US3031519A - Energy source device - Google Patents

Description

APril 1962 J. SILVERMAN 3,031,519

ENERGY SOURCE DEVICE Filed Aug. 7, 1956 INVENTOR Jose 0h Sill/firm: BY MK RNEY United States Patent 3,031,519 ENERGY SOURCE DEVICE Joseph Silverman, Hicksville, N.Y., assignor to Associated Nucleonics, Inc., a corporation of New York Filed Aug. 7, 1956, Ser. No. 602,578 15 Claims. (Cl. 136-89) The present invention relates to nuclear energy, and, more particularly, to a unitary device for supplying such energy and converting the same to light and electrical energy.

Accordingly, an object of the present invention is to provide such a device, with or without cell means in assembly therewith, which is small in size, compact in arrangement, light in weight and economical to manufacture.

Another object is to provide such a device which is capable of producing an electrical output on an order to perform useful work.

A further object is a long useful life.

Other and further objects of the invention will be obvious upon an understanding of the illustrative embodiment about to be described, or will be indicated in the appended claims, and various advantages not referred to herein will occur to one skilled in the art upon employment of the invention in practice.

In accordance with the present invention, the foregoing objects are accomplished by providing an energy source device for converting the disintegrating energy of a radioactive or nuclear source to light and then electrical energy which comprises a sealed receptacle, a source of principally beta radiation emissive particles essentially free from gamma radiation and a phosphor confined and arranged in the receptacle so that light emitted by the phosphor in response to disintegration of the source can be directed on photovoltaic cell means adapted to convert the light to electrical energy.

A preferred embodiment of the invention has been chosen for purposes of illustration and description, and is shown in the accompanying drawing, forming a part of the specification, wherein:

FIG. 1 is a plan view of a invention including a source means.

FIG. 2 is a sectional view taken along the line 2-2 on FIG. 1.

FIG. 3 is a schematic Wiring diagram illustrating the connection of the cell means in an electrical energy supply circuit.

Referring to the drawing in detail a device is shown, FIGS. 1 and 2, which essentially comprises a receptacle 10, a radioactive source 11 and a phosphor 12 confined in the receptacle. Photovoltaic cell means 13 adjacent the phosphor are adapted to be energized by the light emitted by the phosphor in response to disintegration of the source to produce an electrical output.

The source and phosphor may comprise an admixture of radioactive source and phosphor powders, a source in solution or colloidal suspension in a liquid phosphor, or a layer containing or consisting of a radioactive source adjacent one or more layers of a phosphor.

The receptacle is illustrated as being shallow or disclike. The peripheral geometrical configuration of the receptacle may be varied to suit the purpose for which the device is employed and is shown herein as being semicircular for insertion into a circular case containing a mechanism to be powered by the battery.

The receptacle 10 may be formed of transparent materials such as polystyrene or polymerized methyl methacrylate through which light radiations ranging from the visible to the ultra-violet in the spectrum are adapted to be transmitted. A strip 14 of aluminum foil or its equivato provide such a device which has device in accordance with the device and photovoltaic cell lent is applied to the peripheral wall portion of the receptacle, for example, at the interior of the receptacle, and a sheet 15 of aluminum foil or its equivalent is applied to each of the end wall portions of the receptacle. The sheets 15 have one or more openings 16 therein, two being shown in each sheet by Way of example, which provide windows, and a photovoltaic cell 13 is positioned in each of the openings. The aluminum foil or its equivalent serves as a light reflecting means adapted to direct the light emitted by the phosphor through the windows and onto the light sensitive means of the cells to more efiicia ently utilize the emitted light for conversion to electrical energy. The aluminum foil strip 14 is impervious to beta particles, whereby radiation damage to the peripheral wall portion of the receptacle is prevented.

The foregoing arrangement renders the receptacle opaque and confines the emitted light therein except as the light passes into the cells 13. Alternatively, the cells 13 and the sheets 15 could be positioned within the receptacle adjacent the end walls, or the cells could be so positioned and sheets 15 with or without openings 16 could be applied to the exterior of the end walls to render the receptacle opaque. Also, it will be appreciated that the receptacle and cells may be of such dimensions whereby a cell at each side would constitute the end wall and would render the receptacle opaque thereat without resorting to sheets 15. Still another arrangement which is contemplated comprises molding the cells into the end wall structure to unitize the receptacle and cell assembly. In certain cases for example where the reflectors 15 are at the interior or are omitted, the receptacle may be formed of material which renders it opaque. In all cases, it is desirable that the receptacle is sealed securely to confine the source and phosphor therein.

As previously indicated, the radioactive source and phosphor may be in layer or sandwich arrangement. In the preferred form of the device a layer of source material 11 is sandwiched between a pair of layers of phosphor material 12. The -layers of phosphor material are impervious to beta ray penetration, whereby radiation damage to the portions of the receptacle adjacent such layers is prevented.

