 2 is what is known in the art as a point electrode and electrode 3 is relatively larger in surface area than electrode 2. This arrangement is de signed to induce a concentration of'the electric iield about the point electrode 2 when utilized as a cathode so that the emissivity of electrons therefrom in a cold electric discharge is augmented.

In all of the modifications shown, envelop I It may be comprised of material permeable to all wave lengths of radiation or it may be comprised of material impermeable to some wave lengths and permeable to other wave lengths; or alternatively it may be provided with a window or section thereof which is permeable to a desired band of wave lengths of radiation; or enclosed in a radiation impermeable housing having means to permit the projection thereinto of a preferred or desired band of wave lengths of radiation.

In all modifications shown the gaseous filling of ionizable gas may be varied widely without departing essentially from the nature and scope of the present invention, nor am I limited in the use of a pure or substantially pure ionizable gas. I may employ any one of the monatomic gases, or may employ hydrogen; nitrogen, carbon oxides and the like gases. Various adrnixtures of gases may be used and to these gases I may add a proportion of metal vapor such as mercury, gadolinium, mercury amalgams of the alkali or alkaline earth metals or alloys of the alkali and alkaline earth metals to reduce the internal resistance of the gaseous conduction device. I may even employ air as a gaseous conduction atmosphere if desired. y

'I'he pressure of the ionizable gas employed may also vary widely without departing from the nature and scope of the present invention. All pressures of gases from atmospheric pressure down to a pressure approximating a substantial vacuum may be employed in accordance with the present invention, the essential feature being to adjust the pressure of gas with respect tojthe electrode spacing, electrode composition, electrode size, shape and configuration, and operating voltages, to obtain the desired result, namely, a measurable leakage current between the electrodes.

It is believed apparent, therefore, from the above description 'and accompanying drawing that the present invention is adapted to wide modification and adaptation to serve a plurality of useful applications in the art.

It may be adapted as indicated to the direct measurements of or detection of all types of radiation; it may be adapted to replace in every instance of application the heretofore employed photo-electric cell or tube; it may be adapted widely in the art of broadcasting, receiving and recording of radiation and sound frequencies. 'In this latter use the response of the tube to interruptions of a beam of radiation projected thereon is direct with respect to all frequencies up to Y 8000 cycles.

It may be adapted to be used as a thermostat control element in temperature regulating devices and in fire alarm systems and the like. In connection with the use and application of the present invention as a thermostat element the feature of the effect-of heat radiation upon the electrical conductivity of the gas path is employed. The upper temperature limit is the melting or vaporization temperature of the envelopor enclosed electrodes. The present invention also may bey adapted to be used as an automatic light sensitive element to turn off .and on the electric currents of lighting systems. It

may be adapted to be used to control and limit the time of exposure of objects to specific radiation such as X-radiation, cathode radiation and ultraviolet radiation.

Having broadly and specifically disclosed the present invention, all such modifications and departures thereof are contemplated as may fall within the scope of the following claims.

What I' claim is:

l. Ihe gaseous conduction discharge device including a pair of spaced electrodes of the cold electrode type, a radiation permeable envelop enclosing said electrodes and a filling of an ionizable gas within said envelop, said spaced electrodes each being comprised of substantially pure iron, the surface areas of said electrodes being substantially equal and the spacingtherebetween being substantially 3 millimeters, and said gas consisting substantially of neon at a pressure of about 1.1 millimeters of mercury.

2. 'I'he gaseous conduction discharge device including a pair of spaced electrodes of the cold electrode type, a radiation permeable envelop enclosing said electrodes and a filling of an ionizable gas within said envelop, wherein a. dielectric insulating base member is provided within said envelop and said electrodes are disposed in parallel spaced relation on a face of said base and wherein each of the said electrodes is provided with a plurality of arms extending therefrom towards the other electrode, the said arms lying in alternate relatively close spaced relation along the said face of said base.

3. The gaseous conduction discharge device including a pair of spaced electrodes of the cold electrode type, a radiation permeable envelop enclosing said electrodes and a lling of an ionizable gas within said envelop, the said ionizable gas being a mixture of gases, one of which is a monatomic gas and the other of which is one of the gases, nitrogen, hydrogen and carbon dioxide.

4. 'I'he gaseous conduction discharge device including a lpair of spaced electrodes of the cold electrode type, a radiation permeable envelop enclosing said electrodes and a lling of an ionizable gas within said envelop, said electrodes being of substantially pure iron surfaced with barium, and wherein' the spacing between said electrodes approximates 3 millimeters and wherein the said gas is comprised substantially of neon at a pressure of about 1.1 millimeters of mercury.

HERMANN KO'I'I'.

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