Current U.S. Classification: 313/54; 310/303; 310/304; 313/146; 313/148
Patent number: 2926268
Filing date: Dec 29, 1954
Issue date: Feb 23, 1960
This invention relates to electron discharge tube devices and more particularly to a multi-element tube which has incorporated therewith an internal source of power.
Heretofore a triode type of tube, for example, has consisted, in its basic form, of a heater filament, emitter cathode, control grid and collector plate, the cathode, gride and plate or anode making up the base elements. In an infinite variety of circuits such tubes have been connected to external power supplies to derive their source of energy for heating the filament and thereby drive the cathode. In some tubes the cathode has been heated directly instead of indirectly. In their various environments such tubes have been very successful, yet they have had the shortcoming of having to have associated with them an expensive and heavy power supply. Furthermore, they have been of relatively short life.
This invention overcomes the disadvantages inherent in these prior externally powered tubes. Indeed, it is an object of this invention to provide a tube in which the power source is an integral element of the tube itself.
It is a further object of this invention to provide a tube in which the cathode source of electrons is replaced by a radioactive source providing charged particle emission.
Still another object of this invention is to provide a tube in which little or no heat is developed.
In general the objects of this invention are accomplished by substituting a radioactive source of charged particle emission, and an associated secondary electron emitting material, for the filament and cathode of a multielement tube. The electrons driven off from the secondary emitting element, when radiation particles strike the emitting element, will flow toward a collector plate or anode. Intermediate the plate and emitter is the necessary control grid and/or suppression grid or grids.
The above and other objects of the claimed invention will become clear through a study of the description when read in conjunction with the accompanying drawings. Throughout the description and drawings like parts are represented by like numerals.
Fig. 1 is a sectional side view of a preferred embodiment of the tube made in accordance with the invention, and
Fig. 2 is a sectional side view of another preferred embodiment of tube made in accordance with the teachings of the invention.
Referring now to Fig. 1, a source 1 of radioactive radiation designated by arrows 2 is positioned close to a semiconducting material 3. On the side of the semi-conducting material away from the radioactive hard particles radiation source is positioned a grid 4, and beyond the grid from the semi-conducting material is positioned a plate 5.
The above described elements are enclosed within a sealed tube 6. Leads 7 and 8 extend through the tube envelope so that effective utilization may be made of the tube through the grid 4 and plate 5. Around the semi-conductor 3 is positioned a collector 9 having an external lead 10.
To effectively position the radioactive source of charged particles emission with respect to the semi-conductor the 5 source may be held by an insulating rod 11 having a section extending through the envelope. A vacuum type seal shown schematically at 14 may be used so that suitable adjustment of the axial position of the radioactive source of emission may be made without affecting the.
10 gaseous state of the tube. One example of a seal which might be used is shown and described in Hotine Patent No. 2,416,318, of February 25, 1947. This is riot intended to be limiting, however, since it is obvious that many ways may be devised for positioning the source.
In the operation of the tube, a radioactive source1 of atomic material, such as strontium 90, a waste material of the atomic fission of uranium emits hard radiation rays 2 which are primarily high energy beta particles.-These are directed by the proper shaping of the source to a semi-conductive wafer 3 which is in close proximity to the radiation source. Possible semi-conductive materials are silicon, lead sulfite, selenium and other similar materials. The semi-conducting material serves as the source of”:emitted electrons shown as arrows 13. The initial linear velocity of the high energy particles emitted by the radioactive source is used to knock electrons out of the secondary emitting wafer, and the electrons move as a stream out of the wafer toward the collector plate; Multiple secondary emission within the secondary emitter takes place and increases the density of the stream. Since silicon has electrons whose bonds are not so great as those of the other materials, it would seem to be a preferred material to use.
As the high energy radiation particle 2 strikes and passes through the silicon, it drives off an estimated 200,000 electrons 13. Since the strontium 90 emits , several billion particles per second a great number of. electrons are driven from the semi-conductor or wafer 3. The output from this source is in the nature of one-millionth watt. The electrons which are driven from the wafer 3 are directed through the control grid which is connected to a modulating source of signals to a plate where they may be received and utilized as a rectified, amplified, or oscillating signal. This wafer 3 may serve as a lens to guide the electrons to the plate and to’this end may be suitably shaped.
Since electrons are continuously being driven from the wafer, it will be positively charged and therefore can be used to polarize the plate through connection 12 which may be made on the edge of said wafer. To eliminate any spurious electron flow from the secondary source 3, a collector 9 is provided which will pick up any stray electrons and conduct them through a lead 10 to ground.
Referring now to Fig. 2 the radioactive radiation source 1′ is positioned at the center of a spherical arrangement of parts. These include the emitter materials 3′ which is in close proximity to the source. Surrounding the emitter 3′ as a concentric sphere is the grid 4′ and lying still further from the source is the collector plate 5′ as a concentric sphere.
All of these elements, excluding the source which may or may not be, are maintained in spaced relationship with one another within a sealed envelope 6′ which is also spherical in shape.
To provide access to the radioactive radiation source, which is movable toward and away from the geometrical center of the spherical elements by means of insulating rod 11′, a conical shaped section is provided which forms a cavity in the assembly into which the source may be inserted.
Within the sealed envelope but about the conical cutout cavity is positioned a truncated conical element … download full version with images