Patent Number: 058617019
Section: description

DETAILED DESCRIPTION Structural components of a charged-particle powered battery are schematically illustrated in the drawing to show a representative path of a charged particle B from a primary energy source 20. The energy source 20 (shown for illustration purposes as a side elevation or edge-on cross-sectional view of a plate) preferably predominantly produces one type of the primary charged particles (nuclear or non-nuclear energetic particles) described above. For example, the illustrated energy source 20, producing primarily beta particles B, may comprise strontium 90 or carbon 14. Note that although energy source 20 is schematically illustrated as a structure spaced apart from collector and emitter plates, preferred embodiments of the improved battery may incorporate an energy source 20 within one or more secondary emitter plates 30,30'. Physically, a secondary emitter plate in the latter configuration may comprise, for example, a carbon film substrate which itself comprises carbon 14 and which has a magnesium oxide coating. A beta particle B leaving source 20 preferably impinges on a proximate (thin) secondary emitter plate 30 (illustrated in edge-on cross-sectional view), resulting in emission of a plurality of secondary electrons e and possibly one or more relatively energetic secondary electrons e'. While passing through the secondary emitter plate 30 on its way to (thin) collector plate 40 (illustrated in edge-on cross-sectional view), the beta particle B pathway is deviated and the particle itself has incrementally-reduced kinetic energy, at least a portion of which has been converted to the (relatively lower) kinetic energy of (relatively many) emitted secondary electrons. Analogously, while passing through the (thin) collector plate 40 on its way to secondary emitter plate 30', the pathway of the relatively energetic secondary electron e' may be deviated and the electron itself experience an incremental reduction in kinetic energy, at least a portion of which has been converted to the (relatively lower) kinetic energy of (relatively few) secondary electrons emitted from collector plate 40. A further portion of the kinetic energy of electron e' is then shown being converted to the (relatively lower) kinetic energy of (relatively many) secondary electrons emitted from emitter plate 30' (two of which are schematically illustrated as being captured by collector plate 40'). In addition to beta particle B and relatively energetic secondary electron e' shown in the drawing as moving toward collector 40, a portion of the remaining secondary electrons emitted from plate 30 is also moving toward collector 40 (two secondary electrons e are shown being captured by collector 40). Note that secondary electron emission by plate 30 and subsequent capture and retention by collector 40 of these secondary electrons will preferably be enhanced by appropriate choice of material work functions and Fermi energy levels in the emitter and collector plates as described herein. As in the case of relatively energetic electrons e', beta particle B (schematically illustrated impinging on collector plate 40) causes release of relatively fewer secondary electrons e than would be expected to be released from adjacent secondary emitter plates. Again, beta particle B changes its course (during passage through collector plate 40) on its way to another (thin) secondary emitter plate 30'. A plurality of secondary electrons e is emitted from secondary emitter plate 30', a portion of which is then captured by (thin) collector plate 40' (two such electrons are schematically illustrated as being captured by collector plate 40'). Beta particle B may continue through collector plate 40' (causing the emission of relatively few secondary electrons) but its kinetic energy will again have been incrementally reduced. Improved batteries may have many cells and will preferably be designed to transform substantially all of the kinetic energy of the primary charged particles to the kinetic energy of secondary electrons. Preferably, relatively little kinetic energy is transformed to heat in the emitter or collector plates or in shielding 50 (such as lead or stainless steel sheet) which will preferably be present to prevent primary charged particles or other potentially harmful radiation from escaping from the battery. Accumulation of collected (that is, captured) secondary electrons e as schematically illustrated on collector plates 40,40' gives these plates (shown connected in parallel in the drawing) a negative charge with respect to secondary emitter plates 30,30' (shown connected in parallel in the drawing). Thus, emitter plate 30 and collector plate 40 comprise a first cell, while emitter plate 30' and collector plate 40' comprise a second cell, the first and second cells being electrically connected in parallel and to the terminals of the improved battery. Note that whenever the energy source 20 is present, a cell potential will exist and will tend to increase. Space charge, for example, and other effects such as internal leakage currents will tend to limit any rise in cell potential, but preferred embodiments of the improved battery may also comprise maintenance circuits to manage load on the battery cells for optimal energy conversion and battery life and/or minimum heating. Note that specification of various improved battery design parameters such as emitter and collector plate materials and geometry, preferred cell potential, the number and location of primary energy sources as well as their composition, plate spacing, dielectric constants of any insulators present between cells and/or between plates of individual cells, the number of cells and the manner of interconnecting them, the type of shielding and heat dissipation capability desired, the preferred temperature rise, and related parameters is a multifactorial design problem. The design approach will depend strongly on the intended application(s) for the improved battery. All improved batteries, however, are characterized by relatively efficient incremental conversion of relatively high kinetic energies of relatively few primary charged particles to relatively low kinetic energies of relatively many secondary electrons, resulting in preferred cell potentials not exceeding about 50 volts and even more preferred cell voltages not exceeding about 3 volts to about 10 volts. The incremental nature of the above energy conversions is reflected in at least a portion of primary charged particles' impinging on (and kinetic-energy-converting interaction with) at least two secondary emitter plates. The resulting substantially stepwise (incremental) reduction in the relatively high kinetic energy of each participating primary charged particle tends to reduce the likelihood of relatively wastful (that is, heat-generating) interactions of the primary charged particle with other structures of the improved battery, thus increasing its efficiency while simultaneously providing relatively low kinetic energy secondary electrons to maintain the relatively low cell potentials so useful in microelectronic and sensor applications.