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Sample records for harmonic converter crystals

  1. Optical and environmentally protective coatings for potassium dihydrogen phosphate (KDP) harmonic converter crystals

    SciTech Connect

    Thomas, I.M.

    1991-06-24

    Potassium dihydrogen phosphate (KDP) crystals have been used as harmonic converters on the Nova laser at LLNL for over six years. All crystals were coated with a single layer, quarterwave AR coating of porous silica with a refractive index of 1.22. This was prepared by a sol-gel process and was applied from a colloidal suspension by spin coating at room temperature. A few crystals were also coated with a methyl silicone coating prior to the application of the AR coating for environmental protection. The initial optical performance of all crystals was very good but there has been some deterioration over the years because of environmental and laser damage degradation. The deterioration in the silicone samples was, however, much less than the others. We are now in the process of replacing all ten KDP arrays with new crystals and will apply the silicone undercoat to all samples. Recently we have been evaluating a new perfluorinated organic polymer coating which has a refractive index of 1.29. This material is soluble in fluorinated solvents and can be applied by dip coating from solution at room temperature. We hope that this can provide environmental protection when applied to KDP and also act as an AR coating at the same time. The optical performance is not as good as our porous silica because of the higher index; about 0.3% reflection per surface is obtained. 4 refs., 10 figs., 1 tab.

  2. Elimination of Harmonics in a Multilevel Converter for HEV Applications

    E-print Network

    Tolbert, Leon M.

    1 Elimination of Harmonics in a Multilevel Converter for HEV Applications Leon M. Tolbert1,2 , John Elimination, Resultants I. Introduction Designs for heavy duty hybrid-electric vehicles (HEVs) that have large of a large electric traction drive. For parallel-conÞgured HEVs, a cascaded H-bridges inverter can be used

  3. Second harmonic generation from the ‘centrosymmetric’ crystals

    PubMed Central

    Nalla, Venkatram; Medishetty, Raghavender; Wang, Yue; Bai, Zhaozhi; Sun, Handong; Wei, Ji.; Vittal, Jagadese J.

    2015-01-01

    Second harmonic generation (SHG) is a well known non-linear optical phenomena which can be observed only in non-centrosymmetric crystals due to non-zero hyperpolarizability. In the current work we observed SHG from a Zn(II) complex which was originally thought to have crystallized in the centrosymmetric space group C2/c. This has been attributed to the unequal antiparallel packing of the metal complexes in the non-symmetric space group Cc or residual non-centrosymmetry in C2/c giving rise to polarizability leading to strong SHG. The enhancement of SHG by UV light has been attributed to the increase in non-centrosymmetry and hence polarity of packing due to strain induced in the crystals. The SHG signals measured from these crystals were as large as potassium dihydrogen phosphate crystals, KH2PO4 (KDP), and showed temperature dependence. The highest SHG efficiency was observed at 50?K. The SHG phenomenon was observed at broad wavelengths ranging from visible to below-red in these crystals. PMID:25995840

  4. Second harmonic generation from the 'centrosymmetric' crystals.

    PubMed

    Nalla, Venkatram; Medishetty, Raghavender; Wang, Yue; Bai, Zhaozhi; Sun, Handong; Wei, Ji; Vittal, Jagadese J

    2015-05-01

    Second harmonic generation (SHG) is a well known non-linear optical phenomena which can be observed only in non-centrosymmetric crystals due to non-zero hyperpolarizability. In the current work we observed SHG from a Zn(II) complex which was originally thought to have crystallized in the centrosymmetric space group C2/c. This has been attributed to the unequal antiparallel packing of the metal complexes in the non-symmetric space group Cc or residual non-centrosymmetry in C2/c giving rise to polarizability leading to strong SHG. The enhancement of SHG by UV light has been attributed to the increase in non-centrosymmetry and hence polarity of packing due to strain induced in the crystals. The SHG signals measured from these crystals were as large as potassium dihydrogen phosphate crystals, KH2PO4 (KDP), and showed temperature dependence. The highest SHG efficiency was observed at 50?K. The SHG phenomenon was observed at broad wavelengths ranging from visible to below-red in these crystals. PMID:25995840

  5. Fourier's Law for a Harmonic Crystal with Selfconsistent Stochastic Reservoirs

    E-print Network

    Roma "La Sapienza", Università di

    Fourier's Law for a Harmonic Crystal with Self­consistent Stochastic Reservoirs Federico Bonetto is the coupling to the intermediate reservoirs. We also analyze the e#ect of having a non­uniform distribution­Kubo formula. Suggested running head: Fourier's Law for a Harmonic Crystal with Self­consistent Reservoirs

  6. Aalborg Universitet Harmonic Analysis of Offshore Wind Farms with Full Converter Wind Turbines

    E-print Network

    Bak, Claus Leth

    Aalborg Universitet Harmonic Analysis of Offshore Wind Farms with Full Converter Wind Turbines International Conference on Large-Scale Integration of Wind Power into Power Systems Publication date: 2009 Analysis of Offshore Wind Farms with Full Converter Wind Turbines. In Proceeding of the 8th International

  7. Photovoltaic power converter system with a controller configured to actively compensate load harmonics

    DOEpatents

    de Rooij, Michael Andrew (Clifton Park, NY); Steigerwald, Robert Louis (Burnt Hills, NY); Delgado, Eladio Clemente (Burnt Hills, NY)

    2008-12-16

    Photovoltaic power converter system including a controller configured to reduce load harmonics is provided. The system comprises a photovoltaic array and an inverter electrically coupled to the array to generate an output current for energizing a load connected to the inverter and to a mains grid supply voltage. The system further comprises a controller including a first circuit coupled to receive a load current to measure a harmonic current in the load current. The controller includes a second circuit to generate a fundamental reference drawn by the load. The controller further includes a third circuit for combining the measured harmonic current and the fundamental reference to generate a command output signal for generating the output current for energizing the load connected to the inverter. The photovoltaic system may be configured to compensate harmonic currents that may be drawn by the load.

  8. Temperature-insensitive phase-matched optical harmonic conversion crystal

    DOEpatents

    Barker, C.E.; Eimerl, D.; Velsko, S.P.; Roberts, D.

    1993-11-23

    Temperature-insensitive, phase-matched harmonic frequency conversion of laser light at a preferred wavelength of 1.064 microns can be achieved by use of a crystal of deuterated l-arginine phosphate. The crystal is cut and oriented so that the laser light propagates inside the crystal along one of several required directions, which correspond to a temperature-insensitive, phase-matching locus. The method of measuring and calculating the temperature-insensitive, phase-matching angles can be extended to other fundamental wavelengths and other crystal compositions. 12 figures.

  9. Aalborg Universitet Harmonic models of a back-to-back converter in large offshore wind farms compared

    E-print Network

    Bak, Claus Leth

    -to-back converter in large offshore wind farms compared with measurement data. In Proceedings of Nordic Wind Power power converter in wind turbines is studied. As an example the Burbo Bank offshore wind farm offshore wind farm. The delimitations of both power converter models with referent to harmonic analysis

  10. A gyroresonance harmonic converter to drive NCL, the next linear collider

    SciTech Connect

    Hirshfield, J.L. Physics Department, Yale University, Box 6666, New Haven, Connecticut 06511 ); Ganguly, A.K. )

    1992-07-01

    Current approaches are reviewed for developing an rf source for driving the Next Linear Collider (NLC) based on various gyroresonance interactions. An alternative mechanism is described, with the potential of converting 2.85 GHz power from a SLAC klystron to output at a harmonic ranging from 11.4 to 31.4 GHz. Preliminary calculations show that this new process can enjoy high conversion efficiency, strong resilience to axial momentum spread on the beam, and weak power flow into competing modes.

  11. Quartz crystal microbalance based on passive frequency to voltage converter

    SciTech Connect

    Burda, Ioan; Tunyagi, Arthur

    2012-02-15

    In dynamics of evaporation or drying of microdrops from a solid surface, a faster and precise quartz crystal microbalance (QCM) is needed. The fast QCM based on frequency to voltage converter is an attractive and powerful tool in the investigation of the dynamic regime of evaporation to translate the frequency shift in terms of a continuous voltage change. The frequency shift monitoring in fast QCM applications is a real challenge for electronic processing interface. Originally developed as a frequency shift processing interface, this novel passive frequency to voltage converter can produce faster, stable, and accurate results in regard to the QCM sensor behavior. In this article, the concept and circuit of passive frequency to voltage converter will be explained followed by static and dynamic characterization. Experimental results of microdrops evaporation will be given.

  12. Generation of higher odd harmonics in a defective photonic crystal

    NASA Astrophysics Data System (ADS)

    Ramanujam, N. R.; Wilson, K. S. Joseph

    2015-06-01

    A photonic crystal (AB)2(DB)(AB)2 with high refractive index medium as silicon and low refractive medium as air is considered. Using the transfer matrix method, the transmission properties as a function of wavelength with photonic band gaps has been obtained. We are able to demonstrate the generation of third, fifth, seventh and ninth harmonics in the present work. We show that if the air medium is removed in the defect, the defect modes are generated but not harmonics. It can be designed to have a frequency conversion, and have a potential for becoming the basis for the next generation of optical devices.

  13. Harmonic Optimization of Multilevel Converters Using Genetic Algorithms Abstract--In this paper, a genetic algorithm (GA) optimization

    E-print Network

    Tolbert, Leon M.

    Harmonic Optimization of Multilevel Converters Using Genetic Algorithms Abstract-- In this paper, a genetic algorithm (GA) optimization technique is applied to multilevel inverter to determine optimum. In this paper, a general genetic algorithm (GA) approach will be presented, which solves the same problem

  14. Resonant second harmonic generation in a gallium nitride two-dimensional photonic crystal on silicon

    SciTech Connect

    Zeng, Y.; Roland, I.; Checoury, X.; Han, Z.; El Kurdi, M.; Sauvage, S.; Boucaud, P.; Gayral, B.; Brimont, C.; Guillet, T.; Mexis, M.; Semond, F.

    2015-02-23

    We demonstrate second harmonic generation in a gallium nitride photonic crystal cavity embedded in a two-dimensional free-standing photonic crystal platform on silicon. The photonic crystal nanocavity is optically pumped with a continuous-wave laser at telecom wavelengths in the transparency window of the nitride material. The harmonic generation is evidenced by the spectral range of the emitted signal, the quadratic power dependence vs. input power, and the spectral dependence of second harmonic signal. The harmonic emission pattern is correlated to the harmonic polarization generated by the second-order nonlinear susceptibilities ?{sub zxx}{sup (2)},??{sub zyy}{sup (2)} and the electric fields of the fundamental cavity mode.

  15. Self-Action of Second Harmonic Generation and Longitudinal Temperature Gradient in Nonlinear-Optical Crystals

    NASA Astrophysics Data System (ADS)

    Baranov, A. I.; Konyashkin, A. V.; Ryabushkin, O. A.

    2015-09-01

    Model of second harmonic generation with thermal self-action was developed. Second harmonic generation temperature phase matching curves were measured and calculated for periodically polled lithium niobate crystal. Both experimental and calculated data show asymmetrical shift of temperature tuning curves with pump power.

  16. Superposed second-harmonic Talbot self-image from a PPLT crystal

    NASA Astrophysics Data System (ADS)

    Wei, Dunzhao; Liu, Dongmei; Hu, Xiaopeng; Zhang, Yong; Xiao, Min

    2014-09-01

    We experimentally demonstrate the superposed second-harmonic Talbot self-image in a z-cut periodically-poled LiTaO3 crystal. The generated second-harmonic (SH) waves in the positive and negative domains have the same intensity but different phases (a phase shift of ?) due to the opposite poling directions, i.e. a second-harmonic phase pattern is generated from the crystal. By introducing a reference SH wave, we can selectively study the self-imaging originating from the SH patterns with different phases. In the integer and fractional Talbot planes, the two patterns interfere with each other and form superposed self-imaging patterns.

  17. Coded output photonic A/D converter based on photonic crystal slow-light structures

    E-print Network

    Park, Namkyoo

    Coded output photonic A/D converter based on photonic crystal slow-light structures Sunkyu Yu) utilizing a slow- light photonic crystal Mach-Zehnder interferometer (MZI) is proposed, to enable Resonator Optical Waveguides: toward the slowing and storage of light," Opt. Photon. News 16, 36-40 (2005

  18. Deep-UV 236.5??nm laser by fourth-harmonic generation of a single-crystal fiber Nd:YAG oscillator.

    PubMed

    Deyra, Loïc; Martial, Igor; Didierjean, Julien; Balembois, François; Georges, Patrick

    2014-04-15

    We demonstrate a deep-UV laser at 236.5 nm based on extracavity fourth-harmonic generation of a Q-switched Nd:YAG single-crystal fiber laser at 946 nm. We first compare two nonlinear crystals available for second-harmonic generation: LBO and BiBO. The best results at 473 nm are obtained with a BiBO crystal, with an average output power of 3.4 W at 20 kHz, corresponding to a second-harmonic generation efficiency of 38%. This blue laser is frequency-converted to 236.5 nm in a BBO crystal with an overall fourth-harmonic generation yield of 6.5%, corresponding to an average output power of 600 mW at 20 kHz. This represents an order of magnitude increase in average power and energy compared to previously reported pulsed lasers at 236.5 nm. This work opens the possibility of LIDAR detection of dangerous compounds for military or civilian applications. PMID:24978960

  19. Huge enhancement of backward second-harmonic generation with slow light in photonic crystals

    SciTech Connect

    Iliew, Rumen; Etrich, Christoph; Pertsch, Thomas; Kivshar, Yuri S.

    2010-02-15

    We study theoretically forward and backward second-harmonic generation in a two-dimensional photonic crystal structure made of lithium niobate. The aim of this article is twofold: First, we propose a reliable modal algorithm for describing the light propagation taking into account the vectorial character of the interacting fields as well as the tensorial character of the nonlinearity and verify it by means of the nonlinear finite-difference time-domain method. Second, we propose a photonic crystal where we obtain a giant efficiency increase for backward second-harmonic generation with slow light.

  20. Second harmonic generation in photonic crystal cavities in (111)-oriented GaAs

    SciTech Connect

    Buckley, Sonia Radulaski, Marina; Vu?kovi?, Jelena; Biermann, Klaus

    2013-11-18

    We demonstrate second harmonic generation at telecommunications wavelengths in photonic crystal cavities in (111)-oriented GaAs. We fabricate 30 photonic crystal structures in both (111)- and (100)-oriented GaAs and observe an increase in generated second harmonic power in the (111) orientation, with the mean power increased by a factor of 3, although there is a large scatter in the measured values. We discuss possible reasons for this increase, in particular, the reduced two photon absorption for transverse electric modes in (111) orientation, as well as a potential increase due to improved mode overlap.

  1. Nonlinear pulse compression in inhomogeneous photonic crystals upon backward second harmonic generation

    SciTech Connect

    Sapaev, U K; Kulagin, I A; Usmanov, T

    2009-04-30

    Frequency doubling of phase-modulated laser pulses, which is caused by a quasi-synchronous interaction of counterpropagating waves, is studied theoretically in crystals with an aperiodic domain structure. The simultaneous influence of the change in the domain period and the phase-modulation depth of fundamental radiation on the formation of a second-harmonic pulse is analysed in the nonstationary regime. It is shown that there exists an optimal relation between chirps in an aperiodic crystal and the phase modulation of fundamental radiation at which the maximum nonlinear compression of the second-harmonic pulse duration is possible. (nonlinear optical phenomena)

  2. Temperature-insensitive phase-matched optical harmonic conversion crystal

    DOEpatents

    Barker, Charles E. (Sunnyvale, CA); Eimerl, David (Livermore, CA); Velsko, Stephan P. (Livermore, CA); Roberts, David (Sagamore Hills, OH)

    1993-01-01

    Temperature-insensitive, phase-matched harmomic frequency conversion of laser light at a preferred wavelength of 1.064 microns can be achieved by use of a crystal of deuterated l-arginine phosphate. The crystal is cut and oriented so that the laser light propagates inside the crystal along one of several required directions, which correspond to a temperature-insensitive, phase-matching locus. The method of measuring and calculating the temperature-insensitive, phase-matching angles can be extended to other fundamental wavelengths and other crystal compositions.

  3. Cherenkov high-order harmonic generation by multistep cascading in {chi}{sup (2)} nonlinear photonic crystal

    SciTech Connect

    An Ning; Ren Huaijin; Zheng Yuanlin; Deng Xuewei; Chen Xianfeng

    2012-05-28

    We propose a scheme for efficient Cherenkov high-order harmonic generation. Second to fifth order harmonic wave are observed in a single periodically poled ferroelectric crystal in our experiment. The noncollinear high-order harmonic generation is produced via enhanced Cherenkov second harmonic cascaded with successive multistep sum-frequency generation with simultaneously longitudinal phase-matching. The emission angle and power dependencies are analyzed in detail experimentally, which coincide with theoretical predictions.

  4. Investigation of a metallic photonic crystal high power microwave mode converter

    NASA Astrophysics Data System (ADS)

    Wang, Dong; Qin, Fen; Xu, Sha; Yu, Aimin; Wu, Yong

    2015-02-01

    It is demonstrated that an L band metallic photonic crystal TEM-TE11 mode converter is suitable for narrow band high power microwave application. The proposed mode converter is realized by partially filling metallic photonic crystals along azimuthal direction in a coaxial transmission line for phase-shifting. A three rows structure is designed and simulated by commercial software CST Microwave Studio. Simulation results show that its conversion efficiency is 99% at the center frequency 1.58 GHz. Over the frequency range of 1.56-1.625 GHz, the conversion efficiency exceeds 90 %, with a corresponding bandwidth of 4.1 %. This mode converter has a gigawatt level power handling capability which is suitable for narrow band high power microwave application. Using magnetically insulated transmission line oscillator(MILO) as a high power microwave source, particle-in-cell simulation is carried out to test the performance of the mode converter. The expected TE11 mode microwave output is obtained and the MILO works well. Mode conversion performance of the converter is tested by far-field measurement method. And the experimental result confirms the validity of our design. Then, high power microwave experiment is carried out on a Marx-driven Blumlein water line pulsed power accelerator. Microwave frequency, radiated pattern and power are measured in the far-field region and the results agree well with simulation results. The experiment also reveals that no microwave breakdown or pulse shortening took place in the experimental setup.

  5. Second optical harmonic near the surface of ferroelectric photonic crystals and photon traps

    NASA Astrophysics Data System (ADS)

    Voinov, Yu. P.; Gorelik, V. S.; Zaitsev, K. I.; Zlobina, L. I.; Sverbil', P. P.; Yurchenko, S. O.

    2015-03-01

    This paper reports on the results of experimental investigations of the generation of the second optical harmonic localized in a thin subsurface layer of ferroelectric photonic crystals and photon traps. To excite the second optical harmonic, a KGW: Yb solid-state pulsed-periodic laser generating the radiation with a wavelength of 1026 nm in a form of pulses ˜10-13 s long with a repetition frequency of 200 kHz at the average power of 0.1-3.5 W and power density of ˜109-1012 W/cm2 in a spot less than 100 ?m in diameter focused near the surface was used. Ferroelectrics, notably, barium titanate or sodium nitrite, were introduced into the pores between SiO2 nanoglobules. It is established that the maximal conversion efficiency of the exciting radiation into the second optical harmonic was several percents. The generation characteristics of the second optical harmonic near the surface of photonic crystals filled with ferroelectrics are compared with the generation of the second optical harmonic in ferroelectric photon traps of barium titanate ceramics and sodium nitrite microcrystals.

  6. Ultrashort pulse chirp measurement via transverse second-harmonic generation in strontium barium niobate crystal

    SciTech Connect

    Trull, J.; Wang, B.; Parra, A.; Vilaseca, R.; Cojocaru, C.; Sola, I.; Sheng, Y.

    2015-06-01

    Pulse compression in dispersive strontium barium niobate crystal with a random size and distribution of the anti-parallel orientated nonlinear domains is observed via transverse second harmonic generation. The dependence of the transverse width of the second harmonic trace along the propagation direction allows for the determination of the initial chirp and duration of pulses in the femtosecond regime. This technique permits a real-time analysis of the pulse evolution and facilitates fast in-situ correction of pulse chirp acquired in the propagation through an optical system.

  7. Nonequilibrium stationary state of a harmonic crystal with alternating masses

    NASA Astrophysics Data System (ADS)

    Kannan, Venkateshan; Dhar, Abhishek; Lebowitz, J. L.

    2012-04-01

    We analyze the nonequilibrium steady states (NESS) of a one-dimensional harmonic chain of N atoms with alternating masses connected to heat reservoirs at unequal temperatures. We find that the temperature profile defined through the local kinetic energy T(j)?/mj oscillates with period two in the bulk of the system. Depending on boundary conditions, either the heavier or the lighter particles in the bulk are hotter. We obtain explicit integral expressions for the bulk temperature profile and steady state current in the limit N??. These depend on whether N is odd or even. We also study similar temperature oscillations in the NESS of systems with noise in the dynamics. These die out as N??.

  8. Nonequilibrium stationary state of a harmonic crystal with alternating masses.

    PubMed

    Kannan, Venkateshan; Dhar, Abhishek; Lebowitz, J L

    2012-04-01

    We analyze the nonequilibrium steady states (NESS) of a one-dimensional harmonic chain of N atoms with alternating masses connected to heat reservoirs at unequal temperatures. We find that the temperature profile defined through the local kinetic energy T(j)?/mj oscillates with period two in the bulk of the system. Depending on boundary conditions, either the heavier or the lighter particles in the bulk are hotter. We obtain explicit integral expressions for the bulk temperature profile and steady state current in the limit N??. These depend on whether N is odd or even. We also study similar temperature oscillations in the NESS of systems with noise in the dynamics. These die out as N??. PMID:22680430

  9. Towards protein-crystal centering using second-harmonic generation (SHG) microscopy

    PubMed Central

    Kissick, David J.; Dettmar, Christopher M.; Becker, Michael; Mulichak, Anne M.; Cherezov, Vadim; Ginell, Stephan L.; Battaile, Kevin P.; Keefe, Lisa J.; Fischetti, Robert F.; Simpson, Garth J.

