nuclear microbatteries

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Guided ByREMYA BHARATHY K9 March 2016 NUCLEAR MICROBATTERIES1

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OUTLINEOBJECTIVESNEED OF NUCLEAR MICROBATTERIESHISTORICAL DEVELOPMENTSENERGY PRODUCTION MECHANISM BETAVOLTAICSBASIC BETAVOLTAIC CONVERSIONTHE ENERGY CONVERSION MECHANISMDIRECT CHARGING GENERATORSSCHEMATIC DIAGRAM OF AN LC RESONANT CIRCUITWORKING

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OUTLINENUCLEAR MICROBATTERIES3FUEL SELECTION CONSIDERATIONSDESIGN AND THEORYDIRECT CHARGING GENERATORSADVANTAGESAPPLICATIONSDRAWBACKSCONCLUSIONREFERENCE

OBJECTIVESChemical batteries require frequent replacements and are bulky.Need for compact reliable light weight and self-contained power supplies.Nuclear reactors offer economical and technical problems.Fuel cells are expensive.Solar cells are expensive and requires sunlight.NUCLEAR MICROBATTERIES4

NEED FOR NUCLEAR MICROBATTERIESNUCLEAR MICROBATTERIES5Nuclear batteries have lifespan up to decades and nearly 200 times more efficient.Not based on nuclear reaction , so no radioactive wastes.Uses emissions from radioactive isotope to generate electricity.It can be used in inaccessible and extreme conditions.

HISTORICAL DEVELOPMENTSIdea of nuclear batteries was introduced in 1950 and patented to Tracer Lab.Radioisotope electric power system is developed by Paul Brown.He organized an approach to harness energy from the magnetic field of alpha and beta particles using Radium-226.It had low efficiency due to loss of electrons.

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ENERGY PRODUCTION MECHANISM-BETAVOLTAICS Uses energy from beta particlesProvides extended battery life and power density.Beta particles from radioactive gas captured in Si wafer coated with semiconductor material.Absorbed radiation creates electron-hole pair.Results in the generation of electric current.

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BASIC BETAVOLTAIC CONVERSION

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THE ENERGY CONVERSION MECHANISMBefore the radioactive source is introduced , current flow is absent as the electrical forces are in equilibrium.As a beta emitter is introduced, electrons are knocked out by its energy. Generates electron-hole pairs in the junction.

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THE ENERGY CONVERSION MECHANISMWhen beta particle imparts more than ionization potential the electron rises to a higher level.Fermi voltage established between the electrodes.Potential difference drives electrons from electrode A through the load where they give up the energy.

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THE ENERGY CONVERSION MECHANISMElectron is then driven into electrode B to recombine with a junction ion.Betavoltaics efficiency is lesser compared to solar- cell.Electrons shoot out in all directions decreases the efficiency due to energy loss.Efficiency can be improved by using Porous Si diodes with pits to provide a 3-D surface.

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DIRECT CHARGING GENERATORSNUCLEAR MICROBATTERIES12Primary generator consists of LC tank circuit.Energy from radioactive decay products sustain and amplify oscillations.Circuit impedance has coil wound on a core composed of radioactive elements.Decay by alpha emission; hence greater flux of radioactive decay.

SCHEMATIC DIAGRAM OF AN LC RESONANT CIRCUIT

3 capacitor 5 inductor9 transformer T primary winding11 resistance7 core with radioactive elementsNUCLEAR MICROBATTERIES13

WORKINGOscillations induced in LCR circuit damp out due to loss of energy.Here energy is imparted to the alpha particles during the decay of elements in the core.This energy is introduced to circuit when alpha particles are absorbed by the inductor.Oscillations sustain until Energy absorbed = Energy dissipated in resistance. This excess energy is delivered to the load connected across transformer T secondary winding.

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FUEL SELECTION CONSIDERATIONSAvoid gamma rays in decay chain.Half life of the radio active material.Particle range.Cost.

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DESIGN AND THEORY

FIG:A three-dimension schematic view of the SWNTsthin film-Si heterojunction beta voltaic micro battery.NUCLEAR MICROBATTERIES16

DESIGN AND THEORYNUCLEAR MICROBATTERIES17Beta voltaic micro battery consists of energy conversion part and a source part.The former mainly has p-type SWNTs thin film prepared on n-type silicon wafer forming p-n heterojunction. The front and back electrodes are used to transport carriers to external circuit. The SiO2 layer is used to insulate the front electrode from the underlying silicon substrate.

DESIGN AND THEORYNUCLEAR MICROBATTERIES18 The latter has 63Ni thin film prepared on a Nickel foil for the energy supply. 63Ni as a pure emitter radiation source was chosen Because it has a half-life of about 100 years.Maximum beta decay energy of 65.9keV.An average kinetic energy of 16.7keV.

ADVANTAGESLife span- minimum of 10 years.Reliable electricity.Amount of energy highest.Lighter with high energy density.Efficient; less waste generation.Reduces green house and associated effects.Fuel used is the nuclear waste from nuclear fission.NUCLEAR MICROBATTERIES19

APPLICATIONSSpace applications: Unaffected by long period of darkness and radiation belts like Van-Allen belt.Compact and lighter in weight.Can avoid heating equipment required for storage batteries.High power for long time independent of atmospheric conditions.NASA is trying to harness this technology in space applications.

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APPLICATIONSNUCLEAR MICROBATTERIES21 Medical applications:In Cardiac pacemakers.Batteries should have reliability and longevity to avoid frequent replacements. Mobile devices:Nuclear powered laptop battery Xcell-N has 7000-8000 times more life.No need for charging, battery replacing.

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APPLICATIONSNUCLEAR MICROBATTERIES22Automobiles:In initial stages.No running short of fuel.Possibility of replacing ionic fuels with its advantages.

APPLICATIONSNUCLEAR MICROBATTERIES23Under-water sea probes and sea sensors:In sensors working for long time.At inaccessible and extreme conditions.Use in coal mines and polar sensor applications too.For powering MEMS devices : in optical switches and smart dust sensors.

DRAWBACKSHigh initial cost of production as its in the experimental stage.Energy conversion methodologies are not much advanced.Regional and country-specific laws regarding use and disposal of radioactive fuels.Social acceptance of Nuclear equipment'sNUCLEAR MICROBATTERIES24

CONCLUSIONBatteries of the near future.Small compact devices of future require small batteries.Nuclear batteries increase functionality, reliability and longevity.Until final disposal all Radiation Protection Standards must be met.It will make its way to commonly used products like laptops and smart phones. Surely its the batteries of near future.

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referenceNational Key Lab of Micro/Nanometer fabrication technology, Institute of Microelectronics, peking university Beiging 100871, China.C.C. Chen, Y.Y chang and J .W. ZhangA NOVEL BETAVOLTAIC MICROBATTERY BASED ON SWNTS THIN FILM SILICON HETEROJUNCTIONMEMS 2012 IEEE 2012 PAGE NUMBER: 1197YEAR: 2012

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referenceNUCLEAR MICROBATTERIES27Brown, Paul: "Resonant Nuclear Battery Supply", Raum & Zeit, 1(3) (August-September, 1989)Nuclear and radiochemistry , Gerhardt Friedlander, Joseph.W.Kennedy and Julian Malcolm Miller,Particles and Nuclei, an Introduction to the Physical Concepts. B.Povh, K.Rith, C. Scolz and F.Zetche.

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