Showing papers on "Energy conversion efficiency published in 1973"
TL;DR: In this article, the authors considered third-harmonic generation in phase-matched mixtures of alkali metal vapors and inert gases and showed that the combination of near-resonant nonlinear susceptibilities, the ability to phase match, and the relatively high UV transparency of these vapors should allow high conversion efficiency for picosecond laser pulses with a peak power of 108-109W.
Abstract: This paper considers third-harmonic generation in phase-matched mixtures of alkali metal vapors and inert gases. Calculations show that the combination of near-resonant nonlinear susceptibilities, the ability to phase match, and the relatively high UV transparency of these vapors should allow high conversion efficiency for picosecond laser pulses with a peak power of 108-109W. Calculations of the nonlinear susceptibility and of the ratio of xenon atoms to metal vapor atoms which is necessary to achieve phase matching are given for each of the alkalies as a function of incident laser wavelength. Processes that limit the allowable peak power density and energy density are discussed and guides for determining the metal vapor pressure, cell length, and beam area are given.
253 citations
TL;DR: In this paper, a phase matched mixture of Xe and Ar was used for third-harmonic generation from 3547 to 1182 A, where Xe is negatively dispersive, and phase matching was obtained at a ratio Xe:Ar = 1:430.
Abstract: Coherent radiation at 1182 A is obtained by third‐harmonic generation in a phase‐matched mixture of Xe and Ar. For generation from 3547 to 1182 A, Xe is negatively dispersive, and phase matching is obtained at a ratio of Xe:Ar=1:430. A conversion efficiency of 2.8% is obtained at an input power of 13 MW. As predicted by theory the conversion efficiency increases linearly to the limit of our available input power.
164 citations
TL;DR: In this paper, a large volume high pressure pulsed electrical CO2 laser that employs volumetric photopreionization of the gas by ultraviolet radiation was investigated and an optical energy extraction of 40 J/literatm at 700 Torr and a conversion efficiency of 24% were obtained.
Abstract: Investigations of a large‐volume high‐pressure pulsed electrical CO2 laser that employs volumetric photopreionization of the gas by ultraviolet radiation are reported. An optical energy extraction of 40 J/literatm at 700 Torr and a conversion efficiency of 24% have been obtained.
77 citations
TL;DR: In this article, the angular-dependent transmission of ribbon grids, which resemble Venetian blinds, is used to recover the energy of particles leaking out of a fusion reactor.
Abstract: A new direct energy conversion technique that uses the angular-dependent transmission of ribbon grids, which resemble Venetian blinds, to recover the energy of particles leaking out of a fusion reactor is discussed. This converter works well, even to energies as low as 10 keV, because of its excellent space-charge handling ability. This low-energy operating range makes direct energy conversion possible on closed confinement devices; operation at about 100 keV might be useful on open confinement devices. Energy recovery efficiencies of 60 to 70% are predicted. Examples are presented in which a direct energy converter with efficiencies in this range, when viewed as a topping cycle to a thermal converter, could considerably improve the reactor prospects of both open- and closed-field-line confinement schemes.
66 citations
TL;DR: In this article, the authors described the generation of continuously tunable UV radiation in the wavelength range 2300-3000 A by frequency doubling the output of a nitrogen pumped dye laser.
41 citations
Patent•
10 Dec 1973
TL;DR: In this paper, a new thermoelectric generator is proposed, the operation of which is due to a new effect that takes place in a closed chain uniformly heated at an optimum temperature, the chain consisting of a semi-conductor comprises between two different metals the difference of the work-function of which are related to the value of the optimum temperature quantitatively, through a certain formula given in the specification.
Abstract: The present invention concerns a new thermoelectric generator, the operation of which is due to a new effect that takes place in a closed chain uniformly heated at an optimum temperature, the chain consisting of a semi-conductor comprises between two different metals the difference of the work-function of which are related to the value of the optimum temperature quantitatively, through a certain formula given in the specification. For maximum electric power delivered, the concentration of the holes into the semiconductor must be of the order of 10 18 n/cm 3 , and the concentration of electrons into the same of the order of 10 8 n/cm 3 , at 20° C. Such a chain has in the absence of any temperature gradient, an efficiency near unity.
38 citations
Patent•
26 Feb 1973
TL;DR: In this paper, an electro-mechanical energy conversion system for the operation of micropower electronic devices is described, in which high conversion efficiency is achieved through the use of a load demand actuated energy metering system and capacitive storage means.
Abstract: The present disclosure describes an electro-mechanical energy conversion system which may be utilized as a long shelf-life energy source for the operation of micropower electronic devices. High conversion efficiency is achieved through the use of a load demand actuated energy metering system and capacitive storage means. An operative embodiment of the system employs electronic means for continuously sensing the level of electrical energy present in the storage means and for releasing a spring-driven miniature alternator to permit it to rotate when the level falls to a predetermined lower voltage limit. Mechanical means are employed to allow the alternator to rotate through a fixed angle and to terminate the powered rotation when this angle has been reached.