    2013-01-01

    The potential of second-harmonic generation (SHG) microscopy for automated crystal centering to guide synchrotron X-­ray diffraction of protein crystals was explored. These studies included (i) comparison of microcrystal positions in cryoloops as determined by SHG imaging and by X-ray diffraction rastering and (ii) X-ray structure determinations of selected proteins to investigate the potential for laser-induced damage from SHG imaging. In studies using ?2 adrenergic receptor membrane-protein crystals prepared in lipidic mesophase, the crystal locations identified by SHG images obtained in transmission mode were found to correlate well with the crystal locations identified by raster scanning using an X-­ray minibeam. SHG imaging was found to provide about 2?µm spatial resolution and shorter image-acquisition times. The general insensitivity of SHG images to optical scatter enabled the reliable identification of microcrystals within opaque cryocooled lipidic mesophases that were not identified by conventional bright-field imaging. The potential impact of extended exposure of protein crystals to five times a typical imaging dose from an ultrafast laser source was also assessed. Measurements of myoglobin and thaumatin crystals resulted in no statistically significant differences between structures obtained from diffraction data acquired from exposed and unexposed regions of single crystals. Practical constraints for integrating SHG imaging into an active beamline for routine automated crystal centering are discussed. PMID:23633594

  10. Efficient second harmonic generation from large band gap II-VI semiconductor photonic crystal

    NASA Astrophysics Data System (ADS)

    Yang, H.; Xie, P.; Chan, S. K.; Zhang, Z. Q.; Sou, I. K.; Wong, G. K. L.; Wong, K. S.

    2005-09-01

    Dramatic enhancement of second harmonic generation (SHG) near the photonic band edge was observed in a one-dimensional ZnSe /ZnMgS semiconductor photonic crystal (PC) structure. Over two orders of magnitude increase in SHG intensity was observed at the photonic band edge at ˜1400nm compared to the nonphase matching region. The maximum SHG conversion efficiency of 0.8% is observed in only seven micrometers length of crystal. This enhancement came from a combination of large ZnSe second order susceptibility coefficient (?(2)), high density of optical modes and phase matching of the fundamental and second harmonic waves near the photonic band edge due to modification of the dispersion curve by the PC structure.

  11. Efficient second-harmonic generation of CW radiation in an external optical cavity using non-linear crystal BIBO

    E-print Network

    Kobtsev, Sergei M.

    Efficient second-harmonic generation of CW radiation in an external optical cavity using non power enhancement factor. Enhancement factor of input radiation power achievable in the best external.nsu.rulsrd/lls/englishl Efficient second-harmonic generation of CW radiation in an external optical cavity using non-linear crystal

  12. Highly efficient nanojoule second harmonic generation of a femtosecond Cr:forsterite laser radiation in a lithium niobate crystal

    SciTech Connect

    Gordienko, Vyacheslav M; Dyakov, Vladimir A; Mikheev, Pavel M; Syrtsov, Vladimir S

    2006-11-30

    Highly efficient ({approx}70%) second harmonic generation of tightly focused femtosecond radiation from a Cr:forsterite laser is obtained in a LiNbO{sub 3} crystal. The pulse energy amounts to 10 nJ, the spatial and spectral quality of second harmonic radiation being preserved. (nonlinear optical phenomena)

  13. BRIEF COMMUNICATIONS: Optical and harmonic generation properties of barium sodium niobate crystals of different compositions

    NASA Astrophysics Data System (ADS)

    Kuz'minov, Yu S.; Osiko, Vyacheslav V.; Sil'verstova, I. V.; Chusovitina, O. K.

    1982-07-01

    A comparison was made of three compositions of barium sodium niobate single crystals grown by the Czochralski method using Donets-1 apparatus with an improved stabilization of the output power of an hf oscillator. The absorption spectra were recorded. Measurements were made of the relative yield of the second harmonic of YAG:Nd laser radiation and of the absorption coefficient at the wavelengths of 0.63 and 1.15 ?. The best values of all three criteria were obtained for Ba2.09Na0.72Nb5.02O15 crystals.

  14. Conical second harmonic generation in KDP crystal assisted by optical elastic scattering.

    PubMed

    Li, Tianlun; Zhao, Xiaohui; Zheng, Yuanlin; Chen, Xianfeng

    2015-09-01

    We observed the generation of phase-matching conical second harmonic generation (SHG) inside KDP crystal under anomalous dispersion condition, which is attributed to complete phase-matching assisted by fundamental wave (FW) and scattering wave. The double-ring pattern of the conical SHG implies that elastic scattering can stimulate two different polarization states of scattering wave. Furthermore, SH ring of KDP displays inhomogeneous intensity around the ring, which has relevance to effective nonlinear coefficient, and it can be used to investigate crystal symmetry. PMID:26368476

  15. Third harmonic frequency generation by type-I critically phase-matched LiB3O5 crystal by means of optically active quartz crystal.

    PubMed

    Gapontsev, Valentin P; Tyrtyshnyy, Valentin A; Vershinin, Oleg I; Davydov, Boris L; Oulianov, Dmitri A

    2013-02-11

    We present a method of third harmonic generation at 355 nm by frequency mixing of fundamental and second harmonic radiation of an ytterbium nanosecond pulsed all-fiber laser in a type-I phase-matched LiB(3)O(5) (LBO) crystal where originally orthogonal polarization planes of the fundamental and second harmonic beams are aligned by an optically active quartz crystal. 8 W of ultraviolet light at 355 nm were achieved with 40% conversion efficiency from 1064 nm radiation. The conversion efficiency obtained in a type-I phase-matched LBO THG crystal was 1.6 times higher than the one achieved in a type-II LBO crystal at similar experimental conditions. In comparison to half-wave plates traditionally used for polarization alignment the optically active quartz crystal has much lower temperature dependence and requires simpler optical alignment. PMID:23481827

  16. Multiple copies of orbital angular momentum states through second-harmonic generation in a two-dimensional periodically poled LiTaO3 crystal

    NASA Astrophysics Data System (ADS)

    Fang, Xinyuan; Wei, Dunzhao; Liu, Dongmei; Zhong, Weihao; Ni, Rui; Chen, Zhenhua; Hu, Xiaopeng; Zhang, Yong; Zhu, S. N.; Xiao, Min

    2015-10-01

    We experimentally demonstrate multiple copies of optical orbital angular momentum (OAM) states through quasi-phase-matched (QPM) second-harmonic (SH) generation in a 2D periodically poled LiTaO3 (PPLT) crystal. Since the QPM condition is satisfied by involving different reciprocal vectors in the 2D PPLT crystal, collinear and noncollinear SH beams carrying OAMs of l2 are simultaneously generated by the input fundamental beam with an OAM of l1. The OAM conservation law (i.e., l2 = 2l1) holds well in the experiment, which can tolerate certain phase-mismatch between the interacting waves. Our results provide an efficient way to obtain multiple copies of the wavelength-converted OAM states, which can be used to enhance the capacity in optical communications.

  17. Real-time observation of interfering crystal electrons in high-harmonic generation.

    PubMed

    Hohenleutner, M; Langer, F; Schubert, O; Knorr, M; Huttner, U; Koch, S W; Kira, M; Huber, R

    2015-07-30

    Acceleration and collision of particles has been a key strategy for exploring the texture of matter. Strong light waves can control and recollide electronic wavepackets, generating high-harmonic radiation that encodes the structure and dynamics of atoms and molecules and lays the foundations of attosecond science. The recent discovery of high-harmonic generation in bulk solids combines the idea of ultrafast acceleration with complex condensed matter systems, and provides hope for compact solid-state attosecond sources and electronics at optical frequencies. Yet the underlying quantum motion has not so far been observable in real time. Here we study high-harmonic generation in a bulk solid directly in the time domain, and reveal a new kind of strong-field excitation in the crystal. Unlike established atomic sources, our solid emits high-harmonic radiation as a sequence of subcycle bursts that coincide temporally with the field crests of one polarity of the driving terahertz waveform. We show that these features are characteristic of a non-perturbative quantum interference process that involves electrons from multiple valence bands. These results identify key mechanisms for future solid-state attosecond sources and next-generation light-wave electronics. The new quantum interference process justifies the hope for all-optical band-structure reconstruction and lays the foundation for possible quantum logic operations at optical clock rates. PMID:26223624

  18. Real-time observation of interfering crystal electrons in high-harmonic generation

    NASA Astrophysics Data System (ADS)

    Hohenleutner, M.; Langer, F.; Schubert, O.; Knorr, M.; Huttner, U.; Koch, S. W.; Kira, M.; Huber, R.

    2015-07-01

    Acceleration and collision of particles has been a key strategy for exploring the texture of matter. Strong light waves can control and recollide electronic wavepackets, generating high-harmonic radiation that encodes the structure and dynamics of atoms and molecules and lays the foundations of attosecond science. The recent discovery of high-harmonic generation in bulk solids combines the idea of ultrafast acceleration with complex condensed matter systems, and provides hope for compact solid-state attosecond sources and electronics at optical frequencies. Yet the underlying quantum motion has not so far been observable in real time. Here we study high-harmonic generation in a bulk solid directly in the time domain, and reveal a new kind of strong-field excitation in the crystal. Unlike established atomic sources, our solid emits high-harmonic radiation as a sequence of subcycle bursts that coincide temporally with the field crests of one polarity of the driving terahertz waveform. We show that these features are characteristic of a non-perturbative quantum interference process that involves electrons from multiple valence bands. These results identify key mechanisms for future solid-state attosecond sources and next-generation light-wave electronics. The new quantum interference process justifies the hope for all-optical band-structure reconstruction and lays the foundation for possible quantum logic operations at optical clock rates.

  19. Noncollinear third-harmonic generation with large angular acceptance by noncritical phase matching in KDP crystal.

    PubMed

    Chen, Jing; Zheng, Yuanlin; An, Ning; Chen, Xianfeng

    2015-10-01

    The scheme of prefocusing to focus sum frequency generation (SFG) without a lens is proposed and experimentally verified in this study. Noncollinear type-I noncritical phase-matching SFG to generate a third-harmonic wave with large angular acceptance is presented. The principle of broad angular acceptance and the advantages of this PM configuration are also described in detail. External angular bandwidth of 7.33° for noncollinear SFG was measured in a 2 mm long KH2PO4 (KDP) crystal, which is in reasonably good agreement with the theoretical calculation. The mechanism of broadband SFG and the prefocusing scheme make it possible for the realization of convergent third-harmonic generation without involving a lens, which provides a promising way to avoid damage to optical components during the focusing of high-energy UV light in high-power laser facilities. PMID:26421562

  20. Nuclear motion effects on the density matrix of crystals: An ab initio Monte Carlo harmonic approach

    NASA Astrophysics Data System (ADS)

    Pisani, Cesare; Erba, Alessandro; Ferrabone, Matteo; Dovesi, Roberto

    2012-07-01

    In the frame of the Born-Oppenheimer approximation, nuclear motions in crystals can be simulated rather accurately using a harmonic model. In turn, the electronic first-order density matrix (DM) can be expressed as the statistically weighted average over all its determinations each resulting from an instantaneous nuclear configuration. This model has been implemented in a computational scheme which adopts an ab initio one-electron (Hartree-Fock or Kohn-Sham) Hamiltonian in the CRYSTAL program. After selecting a supercell of reasonable size and solving the corresponding vibrational problem in the harmonic approximation, a Metropolis algorithm is adopted for generating a sample of nuclear configurations which reflects their probability distribution at a given temperature. For each configuration in the sample the "instantaneous" DM is calculated, and its contribution to the observables of interest is extracted. Translational and point symmetry of the crystal as reflected in its average DM are fully exploited. The influence of zero-point and thermal motion of nuclei on such important first-order observables as x-ray structure factors and Compton profiles can thus be estimated.

  1. Efficient second-harmonic generation of a broadband radiation by control of the temperature distribution along a nonlinear crystal.

    PubMed

    Regelskis, K; Želudevi?ius, J; Gavrilin, N; Ra?iukaitis, G

    2012-12-17

    We demonstrate an efficient technique for the second harmonic generation (SHG) of the broadband radiation based on the temperature gradient along a nonlinear crystal. The characteristics of Type I non-critical phase-matched SHG of broadband radiation in the LiB(3)O(5) (LBO) crystal with the temperature gradient imposed along the crystal were investigated both numerically and experimentally. The frequency doubling efficiency of the broadband pulsed fiber laser radiation as high as 68% has been demonstrated. PMID:23263092

  2. A comparative study of second harmonic generation of pulsed CO 2 laser radiation in some infrared crystals

    NASA Astrophysics Data System (ADS)

    Das, S.; Ghosh, C.; Gangopadhyay, S.

    2007-07-01

    A comparative study of second harmonic generation of CO2 laser radiation in different infrared transmitting crystals like HgGa2S4, AgGaxIn(1-x)Se2, sulphur and indium doped GaSe and ZnGeP2 is reported. It is also shown that sulphur doped GaSe crystal is more efficient than ZnGeP2 crystal in terms of effective figure of merit.

  3. Calculation of optical second-harmonic susceptibilities and optical activity for crystals

    SciTech Connect

    Levine, Z.H.

    1994-12-31

    A new generation of nearly first-principles calculations predicts both the linear and second-harmonic susceptibilities for a variety of insulating crystals, including GaAs, GaP, AlAs, AlP, Se, {alpha}-quartz, and c-urea. The results are typically in agreement with experimental measurements. The calculations have been extended to optical activity, with somewhat less success to date. The theory, based on a simple self-energy correction to the local density approximation, and results are reviewed herein.

  4. Harmonic Crystals in the Half-Space, I. Convergence to Equilibrium

    E-print Network

    T. V. Dudnikova

    2009-05-21

    We consider the dynamics of a harmonic crystal in the half-space with zero boundary condition. It is assumed that the initial date is a random function with zero mean, finite mean energy density which also satisfies a mixing condition of Rosenblatt or Ibragimov type. We study the distribution $\\mu_t$ of the solution at time $t\\in\\R$. The main result is the convergence of $\\mu_t$ to a Gaussian measure as $t\\to\\infty$ which is time stationary with a covariance inherited from the initial (in general, non-Gaussian) measure.

  5. Analysis of Second Harmonic Generation of a KDP crystal based on multi-scale topography simulation

    NASA Astrophysics Data System (ADS)

    Liu, Hai Tao; Su, Rui Feng; Sun, Ya Zhou; Wang, He Ran

    2015-04-01

    The surface topography of the supporting frame of a KDP crystal is studied, as well as its influence on the deformation and stress of the KDP crystal, together with the Second Harmonic Generation (SHG). A comprehensive model incorporating principles of multi-scale surface analysis, mechanics, and optics is proposed, and it is applied to investigate the surface topography of the supporting frame, the deformation and stress of the KDP crystal, as well as the SHG efficiency. The surface topography is analyzed using fractural theory, and then classified according to its multi-scale specifics. Based on the surface analysis results, the mounting configuration of the KDP crystal is modeled and analyzed in global and local modes, respectively, using the Finite Element Method (FEM). Moreover, deformation and stress of the KDP crystal that is induced by the mechanical mounting is studied using the FEM, together with the effects of the surface topography on them. Furthermore, the change of the refractive index that induced by the deformation and stress are calculated, respectively, the results of which is applied to studied the phase mismatch, and the SHG efficiency considering the phase mismatch is eventually obtained. The numerical results demonstrate that the frame surface with multi-scale dimensions has diverse influences on the distortion and stress, as well as the SHG efficiency.

  6. Multi-direction high-efficiency second harmonic generation in ellipse structure nonlinear photonic crystals

    SciTech Connect

    Chen, Bao-Qin; Zhang, Chao; Liu, Rong-Juan; Li, Zhi-Yuan

    2014-10-13

    We have designed and fabricated a lithium niobate (LN) nonlinear photonic crystal (NPC) with a two-dimensional (2D) ellipse structure of inverse poling domains. The structure can offer continuously varying reciprocal lattice vectors in different directions to compensate the phase-mismatching during the second harmonic generation (SHG) for diverse pump wavelengths. We consider three propagation directions with large effective nonlinear susceptibility and measure the nonlinear conversion efficiency of SHG. The experimental data are in good agreement with the quantitative calculation results using the effective susceptibility model with pump depletion. With high-efficiency SHG in multiple propagation direction, the 2D ellipse structure of LN NPC has the potential to realize various broadband nonlinear frequency conversion processes in different propagation direction with a single crystal.

  7. Laser-Induced Damage in DKDP Crystals under Simultaneous Exposure to Laser Harmonics

    SciTech Connect

    Negres, R A; DeMange, P; Radousky, H B; Demos, S G

    2005-10-28

    While KDP and DKDP crystals remain the only viable solution for frequency conversion in large aperture laser systems in the foreseeable future, our understanding of damage behavior in the presence of multiple colors is very limited. Such conditions exist during normal operation where, for third harmonic generation, 1{omega}, 2{omega} and 3{omega} components are present with different energy ratios as they propagate inside the crystal. The objective of this work is to shed light into the damage behavior of frequency conversion crystals during operational conditions as well as probe the fundamental mechanisms of damage initiation. We have performed a series of experiments to quantify the damage performance of pristine (unconditioned) DKDP material under simultaneous exposure to 2{omega} and 3{omega} laser pulses from a 3-ns Nd:YAG laser system as a function of the laser influences at each frequency. Results show that simultaneous dual wavelength exposure leads to a much larger damage density as compared to the total damage resulting from separate exposure at each wavelength. Furthermore, under such excitation conditions, the damage performance is directly related to and can be predicted from the damage behavior of the crystal at each wavelength separately while the mechanism and type of defects responsible for damage initiation are shown to be the same at both 2{omega} and 3{omega} excitation.

  8. XTL Converter

    SciTech Connect

    2015-10-07

    "XTL Converter" is a short Python script for electron microscopy simulation. The program takes an input crystal file in the VESTA *.XTL format and converts it to a text format readable by the multislice simulation program ìSTEM. The process of converting a crystal *.XTL file to the format used by the ìSTEM simulation program is quite tedious? it generally requires the user to select dozens or hundreds of atoms, rearranging and reformatting their position. Header information must also be reformatted to a specific style to be read by ìSTEM. "XTL Converter" simplifies this process, saving the user time and allowing for easy batch processing of crystals.

  9. Vibrational spectra and chemical quantum calculations for 2-adamantylamino-5-nitropyridine crystals--a novel material for laser Raman converters.

    PubMed

    Lorenc, J; Hanuza, Jerzy; Maczka, Miros?aw; Kucharska, Edyta; Kaminskii, Alexander A; Kaino, Toshikuni; Yaima, Tetsuya; Yokoo, Atsushi

    2005-02-01

    Polycrystalline infrared and polarized FT-Raman spectra have been measured for 2-adamantylamino-5-nitropyridine, a novel organic material for laser Raman converters. The assignment of IR and Raman bands is given on the basis of DFT calculations. The spectroscopic studies have not indicated the presence of any significant intermolecular interactions in the crystal structure of this compound. The lines observed in the stimulated Raman spectrum of this crystal are assigned to the respective molecular vibrations. PMID:15649801

  10. The origin of inhibition of high power second harmonic generation in periodically poled lithium niobate crystal

    NASA Astrophysics Data System (ADS)

    Li, Guohui; Wang, Jing; Cui, Yanxia

    2015-10-01

    This paper investigates the origin of the inhibition of the second harmonic generation (SHG) in a periodically poled lithium niobate (PPLN) crystal by using coupled-mode equations in which both absorption and photorefractive properties of the crystal were taken into account. SHG, using fundamental laser beams with radii of 150, 33, and 25 ?m, respectively, were calculated. The calculated results showed that the changes of refractive index difference resulting from the photorefractive effect were ?300 times smaller than that from absorption-induced heating in SHG using a fundamental laser beam with a radius of 150 ?m. However, in SHG using a fundamental laser beam with a radius smaller than 33 ?m, the changes of refractive index difference resulting from the photorefractive effect were comparable to those resulting from absorption-induced heating. It revealed that the photorefractive effect is one of the main factors that inhibits the SHG using a fundamental laser beam with a radius smaller than 33 ?m at high pump powers.

  11. Multifrequency third-harmonic generation by red-shifting solitons in a multimode photonic-crystal fiber.

    PubMed

    Fedotov, A B; Voronin, A A; Serebryannikov, E E; Fedotov, I V; Mitrofanov, A V; Ivanov, A A; Sidorov-Biryukov, D A; Zheltikov, A M

    2007-01-01

    While the standard scenario of third-harmonic generation (THG) by a dispersive-wave pump involves the emission of light with a frequency 3omega, thrice the frequency omega of the input pump field, solitons undergoing a continuous shift of their central frequency omega due to the Raman effect in a multimode optical fiber can generate the third harmonic in a different fashion. In the experiments reported here, we provide the first direct experimental evidence of THG by a continuously red-shifting soliton pump by studying the third-harmonic buildup in relation to the spectral evolution of the soliton pump field in a silica photonic-crystal fiber (PCF). We show that solitons excited in a PCF by unamplified femtosecond pulses of a Cr:forsterite laser sweep through the spectral range from 1.25 to 1.63 microm , scanning through a manifold of THG phase-matching resonances with 3omega dispersive waves in PCF modes. As a result, intense third-harmonic peaks build up in the range of wavelengths from 370 to 550 nm at the output of the fiber, making PCF a convenient fiber-format multifrequency source of short-wavelength radiation. Time-resolved fluorescence measurements with photoexcitation provided by the third-harmonic PCF output are presented, demonstrating the high potential of PCF sources for an ultrafast photoexcitation of fluorescent molecular systems in physics, chemistry, and biology. PMID:17358282

  12. Optically switchable second harmonic generation in a liquid crystal thin film within femtoliter volume

    NASA Astrophysics Data System (ADS)

    Chen, Kuan-Chieh; Zhuo, Guan-Yu; Chu, Shi-Wei

    2013-03-01

    Nematic liquid crystal (NLC) is one of most useful soft matters. Because the molecular orientation can be controlled electrically, NLC is widely applied to display devices. It is known that NLC exhibits strong second-harmonic-generation (SHG) due to its orderly arranged molecules. The strength of SHG is strongly dependent on the angle between the incident beam polarization and the NLC molecular orientation, so the SHG in NLC can be switched on/off by rotating the NLC director. However, it is very difficult to control the orientation of NLC director electrically within a micrometer spatial domain. In this report, we demonstrated the orientation control of NLC with sub-micrometer spatial resolution based on optical Freedericksz transition (OFT) combined with a high-numerical-aperture objective. We used azo-dye doped NLC to reduce the intensity threshold of OFT with 473-nm excitation. Interestingly, we found that the threshold of OFT increases with tighter focuses. This effect can be explained by the intermolecular forces from the NLC molecules around the focal spot. By incorporating both the blue laser and a femtosecond near-infrared laser into an optical scanning microscope, we have successfully demonstrated switch of SHG inside a NLC thin film. Note that SHG is confined within femtoliter focal volume due to its intrinsic nonlinearity. That is, we have achieved an ultrasmall switch of nonlinear optical signal in NLC. This work will find applications in optical communication as well as optical-base storage system.

