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Showing papers on "Energy conversion efficiency published in 1970"


Journal ArticleDOI
TL;DR: In this article, the nonlinear optical coefficient, optical transmission, and refractive indices of orthorhombic lithium formate monohydrate single crystals have been measured, and both d24 and d32 are phase-matchable and the conversion efficiency is twice that of LiIO3.
Abstract: Nonlinear optical coefficient, optical transmission, and refractive indices of orthorhombic lithium formate monohydrate single crystals have been measured The crystals are transparent from 025 to about 12μm and suffer no optical damage The SHG can be phase‐matched for a large number of fundamental wavelengths in the range of transparency of the material The phase‐matchable nonlinear coefficient d24=d32=35× d11α‐SiO2 For the 1064 to 0532μm conversion, both d24 and d32 are phase‐matchable and the conversion efficiency is found to be twice that of LiIO3

52 citations


Journal ArticleDOI
TL;DR: In this paper, the collection efficiency and spectral response calculations for semiconductor heterojunction solar cells were performed for the first time, and the spectral response was calculated for the same class of cells.
Abstract: Collection efficiency and spectral response calculations for semiconductor heterojunction solar cells

41 citations


Journal ArticleDOI
TL;DR: In this paper, the second harmonic of a ruby laser has been produced in LiIO3 crystals, showing hardly any optical absorption at 0.347 μ. Using these new crystals external to the laser cavity conversion efficiencies up to 40% have been achieved using an incident unfocussed beam of about 130 MW/cm2.
Abstract: The second harmonic of a ruby laser has been produced in LiIO3 crystals, showing hardly any optical absorption at 0.347 μ. Using these new crystals external to the laser cavity conversion efficiencies up to 40% have been achieved using an incident unfocussed beam of about 130 MW/cm2. After 5–10 shots, a first small internal damage spot appeared inside the LiIO3 crystal. For a beam diameter of 3 mm several hundred shots with a conversion efficiency of 40% were possible.

38 citations


Journal ArticleDOI
TL;DR: In this article, a simple model consisting of three simultaneous rate equations is proposed to account for the conversion of infrared excitation to visible emission by LiY0.799Yb0.2Ho0.001F4.
Abstract: A simple model consisting of three simultaneous rate equations is proposed to account for the conversion of infrared excitation to visible emission by LiY0.799Yb0.2Ho0.001F4. All of the parameters appearing in the equations are measured. The time development of the luminescence and the conversion efficiency are calculated and found to be in reasonable agreement with the measurements.

36 citations


Journal ArticleDOI
J.R. Hechtel1
TL;DR: In this paper, the potential energy stored in a bunched electron beam is calculated using analytical and numerical methods, and the ratio of stored potential energy to the total beam energy increases with the degree of bunching and with decreasing beam filling factor b/a.
Abstract: The potential energy stored in a bunched electron beam is calculated using analytical and numerical methods. The ratio of stored potential energy to the total beam energy W_{p}/W_{0} increases rapidly with the degree of bunching and with decreasing beam filling factor b/a . W_{p}/W_{0} is proportional to the beam perveance and independent of the beam voltage, as long as relativistic effects are neglected. In a velocity-modulated linear beam-type device, such as a klystron or a traveling-wave beam tube, stored potential beam energy affects both the bunching process and the process of dc to RE energy conversion adversely. For maximum conversion efficiency W_{p}/W_{0} should be kept as low as possible. Several ways of reducing W_{p}/W_{0} are discussed.

25 citations


Journal ArticleDOI
TL;DR: In this paper, the authors analyzed second-harmonic generation (SHG) with focused pump beams in the high-conversion regime where pump depletion was significant, and derived numerical solutions of the coupled equations for pump and harmonic fields for cylindrically symmetric case of collinear phase matching.
Abstract: We analyze second-harmonic generation (SHG) with focused pump beams in the high-conversion regime where pump depletion is significant. Numerical solutions of the coupled equations for pump and harmonic fields are obtained for the cylindrically symmetric case of collinear phase matching. The optimum values of phase mismatch and confocal parameters σ and b found by Boyd and Kleinman are very nearly independent of pump power to above 95 percent conversion. When phase mismatch is not optimized, the best confocal parameter depends upon the input power. The conversion efficiency versus input power is determined numerically for optimum \sigma, b , and approximate analytical formulas are given for this relation.

22 citations


Journal ArticleDOI
TL;DR: In this paper, it was shown that the mechanism of excitation is a hot rod model in which the shower deposits heat in the bar and the hot zone expands causing mechanical vibrations.
Abstract: Investigations into the production of mechanical oscillations in aluminum cylinders by high energy electrons reveal that the mechanism of excitation is a "hot rod model" in which the shower deposits heat in the bar and the hot zone expands causing mechanical vibrations. The conversion efficiency of this process is evaluated in these experiments. The hot rod mechanism does not present a significant background for gravitational events from cosmic rays in room temperature gravitational radiation detectors.