25 citations
TL;DR: Polarization conversion in optical waveguides on birefringent substrates is discussed with the aid of a coupled wave model in this article, where structures are described which tolerate large thickness variations (up to 45%) while achieving the phase matching necessary for high conversion efficiency.
17 citations
TL;DR: In this paper, the authors reported 100% conversion of infrared photons into visible photons through three wave interactions in a nonlinear medium, present the first experimental evidence of overconversion, and confirm the classical theory of up-conversion in the high conversion efficiency region.
Abstract: We report 100% conversion of infrared photons into visible photons through three wave interactions in a nonlinear medium, present the first experimental evidence of overconversion, and confirm the classical theory of up‐conversion in the high‐conversion‐efficiency region. A laser pump light feedback technique is described that promises to make the process practical with modestly powerful pump lasers and less than perfect nonlinear crystals. The nonlinear medium used was a LiIO3 crystal that cannot be 90° phase matched. The ``walk off'' that resulted helped make possible the attainment of 100% conversion efficiency.
16 citations
TL;DR: In this article, the lifetime of the ytterbium excited state showed a marked increase and, in a typical instance, became as long as 3.6 msec, and an over-all conversion efficiency of nearly 0.04% was obtained for a 50mA diode-exciting current.
Abstract: Efficient up‐conversion of near‐infrared energy was realized by confinement of infrared energy in an optical cavity containing a BaY2F8 : Yb,Er single crystal. The lifetime of the ytterbium excited state showed a marked increase and, in a typical instance, became as long as 3.6 msec. Combined with 8% efficiency GaAs : Si diode, an over‐all conversion efficiency of nearly 0.04% was obtained for a 50‐mA diode‐exciting current.
15 citations
TL;DR: In this paper, the intracavity second harmonic generation of YAlG/Nd laser using KNbO3 single crystal was demonstrated and it was compared with that using Ba2NaNb5O15 crystal.
Abstract: The intracavity second harmonic generation of YAlG/Nd laser using KNbO3 single crystal was demonstrated and it was compared with that using Ba2NaNb5O15 crystal KNbO3 was found to be suitable for this application because of (1) its large conversion efficiency, ie (d2/n3)KNbO3 =08±01(d2/n3)Ba2NaNb5O15 , (2) its resistance to damage by intense green light output, and (3) its very low optical loss coefficients at the fundamental and the harmonic wavelengths (about 025%/cm at 106 µm) About 90% conversion of the optical second harmonics was obtained The thermal conductivity of KNbO3 was found to be larger than that of Ba2NaNb5O15 due to the increasing crystal temperature caused by the internal laser power
TL;DR: In this article, a planar field emission electron beam diode was used to initiate the reaction of F with H2 in SF6-H2 mixtures, and the conversion efficiency of electron beam energy input to the medium to laser output energy was 5.2%.
Abstract: A 3.5‐cm × 35‐cm planar field emission electron beam diode, producing a total beam current of 4.65 kA of 120‐keV electrons in 26‐nsec pulses was used to initiate the reaction of F with H2 in SF6–H2 mixtures. From an optical volume of approximately 1 liter we observed HF laser pulses of 20–30 nsec duration with a maximum energy of 0.2 J at 450 Torr. The application of a secondary potential, very near the self‐breakdown limit of the gas, to the laser medium increased the laser output by only a factor of 2. Numerical analysis of the experiments without secondary field shows that 2.7 × 104 F atoms are produced by each 120‐keV electron fully stopped in the gas. This corresponds to an energy of 4.5 eV required for the production of one F atom from SF6 by high‐energy electrons. The conversion efficiency of electron beam energy input to the medium to laser output energy was 5.2%.
TL;DR: In this article, the authors considered the useful work output from the magnetic compression, decompression and α-particle energy deposition of a single cycle of a D-T θ-pinch reactor.
Abstract: We consider the useful work output from the magnetic compression, decompression and α-particle energy deposition of a single cycle of a D-T θ-pinch reactor. The intrinsic thermodynamic efficiency of the direct conversion cycle from α-particle energy to work is 62%. The direct-conversion output work is available to the reactor system at essentially 100% efficiency, and has an appreciable effect on the circulating power fraction and plant efficiency.
TL;DR: In this paper, a LiIO3 crystal, placed inside a doubly resonant oscillator, was pumped with the second harmonic of a Q•switched ruby laser, and a 0.415 to 2.1μm tuning range for both signal and idler was obtained.
Abstract: A LiIO3 crystal, placed inside a doubly resonant oscillator, was pumped with the second harmonic of a Q‐switched ruby laser. A 0.415‐ to 2.1‐μm tuning range for both signal and idler was obtained. The conversion efficiency from pump to signal power amounts to 8%. The peak power of the signal radiation was 10 kW and the pulse duration was 5 nsec.
Patent•
05 Jul 1973
TL;DR: In this article, the authors measured the electrical potential between two points spaced apart in the direction of gas flow to determine the conversion efficiency of a catalyst for a given fuel mixture and air flow rate.