  13. XTL Converter

    Energy Science and Technology Software Center (ESTSC)

    2015-10-07

    "XTL Converter" is a short Python script for electron microscopy simulation. The program takes an input crystal file in the VESTA *.XTL format and converts it to a text format readable by the multislice simulation program ìSTEM. The process of converting a crystal *.XTL file to the format used by the ìSTEM simulation program is quite tedious? it generally requires the user to select dozens or hundreds of atoms, rearranging and reformatting their position. Headermore »information must also be reformatted to a specific style to be read by ìSTEM. "XTL Converter" simplifies this process, saving the user time and allowing for easy batch processing of crystals.« less

  14. High-Efficiency Broadband High-Harmonic Generation from a Single Quasi-Phase-Matching Nonlinear Crystal.

    PubMed

    Chen, Bao-Qin; Zhang, Chao; Hu, Chen-Yang; Liu, Rong-Juan; Li, Zhi-Yuan

    2015-08-21

    Nonlinear frequency conversion offers an effective way to expand the laser wavelength range based on birefringence phase matching (BPM) or quasi-phase-matching (QPM) techniques in nonlinear crystals. So far, efficient high-harmonic generation is enabled only via multiple cascaded crystals because of the extreme difficulty to simultaneously satisfy BPM or QPM for multiple nonlinear up-conversion processes within a single crystal. Here we report the design and fabrication of a chirped periodic poled lithium niobate (CPPLN) nonlinear crystal that offers controllable multiple QPM bands to support 2nd-8th harmonic generation (HG) simultaneously. Upon illumination of a mid-IR femtosecond pulse laser, we observe the generation of an ultrabroadband visible white light beam corresponding to 5th-8th HG with a record high conversion efficiency of 18%, which is high compared to conventional supercontinuum generation, especially in the HG parts. Our CPPLN scheme opens up a new avenue to explore and engineer novel nonlinear optical interactions in solid state materials for application in ultrafast lasers and broadband laser sources. PMID:26340190

  15. High-Efficiency Broadband High-Harmonic Generation from a Single Quasi-Phase-Matching Nonlinear Crystal

    NASA Astrophysics Data System (ADS)

    Chen, Bao-Qin; Zhang, Chao; Hu, Chen-Yang; Liu, Rong-Juan; Li, Zhi-Yuan

    2015-08-01

    Nonlinear frequency conversion offers an effective way to expand the laser wavelength range based on birefringence phase matching (BPM) or quasi-phase-matching (QPM) techniques in nonlinear crystals. So far, efficient high-harmonic generation is enabled only via multiple cascaded crystals because of the extreme difficulty to simultaneously satisfy BPM or QPM for multiple nonlinear up-conversion processes within a single crystal. Here we report the design and fabrication of a chirped periodic poled lithium niobate (CPPLN) nonlinear crystal that offers controllable multiple QPM bands to support 2nd-8th harmonic generation (HG) simultaneously. Upon illumination of a mid-IR femtosecond pulse laser, we observe the generation of an ultrabroadband visible white light beam corresponding to 5th-8th HG with a record high conversion efficiency of 18%, which is high compared to conventional supercontinuum generation, especially in the HG parts. Our CPPLN scheme opens up a new avenue to explore and engineer novel nonlinear optical interactions in solid state materials for application in ultrafast lasers and broadband laser sources.

  16. High harmonic generation in a gas-filled hollow-core photonic crystal fiber

    NASA Astrophysics Data System (ADS)

    Heckl, O. H.; Baer, C. R. E.; Kränkel, C.; Marchese, S. V.; Schapper, F.; Holler, M.; Südmeyer, T.; Robinson, J. S.; Tisch, J. W. G.; Couny, F.; Light, P.; Benabid, F.; Keller, U.

    2009-10-01

    High harmonic generation (HHG) of intense infrared laser radiation (Ferray et al., J. Phys. B: At. Mol. Opt. Phys. 21:L31, 1988; McPherson et al., J. Opt. Soc. Am. B 4:595, 1987) enables coherent vacuum-UV (VUV) to soft-X-ray sources. In the usual setup, energetic femtosecond laser pulses are strongly focused into a gas jet, restricting the interaction length to the Rayleigh range of the focus. The average photon flux is limited by the low conversion efficiency and the low average power of the complex laser amplifier systems (Keller, Nature 424:831, 2003; Südmeyer et al., Nat. Photonics 2:599, 2008; Röser et al., Opt. Lett. 30:2754, 2005; Eidam et al., IEEE J. Sel. Top. Quantum Electron. 15:187, 2009) which typically operate at kilohertz repetition rates. This represents a severe limitation for many experiments using the harmonic radiation in fields such as metrology or high-resolution imaging. Driving HHG with novel high-power diode-pumped multi-megahertz laser systems has the potential to significantly increase the average photon flux. However, the higher average power comes at the expense of lower pulse energies because the repetition rate is increased by more than a thousand times, and efficient HHG is not possible in the usual geometry. So far, two promising techniques for HHG at lower pulse energies were developed: external build-up cavities (Gohle et al., Nature 436:234, 2005; Jones et al., Phys. Rev. Lett. 94:193, 2005) and resonant field enhancement in nanostructured targets (Kim et al., Nature 453:757, 2008). Here we present a third technique, which has advantages in terms of ease of HHG light extraction, transverse beam quality, and the possibility to substantially increase conversion efficiency by phase-matching (Paul et al., Nature 421:51, 2003; Ren et al., Opt. Express 16:17052, 2008; Serebryannikov et al., Phys. Rev. E (Stat. Nonlinear Soft Matter Phys.) 70:66611, 2004; Serebryannikov et al., Opt. Lett. 33:977, 2008; Zhang et al., Nat. Phys. 3:270, 2007). The interaction between the laser pulses and the gas occurs in a Kagome-type Hollow-Core Photonic Crystal Fiber (HC-PCF) (Benabid et al., Science 298:399, 2002), which reduces the detection threshold for HHG to only 200 nJ. This novel type of fiber guides nearly all of the light in the hollow core (Couny et al., Science 318:1118, 2007), preventing damage even at intensities required for HHG. Our fiber guided 30-fs pulses with a pulse energy of more than 10 ?J, which is more than five times higher than for any other photonic crystal fiber (Hensley et al., Conference on Lasers and Electro-Optics (CLEO), IEEE Press, New York, 2008).

  17. Ultra-compact broadband mode converter and optical diode based on linear rod-type photonic crystal waveguide.

    PubMed

    Ye, Han; Wang, Donglin; Yu, Zhongyuan; Zhang, Jinqiannan; Chen, Zhihui

    2015-04-20

    In this paper, we present extremely compact designs of both broadband mode converter and optical diode in linear rod-type photonic crystal (PhC) waveguide with functional region consisting of only 4 × 1 unit cells of perfect PhC. The dielectric distribution inside functional region are optimized by combining geometry projection method and method of moving asymptotes. Bidirectional mode converter realizes above 60% transmission efficiency within bandwidth 0.02c/a, where c and a represent light velocity and PhC lattice constant respectively. Optical diode achieves above 19 dB unidirectionality for even mode within bandwidth 0.01c/a. Moreover, the proposed designs have reasonable tolerance of rod boundary fluctuation. We expect the results will help developing recipes for future PhC devices in all-optical integrated circuits. PMID:25969004

  18. Structure, crystalline perfection, mechanical, second harmonic generation efficiency, laser damage threshold and piezoelectric properties of bis nicotinamidium bis D-tartrate 1.25-hydrate single crystals

    NASA Astrophysics Data System (ADS)

    Senthil Murugan, G.; Ramasamy, P.

    2015-08-01

    Bis nicotinamidium bis D-tartrate 1.25-hydrate single crystals have been grown by slow evaporation solution growth technique. Single crystal X-ray diffraction study indicates that the grown crystal crystallizes in monoclinic system with space group P21. Crystalline perfection of the crystal has been evaluated by high resolution X-ray diffraction technique and it reveals that the crystal is free from structural grain boundaries. Mechanical stability of the crystal has been analyzed by Vickers microhardness measurement and it exhibits reverse indentation size effect. The second harmonic generation efficiency of the grown crystal has been checked and its value is 1.24 times that of potassium dihydrogen phosphate. The surface laser damage threshold for the crystal has been analyzed and its value is 0.644 GW/cm2. Piezoelectric d33 co-efficient for the crystal has been examined and its value is 29.8 pC/N.

  19. Interband Bloch oscillation mechanism for high-harmonic generation in semiconductor crystals

    NASA Astrophysics Data System (ADS)

    McDonald, C. R.; Vampa, G.; Corkum, P. B.; Brabec, T.

    2015-09-01

    High harmonic generation in semiconductors is analyzed for high mid-infrared laser intensities for which the electron-hole pair is driven beyond the first Brillouin zone and exhibits Bloch oscillations. We find that even a two-band analysis exhibits second and higher plateaus. Whereas the first plateau is shown to be consistent with high harmonic generation through electron-hole recollision, the higher plateaus arise from dynamic Bloch oscillations; however, the driving process is interband in nature, in contrast to the generally accepted intraband Bloch oscillation mechanism. Energy conservation is fulfilled, as harmonics beyond the first plateau come from a cascaded nonlinearity.

  20. Growth and characterization of crystals for IR detectors and second harmonic gereration devices

    NASA Astrophysics Data System (ADS)

    Lal, Ravi B.; Batra, Ashok K.; Rao, Sistla M.; Bhatia, S. S.; Chunduru, Kunar P.; Paulson, Ron; Moorkherji, Tripty K.

    Two types of materials, L-arginine phosphate (LAP) and doped triglycine sulfate (TGS), are examined for their growth characteristics and relevant properties for second harmonic generation and IR detector applications, respectively.

  1. Growth and characterization of crystals for IR detectors and second harmonic gereration devices

    NASA Technical Reports Server (NTRS)

    Lal, Ravi B.; Batra, Ashok K.; Rao, Sistla M.; Bhatia, S. S.; Chunduru, Kunar P.; Paulson, Ron; Moorkherji, Tripty K.

    1989-01-01

    Two types of materials, L-arginine phosphate (LAP) and doped triglycine sulfate (TGS), are examined for their growth characteristics and relevant properties for second harmonic generation and IR detector applications, respectively.

  2. Electro-optic harmonic conversion to switch a laser beam out of a cavity

    DOEpatents

    Haas, Roger A. (Pleasanton, CA); Henesian, Mark A. (Livermore, CA)

    1987-01-01

    The invention is a switch to permit a laser beam to escape a laser cavity through the use of an externally applied electric field across a harmonic conversion crystal. Amplification takes place in the laser cavity, and then the laser beam is switched out by the laser light being harmonically converted with dichroic or polarization sensitive elements present to alter the optical path of the harmonically converted laser light. Modulation of the laser beam can also be accomplished by varying the external electric field.

  3. Crystalline perfection, optical and third harmonic generation analyses of non-linear optical single crystal of L-lysine acetate.

    PubMed

    Rani, Neelam; Vijayan, N; Thukral, Kanika; Maurya, K K; Haranath, D; Bhagavannarayana, G; Verma, S; Wahab, M A

    2013-03-15

    The potential organic non-linear optical single crystal of L-lysine acetate has been grown by slow evaporation solution growth technique (SEST) at room temperature. It crystallizes in the monoclinic system with space group of P2(1). The crystalline perfection of the grown single crystal has been examined by high resolution X-ray diffraction analysis (HRXRD). The functional groups of the synthesized compound have been identified by (13)C NMR, (1)H NMR and FTIR analyses. The optical absorption studies show that the crystal is transparent in the entire visible region with a cut-off wavelength of 236 nm. The optical band gap is found to be 5.29 eV. The steady-state PL spectra was recorded for pure L-lysine acetate crystal at room temperature. The third harmonic generation efficiency of the crystal has been evaluated by Z-scan technique and its non-linear optical coefficient has been calculated. Birefringence measurement has been carried out in order to see the optical homogeneity of the grown specimen. Its electrical properties has been assessed by dielectric measurement at different temperatures. The calculated optical band gap is 5.29 eV. Its thermal parameters like thermal diffusivity (?), thermal effusivity (e), thermal conductivity (k) and heat capacity (C(p)) have been determined by photopyroelectric technique. Vickers micro hardness studies were carried out using a Vickers hardness tester equipped with a diamond square indenter. The piezoelectric measurement for L-lysine acetate has been also been carried at ambient condition. PMID:23305871

  4. Crystalline perfection, optical and third harmonic generation analyses of non-linear optical single crystal of L-lysine acetate

    NASA Astrophysics Data System (ADS)

    Rani, Neelam; Vijayan, N.; Thukral, Kanika; Maurya, K. K.; Haranath, D.; Bhagavannarayana, G.; Verma, S.; Wahab, M. A.

    2013-03-01

    The potential organic non-linear optical single crystal of L-lysine acetate has been grown by slow evaporation solution growth technique (SEST) at room temperature. It crystallizes in the monoclinic system with space group of P21. The crystalline perfection of the grown single crystal has been examined by high resolution X-ray diffraction analysis (HRXRD). The functional groups of the synthesized compound have been identified by 13C NMR, 1H NMR and FTIR analyses. The optical absorption studies show that the crystal is transparent in the entire visible region with a cut-off wavelength of 236 nm. The optical band gap is found to be 5.29 eV. The steady-state PL spectra was recorded for pure L-lysine acetate crystal at room temperature. The third harmonic generation efficiency of the crystal has been evaluated by Z-scan technique and its non-linear optical coefficient has been calculated. Birefringence measurement has been carried out in order to see the optical homogeneity of the grown specimen. Its electrical properties has been assessed by dielectric measurement at different temperatures. The calculated optical band gap is 5.29 eV. Its thermal parameters like thermal diffusivity (?), thermal effusivity (e), thermal conductivity (k) and heat capacity (Cp) have been determined by photopyroelectric technique. Vickers micro hardness studies were carried out using a Vickers hardness tester equipped with a diamond square indenter. The piezoelectric measurement for L-lysine acetate has been also been carried at ambient condition.

  5. Repetitively pulsed TEA CO2 laser and its application for second harmonic generation in ZnGeP2 crystal

    NASA Astrophysics Data System (ADS)

    Koval'chuk, L. V.; Grezev, A. N.; Niz'ev, V. G.; Yakunin, V. P.; Mezhevov, V. S.; Goryachkin, D. A.; Sergeev, V. V.; Kalintsev, A. G.

    2015-10-01

    Experimental results are presented on the development of a radiation source emitting at a wavelength of 4.775 ?m with a pulse energy up to 50 mJ and an average power up to several watts in short pulse trains. A TEA CO2 laser and a nonlinear converter based on a ZnGeP2 crystal, which are specially designed for these experiments, are described. The main limitations of nonlinear conversion and possible ways to overcome these limitations are considered.

  6. Characterization of Cholesterol Crystals in Atherosclerotic Plaques Using Stimulated Raman Scattering and Second-Harmonic Generation

    E-print Network

    Potma, Eric Olaf

    Characterization of Cholesterol Crystals in Atherosclerotic Plaques Using Stimulated Raman ABSTRACT Cholesterol crystals (ChCs) have been identified as a major factor of plaque vulnerability cholesterol in its native tissue environment, the physiochemical role of ChCs in atherosclerotic progression

  7. In-plane time-harmonic elastic wave motion and resonance phenomena in a layered phononic crystal with periodic cracks.

    PubMed

    Golub, Mikhail V; Zhang, Chuanzeng

    2015-01-01

    This paper presents an elastodynamic analysis of two-dimensional time-harmonic elastic wave propagation in periodically multilayered elastic composites, which are also frequently referred to as one-dimensional phononic crystals, with a periodic array of strip-like interior or interface cracks. The transfer matrix method and the boundary integral equation method in conjunction with the Bloch-Floquet theorem are applied to compute the elastic wave fields in the layered periodic composites. The effects of the crack size, spacing, and location, as well as the incidence angle and the type of incident elastic waves on the wave propagation characteristics in the composite structure are investigated in details. In particular, the band-gaps, the localization and the resonances of elastic waves are revealed by numerical examples. In order to understand better the wave propagation phenomena in layered phononic crystals with distributed cracks, the energy flow vector of Umov and the corresponding energy streamlines are visualized and analyzed. The numerical results demonstrate that large energy vortices obstruct elastic wave propagation in layered phononic crystals at resonance frequencies. They occur before the cracks reflecting most of the energy transmitted by the incoming wave and disappear when the problem parameters are shifted from the resonant ones. PMID:25618055

  8. Investigation about relationships between the symmetries of ferroelectric crystal Ca0.28Ba0.72Nb2O6 and second-harmonic patterns

    NASA Astrophysics Data System (ADS)

    Xu, Tianxiang; Yu, Haohai; Zhang, Huaijin; Wang, Jiyang

    2015-08-01

    The broadband quasi-phase matching (QPM) process in a uniaxial ferroelectric crystal Ca0.28Ba0.72Nb2O6 (CBN-28) was demonstrated with the second-harmonic wavelength range from 450 nm to 650 nm, and the relationship between the symmetries of CBN-28 and the second-harmonic patterns was experimentally and theoretically investigated based on the random anti-parallel domains in the crystal and QPM conditions. The dependences of frequency-doubled patterns on the wavelength and anisotropy of the nonlinear crystal were also studied, and the frequency-doubled photons were found to be trapped on circles. By analyzing the light-matter interacting Hamiltonians, the trapping force for second-harmonic photons was found to be centripetal and tunable by the fundamental lasers, and the variation tendencies of the rotational velocity of second-harmonic generation photons could also be predicated. The results indicate that the CBN-28 ferroelectric crystal is a promising nonlinear optical material for the generation of broadband frequency-doubled waves, and the analysis on centripetal force based on the interaction Hamiltonians may provide a novel recognition for the investigation of QPM process to be further studied.

  9. Second harmonic generation of femtosecond radiation from a Cr:forsterite laser in a nonlinear-optical crystal at the plasma-formation threshold

    SciTech Connect

    Gordienko, V M; Dyakov, V A; Mikheev, P M; Syrtsov, V S

    2007-11-30

    The second harmonic generation in KDP and LiNbO{sub 3} crystals exposed to tightly focused radiation from a Cr:forsterite laser is studied. The negative influence exerted on this process by a plasma produced due to multiphoton ionisation in the focal region at laser pulse intensities above 10{sup 13} W cm{sup -2} is discussed. (nonlinear optical phenomena)

  10. Enhancement of second harmonic generation in NaNO{sub 2}-infiltrated opal photonic crystal using structural light focusing

    SciTech Connect

    Zaytsev, Kirill I. Yurchenko, Stanislav O.

    2014-08-04

    Experimental and numerical results for second harmonic generation (SHG) in photonic crystal (PC) based on NaNO{sub 2}-infiltrated opal matrix are presented. SHG is performed in reflection mode; thus, the direction of the SHG maximum is equal to the angle of mirror reflection. The PC was pumped with femtosecond optical pulses at different angles of incidence, allowing the dependence of the SHG efficiency on the location of the fundamental wavelength toward the PC band gap (BG) to be examined. The most efficient SHG was observed when pumping the BG of the PC. To interpret the experimental results, finite-difference time-domain numerical simulations of the light interaction with the PC were conducted. The observed effect of highly efficient SHG is associated with structural light focusing, and, as a consequence, with strong optical field localization within certain near-surface PC regions. Thus, SHG enhancement based on structural light focusing in PC was demonstrated.

  11. Simultaneous negative refraction and focusing of fundamental frequency and second-harmonic fields by two-dimensional photonic crystals

    NASA Astrophysics Data System (ADS)

    Zhang, Jun; Zhang, Xiangdong

    2015-09-01

    Simultaneous negative refraction for both the fundamental frequency (FF) and second-harmonic (SH) fields in two-dimensional nonlinear photonic crystals have been found through both the physical analysis and exact numerical simulation. By combining such a property with the phase-matching condition and strong second-order susceptibility, we have designed a SH lens to realize focusing for both the FF and SH fields at the same time. Good-quality non-near field images for both FF and SH fields have been observed. The physical mechanism for such SH focusing phenomena has been disclosed, which is different from the backward SH generation as has been pointed out in the previous investigations. In addition, the effect of absorption losses on the phenomena has also been discussed. Thus, potential applications of these phenomena to biphotonic microscopy technique are anticipated.

  12. Temperature nonuniformity occurring during the cooling process of a KDP crystal and its effects on second-harmonic generation.

    PubMed

    Liang, Yingchun; Su, Ruifeng; Lu, Lihua; Liu, Haitao

    2014-08-10

    The temperature nonuniformity occurring during the cooling process of a KDP crystal is studied, along with its effects on the second-harmonic generation (SHG) of a high-average-power laser. A comprehensive model is proposed incorporating principles of thermodynamics, mechanics, and optics, and it is applied to investigate the temperature nonuniformity and its effects. The temperature rise caused by linear absorption is calculated, while the temperature nonuniformity occurring during the cooling process is analyzed using the finite-element method (FEM). The stress induced by the nonuniformity is then studied using the FEM, and the trend of its change is determined. Moreover, the changes in refractive index caused by the stress are calculated, the results of which are used to determine the variations in the induced phase mismatch. The SHG efficiency considering the phase mismatch is eventually obtained by solving the coupling wave equations. The results demonstrate that the temperature nonuniformity has negative effects on the SHG efficiency. PMID:25320918

  13. Precise, motion-free polarization control in Second Harmonic Generation microscopy using a liquid crystal modulator in the infinity space

    PubMed Central

    Lien, Chi-Hsiang; Tilbury, Karissa; Chen, Shean-Jen; Campagnola, Paul J.

    2013-01-01

    Second Harmonic Generation (SHG) microscopy coupled with polarization analysis has great potential for use in tissue characterization, as molecular and supramolecular structural details can be extracted. Such measurements are difficult to perform quickly and accurately. Here we present a new method that uses a liquid crystal modulator (LCM) located in the infinity space of a SHG laser scanning microscope that allows the generation of any desired linear or circular polarization state. As the device contains no moving parts, polarization can be rotated accurately and faster than by manual or motorized control. The performance in terms of polarization purity was validated using Stokes vector polarimetry, and found to have minimal residual polarization ellipticity. SHG polarization imaging characteristics were validated against well-characterized specimens having cylindrical and/or linear symmetries. The LCM has a small footprint and can be implemented easily in any standard microscope and is cost effective relative to other technologies. PMID:24156059

  14. Annealed proton-exchanged waveguide quasi-phase-matched second-harmonic generation devices in 8 mol % MgO-doped congruent LiTaO3 crystal

    NASA Astrophysics Data System (ADS)

    Oka, Toshiharu; Suhara, Toshiaki

    2015-10-01

    Heavily (8 mol %) MgO-doped congruent LiTaO3 (MgO:cLT) crystal has wider transparency range and higher photorefractive damage resistance than LiNbO3 or non-doped LiTaO3 crystal. We examined the possibility of forming annealed proton-exchanged (APE) waveguides with various conditions. We obtained good quality APE waveguides with the propagation loss 0.7 dB/cm for 1.064 µm wavelength and demonstrated a prototype waveguide quasi-phase-matched second-harmonic generation device of 56%/W normalized efficiency for the first time in MgO:cLT crystal.