However, in a simplified but less efficient device having a window or windows at only one side wall portion, it is conceivable that a layer of source material could be placed adjacent a dense or opaque windowless wall portion and a layer of phosphor material could be placed between the source layer and the windowed wall.

In the foregoing preferred arrangement, the source layer 11 may be apowder, a metal foil or a powder dispersed in a foil, and the phosphor layer 12 may be a single crystal, a packed powder or a liquid.

In a practical embodiment of the device illustrated herein, the receptacle is formed of optical grade polystyrene having a thickness of about .007 inch. The receptacle has a thickness of about .0515 inch, and is semicircular in-form, with the straight peripheral edge portion having a length of about .675 inch, whereby the volumetric capacity of the receptacle is about .0067 cubic inch. The layer 11 has a thickness of about .0115 inch, and the layers 12 have a thickness of about .013 inch. The aluminum strip 14 has a thickness of about .008 inch, the reflector sheets 15 have a thickness of about .005 inch, and the cells 13 have a thickness of about .010 inch, whereby the overall thickness of the device does not exceed about .0715 inch.

The thickness of the phosphor layers 12 is sufficient to stop beta particles emitted by the radioactive source, whereby all significant radiation is confined to the sandwich or is stopped by the aluminum foil strip 14, whereby a highly efficient conversion of beta rays tolight is attained.

A suitable source of radioactive material is Pm O and a suitable phosphor is hexagonal zinc sulphide (ZnS) preferably activated with .0l% copper powder. A more efificient light emitting unit can be provided by these materials by employing a source layer 11 comprising an admixture of 48 mg. of the activated zinc sulphide and 5.7 mg. of the carrier-free Pm O and a phosphor lager 12 consisting of 54 mg. of the activated zinc sulp 'de.

This intermediate source layer 111 is relatively thin (.0115 inch) and the source particles are well scattered therein because of the 5.7 to 48 ratio of Pm O to zinc sulphide. Since hexagonal zinc sulphide has a relatively low light absorbing coefficient, the layers 12 and the layer 11 are suificiently translucent to enable light reflected by the sheet 15 at one end wall to be directed through these layers and impinge on the cell means 13 or the sheet 15 at the other end wall. If such reflected light is of a high value, it is conceivable that it may be again reflected in the opposite direction through the layers to impinge on the cell means at the end walls where reflection first took place, ad infinitum.

The use of a mixture of source and phosphor powders in the layer '11 also reduces self-absorption of the radioactive emissions to a minimum. Thus, absorption taking place results in a more efiicient production of light.

The source is equivalent to 4.5 curies of Pm which has a 2.7 years one-half life and has a beta power output of 2200 microwatts, falling ed to 1000 microwatts at the end of three years. This source is a pure beta emitter with a maximum beta energy of .22 m.e.v. The beta to light conversion causes about 550 microwatts to be emitted by the phosphor mixture when made up and about 250 microwatts at the end of three years, with the luminous light output decreasing from .24 to .11 lumens in the three year period. This light output is converted by the cells to about 27 inicrowatts at the beginning and about 13 microwatts at the end of the period. These cells are capable of providing a voltage of about .25 per cell at the end of three year For example, silicon and cadmium sulphide type cells are suitable for this purpose.

' Preferably, 'where two or more cells -13 are utilized, these cells are connected in a series circuit, as shown in FIG. 3, whereby the sum e of the cell voltages is of a value to operate an electromagnetic device (not shown).

The photocell-source assembly described herein may further be encased in tantalum .or its equivalent having a thickness of about .077 inch, whereby the completed unit does not constitute a health hazard.

As previously indicated herein the source could be in a liquid phosphor, forexample, Pm Cl in a solution of para-terphenyl in dioxane.

From the foregoing description, it will be seen that the present invention provides an energy source device or battery which is simple and practical and sufiiciently efiicient to produce electrical energy for a useful purpose. The specific ilustrative embodiment herein has the advantageous characteristics of negligible radiation damage to the container and the photocells, the source and phosphor arrangement results in almost all of the radioactive emissions being absorbed in the phosphor, and light is radiated and/or reflected from the phosphor to the photocells in an eflicient manner.

The energy which is not converted to electricity appears as heat, but the calorific value thereof is so low that no sensible heating can occur which might cause thermal disintegration of the device.

As various changes may be made in the form, construction and arrangement of the parts herein, without departing from the spiritand scope of the invention and without sacrificing any of its advantages, it is to be understood that all matter hereinis to be interpreted as i1- lustrative and not in any limiting sense.

I claim:

1. A unitary source device for converting the disintegration energy of a radioactive source to electricity comprising a sealed receptacle having closely spaced opposite walls joined by a side wall defining a space therein, at least one of said opposite walls having a portion capable of transmitting light outwardly from said space, a phosphor and a radioactive beta particle source free of nonlight generating beta ray energy absorbent material confined and arranged in said space substantially to fill the same so that light emitted by said phosphor in response to disintegration of said source is directed outwardly through said one opposite wall with absorption of beta particles from said source by said phosphor,

and a photovoltaic cell overlying said light transmitting wall portion and having photosensitive means disposed to respond to light transmitted through said wall portion from inside the receptacle.

