The terms atomic batteries , nuclear batteries , tritium batteries and radioisotope generators are used to describe devices that use energy from isotope decay radioactive to generate electricity. Like nuclear reactors, they generate electricity from atomic energy, but are different because they do not use chain reactions. Compared to other batteries they are very expensive, but have a very long life and high energy density, so it is mainly used as a power source for equipment that must operate unattended for long periods of time, such as spacecraft, pacemakers, water and scientific stations automatically in remote parts of the world.
The technology of nuclear batteries began in 1913, when Henry Moseley first showed the beta cells. This field received considerable in-depth research attention for applications requiring long-lasting resources for space requirements during the 1950s and 1960s. In 1954 RCA examined small atomic batteries for small radio receivers and hearing aids. Since the beginning of RCA research and development in the early 1950s, many types and methods have been designed to extract electrical energy from nuclear sources. Scientific principles are well known, but modern nanoscale technology and new broadband semiconductors have created new devices and attractive material properties that were not previously available.
Batteries using radioisotope decay energy to provide long-lasting strength (10-20 years) are being developed internationally. Conversion techniques can be grouped into two types: thermal and non-thermal. Thermal converters (whose output power is a function of the temperature difference) include thermoelectric and thermionic generators. A non-thermal converter (whose power output is not a function of temperature difference) extracts the fraction of the incident energy as it is degraded to heat rather than using heat energy to run electrons in the cycle. Atomic batteries typically have an efficiency of 0.1-5%. High-efficiency betavoltaics have 6-8%.
Video Atomic battery
Konverter termal
Konverter termionik
The thermionic converter consists of a thermal electrode thermally emitting electrons through a space charge barrier to a cooler electrode, producing useful power output. Caesium vapor is used to optimize the working function of the electrode and provide an ion supply (with surface ionization) to neutralize the electron space charge.
Thermoelectric radioisotope generator
The thermoelectric radioisotope (RTG) generator uses thermocouples. Each thermocouple is made up of two wires of different metals (or other materials). A temperature gradient along the length of each wire produces a voltage gradient from one end of the wire to the other; but different materials produce different voltages per level of temperature difference. By connecting the cable at one end, heating the tip but cooling the other end, a usable, but small (milivolt) voltage, is generated between the ends of the disconnected wire. In practice, many are connected in series to produce a greater voltage from the same heat source, because heat flows from the hot tip to the cold end. Metal thermocouples have low thermal-to-electric efficiency. However, the density and carrier load can be adjusted in semiconductor materials such as bismuth telluride and silicon germanium to achieve much higher conversion efficiency.
Thermophotovoltaic cells
Thermophotovoltaic cells work on the same principle as photovoltaic cells, except that they convert infrared light (not visible light) emitted by the hot surface, into electricity. Thermophotovoltaic cells have slightly higher efficiencies than thermoelectric pairs and can be spread over thermoelectric pairs, potentially doubling the efficiency. University of Houston TPV Radioisotope Power Conversion Technology development effort aims at combining thermophotovoltaic cells simultaneously with thermocouples to deliver a 3 to 4 fold increase in system efficiency over current thermoelectric radioisotope generators.
Stirling radioisotope generator
Stirling's radioisotope generator is a Stirling engine that is driven by the temperature difference generated by radioisotopes. The more efficient version, a sophisticated Stirling radioisotope generator, is being developed by NASA, but was canceled in 2013 due to massive cost overruns.
Maps Atomic battery
Non-thermal converter
Non-thermal converters extract a small portion of nuclear energy when degraded to heat. The output is not a function of temperature difference such as thermoelectric and thermionic converters. Non-thermal generators can be grouped into three classes.
Direct chargers
In the first type, the main generator consists of a capacitor filled by the charged particle current from a radioactive layer stored on one of the electrodes. Distance can be either vacuum or dielectric. Negatively charged beta particles or positively charged alpha particles, positrons or fission fragments can be utilized. Although this form of nuclear-electric generator originated from 1913, several applications have been found in the past for the very low currents and inadequate high voltages provided by the direct charging generator. Oscillator/transformer system is used to reduce the voltage, then the rectifier is used to convert AC power back to direct current.
British physicist H.G.J. Moseley built this first. Moseley equipment consists of silver-coated glass spheres on the inside with radium transmitters mounted on the end of the wire in the center. The charged particles of radium create electrical current as they move rapidly from radium to the inner surface of the sphere. Until the end of 1945, Moseley's model guided other efforts to build experimental batteries that generate electricity from the emission of radioactive elements.
Betavoltaics
Betavoltaics is an electric current generator, in the form of a battery, which uses energy from radioactive sources that emit beta particles (electrons). Common sources used are isotopes of hydrogen, tritium. Unlike most nuclear power sources, which use nuclear radiation to generate heat, which then generates electricity (thermoelectric and thermionic sources), betavoltaics uses a non-thermal conversion process, using a p-n semiconductor connection.
Betavoltaics is particularly suitable for low-power electrical applications where longevity of energy sources is required, such as implantable medical equipment or military and aerospace applications.
Alphavoltaics
Alphavoltaic resources are devices that use semiconductor junctions to generate electrical particles from energetic alpha particles.
Optoelectric
The optolectric nuclear battery has also been proposed by researchers from the Kurchatov Institute in Moscow. A beta-emitter (such as technetium-99) will stimulate an excimer mixture, and light will produce a photocell. The battery will consist of an argon/xenon excimer mixture in a pressure vessel with an internal mirror surface, a finely divided Tc-99, and an intermittent ultrasonic stirrer, illuminating a photocell with a bandgap set for the excimer. The advantage of this design is that precision electrode assemblies are not required, and most beta particles pass from the finely divided bulk material to contribute to the battery's clean power.
Reciprocating Electromechanical Atomic Batteries
The electromechanical atomic battery uses a charge accumulation between two plates to pull a bending plate toward another plate, until two plates touch, release, equalize electrostatic accumulation, and return to the spring. The resulting mechanical motion can be used to generate electricity through the piezoelectric material flexing or through a linear generator. Milliwatts of power produced in a pulse depend on the charge rate, in some cases several times per second (35 Hz).
Radioisotope used
The atomic batteries use radioisotopes that produce low energy beta particles or sometimes alpha particles with different energies. Low energy beta particles are needed to prevent high energy production through Bremsstrahlung radiation that will require heavy shielding. Radioisotopes such as tritium, nickel-63, promethium-147, and technetium-99 have been tested. Plutonium-238, curium-242, curium-244 and strontium-90 have been used.
Potassium-40 (40K) has been suggested as a longer variant because its half-life is more than 1.16GY. If a way can be found to separate it on a commercial scale, it can be extracted from seawater using a battery-like flow system based on "Selective crystallization method through high voltage resonance beam bias negative under magnetic field" currently under patent search provides virtually unlimited energy on a large scale for aquatic operations if high-energy gamma rays can be utilized using appropriate materials such as diamond monocrystalline diamonds that are suitable for N and P type materials.
See also
- List of battery types
- Thermoelectric radioisotope generator
- Gamma emissions are induced from long-spirited nuclei of certain nuclear isomers.
References
External links
- Kantilever Electromechanical Atomic Battery
- Type of Radioisotopic Battery
- Americium Battery Concept Proposed for Space Applications- TFOT Articles
- Nuclear Battery (25 MW)
- Tiny 'nuclear batteries' was unveiled, a BBC article on research by Jae Wan Kwon et al. from The University of Missouri.
Source of the article : Wikipedia
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