  15. Resonant ensembles of stationary quasi-harmonic waves in one-dimensional crystals

    NASA Astrophysics Data System (ADS)

    Kovriguine, D. A.; Nikitenkova, S. P.

    2015-09-01

    Using a simple mathematical model, built on geometric representations of central and noncentral interactions between material particles in a one-dimensional anharmonic chain, nonlinear resonant interactions between quasi-harmonic waves are investigated in the so-called harmonic approximation. The investigation is carried out with standard asymptotic nonlinear dynamics methods. In the first-order approximation, resonant wave triads are established that are formed at a characteristic quadratic nonlinearity of the system provided that the phase-matching conditions are satisfied. It is demonstrated that the resonant triads can be of only three different types and each resonant triad can consist of only one longitudinal and two transverse oscillation modes. In the general case, a nontrivial interaction between different resonant triplets of three different types and spectral scales is implemented in a chain. Cascade processes of the energy exchange between oscillation modes are characterized by both the complicated dynamics typical of Hamiltonian nonintegrable dynamic systems and the presence of Lyapunov-stable multiwave steady-state motions. In ideal crystalline structures, such steady-state coherent wave ensembles can significantly affect the specific heat and other phenomenological parameters of a system, especially at low temperatures. Therefore, the theoretical and experimental study of these ensembles is of great importance.

  16. Crystallization and second harmonic generation in potassium-sodium niobiosilicate glasses

    SciTech Connect

    Aronne, Antonio; Fanelli, Esther; Pernice, Pasquale; Peli, Simone; Giannetti, Claudio; Ferrini, Gabriele

    2009-10-15

    Transparent glasses having molar composition (23-x)K{sub 2}O.xNa{sub 2}O.27Nb{sub 2}O{sub 5}.50SiO{sub 2} (x=0, 5, 10, 15 and 23) have been synthesized by the melt-quenching technique and their devitrification behaviour has been investigated by DTA and XRD. Depending on the composition, the glasses showed a glass transition temperature in the range 660-680 deg. C and devitrified in several steps. XRD measurements showed that the replacement of K{sub 2}O by Na{sub 2}O strongly affects the crystallization behaviour. Particularly, in the glasses with only potassium or low sodium content the first devitrification step is related to the crystallization of an unidentified phase, while in the glass containing only sodium, NaNbO{sub 3} crystallizes. For an intermediate sodium content (x=10 and 15) a potassium sodium niobate crystalline phase, belonging to the tungsten-bronze family, is formed by bulk nucleation. This system looks promising to produce active nanostructured glasses as the tungsten-bronze type crystals have ferroelectric, electro-optical and non-linear optical properties. Preliminary measurements evidenced SHG activity in the crystallized glasses containing this phase. - Graphical abstract: Synthesis of glasses (23-x)K{sub 2}O.xNa{sub 2}O.27Nb{sub 2}O{sub 5}.50SiO{sub 2} (x=0, 5, 10, 15 and 23) from which SHG active phases crystallize by bulk nucleation for non-linear optical nanostructured glasses.

  17. Non-equilibrium stationary state of a harmonic crystal with alternating masses

    E-print Network

    Venkateshan Kannan; Abhishek Dhar; J. L. Lebowitz

    2012-02-22

    We analyze the non-equilibrium steady states (NESS) of a one dimensional harmonic chain of $N$ atoms with alternating masses connected to heat reservoirs at unequal temperatures. We find that the temperature profile defined through the local kinetic energy $T(j) \\equiv {}/{m_j}$, oscillates with period two in the bulk of the system. Depending on boundary conditions, either the heavier or the lighter particles in the bulk are hotter. We obtain exact expressions for the bulk temperature profile and steady state current in the limit $N \\rightarrow \\infty$. These depend on whether $N$ is odd or even. We also study similar temperature oscillations in the NESS of systems with noise in the dynamics. These die out as $N \\rightarrow \\infty$.

  18. Second harmonic generation of spectrally broadened femtosecond ytterbium laser radiation in a gas-filled capillary

    SciTech Connect

    Didenko, N V; Konyashchenko, Aleksandr V; Kostryukov, P V; Losev, Leonid L; Tenyakov, S Yu

    2011-09-30

    A 300-fs radiation pulse of an ytterbium laser with a wavelength of 1030 nm and energy of 150 {mu}J were converted to a 15-fs pulse with a wavelength of 515 nm by broadening the emission spectrum in a capillary filled with xenon and by generating the second harmonic in a KDP crystal. The energy efficiency of the conversion was 30 %.

  19. Harmonic strain-optical response revealed in the isotropic (liquid) phase of liquid crystals

    NASA Astrophysics Data System (ADS)

    Kahl, P.; Baroni, P.; Noirez, L.

    2015-08-01

    A strong optical birefringence is observed when applying a small amplitude oscillatory strain to the liquid phase of a liquid crystal. This unpredicted birefringence is found to oscillate at the same frequency as the driving frequency, with frequencies down to 0.01 Hz. This birefringence is visible up to 15 °C above the liquid crystal transition. This opto-dynamic property is interpreted as a result of a coupling of the orientational pretransitional fluctuations existing in the isotropic phase and long range elastic interactions recently identified in liquids. The conversion of the mechanical wave in an optical response is shapeable. Two examples of synchronized periodic signals are shown: the sine and the square waves. The optimization of the signal is analyzed using a Heaviside-step shear test. This optical property is immediately exploitable to design low energy on/off switching materials.

  20. Second Harmonic Generation of Self-Mode-Locked ??2-Laser Radiation in GaSe and GaSeS Crystals

    NASA Astrophysics Data System (ADS)

    Genin, D. E.; Beloplotov, D. V.; Sitnikov, A. G.; Panchenko, A. N.; Sarkisov, S. Yu.; Chernyshov, A. I.

    2014-03-01

    A TEA CO2 laser generating at the wavelength ? = 10.6 ?m in the modes of free lasing and self-mode-locking was used to obtain and compare second harmonic generation (SHG) in GaSe and GaSe0.7S0.3 crystals. With the self-mode-locked laser, a 5-times higher energy efficiency of SHG was obtained. The efficiency of SHG in the GaSe0.7S0.3 crystal and its second-order nonlinear susceptibility were estimated and compared with their values for undoped GaSe.

  1. Acoustically induced optical second harmonic generation in Pb4.7Ba0.3Ge3O11 crystals

    NASA Astrophysics Data System (ADS)

    Kityk, I. V.; Zmija, J.; Majchrowski, A.; Ebothe, J.

    2003-01-01

    Acoustically induced optical second harmonic generation (AIOSHG) in ferroelectric Pb4.7Ba0.3Ge3O11 (PBG) crystal has been observed. With increasing acoustical power, the AIOSHG for Nd doped yttrium-aluminum garnet laser light (?=1.06 ?m) increases and achieves its maximum value at acoustical power density of about 1.75 W/cm2. The values of the AIOSHG for the PGB are considerably higher than for other photorefractive ferroelectrics. With decreasing temperature, the AIOSHG signal strongly increases below 29 K and correlates well with a ferroelectric phase transition detected by the differential scanning calorimetric method and spontaneous polarization measurements. The AIOSHG maxima were observed at acoustical frequencies lying within the ranges 12-17, 22 to 23, and above 26 kHz. Comparing the obtained results with the acoustically induced Raman spectra at different temperatures one can conclude that the effect is caused prevailingly by acoustically induced electron-phonon anharmonicity, which is larger in the vicinity of the ferroelectric phase transition.

  2. Optical breakdown threshold in nanosecond high repetition second harmonic generation by periodically poled Mg-doped LiTaO{sub 3} crystal

    SciTech Connect

    Louchev, Oleg A.; Wada, Satoshi; Hatano, Hideki; Kitamura, Kenji

    2013-08-26

    Our study shows that a local temperature increase of ?1 K in the crystal lattice caused by second harmonic generation (SHG) and two-photon absorption of 532 nm radiation at the rear of periodically poled stoichiometric LiTaO{sub 3} crystal by changing spontaneous polarization induces a pyroelectric field ?10 kV/cm, accelerating free electrons to an energy of ?10 eV, followed by optical breakdown and crystal damage. Theoretical analysis leads to an explicit expression for the threshold laser fluence of optical breakdown giving ?1.2 J/cm{sup 2} for 1064 nm input radiation in 6.8 kHz pulsed SHG operation, agreeing well with the experimentally found value ?1.32 J/cm{sup 2}.

  3. crystal

    NASA Astrophysics Data System (ADS)

    Bai, Fen; Wang, Qingpu; Tao, Xutang; Li, Ping; Zhang, Xingyu; Liu, Zhaojun; Shen, Hongbin; Lan, Weixia; Gao, Liang; Gao, Zeliang; Zhang, Junjie; Fang, Jiaxiong

    2014-08-01

    An eye-safe Raman laser is realized with BaTeMo2O9 (BTM) nonlinear crystal for the first time. By using a diode-end-pumped acousto-optically Q-switched Nd:YVO4 laser as the pumping source, the BTM crystal converts the fundamental laser at 1,342 nm to first-Stokes laser at 1,531 nm successfully. With an incident power of 10.8 W and a pulse repetition rate of 25 kHz, the average output power at 1,531 nm is obtained to be 0.83 W, corresponding to a diode-to-Stokes conversion efficiency of 7.7 %. The pulse width is 11 ns, and the peak power is 3.0 kW.

  4. Quaternionic Harmonic Analysis of Texture

    Energy Science and Technology Software Center (ESTSC)

    2012-10-01

    QHAT uses various functions and data structures native to MATLAB to analyze crystallographic texture information using harmonic functions on the space of rotations represented as normalized quaternions. These harmonic functions generalize the spherical harmonics in three dimensions, and form the basis for the irreducible representations of the four-dimensional rotation group. This allows the basis of harmonic functions to be reduced to linearly independent combinations that satisfy the crystal and sample symmetry point groups.

  5. On how differently the quasi-harmonic approximation works for two isostructural crystals: Thermal properties of periclase and lime

    NASA Astrophysics Data System (ADS)

    Erba, A.; Shahrokhi, M.; Moradian, R.; Dovesi, R.

    2015-01-01

    Harmonic and quasi-harmonic thermal properties of two isostructural simple oxides (periclase, MgO, and lime, CaO) are computed with ab initio periodic simulations based on the density-functional-theory (DFT). The more polarizable character of calcium with respect to magnesium cations is found to dramatically affect the validity domain of the quasi-harmonic approximation that, for thermal structural properties (such as temperature dependence of volume, V(T), bulk modulus, K(T), and thermal expansion coefficient, ?(T)), reduces from [0 K-1000 K] for MgO to just [0 K-100 K] for CaO. On the contrary, thermodynamic properties (such as entropy, S(T), and constant-volume specific heat, CV(T)) are described reliably at least up to 2000 K and quasi-harmonic constant-pressure specific heat, CP(T), up to about 1000 K in both cases. The effect of the adopted approximation to the exchange-correlation functional of the DFT is here explicitly investigated by considering five different expressions of three different classes (local-density approximation, generalized-gradient approximation, and hybrids). Computed harmonic thermodynamic properties are found to be almost independent of the adopted functional, whereas quasi-harmonic structural properties are more affected by the choice of the functional, with differences that increase as the system becomes softer.

  6. Remarkable enhancement in crystalline perfection, second harmonic generation efficiency, optical transparency, and laser damage threshold in potassium dihydrogen phosphate crystals by L-threonine doping

    SciTech Connect

    Kushwaha, S. K.; Maurya, K. K.; Bhagavannarayana, G.; Shakir, Mohd.; Shah, A. L.; Wahab, M. A.

    2010-08-15

    Effect of L-threonine (LT) doping on crystalline perfection, second harmonic generation (SHG) efficiency, optical transparency, and laser damage threshold (LDT) in potassium dihydrogen phosphate (KDP) crystals grown by slow evaporation solution technique (SEST) has been investigated. The influence of doping on growth rate and morphology of the grown crystals has also been studied. Powder x-ray diffraction data confirms the crystal structure of KDP and shows a systematic variation in intensity of diffraction peaks in correlation with morphology due to varying LT concentration. No extra phase formation was observed which is further confirmed by Fourier transform Raman (FT-Raman) studies. High-resolution x-ray diffraction curves indicate that crystalline perfection has been improved to a great extent at low concentrations with a maximum perfection at 1 mol % doping. At higher concentrations (5 to 10 mol %), it is slightly reduced due to excess incorporation of dopants at the interstitial sites of the crystalline matrix. LDT has been increased considerably with increase in doping concentration, whereas SHG efficiency was found to be maximum at 1 mol % in correlation with crystalline. The optical transparency for doped crystals has been increased as compared to that of pure KDP with a maximum value at 1 mol % doping.

  7. Growth and characterization of crystals for room temperature I.R. detectors and second harmonic generation devices

    NASA Technical Reports Server (NTRS)

    Lal, R. B.

    1995-01-01

    One of the major objectives of this program was to modify the triglycine sulfate (TGS) crystals with suitable dopants and variants to achieve better pyroelectric properties and improved infrared detectivities (D(sup *)), and higher Curie transition temperature compared to undoped TGS crystals. Towards these objectives, many promising dopants, both inorganic and organic, were investigated in the last few years. These dopants gave significant improvement in the D(sup *) value of the infrared detectors fabricated from the grown crystals with no significant increase in the Curie temperature (49 C). The IR detectors were fabricated at EDO/Barnes Engineering Division, Shelton, CT. In the last one year many TGS crystals doped with urea were grown using the low temperature solution crystal growth facility. It is found that doping with urea, the normalized growth yield increased significantly compared to pure TGS crystals and there is an improvement in the pyroelectric and dielectric constant values of doped crystals. This gave a significant increase in the materials figure of merits. The Vicker's hardness of 10 wt percent urea doped crystals is found to be about three times higher in the (010) direction compared to undoped crystals. This report describes in detail the results of urea doped TGS crystals.

  8. Optical harmonic generator

    DOEpatents

    Summers, M.A.; Eimerl, D.; Boyd, R.D.

    1982-06-10

    A pair of uniaxial birefringent crystal elements are fixed together to form a serially arranged, integral assembly which, alternatively, provides either a linearly or elliptically polarized second-harmonic output wave or a linearly polarized third-harmonic output wave. The extraordinary or e directions of the crystal elements are oriented in the integral assembly to be in quadrature (90/sup 0/). For a second-harmonic generation in the Type-II-Type-II angle tuned case, the input fundamental wave has equal amplitude o and e components. For a third-harmonic generation, the input fundamental wave has o and e components whose amplitudes are in a ratio of 2:1 (o:e reference first crystal). In the typical case of a linearly polarized input fundamental wave this can be accomplished by simply rotating the crystal assembly about the input beam direction by 10/sup 0/. For both second and third harmonic generation input precise phase-matching is achieved by tilting the crystal assembly about its two sensitive axeses (o).

  9. Nonlinear single-crystal fibers of undoped or Nd 3+-doped niobates: growth by LHPG, spectroscopy and second harmonic generation

    NASA Astrophysics Data System (ADS)

    Foulon, Gisèle; Ferriol, Michel; Brenier, Alain; Cohen-Adad, Marie-Thérèse; Boudeulle, Micheline; Boulon, Georges

    1997-07-01

    The renewal of second order non-linear crystals is very strong in laser materials optics. We are involved in the search of new systems based upon the highly non-linear niobate crystal family. Among these crystals, Ba 2NaNb 5O 15 (BNN) and K 3Li 2- xNb 5+ xO 15+2 x (KLN, 0.15 < x < 0.5) with a tungsten bronze-type structure are very efficient materials for the obtention of, respectively, green and blue laser light by frequency doubling or by self-frequency doubling after doping by Nd 3+ ions. Unfortunately, BNN and KLN are difficult to grow by conventional techniques such as Czochralski without cracks caused by a strong lattice change occurring during cooling of the crystals. In addition, microtwins in BNN crystals and compositional inhomogeneities in KLN ones are often encountered. The obtention of good quality and crackless BNN and KLN single crystals doped with different amounts of Nd 2O 3 is reported. The crystals were grown by the laser heated pedestal growth (LHPG) technique. This method allowed to obtain good quality and homogeneous crystals of BNN and KLN overcoming the problems encountered with other growth techniques. More particularly, for BNN crystals, a structural transition between orthorhombic (space group: Pba2) and tetragonal symmetry (space group: P4bm) was found to occur for a Nd 3+ amount between 2 and 3 at% avoiding the microtwinning which disturbs the optical properties of the crystals. Low temperature spectroscopy revealed that Nd 3+ ions substitute both Ba 2+ and Na + ions in the pentagonal and square sites of the tungsten bronze-type structure of BNN whereas they substitute only K + ions in the pentagonal sites of that of KLN. Non-critical phase matching at room temperature was also investigated for both materials.

  10. Phase-matched electric-field-induced second-harmonic generation in Xe-filled hollow-core photonic crystal fiber.

    PubMed

    Ménard, Jean-Michel; Russell, Philip St J

    2015-08-01

    Second-order nonlinearity is induced inside a Xe-filled hollow-core photonic crystal fiber (PCF) by applying an external dc field. The system uniquely allows the linear optical properties to be adjusted by changing the gas pressure, allowing for precise phase matching between the LP01 mode at 1064 nm and the LP02 mode at 532 nm. The dependence of the second-harmonic conversion efficiency on the gas pressure, launched pulse energy, and applied field agrees well with theory. The ultra-broadband guidance offered by anti-resonant reflecting hollow-core PCFs, for example, a kagomé PCF, offers many possibilities for generating light in traditionally difficult-to-access regions of the electromagnetic spectrum, such as the ultraviolet or the terahertz windows. The system can also be used for noninvasive measurements of the transmission loss in a hollow-core PCF over a broad spectrum, including the deep and vacuum UV regions. PMID:26258387

  11. Improvement and formation of UV-induced damage on LBO crystal surface during long-term high-power third-harmonic generation.

    PubMed

    Hong, Hailong; Liu, Qiang; Huang, Lei; Gong, Mali

    2013-03-25

    We demonstrate the improvement and formation of UV-induced damage on LBO crystal output surface during long-term (130 h) high-power (20 W) high-repetition-rate (80 kHz) third-harmonic generation. The output surface was super-polished (RMS surface roughness <0.6 nm) to sub-nanometer scale super smooth roughness. The surface lifetime has been improved more than 20-fold compared with the as-polished ones (RMS surface roughness 4.0~8.0 nm). The damage could be attributed to the consequence of thermal effects resulted from impurity absorptions. Simultaneously, it was verified that the impurities originated in part from the UV-induced deposition. PMID:23546112

  12. Fast ion energy distribution from third harmonic radio frequency heating measured with a single crystal diamond detector at the Joint European Torus.

    PubMed

    Nocente, M; Cazzaniga, C; Tardocchi, M; Binda, F; Eriksson, J; Giacomelli, L; Muraro, A; Rebai, M; Sharapov, S; Gorini, G

    2015-10-01

    Neutron spectroscopy measurements with a single crystal diamond detector have been carried out at JET, for the first time in an experiment aimed at accelerating deuterons to MeV energies with radio frequency heating at the third harmonic. Data are interpreted by means of the expected response function of the detector and are used to extract parameters of the highly non-Maxwellian distribution function generated in this scenario. A comparison with observations using a time of flight and liquid scintillator neutron spectrometers is also presented. The results demonstrate the capability of diamond detectors to contribute to fast ion physics studies at JET and are of more general relevance in view of the application of such detectors for spectroscopy measurements in the neutron camera of next step tokamak devices. PMID:26520949

  13. Fast ion energy distribution from third harmonic radio frequency heating measured with a single crystal diamond detector at the Joint European Torus

    NASA Astrophysics Data System (ADS)

    Nocente, M.; Cazzaniga, C.; Tardocchi, M.; Binda, F.; Eriksson, J.; Giacomelli, L.; Muraro, A.; Rebai, M.; Sharapov, S.; Gorini, G.

    2015-10-01

    Neutron spectroscopy measurements with a single crystal diamond detector have been carried out at JET, for the first time in an experiment aimed at accelerating deuterons to MeV energies with radio frequency heating at the third harmonic. Data are interpreted by means of the expected response function of the detector and are used to extract parameters of the highly non-Maxwellian distribution function generated in this scenario. A comparison with observations using a time of flight and liquid scintillator neutron spectrometers is also presented. The results demonstrate the capability of diamond detectors to contribute to fast ion physics studies at JET and are of more general relevance in view of the application of such detectors for spectroscopy measurements in the neutron camera of next step tokamak devices.

  14. Role of Acentric Displacements on the Crystal Structure and Second-Harmonic Generating Properties of RbPbCO3F and CsPbCO3F

    PubMed Central

    2015-01-01

    Two lead fluorocarbonates, RbPbCO3F and CsPbCO3F, were synthesized and characterized. The materials were synthesized through solvothermal and conventional solid-state techniques. RbPbCO3F and CsPbCO3F were structurally characterized by single-crystal X-ray diffraction and exhibit three-dimensional (3D) crystal structures consisting of corner-shared PbO6F2 polyhedra. For RbPbCO3F, infrared and ultraviolet–visible spectroscopy and thermogravimetric and differential thermal analysis measurements were performed. RbPbCO3F is a new noncentrosymmetric material and crystallizes in the achiral and nonpolar space group P6?m2 (crystal class 6?m2). Powder second-harmonic generation (SHG) measurements on RbPbCO3F and CsPbCO3F using 1064 nm radiation revealed an SHG efficiency of approximately 250 and 300 × ?-SiO2, respectively. Charge constants d33 of approximately 72 and 94 pm/V were obtained for RbPbCO3F and CsPbCO3F, respectively, through converse piezoelectric measurements. Electronic structure calculations indicate that the nonlinear optical response originates from the distorted PbO6F2 polyhedra, because of the even–odd parity mixing of the O 2p states with the nearly spherically symmetric 6s electrons of Pb2+. The degree of inversion symmetry breaking is quantified using a mode-polarization vector analysis and is correlated with cation size mismatch, from which it is possible to deduce the acentric properties of 3D alkali-metal fluorocarbonates. PMID:24867361

  15. Parametric frequency converters with LiInSe2, AgGaGeS4, HgGa2S4 and Hg0.65Cd0.35Ga2S4 crystals

    NASA Astrophysics Data System (ADS)

    Andreev, Yuri M.; Geiko, Pavel P.; Badikov, Valery V.; Panyutin, Vladimir L.; Shevyrdayeva, Galina S.; Ivaschenko, Maxim V.; Karapuzikov, Alexander I.; Sherstov, Igor V.