21 citations


Journal ArticleDOI
TL;DR: In this article, a tunable infrared laser has been achieved using spin-flip magneto-Raman scattering in InSb. Dielectric coatings on the sides of the laser cavity gave the unexpected result of enhancing the collinear output up to a value of 10 W-a conversion efficiency approximately 1%.
Abstract: A tunable infrared laser has been achieved using spin-flip magneto-Raman scattering in InSb. Dielectric coatings on the sides of the laser cavity gave the unexpected result of enhancing the collinear output up to a value of 10 W-a conversion efficiency approximately=1%.

18 citations


Journal ArticleDOI
TL;DR: In this article, photoluminescence from evaporated films of approximately 1µ thick has been studied at room temperature as a function of the fluoride concentration and the excitation or pumping wavelength varies from 4880 to 2600Aa, while the Tb3+ emission transition at 5425Aa is monitored at the output.
Abstract: Photoluminescence from evaporated films of approximately 1µ thick has been studied at room temperature as a function of the fluoride concentration. The excitation or pumping wavelength varies from 4880 to 2600Aa, while the Tb3+ emission transition at 5425Aa is monitored at the output. For pumping photon energies below the forbidden gap, the excitation spectra resemble that of the pure film or single crystal. For this case, the conversion efficiency with 4880Aa pumping in samples that contain 0.86% is close to 100% as compared to 0.8% for pure . With pumping energies above the gap, photoluminescence presumably due to energy transfer from electron‐hole pairs has also been observed; however, such a process yields conversion efficiency generally in the 10−5–10−6 range. These results support the model that electroluminescence in devices using similar films arises from direct excitation of Tb3+ levels by hot electrons as proposed by one of the authors.

13 citations


Patent
03 Aug 1970
TL;DR: The hydrated and deuterated forms of lithium formate are useful nonlinear materials for use over a wavelength range including the visible spectrum and resistance to radiation damage is significantly greater as mentioned in this paper.
Abstract: The hydrated and deuterated forms of lithium formate are found to be useful nonlinear materials for use over a wavelength range including the visible spectrum. While conversion efficiency is inferior to that of lithium niobate or barium sodium niobate, resistance to radiation damage is significantly greater. Operation at power levels in excess of 106 watts/cm2 has resulted in no perceptible damage. These materials are suitably incorporated in second harmonic generators as well as in other parametric devices.

10 citations


Proceedings Article
01 Jan 1970
TL;DR: Si solar cells low temperature and solar intensity performance optimization by identifying and eliminating low output problems was discussed in this paper. But the authors did not consider the performance of the Si solar cells in terms of energy efficiency.
Abstract: Si solar cells low temperature and solar intensity performance optimization by identifying and eliminating low output problems

Journal ArticleDOI
Daniel L. Rode1
TL;DR: In this paper, the self-resonance of a cylindrical LSA diode loaded externally by a concentric dielectric ring is exploited to achieve a design consistent with heat dissipation requirements for CW operation at frequencies in excess of 70 GHz.
Abstract: The realization of the predicted dc to RF conversion efficiency of LSA oscillators operating around 100 GHz is expected to require low-loss resonant circuits. At these higher frequencies, the practical difficulties attendant upon the construction of conventional waveguide elements suggest that a more compact resonant circuit may be useful. The resonator studied theoretically in the present paper takes advantage of the self-resonance of a cylindrical LSA diode loaded externally by a concentric dielectric ring. By this means, a design consistent with heat dissipation requirements for CW operation is reached for frequencies in excess of 70 GHz.

Journal ArticleDOI
William C. Brown1
TL;DR: In this article, a dc-to-rf energy conversion efficiency of 93% and an overall efficiency of 86% have been demonstrated in a high power magnetron with continuous power over 400 kW at 3000 MHz and an efficiency of 76% has been obtained from the Amplifron, a crossed-field amplifier device.
Abstract: The proposal to obtain electrical energy from the sun by means of an enormous solar cell array positioned in space at synchronous orbit altitude places a challenging requirement upon the means of converting this energy info microwave\orm so that it can be relayed to the earth’s surface. Crossed-field device technology is con-sistent with the needs for high efficiency, long life, and for either modest or very high power levels in the dc to rf energy conversion process. A dc to rf energy conversion efficiency of 93% and an overall efficiency of 86% have been demonstrated in a high power magnetron. Continuous power over 400 kW at 3000 MHz and an efficiency of 76% has been obtained from the Amplifron, a crossed-field amplifier device. The development of a pure-metal, secondary emitter cathode provides long life capability. Newly developed permanent magnet material provides the high magnetic fields needed for high efficiency with low resulting weight.


Patent
Erling L Lien1
03 Sep 1970
TL;DR: In this article, a slow wave tube is disclosed where the signal to be amplified and an harmonic thereof are applied concurrently over at least a portion of the slow wave circuit to increase the RF conversion efficiency of the tube.
Abstract: A slow wave tube is disclosed wherein the signal to be amplified and an harmonic thereof are applied concurrently over at least a portion of the slow wave circuit to increase the RF conversion efficiency of the tube. In a preferred embodiment, the harmonic wave energy is extracted from the output of the tube and fed back onto the slow wave circuit. The slow wave circuit portion, which provides the harmonic interaction with the beam, preferably has a dispersive characteristic such that the harmonic wave energy has a higher phase velocity than the fundamental wave energy for enhanced RF conversion efficiency.