Abstract: The efficiency of a catalyst in converting hydrocarbons to carbon dioxide and water is determined by passing hydrocarbon fumes, mixed with air, over a substrate coated with the catalyst and measuring an electrical potential between two points spaced apart in the direction of gas flow. The magnitude of the electrical potential thus developed is representative of the conversion efficiency of the catalyst for a given fuel mixture and air flow rate.
TL;DR: In this article, the authors measured the conversion efficiency of ZnS transducers on a glass substrate for elastic surface waves and analyzed it by using a simple model, showing that the internal impedance of the thin-film transducers is not simply proportional to Δ vs/vs, where Δ vs is the perturbation in surface-wave velocity when the electrodes are replaced by a thin-, perfect conductor.
Abstract: The conversion efficiency of ZnS transducers evaporated on a glass substrate for elastic surface waves has been measured as a function of the ZnS film thickness and analyzed by using a simple model. It is found that the thickness dependence of the conversion efficiency is affected by elliptic particle motion at the position of electrodes located at the interface between the ZnS film and the substrate (type I) or at the surface of the ZnS film (type II). Conversion efficiency calculated from the potential induced at the electrodes is in good agreement with the experiments. The analysis shows that the internal impedance of the thin‐film transducer is not simply proportional to Δ vs/vs, where Δ vs is the perturbation in surface‐wave velocity when the electrodes are replaced by a thin‐film perfect conductor. Theory suggests that type I is most efficient when the thickness is about 0.4 times the surface wavelength.
TL;DR: In this paper, the authors show that the optimum dc to RF conversion efficiency is in descending order for Schottky-barrier GaAs, p+n Si, and n+p Si IMPATT diodes.
Abstract: Computer simulation results show that optimum dc to RF conversion efficiency is in descending order for Schottky-barrier GaAs, p+-n Si, and n+-p Si IMPATT diodes.
TL;DR: In this paper, the authors developed a method of systematic evaluation and determination of host parameters for infrared-to-visible conversion phosphors based on a simple rate equation model and calculated rise characteristics of the visible emissions are in satisfactory agreement with the experimental results obtained for YF3: Yb, Er phosphors.
Abstract: A method of systematic evaluation and determination of host parameters is developed for infrared-to-visible conversion phosphors based on a simple rate equation model. Calculated rise characteristics of the visible emissions are in satisfactory agreement with the experimental results obtained for YF3: Yb, Er phosphors. Several host parameters, such as nonradiative decay rate and energy transfer coefficient, were obtained systematically by fitting the calculated curves with expermental data. It was shown that the conversion efficiency of the infrared light into the green emission is dependent on nonradiative decay rate as well as sensitizer excited state lifetime, both of which are sensitive to preparation procedures. Discussions are presented on the applicability limit of the rate equation model.
TL;DR: In this article, the jacobian elliptic function parameter η 2 and the overall gain were expressed in terms of the JE and the jE, and the conversion efficiency for amplifiers and oscillators was shown to be O(n 2 ) for any gain larger than 5.
TL;DR: In this paper, a large-signal analysis is used to discuss the effect of lattice temperature and temperature gradients on the RF behavior of stabilized transferred-electron devices, and the influence of the value of donor density and density gradients upon RF conversion efficiency is also discussed.
Abstract: A large-signal analysis is used to discuss the effect of lattice temperature and temperature gradients on the RF behavior of stabilized transferred-electron devices. The influence of the value of donor density and density gradients upon RF conversion efficiency is also discussed. It is shown that efficiency can be improved if either the heat sink is located at the anode or the donor density is increased near the anode end.
TL;DR: In this paper, the energy conversion in n-type InSb has been investigated, and the dependence of the conversion efficiency on the external field is shown, where an electric field enhances its intensity, and a transverse magnetic field also affects it.
Abstract: Acoustoelectric energy conversion in n‐type InSb has been investigated. Electromagnetic radiation is observed at 77°K when the externally injected acoustic wave arrives at the end of a sample. The frequency of the radiation is the same as that of the acoustic wave. Application of an electric field enhances its intensity, and a transverse magnetic field also affects it. Dependence of the conversion efficiency on the external field is shown.
TL;DR: In this article, an adiabatic theory of the energy exchange between magnetically confined charged particles and a traveling electrostatic wave with slowly varying phase speed and amplitude is presented.
Abstract: An adiabatic theory of the energy exchange between magnetically confined charged particles and a traveling electrostatic wave with slowly varying phase speed and amplitude is presented. The results are applied to a basic assessment of the usefulness of traveling‐wave techniques for efficient energy recovery from energetic plasma streams. Severe constraints on the energy conversion efficiency attainable by this approach are indicated by the model.
Dissertation•
10 Aug 1973
01 Dec 1973
TL;DR: In this paper, economic feasibilities and energy conversion efficiencies for various alternative energy sources that utilize wind forces are considered for different types of wind energy sources, including solar, wind, and bio-diesel.
Abstract: Economic feasibilities and energy conversion efficiencies are considered for various alternative energy sources that utilize wind forces.