    2003-04-01

    Second harmonic generation of 9 ?m emission band of CO2 laser is for the first time realized with a number of new nonlinear crystals: biaxial LiInSe2, AgGaGeS4 and uniaxial HgGa2S4, Cd0.35,Hg0.65Ga2S4. For LiInSe2 and AgGaGeS4 it is first type of frequency conversion realized some time or other. Main feature of this crystals is wide range transparency from 0.4-0.6 to 12.5-16.2 ?m. Their damage thresholds for 30 ns TEA CO2 laser pulses at 9.55 ?m is determined as 1.7 to 2.3 times higher than for popular middle IR crystals such as ZnGeP2 or AgGaSe2. Parmateters of second harmonic generation were determined correctly in comparison with ZnGeP2 crystals at 33 ns pump pulses and intensities that are about 28.5% of damage thresholds of ZnGeP2. As high as 7% external peak power power efficiencies is typical for orange and yellow phases of 3.1 mm HgGa2S4 crystal at such pump that is only 13% of its damage threshold. Efficiencies as high as 0.45% and 0.3% are realized in 2.1 mm AgGaGeS4 crystal at pump intensities that is only 11% of damage threshold. It was determined phase-matching angles, spectral dependence of second harmonic generation efficiencies, so as angular and spectral phase-matching widths that are investigated in details.

  16. Orientations of side chains and adsorbed liquid crystal molecules on a rubbed polyimide surface studied by optical second harmonic generation

    E-print Network

    Zhuang, Xiaowei

    Orientations of side chains and adsorbed liquid crystal molecules on a rubbed polyimide surface on a rubbed side-chain polyimide surface. Both the side chains and the LC molecules appear to be well aligned a negative pretilt angle in a homogeneously aligned LC film sandwiched between two such surfaces. The side

  17. An Investigation of Method to Reduce Harmonic Components using Specific Harmonic Control Method

    NASA Astrophysics Data System (ADS)

    Harimoto, Tsuyoshi; Hayashi, Hidemi; Murata, Katsuaki

    Low Harmonic Components Elimination Method is effective to suppress the Harmonics of self-commutated converter. But this method can't control the harmonic voltage. Recently the technique have been proposed to control self-commutated converter as shunt active filter to suppress the harmonics voltage of power system, but this method can't be used for this purpose. In this paper, a new PWM method is proposed to control specific low harmonic component. The proposed method uses the approximate equation that was led from theoretical value. The proposed method turned out decreasing the total harmonic distortion of the power system more than conventional Low Harmonic Component Elimination Method by some experimental results employing STATCOM.

  18. Multiple-channel wavelength conversions in a photonic crystal cavity.

    PubMed

    Jeon, Seungwoo; Song, Bong-Shik; Yamada, Shota; Yamaguchi, Yuki; Upham, Jeremy; Asano, Takashi; Noda, Susumu

    2015-02-23

    We demonstrate multiple-channel wavelength conversions of second harmonic and sum frequency generations in a silicon carbide photonic crystal cavity. The cavity is designed to have multiple modes including a nanocavity mode and Fabry-Pérot modes. Multiple-channel wavelength conversions in the nanocavity and Fabry-Pérot modes are shown experimentally. Furthermore, we investigate the polarization characteristics of wavelength-converted light. The experimental results of the polarization are in good agreement with calculation. PMID:25836489

  19. CAVE: the design of a precision metrology instrument for studying performance of KDP crystals

    SciTech Connect

    Hibbard, R.L., LLNL

    1998-03-30

    A device has been developed to measure the frequency conversion performance of large aperture potassium dihydrogen phosphate (KDP) crystals. Third harmonic generation using ICDP is critical to the function of the National Ignition Facility (NIF) laser. The crystals in the converter can be angularly or thermally tuned but are subject to larger aperture inhomogeneities that are functions of growth manufacturing and - mounting. The CAVE (Crystal Alignment Verification Equipment) instrument scans the crystals in a thermally and mechanically controlled environment to determine the local peak tuning angles. The CAVE can then estimate the optimum tuning angle and conversion efficiency over the entire aperture. Coupled with other metrology techniques, the CAVE will help determine which crystal life-cycle components most affect harmonic conversion.

  20. Variable wave vector second harmonic generation in phenanthrene

    E-print Network

    Johnson, Carey K.; Small, Gerald J.

    1982-01-01

    Second harmonic generation is observed in phenanthrene crystals. The experimental set is used allowed the simultaneous detection of two proton excitation (TPE) and second harmonic generation.(SHG). (AIP)

  1. Magnetorheological converters

    SciTech Connect

    Zal'tsgendler, E.A.; Kolomentsev, A.V.; Kordonskii, V.I.; Madorskii, L.S.

    1986-04-01

    The authors study the problems of constructing an electrohydraulic converter functioning based on the magnetoheological effect: the magnetorheological throttle (MR throttle). Requirements are listed that must be taken into account in developing the MR throttle. The paper attempts to calculate the flow-rate characteristics of the MR throttle. The rheological equation which describes sufficiently the mechanical properties of the magnetoheological suspensions is presented. The paper examines the calculation of the magnetic inductor for the example of a toroidal core with a gap, which simultaneously functions as the slot throttling channel. The use of the designs described enabled the development of bridge converters, which have a flat amplitude-frequency characteristic in the range 200-250 Hz and which have good energy indicators. Typical experimental logarithmic amplitude-frequency and phase-frequency characteristics of a bridge converter are shown.

  2. Coherent combining of fiber-laser-pumped frequency converters using all fiber electro-optic modulator for active phase control

    NASA Astrophysics Data System (ADS)

    Bourdon, P.; Durécu, A.; Canat, G.; Le Gouët, J.; Goular, D.; Lombard, L.

    2015-03-01

    Coherent beam combining (CBC) by active phase control could be useful for power scaling fiber-laser-pumped optical frequency converters like OPOs. However, a phase modulator operating at the frequency-converted wavelength is needed, which is non standard component. Fortunately, nonlinear conversion processes rely on a phase-matching condition correlating, not only the wave vectors of the coupled waves, but also their phases. This paper demonstrates that, using this phase correlation for indirect control of the phase, coherent combining of optical frequency converters is feasible using standard all-fibered electro-optic modulators. For the sake of demonstration, this new technique is experimentally applied twice for continuous wave second-harmonic-generator (SHG) combination: i) combining 2 SHG of 1.55-?m erbium-doped fiber amplifiers in PPLN crystals generating 775-nm beams; ii) combining 2 SHG of 1.064-?m ytterbium-doped fiber amplifiers in LBO crystals generating 532-nm beams. Excellent CBC efficiency is achieved on the harmonic waves in both these experiments, with ?/20 and ?/30 residual phase error respectively. In the second experiment, I/Q phase detection is added on fundamental and harmonic waves to measure their phase variations simultaneously. These measurements confirm the theoretical expectations and formulae of correlation between the phases of the fundamental and harmonic waves. Unexpectedly, in both experiments, when harmonic waves are phase-locked, a residual phase difference remains between the fundamen tal waves. Measurements of the spectrum of these residual phase differences locate them above 50 Hz, revealing that they most probably originate in fast-varying optical path differences induced by turbulence and acoustic-waves on the experimental breadboard.

  3. Discriminating harmonicity

    NASA Astrophysics Data System (ADS)

    Kidd, Gerald; Mason, Christine R.; Brughera, Andrew; Chiu, Chung-Yiu Peter

    2003-08-01

    Simultaneous tones that are harmonically related tend to be grouped perceptually to form a unitary auditory image. A partial that is mistuned stands out from the other tones, and harmonic complexes with different fundamental frequencies can readily be perceived as separate auditory objects. These phenomena are evidence for the strong role of harmonicity in perceptual grouping and segregation of sounds. This study measured the discriminability of harmonicity directly. In a two interval, two alternative forced-choice (2I2AFC) paradigm, the listener chose which of two sounds, signal or foil, was composed of tones that more closely matched an exact harmonic relationship. In one experiment, the signal was varied from perfectly harmonic to highly inharmonic by adding frequency perturbation to each component. The foil always had 100% perturbation. Group mean performance decreased from greater than 90% correct for 0% signal perturbation to near chance for 80% signal perturbation. In the second experiment, adding a masker presented simultaneously with the signals and foils disrupted harmonicity. Both monaural and dichotic conditions were tested. Signal level was varied relative to masker level to obtain psychometric functions from which slopes and midpoints were estimated. Dichotic presentation of these audible stimuli improved performance by 3-10 dB, due primarily to a release from ``informational masking'' by the perceptual segregation of the signal from the masker.

  4. Sellmeier equation and conversion of the radiation of a repetitively pulsed tunable TEA CO{sub 2} laser into the second harmonic in a ZnGeP{sub 2} crystal

    SciTech Connect

    Zakharov, S V; Negin, A E; Filippov, P G; Zhilis, E F

    1999-09-30

    The results are reported of measurements of the spectral dependences of the conversion efficiency and of the phase-matching angles in the conversion of the radiation of a repetitively pulsed TEA CO{sub 2} laser into the second harmonic in ZnGeP{sub 2} crystals. The measured angular phase-matching curves are compared in the range 9.2 - 10.8 {mu}m with curves calculated, on the basis of the spectral dependences of the refractive indices for the ordinary and extraordinary waves, for several Sellmeier coefficients. The Sellmeier coefficients are in agreement with the measured values. (nonlinear optical phenomena)

  5. Organometallic Salts Generate Optical Second Harmonics

    NASA Technical Reports Server (NTRS)

    Marder, Seth R.; Perry, Joseph W.

    1991-01-01

    Series of organometallic salts exhibit large second-order dielectric susceptibilities, as evidenced by generation of second harmonics when illuminated at visible and near-infrared wavelengths. Investigations of these and related compounds continue with view toward development of materials for use as optical second-harmonic generators, electro-optical modulators, optical switches, piezoelectric sensors, and parametric crystals.

  6. Frequency mixing crystal

    DOEpatents

    Ebbers, Christopher A. (Livermore, CA); Davis, Laura E. (Manteca, CA); Webb, Mark (Salida, CA)

    1992-01-01

    In a laser system for converting infrared laser light waves to visible light comprising a source of infrared laser light waves and means of harmoic generation associated therewith for production of light waves at integral multiples of the frequency of the original wave, the improvement of said means of harmonic generation comprising a crystal having the chemical formula X.sub.2 Y(NO.sub.3).sub.5 .multidot.2 nZ.sub.2 o wherein X is selected from the group consisting of Li, Na, K, Rb, Cs, and Tl; Y is selected from the group consisting of Sc, Y, La, Ce, Nd, Pr, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Al, Ga, and In; Z is selected from the group consisting of H and D; and n ranges from 0 to 4.

  7. Poling-induced crystallization of tetragonal BaTiO3 and enhancement of optical second-harmonic intensity in BaO-TiO2-TeO2 glass system

    NASA Astrophysics Data System (ADS)

    Narazaki, Aiko; Tanaka, Katsuhisa; Hirao, Kazuyuki

    1999-11-01

    Effect of poling on surface crystallization behavior of BaTiO3 in 15BaO-15TiO2-70TeO2 glass and on second-harmonic generation of the resultant glass ceramics has been examined. A direct current voltage in a range of 0.3-1 kV was applied to the original glass at around 400 °C, which is above its glass transition temperature, followed by cooling of the sample to room temperature with the voltage kept constant. X-ray diffraction patterns indicate that the poling increased the fraction of crystalline phases precipitated at the glass surface and that BaTiO3 crystallites were precipitated preferentially with (101)- or (110)-orientation. It is also observable that the x-ray diffraction line assigned to BaTiO3 shifted from the position corresponding to bulk cubic crystal to that of ferroelectric tetragonal one when the applied voltage was increased. In other words, the poling treatment stabilizes the tetragonal BaTiO3 phase, leading to a larger optical second-order nonlinear susceptibility. In fact, the second-harmonic intensity for the glass ceramic poled at 420 °C was enhanced by a factor of ten compared with the glass ceramic heat treated without an external electric field.

  8. Power converter

    NASA Technical Reports Server (NTRS)

    Black, J. M. (inventor)

    1981-01-01

    A dc-to-dc converter employs four transistor switches in a bridge to chop dc power from a source, and a voltage multiplying diode rectifying ladder network to rectify and filter the chopped dc power for delivery to a load. The bridge switches are cross coupled in order for diagonally opposite pairs to turn on and off together using RC networks for the cross coupling to achieve the mode of operation of a free running multivibrator, and the diode rectifying ladder is configured to operate in a push-pull mode driven from opposite sides of the multivibrator outputs of the ridge switches. The four transistor switches provide a square-wave output voltage which as a peak-to-peak amplitude that is twice the input dc voltage, and is thus useful as a dc-to-ac inverter.

  9. Full bridge converter Transformers and isolated converters

    E-print Network

    Knobloch,Jürgen

    Full bridge converter Transformers and isolated converters Most DC power supplies have parts of the B-H curve are used. Include: push-pull, half-bridge, full-bridge (explained below). An example - full-bridge converter Fig. 4: (a) Full-bridge converter. (b) voltage and current waveforms

  10. Convertible Stadium

    NASA Technical Reports Server (NTRS)

    1978-01-01

    Air flotation technology used in NASA's Apollo program has found an interesting application in Hawaii's Aloha Stadium near Honolulu. The stadium's configuration can be changed, by moving entire 7,000-seat sections on a cushion of air, for best accommodation of spectators and participants at different types of events. In most stadiums, only a few hundred seats can be moved, by rolling sections on wheels or rails. At Aloha Stadium, 28,000 of the 50,000 seats can be repositioned for better spectator viewing and, additionally, for improved playing conditions. For example, a stadium designed primarily for football may compromise the baseball diamond by providing only a shallow outfield. Aloha's convertibility allows a full-size baseball field as well as optimum configurations for many other types of sports and special events. The photos show examples. The stadium owes its versatility to air flotation technology developed by General Motors. Its first large-scale application was movement of huge segments of the mammoth Saturn V moonbooster during assembly operations at Marshall Space Flight Center.

  11. Power system applications for PASC converter systems

    SciTech Connect

    Donnelly, M.K.; Johnson, R.M.

    1994-04-01

    This paper shows, using computer EMTP simulations, some preliminary results of applying pulse amplitude synthesis and control (PASC) technology to single-source level voltage converter system. The method can be applied to any single terminal pair source with appropriate modifications in power extraction interface and computer control program to match source and load impedance characteristics. The PASC realization as discussed here employs banks of transformers, one bank per phase, in which the primaries are connected in parallel through a switch matrix to the dc source. Two opposite polarity primaries per transformer are pulsed alternatively in time to produce an oscillatory sinusoidal output waveform. PASC conversion system capabilities to produce both leading and lagging power factor power output in single-phase and three-phase {Delta} or Y configurations are illustrated. EMTP simulations are used to demonstrate the converter capabilities. Also included are discussions regarding harmonics and potential control strategies to adapt the converter to an application or to minimize harmonics.

  12. Harmonic engine

    DOEpatents

    Bennett, Charles L. (Livermore, CA)

    2009-10-20

    A high efficiency harmonic engine based on a resonantly reciprocating piston expander that extracts work from heat and pressurizes working fluid in a reciprocating piston compressor. The engine preferably includes harmonic oscillator valves capable of oscillating at a resonant frequency for controlling the flow of working fluid into and out of the expander, and also preferably includes a shunt line connecting an expansion chamber of the expander to a buffer chamber of the expander for minimizing pressure variations in the fluidic circuit of the engine. The engine is especially designed to operate with very high temperature input to the expander and very low temperature input to the compressor, to produce very high thermal conversion efficiency.

  13. Nonlinear single-crystal fibers of undoped and rare earth-doped niobates: growth by LHPG, spectroscopy and second harmonic generation

    NASA Astrophysics Data System (ADS)

    Foulon, Gisele; Ferriol, Michel; Brenier, Alain; Cohen-Adad, Marie-Therese; Boulon, Georges

    1997-11-01

    The renewal of second order non-linear crystals is very strong in laser materials optics. We are involved in the search of new systems based upon highly non-linear niobate crystal family. Among these crystals, Ba2NaNb5O15 (BNN) and K3Li2-xNb5+xO15+2x (KLN, 0.15 < x < 0.5) with a tungsten bronze-type structure are very efficient materials for the obtention of respectively green and blue laser light by frequency doubling or by self-frequency doubling after doping by Nd3+ ions. Unfortunately, BNN and KLN are difficult to grow by conventional techniques such as Czochralski without cracks caused by a strong lattice change occurring during cooling of the crystals. In addition, microtwins in BNN crystals and compositional inhomogeneities in KLN ones are often encountered. The obtention of good quality and crackless BNN and KLN single crystals doped with different amounts of Nd2O3 is reported. The crystals were grown by the laser heated pedestal growth technique. This method allowed to obtain good quality and homogeneous crystals of BNN and KLN overcoming the problems encountered with other growth techniques. More particularly, for BNN crystals, a structural transition between orthohombic and tetragonal symmetry was found to occur for a Nd3+ amount between 2 and 3 atomic percent avoiding the microtwinning which disturbs the optical properties of the crystals. Low temperature spectroscopy revealed that Nd3+ ions substitute both Ba2+ and Na+ ions in the pentagonal and square sites of the tungsten bronze-type structure of BNN whereas they substitute only K+ ions in the pentagonal sites of that of KLN. Non- critical phase matching at room temperature was also investigated for both materials.

  14. A Series-Connected Hybrid Triple Converter System

    NASA Astrophysics Data System (ADS)

    Li, Dongsheng; Fukuda, Shoji; Kubo, Yusuke

    A hybrid converter system aims at a large capacity high voltage high efficiency converter system with being free from harmonics in the output. The system can consist of n GTO converters and a single NPC IGBT converter connected series by n+1 output transformers. It is proved that a triple converter system consists of two GTO converters and one IGBT converter is most feasible based on the performance evaluation. Thus, this paper treats a triple converter system in detail. The GTO converters operate in a square-wave switching mode, while the IGBT converter operates in a PWM switching mode. The former produces a base part of the total output voltage. The latter not only produces an additional part of the total output, but offsets the harmonic components generated by the GTO converters. The control strategy for the system is proposed, and the experiments on inverter, rectifier and STATCOM operation are demonstrated. The experimental results verified the validity of the proposed hybrid triple converter configuration and its control strategy.

  15. Harmonic engine

    DOEpatents

    Bennett, Charles L.; Sewall, Noel; Boroa, Carl

    2014-08-19

    An engine based on a reciprocating piston engine that extracts work from pressurized working fluid. The engine includes a harmonic oscillator inlet valve capable of oscillating at a resonant frequency for controlling the flow of working fluid into of the engine. In particular, the inlet valve includes an inlet valve head and a spring arranged together as a harmonic oscillator so that the inlet valve head is moveable from an unbiased equilibrium position to a biased closed position occluding an inlet. Upon releasing the inlet valve the inlet valve head undergoes a single oscillation past the equilibrium positio to a maximum open position and returns to a biased return position close to the closed position to choke the flow and produce a pressure drop across the inlet valve causing the inlet valve to close. Protrusions carried either by the inlet valve head or piston head are used to bump open the inlet valve from the closed position and initiate the single oscillation of the inlet valve head, and protrusions carried either by the outlet valve head or piston head are used to close the outlet valve ahead of the bump opening of the inlet valve.

  16. Second-harmonic generation in transparent surface crystallized glasses in the BaO-B{sub 2}O{sub 3}-TeO{sub 2} system

    SciTech Connect

    Murugan, G. Senthil; Suzuki, Takenobu; Ohishi, Yasutake; Takahashi, Yoshihiro; Benino, Yasuhiko; Fujiwara, Takumi; Komatsu, Takayuki

    2004-10-18

    A transparent glass-ceramic containing borate crystallites in tellurite glass is reported. Controlled heat treatment resulted in surface crystallization of BaB{sub 4}O{sub 7} in the BaO-B{sub 2}O{sub 3}-TeO{sub 2} glass system. The second-order optical nonlinearities observed in these surface crystallized glasses were attributed to the distortion present in the BaB{sub 4}O{sub 7} unit cell as evidenced by x-ray powder diffraction studies. A d{sub 33} value of 0.08 pm/V was obtained from the Maker fringe analysis for a surface crystallized glass.

  17. Assessment on third order non linearity and other optical analyses of L-Asparagine Monohydrate single crystal: An efficient candidate for harmonic conversions.

    PubMed

    Thukral, Kanika; Vijayan, N; Haranath, D; Jayaramakrishnan, V; Philip, J; Sreekanth, P; Bhagavannaryana, G

    2015-12-01

    Single crystal of l-Asparagine Monohydrate, an organic material has been successfully grown by slow evaporation solution growth technique at ambient condition. The lattice parameters and its strain of the grown crystal have been evaluated from powder X-ray diffraction and found that it belongs to orthorhombic crystal system. The polarizability has been measured by using the Clausius-Mossotti relation. The crystalline perfection of grown single crystal has been examined by high resolution X-ray diffraction and its imperfection in the diffraction plane was clearly visible by recording topographical image of the plane. From the high resolution XRD, it confirms that the crystal contained high crystalline perfection. The optical behavior was analyzed by photoluminescence and birefringence methods. In the photoluminescence, a broad peak has been observed at 475 nm which suggest that it emits blue light. The decay tendency of the material has also been observed by calculating decay constant. The optical homogeneity has been determined by the dispersion pattern of the material. The two photon absorption coefficient was further calculated by Z-scan, which gives the information about the third order non linear optical behavior of the material. The value of two-photon absorption coefficient is 4.25 × 10(-12)m/W. The thermal parameters like thermal effusivity, thermal diffusivity, specific heat and thermal conductivity was obtained by using photopyroelectric technique. The ferroelectric behavior of the grown specimen was analyzed from PE (polarization VS electric field) loop. The loop suggests that the material was a nearly equivalent to ideal capacitor. PMID:26148830

  18. Harmonic and Anharmonic Properties of Diamond Structure Crystals with Application to the Calculation of the Thermal Expansion of Silicon. Ph.D. Thesis. Final Report

    NASA Technical Reports Server (NTRS)

    Wanser, K. H.