Journal ArticleDOI
TL;DR: In this paper, a low-gain amplifier dc-to-RF conversion efficiency analysis is presented, and three power-amplifier-efficiency definitions are compared, and it is shown that the generation efficiency is a useful quality factor for low gain power amplifiers only if it can be assumed to be constant over a wide operating range.
Abstract: A low-gain amplifier dc-to-RF conversion efficiency analysis is presented. Three power-amplifier-efficiency definitions are compared, and it is shown that the generation efficiency is a useful quality factor for low-gain power amplifiers only if it can be assumed to be constant over a wide operating range. In the most frequently occurring case the generation efficiency is a function of drive and the dc operating point, and no single number provides enough information to characterize amplifier-efficiency performance. A graphical technique is presented for selecting the most efficient operating point for an amplifier with variable gain and generation efficiency.

Proceedings ArticleDOI
11 May 1970
TL;DR: In this article, a reflectance amplifier was used to achieve a DC-to-RF conversion efficiency of 50 percent at S-band with 8 to 10 dB gain and 10 watts peak output.
Abstract: Silicon IMP ATT diodes have been used in a reflectance amplifier circuit to achieve a DC to RF conversion efficiency of 50 percent at S-band with 8 to 10 dB gain and 10 watts peak output. The RF circuit used was a four slug coaxial structure similar to that used by others in the production of high efficiency oscillations. A pulse width of one microsecond at a repetition rate of 5 KHz was used. The circuit configuration of the reflectance amplifier is shown in Figure 1.

Journal ArticleDOI
TL;DR: In this paper, the second law of thermodynamics was used to show that the conversion efficiency depends upon the bandwidth and effective temperature of the incoming radiation, and the relationship between the minimum bandwidth of radiation and bias voltage in a recombination diode was derived.
Abstract: The second law of thermodynamics imposes a limit on the maximum efficiency achievable with any rectifier in converting radiation into dc power. By using the second law and Bose photon statistics, a general expression is derived showing that this efficiency depends upon the bandwidth and effective temperature of the incoming radiation. Only for completely coherent radiation can the conversion efficiency be unity. The theoretical implications are illustrated by examining specific thermodynamic cycles involving idealized recombination diodes and thermodynamically ideal rectifiers. The relationship between minimum bandwidth of radiation and bias voltage in a recombination diode is derived. The connection between conversion efficiency and Carnot efficiency is made clear.


Journal ArticleDOI
TL;DR: MHD induction generator efficiency, investigating winding slot finite spacing and width effects, was investigated in this paper, where the authors investigated the effect of the winding slot width on the efficiency of induction generators.

Journal ArticleDOI
TL;DR: A technique which may be used to determine the light conversion efficiency of thin fluorescent crystals is presented and an application was made to the case of a calcium tungstate crystal, for which a Conversion efficiency of [equiation] was determined.
Abstract: A technique which may be used to determine the light conversion efficiency (defined below) of thin fluorescent crystals is presented. The illuminance associated with the visible spectrum emitted by the material under a pulse of x rays and incident on a light intensifier tube is amplified by the tube and is eventually recorded by a photographic film placed on the other side of the tube. A calibration curve relating the conversion efficiency of the crystal (regarded as an unknown variable) and the resulting film density is first obtained analytically. This is then used, in conjunction with the experimentally measured film density, to yield the conversion efficiency. An application of this technique was made to the case of a calcium tungstate crystal, for which a conversion efficiency of (4.4+5.5−2.3)% was determined.

Journal ArticleDOI
TL;DR: In this article, the effect of electrical discharge on series resistance, curve power factor, conversion efficiency and spectral response of silicon solar cells was investigated, and it was found that the cells exhibit unexpectedly large and permanent deterioration in their characteristics.
Abstract: It is generally believed that there is no possibility of deterioration occurring in silicon solar cells on the surface of the earth. As one of the tests for their environmental capabilities, the effect of electrical discharge on series resistance, curve power factor, conversion efficiency and spectral response is investigated. The cells are found to exhibit unexpectedly large and permanent deterioration in their characteristics. Some of the phenomena which might be responsible for the observed degradation are pointed out and discussed.

Journal ArticleDOI
TL;DR: In this article, the authors reported observations of magneto-plasma mode conversion from the TE 01 ° mode to the TM 1 ° mode at 70 GHz, where the maximum conversion efficiency was calculated to be 95 percent under conditions of the present experiment.
Abstract: A magnetoplasma such as that formed in n-type indium antimonide can efficiently transduce energy from one waveguide mode to another. This correspondence reports observations of magneto-plasma mode conversion from the TE 01 ° mode to the TM 01 ° mode at 70 GHz. The maximum conversion efficiency is calculated to be 95 percent under conditions of the present experiment.