2. A device according to claim 1, wherein said source and said phosphor are present in the form of powder.

3. A device according to claim 1, wherein at least portions of said source and said phosphor are present in intimate admixture.

4. A device according to claim 1, wherein said source is admixed in a liquid phosphor.

5. A device according to claim 1, wherein said receptacle has light reflective means on a wall thereof facing the interior of said receptacle.

6. A device according to claim 1, wherein said light reflecting means has beta ray shielding properties.

7. A unitary energy source device for converting the disintegration energy of a radioactive source to electricity comprising a sealed receptacle having a space therein and a wall formed with a plurality of portions through which light can be transmitted outwardly from said space, a radioactive source of beta particles and a phosphor confined and arranged in said space to substantially fill the same so that light emitted by said phosphor in response to disintegration of said source is directed outwardly through said portions, said source and said phosphor being present in an amount to produce sulficient light for causing photovoltaic cell means to produce an electrical output on an order to perform useful work, and a photovoltaic cell overlying and closing each of said light transmitting portions and having means presenting a light sensitive material at said portions to thereby be energized by said transmitted light, said cells being connected in circuit for utilizing the combined output thereof.

8. A unitary energy source device for converting the disintegration energy of a radioactive source to electricity comprising a sealed receptacle having a space therein and a wall formed with a portion through which light can be transmitted outwardly from said space and provided at other portions with light reflecting means facing the interior of said receptacle, a radioactive source of beta particles and a phosphor combined and arranged in said space to substantially fill the same, so that light emitted by said phosphor in response to disintegration of said source is directed outwardly through said portion, said source and said phosphor being present in an amount to produce suflicient light for causing photovoltaic cell means to produce an electrical output on an order to perform useful work, and a photovoltaic cell secured to said receptacle and having means presenting a light sensitive material overlying said portion to thereby be energized by said transmitted light.

9. A unitary energy source for converting the disintegrationenergy of a radioactive source to light comprising a disc-like sealed receptacle having closely spaced opposite walls joined by a side wall defining a space therein, said opposite walls having light transmitting windows formed therein, a radioactive beta particle source layer free of nonlight generating beta ray energy absorbent material in said receptacle, layers of light generating beta particle responsive phosphor disposed between said radioactive source layer and each of said opposite walls, respectively, said layers substantially filling said space and said phosphor layers being substantially impervious to beta particles emitted by said source layer.

10. A device according to claim 9, wherein said intermediate layer comprises an admixture of beta particle source material and a phosphor.

11. A device according to claim 10, wherein said intermediate layer contains an activator for said phosphor.

12. A device according to claim 9, wherein said receptacle wall portions are formed of transparent material and have light reflecting means thereon facing the interior of said receptacle formed with openings to provide said Windows.

13. A device according to claim 12, wherein said light reflecting means are for-med of a material having beta ray shielding properties.

14. A device according to claim 12, wherein said light reflecting means are formed with a plurality of openings at each side of said receptacle wall portions to provide said windows.

15. A unitary energy source device for converting the disintegration energy of a radioactive source to electricity comprising a disc-like sealed receptacle having a space therein and Wall portions formed of transparent material at opposite sides thereof; light reflecting means on said wall portions facing the interior of said receptacle and having a plurality of openings to provide windows through which light can be transmitted outwardly from said space,

a layer of a phosphor in said receptacle adjacent each inner side thereof having a window formed therein, an intermediate layer of a radioactive source of beta particles sandwiched between said phosphor layers, said layers being arranged to substantially fill said space, and a photovoltaic cell positioned adjacent each of said Windows, said cells being in electrical connection for utilizing the combined output thereof.

References Cited in the file of this patent UNITED STATES PATENTS 2,582,981 Fua Jan. 22, 1952 2,681,416 Thompson June 15, 1954 2,754,428 'Franks et a1. July 10, 1956 2,769,916 Tittle Nov. 6, 1956 2,871,555 Foster Feb. 3, 1959 FOREIGN PATENTS 638,106 Great Britain May 31, 1950 1,076,816 France Apr. 21, 1954 OTHER REFERENCES Thomas: Nuclear Batteries Types and Possible Uses, in Nucleonics, vol. 13, No. 1-1, November 1955, pp. 129- 133; pp. 130431 relied upon.

Wallhausen: Uses of Radioisotopes in the Production of Self-Luminous Compounds, in Nations, vol. 15, Aug. 820, 1955, pages 307-309; page 309 relied upon,

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,031,519 April 24, 1962 Joseph Silverman It is hereby certified that error appears in the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

Column 4, line 29 for the claim reference numeral "1" read 5 Signed and sealed this 11th day of September 1962.

(SEAL) Attest:

ERNEST w. SWIDER DAVID LADD Attesting Officer Commissioner of Patents

Images