    1981-01-01

    Silicon has interesting harmonic and anharmonic properties such as the low lying transverse acoustic modes at the X and L points of the Brillouin zone, negative Gruneisen parameters, negative thermal expansion and anomalous acoustic attenuation. In an attempt to understand these properties, a lattice dynamical model employing long range, nonlocal, dipole-dipole interactions was developed. Analytic expression for the Gruneisen parameters of several modes are presented. These expressions explain how the negative Gruneisen parameters arise. This model is applied to the calculation of the thermal expansion of silicon from 5K to 1700K. The thermoelastic contribution to the acoustic attenuation of silicon is computed from 1 to 300 K. Strong attenuation anomalies associated with negative thermal expansion are found in the vicinity of 17K and 125K.

  19. Third-harmonic performance of the Beamlet prototype laser

    SciTech Connect

    Wegner, P.J.; Barker, C.E.; Caird, J.A.; Dixit, S.N.; Henesian, M.A.; Seppala, L.G.; Thompson, C.E.; Van Wonterghem, B.V.

    1997-01-31

    The Beamlet laser is a nearly full-scale, single-aperture prototype of the driver design for the National Ignition Facility (NIF). As part of a test and validation plan for the NIF design, Beamlet was recently equipped with final focusing optics and diagnostics for the purpose of evaluating integrated component performance and equivalent target-plane irradiance conditions at the 0.351-{mu}m output wavelength specified for NIF targets. A 37-cm aperture two-crystal converter scheme generates the third harmonic of the Nd:glass 1.053-{mu}m wavelength with high efficiency. The efficiency of the converter has been characterized and is reported, along with detailed measurements of the near-field and far-field UV irradiance distributions at operating conditions up to and exceeding red-line levels for the NIF. Dependences of observed beam quality on critical laser parameters including output power, B-integral, and spatial filtering are discussed and compared with numerical simulations.

  20. Harmonic analysis of spacecraft power systems using a personal computer

    NASA Technical Reports Server (NTRS)

    Williamson, Frank; Sheble, Gerald B.

    1989-01-01

    The effects that nonlinear devices such as ac/dc converters, HVDC transmission links, and motor drives have on spacecraft power systems are discussed. The nonsinusoidal currents, along with the corresponding voltages, are calculated by a harmonic power flow which decouples and solves for each harmonic component individually using an iterative Newton-Raphson algorithm. The sparsity of the harmonic equations and the overall Jacobian matrix is used to an advantage in terms of saving computer memory space and in terms of reducing computation time. The algorithm could also be modified to analyze each harmonic separately instead of all at the same time.

  1. Spectrum of second-harmonic radiation generated from incoherent light

    SciTech Connect

    Stabinis, A.; Pyragaite, V.; Tamosauskas, G.; Piskarskas, A.

    2011-10-15

    We report on the development of the theory of second-harmonic generation by an incoherent pump with broad angular and frequency spectra. We show that spatial as well as temporal walk-off effects in a nonlinear crystal result in angular dispersion of the second-harmonic radiation. We demonstrate that the acceptance angle in second-harmonic generation by incoherent light is caused by the width of the pump angular spectrum and the resulting angular dispersion of second-harmonic radiation but does not depend on crystal length. In this case the frequency spectrum of second-harmonic radiation is determined by its angular dispersion and the pump angular spectrum. The theory is supported by an experiment in which a LiIO{sub 3} crystal was pumped by a tungsten halogen lamp.

  2. Feasibility study for convertible engine torque converter

    NASA Technical Reports Server (NTRS)

    1985-01-01

    The feasibility study has shown that a dump/fill type torque converter has excellent potential for the convertible fan/shaft engine. The torque converter space requirement permits internal housing within the normal flow path of a turbofan engine at acceptable engine weight. The unit permits operating the engine in the turboshaft mode by decoupling the fan. To convert to turbofan mode, the torque converter overdrive capability bring the fan speed up to the power turbine speed to permit engagement of a mechanical lockup device when the shaft speed are synchronized. The conversion to turbofan mode can be made without drop of power turbine speed in less than 10 sec. Total thrust delivered to the aircraft by the proprotor, fan, and engine during tansient can be controlled to prevent loss of air speed or altitude. Heat rejection to the oil is low, and additional oil cooling capacity is not required. The turbofan engine aerodynamic design is basically uncompromised by convertibility and allows proper fan design for quiet and efficient cruise operation. Although the results of the feasibility study are exceedingly encouraging, it must be noted that they are based on extrapolation of limited existing data on torque converters. A component test program with three trial torque converter designs and concurrent computer modeling for fluid flow, stress, and dynamics, updated with test results from each unit, is recommended.

  3. A laser system for the excitation of rubidium Rydberg states using single pass second harmonic generation in a periodically poled lithium niobate waveguide crystal

    E-print Network

    Koglbauer, Andreas; Gericke, Tatjana; Ott, Herwig

    2010-01-01

    We report on a laser system at a wavelength of 495 nm which is suitable for the excitations of low lying Rydberg states of rubidium atoms. The system is based on frequency doubling of a seeded diode laser in a periodically poled waveguide crystal. We achieve an output power of up to 35 mW and prove the single frequency performance by direct two photon laser spectroscopy of the rubidium 14D_5/2 and 14D_3/2 states. The measured finestructure splitting is consistent with quantum defect theory calculations.

  4. Study on the second harmonic generation of tunable TEA CO2 laser in quasi-phase-matched GaAs crystal

    NASA Astrophysics Data System (ADS)

    Zheng, Yijun; Li, Qiang; Tan, Rongqing; Wang, Hao

    2015-10-01

    In this paper, on the basis of the theory of quasi phase matched, CO2 laser spectrum corresponding to GaAs chip within the scope of the matching length was calculated. Through the numerical solution of the wave equation, the relationship between power density of pump laser and frequency doubling conversion efficiency was given under the different crystal length conditions. By adjusting the CO2 laser gas mixture components, we optimized the pump laser pulse wave to meet the requirements in the temporal distribution of the pump light. On the other hand, we optimize the output beam mode to meet the pump light distribution in space requirements. We use the tunable TEA CO2 laser as the light source to pump quasi phase matching GaAs crystal, When the pump wavelength is changed from 9.23?m to 10.75?m range, the conversion efficiency of frequency doubling output is greater than 4%, when the pump wavelength is 10.68um, the frequency doubling efficiency reached 6.58%.

  5. Basic technology of fast growing normal and partially deuterated KDP crystals

    SciTech Connect

    Fujioka, K.; Matsuo, S.; Kanabe, T.; Nakatsuka, M.; Nakai, S.

    1995-12-31

    The recent key issue of the efficient implosion in an inertial confinement fusion experiments is the improvement of the irradiation uniformity where the partially coherent light and the phase plate were used. The partially coherent light has wide spectral width and large beam divergence. The partially deuterated KDP crystal is suitable as the effective harmonic converter. The distribution coefficient of deuterium in the crystal depends on that of the growth solution. It was not affected, even if the saturated temperature and the supersaturation of the growth solution were changed. 13%-deuterated KDP crystal of 9 x 9 x 11 cm size was grown in which the deuterated rate was constant within the measurement error of {+-} 1 %. The excess energy due to an over heading and/or an acoustic energy to the solution and the pH control realized higher level of supersaturation. KDP crystal were grown up to 50mm/day.

  6. Requirements on Power Converters

    E-print Network

    Burnet, J-P

    2015-01-01

    This paper introduces the requirements for power converters needed for particle accelerators. It describes the role of power converters and the challenges and constraints when power ing magnets. The different circuit layouts are presented as well as the operating cycles. The power converter control and high precision definition are also introduced. This paper lists the key circuit parameters to be taken into consideration to properly specify a power converter that can be compiled in a functional specification.

  7. Controlling Second Harmonic Efficiency of Laser Beam Interactions

    NASA Technical Reports Server (NTRS)

    Barnes, Norman P. (Inventor); Walsh, Brian M. (Inventor); Reichle, Donald J. (Inventor)

    2011-01-01

    A method is provided for controlling second harmonic efficiency of laser beam interactions. A laser system generates two laser beams (e.g., a laser beam with two polarizations) for incidence on a nonlinear crystal having a preferred direction of propagation. Prior to incidence on the crystal, the beams are optically processed based on the crystal's beam separation characteristics to thereby control a position in the crystal along the preferred direction of propagation at which the beams interact.

  8. Frequency doubling crystals

    SciTech Connect

    Wang, F.; Velsko, S.P.

    1989-10-24

    A systematic approach to the production of frequency conversion crystals is described in which a chiral molecule has attached to it a harmonic generating unit which contributes to the noncentrosymmetry of the molecule. Certain preferred embodiments of such harmonic generating units include carboxylate, guanadyly and imidazolyl units. Certain preferred crystals include L- arginine fluoride, deuterated L-arginine fluoride, L-arginine chloride monohydrate, L-arginine acetate, dithallium tartrate, ammonium N-acetyl valine, N-acetyl tyrosine and N-acetyl hydroxyproline. Chemical modifications of the chiral molecule, such as deuteration, halogenation and controlled counterion substitution are available to adapt the dispersive properties of a crystal in a particular wavelength region.

  9. Simple Harmonic Motion in Harmonic Plane Waves.

    ERIC Educational Resources Information Center

    Benumof, Reuben

    1980-01-01

    Discusses the distribution of kinetic and potential energy in transverse and longitudinal waves and examines the transmission of power and momentum. This discussion is intended to aid in understanding the simple harmonic motion of a particle involved in the propagation of a harmonic mechanical plane wave. (HM)

  10. Rotorcraft convertible engine study

    NASA Technical Reports Server (NTRS)

    Gill, J. C.; Earle, R. V.; Mar, H. M.

    1982-01-01

    The objective of the Rotorcraft Convertible Engine Study was to define future research and technology effort required for commercial development by 1988 of convertible fan/shaft gas turbine engines for unconventional rotorcraft transports. Two rotorcraft and their respective missions were defined: a Fold Tilt Rotor aircraft and an Advancing Blade Concept (ABC) rotorcraft. Sensitivity studies were conducted with these rotorcraft to determine parametrically the influence of propulsion characteristics on aircraft size, mission fuel requirements, and direct operating costs (DOC). The two rotorcraft were flown with conventional propulsion systems (separate lift/cruise engines) and with convertible propulsion systems to determine the benefits to be derived from convertible engines. Trade-off studies were conducted to determine the optimum engine cycle and staging arrangement for a convertible engine. Advanced technology options applicable to convertible engines were studied. Research and technology programs were identified which would ensure technology readiness for commercial development of convertible engines by 1988.

  11. Thermionic converters for ISUS

    NASA Astrophysics Data System (ADS)

    James, Edmund L.; Ramsey, William D.; Talbot, Gregory J.

    1997-01-01

    Eight alkali metal thermionic power converters were produced for a ground-based design verification test of a bimodal power and propulsion system. The effort provided a significant development step toward a spaceflight demonstration of the Integrated Solar Upper Stage (ISUS). The converters are electrically connected in series to produce a nominal eight (8) volt, 250 Watt output. In the power mode of the bimodal system, solar energy is concentrated to heat the converters to their operating range of 1900 °K to 2200 °K. The converter design, including thermal diode, heatpipe-radiator physical dimensions and weight are discussed, as are fabrication and prototype development. Test results are presented for individual converters and the 8-converter array, including current voltage characteristics, power density and power-to-weight ratio. Tests of series arrays of 16 and 32 converters are planned as part of this development.

  12. Harmonization of Biodiesel Specifications

    SciTech Connect

    Alleman, T. L.

    2008-02-01

    Worldwide biodiesel production has grown dramatically over the last several years. Biodiesel standards vary across countries and regions, and there is a call for harmonization. For harmonization to become a reality, standards have to be adapted to cover all feedstocks. Additionally, all feedstocks cannot meet all specifications, so harmonization will require standards to either tighten or relax. For harmonization to succeed, the biodiesel market must be expanded with the alignment of test methods and specification limits, not contracted.

  13. Voltage source ac-to-dc converters for high-power transmitters

    NASA Technical Reports Server (NTRS)

    Cormier, R.

    1990-01-01

    This work was done to optimize the design of the components used for the beam power supply, which is a component of the transmitters in the Deep Space Network (DSN). The major findings are: (1) the difference in regulation between a six-pulse and a twelve-pulse converter is at most 7 percent worse for the twelve-pulse converter; (2) the commutation overlap angle of a current source converter equals that of a voltage source converter with continuous line currents; (3) the sources of uncharacteristic harmonics are identified with SPICE simulation; (4) the use of an imperfect phase-shifting transformer for the twelve-pulse converter generates a harmonic at six times the line frequency; and (5) the assumptions usually made in analyzing converters can be relaxed with SPICE simulation. The results demonstrate the suitability of using SPICE simulation to obtain detailed performance predictions of ac-to-dc converters.

  14. IEEE POWER ELECTRONICS LETTERS 1 Harmonic Optimization of Multilevel Converters

    E-print Network

    Tolbert, Leon M.

    to determine the switching angles for a cascaded multilevel inverter which eliminates specified higher order cells, solar cells, or rectified wind turbines or microturbines can be connected through a multilevel elimination techniques are introduced. II. CASCADED MULTILEVEL INVERTERS The cascaded multilevel inverter

  15. System and methods for reducing harmonic distortion in electrical converters

    DOEpatents

    Kajouke, Lateef A; Perisic, Milun; Ransom, Ray M

    2013-12-03

    Systems and methods are provided for delivering energy using an energy conversion module. An exemplary method for delivering energy from an input interface to an output interface using an energy converison module coupled between the input interface and the output interface comprises the steps of determining an input voltage reference for the input interface based on a desired output voltage and a measured voltage and the output interface, determining a duty cycle control value based on a ratio of the input voltage reference and the measured voltage, operating one or more switching elements of the energy conversion module to deliver energy from the input interface to the output interface to the output interface with a duty cycle influenced by the dute cycle control value.

  16. Design of precision mounts for optimizing the conversion efficiency of KDP crystals for the National Ignition Facility

    SciTech Connect

    Hibbard, R.L., LLNL

    1998-03-30

    A key design challenge for the National Ignition Facility (NIF), being constructed at Lawrence Livermore National Laboratory (LLNL), [Hibbard, R L , 1998], is the frequency converter consisting of two KDP crystals and a focusing lens Frequency conversion is a critical performance factor for NIF and the optical mount design for this plays a key role in meeting design specifications The frequency converter is a monolithic cell that mounts the optics and is the point on the beamline where the frequency conversion crystals are optimally aligned and the cell is focused on target The lasing medium is neodymium in phosphate glass with a fundamental frequency (1{omega}) of 1 053 {micro}m Sum frequency generation in a pair of conversion crystals (KDP/KD*P) produces 1 8 MJ of the third harmonic light (3{omega} or {lambda}=O 35 pm). The phase-matching scheme on NIF is type I second harmonic generation followed by type II sum-frequency-mixing of the residual fundamental and the second harmonic light This laser unlike previous laser system designs, must achieve high conversion efficiency, 85%, which is close to the 90 8% theoretical maximum As a result, this design is very sensitive to angular variations in beam propagation and in the crystal axes orientation. Factors that influence the phase matching angle include crystal inhomogeneity, residual and induced stress in the crystals, the crystals` natural and mounted surface figure, mounting imperfections and gravity sag These angular variations need to be controlled within a 40 {micro}rad error budget. The optical mount contributions to the angular error budget are 20 {micro}rad and are what make the frequency converter in the Final Optics Cell (FOC) such a challenging precision design. The premise of using full edge support in the FOC design is primarily driven by the spherical target chamber design that has optics mounted at multiple longitudinal angles and thus gravity sag in the crystals that needs to be minimized To meet the angular performance requirements, a precision monolithic cell with full edge support for mounting the optics to 10 {micro}rad angular and 1-5 {micro}m flatness tolerances is required The NIF frequency converter design is a major step in improving both conversion efficiency and precision of the mount design Another major consideration in the FOC design is the trade-off between cost of manufacturing the cell and the performance of the mount An interesting balance of what can be accomplished with a conventional machine tool in a commercial shop to produce prototype FOC` s will be discussed Metrology issues involved in qualifying the FOC are also discussed.

  17. Interleaved power converter

    DOEpatents

    Zhu, Lizhi (Canton, MI)

    2007-11-13

    A power converter architecture interleaves full bridge converters to alleviate thermal management problems in high current applications, and may, for example, double the output power capability while reducing parts count and costs. For example, one phase of a three phase inverter is shared between two transformers, which provide power to a rectifier such as a current doubler rectifier to provide two full bridge DC/DC converters with three rather than four high voltage inverter legs.

  18. Linking high harmonics from gases and solids.

    PubMed

    Vampa, G; Hammond, T J; Thiré, N; Schmidt, B E; Légaré, F; McDonald, C R; Brabec, T; Corkum, P B

    2015-06-25

    When intense light interacts with an atomic gas, recollision between an ionizing electron and its parent ion creates high-order harmonics of the fundamental laser frequency. This sub-cycle effect generates coherent soft X-rays and attosecond pulses, and provides a means to image molecular orbitals. Recently, high harmonics have been generated from bulk crystals, but what mechanism dominates the emission remains uncertain. To resolve this issue, we adapt measurement methods from gas-phase research to solid zinc oxide driven by mid-infrared laser fields of 0.25 volts per ångström. We find that when we alter the generation process with a second-harmonic beam, the modified harmonic spectrum bears the signature of a generalized recollision between an electron and its associated hole. In addition, we find that solid-state high harmonics are perturbed by fields so weak that they are present in conventional electronic circuits, thus opening a route to integrate electronics with attosecond and high-harmonic technology. Future experiments will permit the band structure of a solid to be tomographically reconstructed. PMID:26108855

  19. Linking high harmonics from gases and solids

    NASA Astrophysics Data System (ADS)

    Vampa, G.; Hammond, T. J.; Thiré, N.; Schmidt, B. E.; Légaré, F.; McDonald, C. R.; Brabec, T.; Corkum, P. B.

    2015-06-01

    When intense light interacts with an atomic gas, recollision between an ionizing electron and its parent ion creates high-order harmonics of the fundamental laser frequency. This sub-cycle effect generates coherent soft X-rays and attosecond pulses, and provides a means to image molecular orbitals. Recently, high harmonics have been generated from bulk crystals, but what mechanism dominates the emission remains uncertain. To resolve this issue, we adapt measurement methods from gas-phase research to solid zinc oxide driven by mid-infrared laser fields of 0.25 volts per ångström. We find that when we alter the generation process with a second-harmonic beam, the modified harmonic spectrum bears the signature of a generalized recollision between an electron and its associated hole. In addition, we find that solid-state high harmonics are perturbed by fields so weak that they are present in conventional electronic circuits, thus opening a route to integrate electronics with attosecond and high-harmonic technology. Future experiments will permit the band structure of a solid to be tomographically reconstructed.

  20. Power line carrier interference from HVDC converter terminals

    SciTech Connect

    Tatro, P.J.; Adamson, K.A. ); Eitzmann, M.A.; Smead, M. . Power Systems Engineering Dept.)

    1993-07-01

    Power line carrier (PLC) equipment typically operates in the frequency range from 25 kHz to 300 kHz. Interference studies for HVDC converters usually concentrate on interference from noise sources within this frequency range. However, operating experience at the Sandy Pond converter terminal has indicated that PLC equipment is also susceptible to interference from sources of power system harmonics below the PLC frequency range. Extensive field testing and analytical studies have shown that each PLC circuit has a resonant frequency below the operating frequency. If excited at this resonant frequency, high voltages may exist within the PLC circuit. The resulting saturation of PLC components leads to local generation of radio frequency (RF) noise that interferes with proper operation of PLC circuits. Sources of power system harmonics in the 3-10 kHz range, such as line commutated dc converters, are potential sources of this type of interference.

  1. Nonlinear harmonic generation in the STARS FEL

    NASA Astrophysics Data System (ADS)

    Abo-Bakr, M.; Goldammer, K.; Kamps, T.; Knobloch, J.; Kuske, B.; Leitner, T.; Meseck, A.

    2008-08-01

    BESSY proposes to build STARS, an FEL to demonstrate cascaded High Gain Harmonic Generation (HGHG). In two HGHG stages, a laser source of 700-900 nm is converted down to a wavelength of 40-70 nm. The STARS facility consists of a normal-conducting RF photoinjector, three superconducting TESLA-type acceleration modules, a magnetic bunch compressor and two stages of HGHG, each consisting of a modulator, dispersive chicane and a radiator. At the entrance of the undulator section, the beam energy is 325 MeV and the peak current is about 500 A. With these parameters, the STARS FEL reaches saturation with a peak power of 100-350 MW. A superradiant mode is also foreseen which boosts the radiation power to the GW-level. Due to nonlinear harmonic generation (NHG), free electron lasers also radiate coherently at higher harmonics of the FEL resonant frequency. STARS can hence extend its output range to even shorter wavelengths. This paper presents studies of the STARS harmonic content in the wavelength range of 6-20 nm. Seeding with high harmonic generation pulses at 32 nm is also discussed.

  2. Frequency conversion in compositionally graded PPLN crystals

    SciTech Connect

    Galutskiy, V V; Stroganova, E V; Shmargilov, S A; Yakovenko, N A

    2014-01-31

    This paper considers the effect of the longitudinal lithium concentration distribution in PPLN converters on their efficiency in high-power cw laser second harmonic generation. (nonlinear optical phenomena)

  3. Cascaded resonant bridge converters

    NASA Technical Reports Server (NTRS)

    Stuart, Thomas A. (Inventor)

    1989-01-01

    A converter for converting a low voltage direct current power source to a higher voltage, high frequency alternating current output for use in an electrical system where it is desired to use low weight cables and other circuit elements. The converter has a first stage series resonant (Schwarz) converter which converts the direct current power source to an alternating current by means of switching elements that are operated by a variable frequency voltage regulator, a transformer to step up the voltage of the alternating current, and a rectifier bridge to convert the alternating current to a direct current first stage output. The converter further has a second stage series resonant (Schwarz) converter which is connected in series to the first stage converter to receive its direct current output and convert it to a second stage high frequency alternating current output by means of switching elements that are operated by a fixed frequency oscillator. The voltage of the second stage output is controlled at a relatively constant value by controlling the first stage output voltage, which is accomplished by controlling the frequency of the first stage variable frequency voltage controller in response to second stage voltage. Fault tolerance in the event of a load short circuit is provided by making the operation of the first stage variable frequency voltage controller responsive to first and second stage current limiting devices. The second stage output is connected to a rectifier bridge whose output is connected to the input of the second stage to provide good regulation of output voltage wave form at low system loads.

  4. Lab 5: Damped simple harmonic motion Simple harmonic oscillation

    E-print Network

    Gustafsson, Torgny

    Lab 5: Damped simple harmonic motion · Simple harmonic oscillation · Damped harmonic oscillation;Friction: retarding motion (energy dissipation) Damped simple harmonic oscillation 1 2 Hooke's law: Damping 381 Mechanics #12;Ideal case: no friction Simple harmonic oscillation Hooke's law: Newton's 2nd law: F

  5. Workshop on Harmonic Oscillators

    NASA Technical Reports Server (NTRS)

    Han, D. (editor); Kim, Y. S. (editor); Zachary, W. W. (editor)

    1993-01-01

    Proceedings of a workshop on Harmonic Oscillators held at the College Park Campus of the University of Maryland on March 25 - 28, 1992 are presented. The harmonic oscillator formalism is playing an important role in many branches of physics. This is the simplest mathematical device which can connect the basic principle of physics with what is observed in the real world. The harmonic oscillator is the bridge between pure and applied physics.

  6. Three-phase Series-Connected Hybrid Converter System

    NASA Astrophysics Data System (ADS)

    Li, Dongsheng; Fukuda, Shoji; Kubo, Yusuke; Kitano, Masayuki

    In this paper, a 3-phase series-connected hybrid converter system is introduced. The converter system is constructed by a GTO converter and an IGBT converter connected in series by two output transformers aiming at a high voltage high efficiency converter. The GTO converter operates in a square-wave switching mode at the same switching rate as a reference output voltage in order to minimize the device switching losses. The IGBT converter is built in an NPC (neutral-point-clamped) arrangement and operates in a PWM switching mode at a high switching rate. The former produces a base part of the total output voltage. The latter not only produces an additional part of the total output, but also offsets the harmonic components generated by the GTO converter. The control strategy for the system is proposed, and the experiment on an inverter, rectifier and STATCOM operation is demonstrated using the proposed hybrid converter. The experimental results verified the validity of the proposed hybrid configuration and its control strategy.

  7. Microminiature thermionic converters

    DOEpatents

    King, Donald B. (Albuquerque, NM); Sadwick, Laurence P. (Salt Lake City, UT); Wernsman, Bernard R. (Clairton, PA)

    2001-09-25

    Microminiature thermionic converts (MTCs) having high energy-conversion efficiencies and variable operating temperatures. Methods of manufacturing those converters using semiconductor integrated circuit fabrication and micromachine manufacturing techniques are also disclosed. The MTCs of the invention incorporate cathode to anode spacing of about 1 micron or less and use cathode and anode materials having work functions ranging from about 1 eV to about 3 eV. Existing prior art thermionic converter technology has energy conversion efficiencies ranging from 5-15%. The MTCs of the present invention have maximum efficiencies of just under 30%, and thousands of the devices can be fabricated at modest costs.

  8. Covariant harmonic oscillators and coupled harmonic oscillators

    NASA Technical Reports Server (NTRS)

    Han, Daesoo; Kim, Young S.; Noz, Marilyn E.

    1995-01-01

    It is shown that the system of two coupled harmonic oscillators shares the basic symmetry properties with the covariant harmonic oscillator formalism which provides a concise description of the basic features of relativistic hadronic features observed in high-energy laboratories. It is shown also that the coupled oscillator system has the SL(4,r) symmetry in classical mechanics, while the present formulation of quantum mechanics can accommodate only the Sp(4,r) portion of the SL(4,r) symmetry. The possible role of the SL(4,r) symmetry in quantum mechanics is discussed.

  9. Harmonic spheres conjecture

    NASA Astrophysics Data System (ADS)

    Sergeev, A. G.

    2010-09-01

    We discuss the harmonic spheres conjecture that the space of harmonic maps of the Riemann sphere into the loop space of a compact Lie group G are related to the moduli space of Yang-Mills G-fields on the four-dimensional Euclidean space.

  10. Polarized IR and Raman spectra and ab initio calculations for bis(guanidine) zirconium bis(nitrilotriacetate) hydrate single crystal [C(NH2)3]2[Zr[N(CH2COO)3]2](H2O)--the new laser Raman converter.

    PubMed

    Hanuza, J; Maczka, M; Sasiadek, W; Roszak, S; Lipkowski, P; Kaminskii, A A; Haussühl, E; Hulliger, J; Hussin, Al-Agail

    2006-11-01

    Fourier transform polarized IR and Raman spectra of bis(guanidine) zirconium bis(nitrilotriacetate) hydrate single crystal [C(NH(2))(3)](2)[Zr[N(CH(2)COO)(3)](2)](H(2)O) have been measured in the regions 30-4000 and 80-4000 cm(-1) and correlated with X-ray structural data. The factor group analysis has been applied in the discussion of the dichroic dependence of the vibrational modes. The assignment of the internal vibrations for the [Zr(nitrilotriacetate)2]2- complex ion has been based on the ab initio quantum chemical calculations. The usefulness of the studied crystal as Raman laser converter was analyzed basing on the comparison of the spontaneous and stimulated Raman spectra. PMID:16697251

  11. Polarized IR and Raman spectra and ab initio calculations for bis(guanidine) zirconium bis(nitrilotriacetate) hydrate single crystal [C(NH 2) 3] 2{Zr[N(CH 2COO) 3] 2}(H 2O)—The new laser Raman converter

    NASA Astrophysics Data System (ADS)

    Hanuza, J.; M?czka, M.; S?siadek, W.; Roszak, S.; Lipkowski, P.; Kaminskii, A. A.; Haussühl, E.; Hulliger, J.; Hussin, Al.-Agail

    2006-11-01

    Fourier transform polarized IR and Raman spectra of bis(guanidine) zirconium bis(nitrilotriacetate) hydrate single crystal [C(NH 2) 3] 2{Zr[N(CH 2COO) 3] 2}(H 2O) have been measured in the regions 30-4000 and 80-4000 cm -1 and correlated with X-ray structural data. The factor group analysis has been applied in the discussion of the dichroic dependence of the vibrational modes. The assignment of the internal vibrations for the {[Zr(nitrilotriacetate) 2]} 2- complex ion has been based on the ab initio quantum chemical calculations. The usefulness of the studied crystal as Raman laser converter was analyzed basing on the comparison of the spontaneous and stimulated Raman spectra.

  12. Development of AC and DC Power Supply Direct Interface Converter

    NASA Astrophysics Data System (ADS)

    Kato, Koji; Itoh, Jun-Ichi

    This paper proposes a novel control method for a direct interface converter for management of the energy flow in either an AC or DC supply. The proposed converter is constructed based on an indirect matrix converter. Therefore a proposed control strategy is based on an indirect control method with a triangular carrier wave. The basic operation of the proposed control method is confirmed by experimental results. In addition, this paper also proposes a commutation error compensation method of an output voltage error and an input current error for an indirect matrix converter. In the proposed method, the output voltage and input current error by the commutation can be compensated at the same time, because the PWM pulse of each switch is directly compensated. The validity of the proposed method is confirmed by experimental results. Those results prove that the proposed compensation method can decrease total harmonic distortion (THD) of the input and output current.

  13. Harmonics in a Wind Power Plant: Preprint

    SciTech Connect

    Preciado, V.; Madrigal, M.; Muljadi, E.; Gevorgian, V.

    2015-04-02

    Wind power generation has been growing at a very fast pace for the past decade, and its influence and impact on the electric power grid is significant. As in a conventional power plant, a wind power plant (WPP) must ensure that the quality of the power being delivered to the grid is excellent. At the same time, the wind turbine should be able to operate immune to small disturbances coming from the grid. Harmonics are one of the more common power quality issues presented by large WPPs because of the high switching frequency of the power converters and the possible nonlinear behavior from electric machines (generator, transformer, reactors) within a power plant. This paper presents a summary of the most important issues related to harmonics in WPPs and discusses practical experiences with actual Type 1 and Type 3 wind turbines in two WPPs.

  14. Lab 6: Forced Harmonic Motion Driven harmonic oscillation

    E-print Network

    Gustafsson, Torgny

    Lab 6: Forced Harmonic Motion Driven harmonic oscillation Example: Atomic force microscope watch;Lab 6: Forced Harmonic Motion · For each measurement allow enough time for the system to reach steady, circuit, ... #12;A constant energy flow at steady state ( )F t dF Rx= - 0oin ut PP + = #12;Forced harmonic

  15. Vector generator scan converter

    DOEpatents

    Moore, James M. (Livermore, CA); Leighton, James F. (Livermore, CA)

    1990-01-01

    High printing speeds for graphics data are achieved with a laser printer by transmitting compressed graphics data from a main processor over an I/O (input/output) channel to a vector generator scan converter which reconstructs a full graphics image for input to the laser printer through a raster data input port. The vector generator scan converter includes a microprocessor with associated microcode memory containing a microcode instruction set, a working memory for storing compressed data, vector generator hardward for drawing a full graphic image from vector parameters calculated by the microprocessor, image buffer memory for storing the reconstructed graphics image and an output scanner for reading the graphics image data and inputting the data to the printer. The vector generator scan converter eliminates the bottleneck created by the I/O channel for transmitting graphics data from the main processor to the laser printer, and increases printer speed up to thirty fold.

  16. Vector generator scan converter

    DOEpatents

    Moore, J.M.; Leighton, J.F.

    1988-02-05

    High printing speeds for graphics data are achieved with a laser printer by transmitting compressed graphics data from a main processor over an I/O channel to a vector generator scan converter which reconstructs a full graphics image for input to the laser printer through a raster data input port. The vector generator scan converter includes a microprocessor with associated microcode memory containing a microcode instruction set, a working memory for storing compressed data, vector generator hardware for drawing a full graphic image from vector parameters calculated by the microprocessor, image buffer memory for storing the reconstructed graphics image and an output scanner for reading the graphics image data and inputting the data to the printer. The vector generator scan converter eliminates the bottleneck created by the I/O channel for transmitting graphics data from the main processor to the laser printer, and increases printer speed up to thirty fold. 7 figs.

  17. Rotorcraft convertible engine study

    NASA Technical Reports Server (NTRS)

    Goldstein, D. N.; Hirschkron, R.; Smith, C. E.

    1983-01-01

    Convertible propulsion systems for advanced rotorcraft are evaluated in terms of their impact on aircraft operating economics and fuel consumption. A variety of propulsion system concepts, including separate thrust and power producing engines, convertible fan/shaft engines, and auxiliary propeller configurations are presented. The merits of each are evaluated in two different rotorcraft missions: an intercity, commercial transport of the ABC(TM) type, and an offshore oil ring supply ship of the X-wing type. The variable inlet guide vane fan/shaft converting engine and auxiliary propeller configurations are shown to offer significant advantages over all the other systems evaluated, in terms of both direct operating cost and fuel consumption.

  18. Simple harmonic motion displacement x

    E-print Network

    Bertulani, Carlos A. - Department of Physics and Astronomy, Texas A&M University

    1 Simple harmonic motion time (s) displacement x 5cm -5cm 2 4 6 8 10 a) what is the amplitude () of the corresponding circular motion? b) What is the period (T) of the harmonic motion? c) What is the frequency (f)? d of the harmonic oscillation? b) what is the period of the harmonic oscillation? c) what is the frequency

  19. Multidimensional high harmonic spectroscopy

    NASA Astrophysics Data System (ADS)

    Bruner, Barry D.; Soifer, Hadas; Shafir, Dror; Serbinenko, Valeria; Smirnova, Olga; Dudovich, Nirit

    2015-09-01

    High harmonic generation (HHG) has opened up a new frontier in ultrafast science where attosecond time resolution and Angstrom spatial resolution are accessible in a single measurement. However, reconstructing the dynamics under study is limited by the multiple degrees of freedom involved in strong field interactions. In this paper we describe a new class of measurement schemes for resolving attosecond dynamics, integrating perturbative nonlinear optics with strong-field physics. These approaches serve as a basis for multidimensional high harmonic spectroscopy. Specifically, we show that multidimensional high harmonic spectroscopy can measure tunnel ionization dynamics with high precision, and resolves the interference between multiple ionization channels. In addition, we show how multidimensional HHG can function as a type of lock-in amplifier measurement. Similar to multi-dimensional approaches in nonlinear optical spectroscopy that have resolved correlated femtosecond dynamics, multi-dimensional high harmonic spectroscopy reveals the underlying complex dynamics behind attosecond scale phenomena.

  20. Liquid metal thermal electric converter

    DOEpatents

    Abbin, Joseph P. (Albuquerque, NM); Andraka, Charles E. (Albuquerque, NM); Lukens, Laurance L. (Albuquerque, NM); Moreno, James B. (Albuquerque, NM)

    1989-01-01

    A liquid metal thermal electric converter which converts heat energy to electrical energy. The design of the liquid metal thermal electric converter incorporates a unique configuration which directs the metal fluid pressure to the outside of the tube which results in the structural loads in the tube to be compressive. A liquid metal thermal electric converter refluxing boiler with series connection of tubes and a multiple cell liquid metal thermal electric converter are also provided.

  1. Liquid metal thermal electric converter

    SciTech Connect

    Abbin, J.P.; Andrake, C.E.; Lukens, L.L.; Moreno, J.B.

    1989-09-19

    This patent describes a liquid metal thermal electric converter which converts heat energy to electrical energy. The design of the liquid metal thermal electric converter incorporates a unique configuration which directs the metal fluid pressure to the outside of the tube which results in the structural loads in the tube to be compressive. A liquid metal thermal electric converter refluxing boiler with series connection of tubes and a multiple cell liquid metal thermal electric converter are also provided.

  2. Definition of Power Converters

    E-print Network

    Bordry, F

    2015-01-01

    The paper is intended to introduce power conversion principles and to define common terms in the domain. The concept s of sources and switches are defined and classified. From the basic laws of source interconnections, a generic method of power converter synthesis is presented. Some examples illustrate this systematic method. Finally, the commutation cell and soft commuta tion are introduced and discussedd.

  3. Fractional Watt AMTEC Converter

    NASA Astrophysics Data System (ADS)

    Hunt, T. K.; Rasmussen, J. R.

    2006-01-01

    We report here the long term performance of a small, multi-tube AMTEC converter. This converter was designed to operate and produce approximately 12 watt of electrical output from a small, 4 to 6 watt radioisotope heat source for remote power applications. It was built and put on test in 1999 using electrical heaters as stand-ins for the radioisotope capsule. Since that time it has accumulated more than 5 years of run time at an input heater temperature of 700 °C, with numerous thermal cycles to ambient that were generally related to grid power failures or physical moves of the test apparatus. The power output has remained, with variations due to orientation changes and minor variations due to small temperature changes, essentially constant at 0.40 W to 0.60 W over the test period and operation is ongoing. The converter casing and mechanical structure was fabricated from 316 SS and the electrodes are sputtered titanium nitride films. Separate static tests of a multilayer insulation package suitable for use with the converter showed the capability to reach 700 °C with a thermal input of < 4 watts.

  4. Generation of octave-spanning multiple harmonics for ultrafast waveform synthesis

    E-print Network

    Hsu, Wei-Chun

    Up to seven laser harmonics covering more than two octaves in frequency have been generated efficiently in a single PPLT crystal, permitting the synthesis of 1.5 femtosecond pulses in a stable and compact setting.

  5. Frequency doubling crystals

    SciTech Connect

    Wang, F.; Velsko, S.P.

    1988-08-15

    A systematic approach to the production of frequency conversion crystals is described in which a chiral molecule has attached to it a harmonic generating unit'' which contributes to the noncentrosymmetry of the molecule. Certain preferred embodiments of such harmonic generating units include carboxylate, guanadyly and imidazolyl units. Certain preferred crystals include L-arginine fluoride, deuterated L-arginine fluoride, L-arginine chloride monohydrate, L-arginine acetate, dithallium tartrate, ammonium N-acetyl valine, N-acetyl tyrosine and N-acetyle hydroxyyproline. Chemical modifications of the chiral molecule, such as deuteration, halogenation and controlled counterion substitution are available to adapt the dispersive properties of a crystal in a particular wavelength region.

  6. Frequency doubling crystals

    DOEpatents

    Wang, Francis (Danville, CA); Velsko, Stephan P. (Livermore, CA)

    1989-01-01

    A systematic approach to the production of frequency conversion crystals is described in which a chiral molecule has attached to it a "harmonic generating unit" which contributes to the noncentrosymmetry of the molecule. Certain preferred embodiments of such harmonic generating units include carboxylate, guanadyly and imidazolyl units. Certain preferred crystals include L-arginine fluoride, deuterated L-arginine fluoride, L-arginine chloride monohydrate, L-arginine acetate, dithallium tartrate, ammonium N-acetyl valine, N-acetyl tyrosine and N-acetyl hydroxyproline. Chemical modifications of the chiral molecule, such as deuteration, halogenation and controlled counterion substitution are available to adapt the dispersive properties of a crystal in a particular wavelength region.

  7. Booster double harmonic setup notes

    SciTech Connect

    Gardner, C. J.

    2015-02-17

    The motivation behind implementing a booster double harmonic include the reduced transverse space charge force from a reduced peak beam current and reduced momentum spread of the beam, both of which can be achieved from flattening the RF bucket. RF capture and acceleration of polarized protons (PP) is first set up in the single harmonic mode with RF harmonic h=1. Once capture and acceleration have been set up in the single harmonic mode, the second harmonic system is brought on and programmed to operate in concert with the single harmonic system.

  8. Mid-IR femtosecond frequency conversion by soliton-probe collision in phase-mismatched quadratic nonlinear crystals.

    PubMed

    Liu, Xing; Zhou, Binbin; Guo, Hairun; Bache, Morten

    2015-08-15

    We show numerically that ultrashort self-defocusing temporal solitons colliding with a weak pulsed probe in the near-IR can convert the probe to the mid-IR. A near-perfect conversion efficiency is possible for a high effective soliton order. The near-IR self-defocusing soliton can form in a quadratic nonlinear crystal (beta-barium borate) in the normal dispersion regime due to cascaded (phase-mismatched) second-harmonic generation, and the mid-IR converted wave is formed in the anomalous dispersion regime between ?=2.2-2.4???m as a resonant dispersive wave. This process relies on nondegenerate four-wave mixing mediated by an effective negative cross-phase modulation term caused by cascaded soliton-probe sum-frequency generation. PMID:26274663

  9. Harmonic prime movers

    NASA Astrophysics Data System (ADS)

    Rice, Ian; Smith, Gordon

    2005-09-01

    Western Kentucky University is undertaking the development of a thermoacoustically powered acoustic agglomerator as a means of pretreating exhaust from coal generators before entering standard industrial electrostatic precipitators. In order to fulfill the design requirement of maintaining a clean, isolated environment for the thermoacoustic components, it will be necessary to operate a thermoacoustic prime mover in a harmonic mode, which normally is not a desirable feature in typical devices. Details of a harmonic-mode prime mover will be presented. [Work supported by KY EPSCoR and the Western Kentucky Office of Sponsored Programs.

  10. General Theory of Harmonics Generation thru Energy Transformation

    NASA Astrophysics Data System (ADS)

    Czyzyk, Don

    2013-04-01

    Energy, whatever its form, can be converted into an electrical signal. When analyzed is found to be comprised of a continuum of sinusoidal frequencies called a harmonic spectrum H/S. This paper addresses the question of how/why, in general, are these sinusoidal frequencies (harmonics) generated and in particular how they are produced in electronic circuits. To address this question many varied experiments were performed. Some experiments used just batteries while others used mechanical, acoustic, pneumatic, thermal, magnetic, hydraulic or photonic devices. All these devices were used to investigate the nature of harmonic generation from the perspective of the en masse movement of conduction electrons. Primarily performing electronic experiments on the envelope of a single pulse revealed that a pulse of one wavelength can be separated into basic individual segments. The energy of each individual segment, when absorbed by conduction electrons, is transformed into a unique H/S. Recombining all the individual segments that comprise a pulse envelope, involves the constructive or destructive interactions of their harmonic spectrums leading to the amplitudes of some harmonics being increased and others reduced or eliminated. The result is a pulse envelope with a different harmonic series.

  11. Cycloidal Wave Energy Converter

    SciTech Connect

    Stefan G. Siegel, Ph.D.

    2012-11-30

    This program allowed further advancing the development of a novel type of wave energy converter, a Cycloidal Wave Energy Converter or CycWEC. A CycWEC consists of one or more hydrofoils rotating around a central shaft, and operates fully submerged beneath the water surface. It operates under feedback control sensing the incoming waves, and converts wave power to shaft power directly without any intermediate power take off system. Previous research consisting of numerical simulations and two dimensional small 1:300 scale wave flume experiments had indicated wave cancellation efficiencies beyond 95%. The present work was centered on construction and testing of a 1:10 scale model and conducting two testing campaigns in a three dimensional wave basin. These experiments allowed for the first time for direct measurement of electrical power generated as well as the interaction of the CycWEC in a three dimensional environment. The Atargis team successfully conducted two testing campaigns at the Texas A&M Offshore Technology Research Center and was able to demonstrate electricity generation. In addition, three dimensional wave diffraction results show the ability to achieve wave focusing, thus increasing the amount of wave power that can be extracted beyond what was expected from earlier two dimensional investigations. Numerical results showed wave cancellation efficiencies for irregular waves to be on par with results for regular waves over a wide range of wave lengths. Using the results from previous simulations and experiments a full scale prototype was designed and its performance in a North Atlantic wave climate of average 30kW/m of wave crest was estimated. A full scale WEC with a blade span of 150m will deliver a design power of 5MW at an estimated levelized cost of energy (LCOE) in the range of 10-17 US cents per kWh. Based on the new results achieved in the 1:10 scale experiments these estimates appear conservative and the likely performance at full scale will exceed this initial performance estimates. In advancing the Technology Readiness Level (TRL) of this type of wave energy converter from 3 to 4, we find the CycWEC to exceed our initial estimates in terms of hydrodynamic performance. Once fully developed and optimized, it has the potential to not just outperform all other WEC technologies, but to also deliver power at a lower LCOE than competing conventional renewables like wind and solar. Given the large wave power resource both domestically and internationally, this technology has the potential to lead to a large improvement in our ability to produce clean electricity at affordable cost.

  12. HARMONIC FUNCTIONS TSOGTGEREL GANTUMUR

    E-print Network

    Tsogtgerel, Gantumur

    properties of harmonic functions, by using relatively elementary methods. Contents 1. Introduction 1 2. Green 7. Green's function approach 9 8. Poisson's formula 12 9. Converse to the mean value property 15 10 law of interaction between point charges was discovered experimentally by Charles Augustin de Coulomb

  13. Harmonic Maps with Potentials

    E-print Network

    Volker Branding

    2015-10-29

    We study harmonic maps from surfaces coupled to a scalar and a two-form potential, which arise as critical points of the action of the full bosonic string. We investigate several analytic and geometric properties of these maps and prove an existence result by the heat flow method.

  14. Harmonically excited orbital variations

    SciTech Connect

    Morgan, T.

    1985-08-06

    Rephrasing the equations of motion for orbital maneuvers in terms of Lagrangian generalized coordinates instead of Newtonian rectangular cartesian coordinates can make certain harmonic terms in the orbital angular momentum vector more readily apparent. In this formulation the equations of motion adopt the form of a damped harmonic oscillator when torques are applied to the orbit in a variationally prescribed manner. The frequencies of the oscillator equation are in some ways unexpected but can nonetheless be exploited through resonant forcing functions to achieve large secular variations in the orbital elements. Two cases are discussed using a circular orbit as the control case: (1) large changes in orbital inclination achieved by harmonic excitation rather than one impulsive velocity change, and (2) periodic and secular changes to the longitude of the ascending node using both stable and unstable excitation strategies. The implications of these equations are also discussed for both artificial satellites and natural satellites. For the former, two utilitarian orbits are suggested, each exploiting a form of harmonic excitation. 5 refs.

  15. Extended range harmonic filter

    NASA Technical Reports Server (NTRS)

    Jankowski, H.; Geia, A. J.; Allen, C. C.

    1973-01-01

    Two types of filters, leaky-wall and open-guide, are combined into single component. Combination gives 10 db or greater additional attenuation to fourth and higher harmonics, at expense of increasing loss of fundamental frequency by perhaps 0.05 to 0.08 db. Filter is applicable to all high power microwave transmitters, but is especially desirable for satellite transmitters.

  16. A Harmonic Motion Experiment

    ERIC Educational Resources Information Center

    Gluck, P.; Krakower, Zeev

    2010-01-01

    We present a unit comprising theory, simulation and experiment for a body oscillating on a vertical spring, in which the simultaneous use of a force probe and an ultrasonic range finder enables one to explore quantitatively and understand many aspects of simple and damped harmonic motions. (Contains 14 figures.)

  17. Introducing Simple Harmonic Motion.

    ERIC Educational Resources Information Center

    Roche, John

    2002-01-01

    Explains the origin and significance of harmonic motion which is an important topic that has wide application in the world. Describes the phenomenon by using an auxiliary circle to help illustrate the key relationships between acceleration, displacement, time, velocity, and phase. (Contains 16 references.) (Author/YDS)

  18. Stress in Harmonic Serialism

    ERIC Educational Resources Information Center

    Pruitt, Kathryn Ringler

    2012-01-01

    This dissertation proposes a model of word stress in a derivational version of Optimality Theory (OT) called Harmonic Serialism (HS; Prince and Smolensky 1993/2004, McCarthy 2000, 2006, 2010a). In this model, the metrical structure of a word is derived through a series of optimizations in which the "best" metrical foot is chosen…

  19. Generating Second Harmonics In Nonlinear Resonant Cavities

    NASA Technical Reports Server (NTRS)

    Kozlovsky, William J.; Nabors, C. David; Byer, Robert L.

    1990-01-01

    Single-axial-mode lasers pump very-low-loss doubling crystals. Important advance in making resonant generation of second harmonics possible for diode-laser-pumped solid-state lasers is recent development of monolithic nonplanar ring geometries in neodymium:yttrium aluminum garnet (Nd:YAG) lasers that produce frequency-stable single-mode outputs. Other advance is development of high-quality MgO:LiNbO3 as electro-optically nonlinear material. Series of experiments devised to improve doubling efficiency of low-power lasers, and particularly of diode-laser-pumped continuous-wave Nd:YAG lasers.

  20. Physics 116 Simple Harmonic Motion

    E-print Network

    Gustafsson, Torgny

    Physics 116 Simple Harmonic Motion Any Simple Harmonic Oscillator (SHO) has the following features Harmonic Motion (SHM). If the system is a SHO, then the following is true: MASS-SPRING system of the motion. Because of (3) above, we characterize SH oscillators based on their oscillation frequencies

  1. Bidirectional buck boost converter

    DOEpatents

    Esser, A.A.M.

    1998-03-31

    A bidirectional buck boost converter and method of operating the same allows regulation of power flow between first and second voltage sources in which the voltage level at each source is subject to change and power flow is independent of relative voltage levels. In one embodiment, the converter is designed for hard switching while another embodiment implements soft switching of the switching devices. In both embodiments, first and second switching devices are serially coupled between a relatively positive terminal and a relatively negative terminal of a first voltage source with third and fourth switching devices serially coupled between a relatively positive terminal and a relatively negative terminal of a second voltage source. A free-wheeling diode is coupled, respectively, in parallel opposition with respective ones of the switching devices. An inductor is coupled between a junction of the first and second switching devices and a junction of the third and fourth switching devices. Gating pulses supplied by a gating circuit selectively enable operation of the switching devices for transferring power between the voltage sources. In the second embodiment, each switching device is shunted by a capacitor and the switching devices are operated when voltage across the device is substantially zero. 20 figs.

  2. Bidirectional buck boost converter

    DOEpatents

    Esser, Albert Andreas Maria (Niskayuna, NY)

    1998-03-31

    A bidirectional buck boost converter and method of operating the same allows regulation of power flow between first and second voltage sources in which the voltage level at each source is subject to change and power flow is independent of relative voltage levels. In one embodiment, the converter is designed for hard switching while another embodiment implements soft switching of the switching devices. In both embodiments, first and second switching devices are serially coupled between a relatively positive terminal and a relatively negative terminal of a first voltage source with third and fourth switching devices serially coupled between a relatively positive terminal and a relatively negative terminal of a second voltage source. A free-wheeling diode is coupled, respectively, in parallel opposition with respective ones of the switching devices. An inductor is coupled between a junction of the first and second switching devices and a junction of the third and fourth switching devices. Gating pulses supplied by a gating circuit selectively enable operation of the switching devices for transferring power between the voltage sources. In the second embodiment, each switching device is shunted by a capacitor and the switching devices are operated when voltage across the device is substantially zero.

  3. Gallium phosphide energy converters

    NASA Technical Reports Server (NTRS)

    Sims, P. E.; Dinetta, L. C.; Goetz, M. A.

    1995-01-01

    Gallium phosphide (GaP) energy converters may be successfully deployed to provide new mission capabilities for spacecraft. Betavoltaic power supplies based on the conversion of tritium beta decay to electricity using GaP energy converters can supply long term low-level power with high reliability. High temperature solar cells, also based on GaP, can be used in inward-bound missions greatly reducing the need for thermal dissipation. Results are presented for GaP direct conversion devices powered by Ni-63 and compared to the conversion of light emitted by tritiarated phosphors. Leakage currents as low as 1.2 x 10(exp -17) A/sq cm have been measured and the temperature dependence of the reverse saturation current is found to have ideal behavior. Temperature dependent IV, QE, R(sub sh), and V(sub oc) results are also presented. These data are used to predict the high-temperature solar cell and betacell performance of GaP devices and suggest appropriate applications for the deployment of this technology.

  4. Enhanced second harmonic generation from coupled asymmetric plasmonic metal nanostructures

    NASA Astrophysics Data System (ADS)

    Yildiz, Bilge Can; Emre Tasgin, Mehmet; Kurtulus Abak, Musa; Coskun, Sahin; Emrah Unalan, Husnu; Bek, Alpan

    2015-12-01

    We experimentally demonstrate that two coupled metal nanostructures (MNSs), a silver nanowire and bipyramid, can produce ?30 times enhanced second harmonic generation compared to the particles alone. We develop a simple theoretical model, presenting the path interference effects in the nonlinear response of coupled MNSs. We show that the reason for such an enhancement can be the occurrence of a Fano resonance due to the coupling of the converter MNS to the long-lived mode of the attached MNS.

  5. Fluorescent radiation converter

    NASA Technical Reports Server (NTRS)

    Viehmann, W. (inventor)

    1981-01-01

    A fluorescence radiation converter is described which includes a substantially undoped optically transparent substrate and a waveshifter coating deposited on at least one portion of the substrate for absorption of radiation and conversion of fluorescent radiation. The coating is formed to substantially 1000 g/liter of a solvent, 70 to 200 g/liter of an organic polymer, and 0.2 to 25 g/liter of at least one organic fluorescent dye. The incoming incident radiation impinges on the coating. Radiation is absorbed by the fluorescent dye and is re-emitted as a longer wavelength radiation. Radiation is trapped within the substrate and is totally internally reflected by the boundary surface. Emitted radiation leaves the substrate ends to be detected.

  6. Electromagnetic wave energy converter

    NASA Technical Reports Server (NTRS)

    Bailey, R. L. (inventor)

    1973-01-01

    Electromagnetic wave energy is converted into electric power with an array of mutually insulated electromagnetic wave absorber elements each responsive to an electric field component of the wave as it impinges thereon. Each element includes a portion tapered in the direction of wave propagation to provide a relatively wideband response spectrum. Each element includes an output for deriving a voltage replica of the electric field variations intercepted by it. Adjacent elements are positioned relative to each other so that an electric field subsists between adjacent elements in response to the impinging wave. The electric field results in a voltage difference between adjacent elements that is fed to a rectifier to derive dc output power.

  7. Frequency Doubling Broadband Light in Multiple Crystals

    SciTech Connect

    ALFORD,WILLIAM J.; SMITH,ARLEE V.

    2000-07-26

    The authors compare frequency doubling of broadband light in a single nonlinear crystal with doubling in five crystals with intercrystal temporal walk off compensation, and with doubling in five crystals adjusted for offset phase matching frequencies. Using a plane-wave, dispersive numerical model of frequency doubling they study the bandwidth of the second harmonic and the conversion efficiency as functions of crystal length and fundamental irradiance. For low irradiance the offset phase matching arrangement has lower efficiency than a single crystal of the same total length but gives a broader second harmonic bandwidth. The walk off compensated arrangement gives both higher conversion efficiency and broader bandwidth than a single crystal. At high irradiance, both multicrystal arrangements improve on the single crystal efficiency while maintaining broad bandwidth.

  8. Three-dimensional simulations of harmonic radiation and harmonic lasing

    SciTech Connect

    Schmitt, M.J.; McVey, B.D.

    1990-01-01

    Characteristics of the harmonic emission from free-electron lasers (FELs) are examined in the spontaneous, coherent-spontaneous and stimulated emission regimes. The radiation at both odd and even harmonic frequencies is treated for electron beams with finite emittance and energy spread. In the spontaneous emission regime, the transverse radiation patterns including the transverse frequency dependences, are given. How this expression is modified to include energy spread and emittance is described. In the coherent-spontaneous emission and stimulated emission regimes, the interaction of the radiation fields with the electrons must be treated self-consistently. Here, a single-frequency distributed transverse source function for each electron is used in the harmonic version of the 3-D code FELEX to model the harmonic radiation. The code has recently been modified to simultaneously model the fundamental and harmonic interactions for multiple-pass oscillator simulations. These modifications facilitate the examination of FELs under various operating conditions. When the FEL is lasing at the fundamental, the evolution of the harmonic fields can be examined. This evolution is unique in the sense that the electron beam radiates at the harmonic frequencies in the presence of the harmonic radiation circulating in the cavity. As a result, enhancements of the harmonic emission can be observed. Finally, harmonic lasing can occur in cases where there is sufficient gain to overcome cavity losses and lasing at the fundamental can be suppressed. The characteristics and efficiency of these interactions are explored. 11 refs., 9 figs.

  9. B1 magnet harmonics

    SciTech Connect

    Barnes, P D

    2000-05-30

    During the B0 Overpass construction for the CDF detector at Fermilab, 33 B1 magnets were measured using a bucked tangential coil. Measurements were made on the midplane, at the centerline and at {+-} 1 inch horizontal displacement. Since the coil was only 62 inches long, measurements were made at four longitudinal positions. Because of the design of the Main Ring, it was sufficient to combine data from all positions and report the harmonic spectrum for the magnet as a whole. For modeling the Scrounge-atron, it is more useful to treat each measurement position separately. The author reports here an analysis of the harmonic spectra at each probe position, based on the original data.

  10. Superradiance of Harmonic Oscillators

    E-print Network

    Delanty, Michael; Twamley, Jason

    2011-01-01

    Superradiance, the enhanced collective emission of light from a coherent ensemble of quantum systems, has been typically studied in atomic ensembles. In this work we study the enhanced emission of energy from coherent ensembles of harmonic oscillators. We show that it should be possible to observe harmonic oscillator superradiance in a variety of physical platforms such as waveguide arrays in integrated photonics and resonator arrays in circuit QED. We find general conditions specifying when emission is superradiant and subradiant and find that superradiant, subradiant and dark states take the form of multimode squeezed coherent states and highly entangled multimode Fock states. The intensity, two-mode correlations and fraction of quanta trapped in the system after decay are calculated for a range of initial states including multimode Fock, squeezed, coherent and thermal states. In order to explore these effects, the Law and Eberly protocol [C. K. Law and J. H. Eberly, Phys. Rev. Lett. 76, 1055 (1996)] is gen...

  11. Quantum Damped Harmonic Oscillator

    E-print Network

    Kazuyuki Fujii

    2012-09-07

    In this chapter we treat the quantum damped harmonic oscillator, and study mathematical structure of the model, and construct general solution with any initial condition, and give a quantum counterpart in the case of taking coherent state as an initial condition. This is a simple and good model of Quantum Mechanics with dissipation which is important to understand real world, and readers will get a powerful weapon for Quantum Physics.

  12. Second-harmonic generation from hyperbolic plasmonic nanorod metamaterial slab

    E-print Network

    Marino, Giuseppe; Krasavin, Alexey V; Ginzburg, Pavel; Olivier, Nicolas; Wurtz, Gregory A; Zayats, Anatoly V

    2015-01-01

    Hyperbolic plasmonic metamaterials provide numerous opportunities for designing unusual linear and nonlinear optical properties. We show that the modal overlap of fundamental and second-harmonic light in an anisotropic plasmonic metamaterial slab results in the broadband enhancement of radiated second-harmonic intensity by up to 2 and 11 orders of magnitudes for TM- and TE-polarized fundamental light, respectively, compared to a smooth Au film under TM-polarised illumination. The results open up possibilities to design tuneable frequency-doubling metamaterial with the goal to overcome limitations associated with classical phase matching conditions in thick nonlinear crystals.

  13. Surface plasma wave assisted second harmonic generation of laser over a metal film

    SciTech Connect

    Chauhan, Santosh; Parashar, J.

    2015-01-15

    Second harmonic generation of laser mode converted surface plasma wave (SPW) over a corrugated metal film is studied. The laser, impinged on the metal film, under attenuated total reflection configuration, excites SPW over the metal–vacuum interface. The excited SPW extends over a much wider surface area than the laser spot cross-section. It exerts a second harmonic ponderomotive force on metal electrons, imparting them velocity that beats with the surface ripple to produce a nonlinear current, driving resonant second harmonic surface plasma wave.

  14. Impact of sideband harmonic pattern on losses in laminated non-oriented steel

    NASA Astrophysics Data System (ADS)

    Sagarduy, Juan; Moses, Anthony J.

    Losses in laminated non-oriented steel under the effect of two high harmonic clusters, caused by voltage excitation typical of two-level pulse-with-modulated (PWM) DC-link and space-vector modulated (SVM) matrix converters, were analyzed. The predicting method proposed, which incorporates anisotropy of loss Ka and grain size gs, describes the magnetizing process within the steel by the means of Poisson statistical distribution. Results are then compared to losses determined by Bertotti's model. The two methods confirmed that spreading of sideband harmonics in the kilohertz range can reduce harmonic losses by up to 40% at low power frequencies.

  15. Self-powered microthermionic converter

    DOEpatents

    Marshall, Albert C.; King, Donald B.; Zavadil, Kevin R.; Kravitz, Stanley H.; Tigges, Chris P.; Vawter, Gregory A.

    2004-08-10

    A self-powered microthermionic converter having an internal thermal power source integrated into the microthermionic converter. These converters can have high energy-conversion efficiencies over a range of operating temperatures. Microengineering techniques are used to manufacture the converter. The utilization of an internal thermal power source increases potential for mobility and incorporation into small devices. High energy efficiency is obtained by utilization of micron-scale interelectrode gap spacing. Alpha-particle emitting radioisotopes can be used for the internal thermal power source, such as curium and polonium isotopes.

  16. Efficient broadband second-harmonic generation by dispersive achromatic nonlinear conversion using only prisms

    SciTech Connect

    Richman, B.A.; Bisson, S.E.; Trebino, R.

    1997-12-01

    Using a lossless dispersive apparatus consisting of six prisms, optimized to match a second-harmonic crystal phase-matching angle vs. wavelength to second order, we efficiently doubled tunable fundamental light near 660 nm over a range of 80 nm using a 4-mm-long type-I {beta}-Barium Borate (BBO) crystal. Another lossless set of six prisms after the crystal realigned the propagation directions of the various second-harmonic frequencies to be collinear to within 1/4 spot diameter in position and 200 {mu}rad in angle. The measured conversion efficiency of a 40-mJ, 5-ns fundamental pulse was 10%.

  17. Proposed electromagnetic wave energy converter

    NASA Technical Reports Server (NTRS)

    Bailey, R. L.

    1973-01-01

    Device converts wave energy into electric power through array of insulated absorber elements responsive to field of impinging electromagnetic radiation. Device could also serve as solar energy converter that is potentially less expensive and fragile than solar cells, yet substantially more efficient.

  18. Algal Supply System Design - Harmonized Version

    SciTech Connect

    Abodeely, Jared; Stevens, Daniel; Ray, Allison; Newby, Deborah; Schaller, Kastli

    2013-03-01

    The objective of this design report is to provide an assessment of current technologies used for production, dewatering, and converting microalgae cultivated in open-pond systems to biofuel. The original draft design was created in 2011 and has subsequently been brought into agreement with the DOE harmonized model. The design report extends beyond this harmonized model to discuss some of the challenges with assessing algal production systems, including the ability to (1) quickly assess alternative algal production system designs, (2) assess spatial and temporal variability, and (3) perform large-scale assessments considering multiple scenarios for thousands of potential sites. The Algae Logistics Model (ALM) was developed to address each of these limitations of current modeling efforts to enable assessment of the economic feasibility of algal production systems across the United States. The (ALM) enables (1) dynamic assessments using spatiotemporal conditions, (2) exploration of algal production system design configurations, (3) investigation of algal production system operating assumptions, and (4) trade-off assessments with technology decisions and operating assumptions. The report discusses results from the ALM, which is used to assess the baseline design determined by harmonization efforts between U.S. DOE national laboratories. Productivity and resource assessment data is provided by coupling the ALM with the Biomass Assessment Tool developed at PNNL. This high-fidelity data is dynamically passed to the ALM and used to help better understand the impacts of spatial and temporal constraints on algal production systems by providing a cost for producing extracted algal lipids annually for each potential site.

  19. Why plasma harmonics?

    NASA Astrophysics Data System (ADS)

    Ganeev, R. A.

    2015-09-01

    We discuss the emergence of interest in the high-order harmonic generation (HHG) of ultrashort pulses propagated through laser-produced plasmas. It is shown that, during the last few years, substantial amendments of plasma HHG allowed in some cases the characteristics of gas HHG to be surpassed. The attractiveness of a new approach in coherent extreme ultraviolet radiation generation is demonstrated, which can also be used as a tool for laser-ablation-induced HHG spectroscopy of a giant class of solids. We present general ideas and prospects for this relatively new field of nonlinear optics.

  20. Hyperincursive discrete harmonic oscillator

    NASA Astrophysics Data System (ADS)

    Antippa, Adel F.; Dubois, Daniel M.

    2008-03-01

    The hyperincursive algorithm for the discrete harmonic oscillator is perfectly stable and energy conserving. By identifying the natural parameters of the system, we transform the algorithm into a normal formalism based on dynamic equations of motion. We find that the simultaneous difference equations of motion are complex, that the natural parameters are classical analogs of the quantum mechanical creation and annihilation operators, and that the solution is of utmost simplicity. The methodology is applicable to any dynamical system, has conceptual importance for discrete physics, and practical utility for numerical simulations.

  1. Next generation data harmonization

    NASA Astrophysics Data System (ADS)

    Armstrong, Chandler; Brown, Ryan M.; Chaves, Jillian; Czerniejewski, Adam; Del Vecchio, Justin; Perkins, Timothy K.; Rudnicki, Ron; Tauer, Greg

    2015-05-01

    Analysts are presented with a never ending stream of data sources. Often, subsets of data sources to solve problems are easily identified but the process to align data sets is time consuming. However, many semantic technologies do allow for fast harmonization of data to overcome these problems. These include ontologies that serve as alignment targets, visual tools and natural language processing that generate semantic graphs in terms of the ontologies, and analytics that leverage these graphs. This research reviews a developed prototype that employs all these approaches to perform analysis across disparate data sources documenting violent, extremist events.

  2. High resolution switching mode inductance-to-frequency converter with temperature compensation.

    PubMed

    Matko, Vojko; Milanovi?, Miro

    2014-01-01

    This article proposes a novel method for the temperature-compensated inductance-to-frequency converter with a single quartz crystal oscillating in the switching oscillating circuit to achieve better temperature stability of the converter. The novelty of this method lies in the switching-mode converter, the use of additionally connected impedances in parallel to the shunt capacitances of the quartz crystal, and two inductances in series to the quartz crystal. This brings a considerable reduction of the temperature influence of AT-cut crystal frequency change in the temperature range between 10 and 40 °C. The oscillator switching method and the switching impedances connected to the quartz crystal do not only compensate for the crystal's natural temperature characteristics but also any other influences on the crystal such as ageing as well as from other oscillating circuit elements. In addition, the method also improves frequency sensitivity in inductance measurements. The experimental results show that through high temperature compensation improvement of the quartz crystal characteristics, this switching method theoretically enables a 2 pH resolution. It converts inductance to frequency in the range of 85-100 µH to 2-560 kHz. PMID:25325334

  3. High Resolution Switching Mode Inductance-to-Frequency Converter with Temperature Compensationti

    PubMed Central

    Matko, Vojko; Milanovi?, Miro

    2014-01-01

    This article proposes a novel method for the temperature-compensated inductance-to-frequency converter with a single quartz crystal oscillating in the switching oscillating circuit to achieve better temperature stability of the converter. The novelty of this method lies in the switching-mode converter, the use of additionally connected impedances in parallel to the shunt capacitances of the quartz crystal, and two inductances in series to the quartz crystal. This brings a considerable reduction of the temperature influence of AT-cut crystal frequency change in the temperature range between 10 and 40 °C. The oscillator switching method and the switching impedances connected to the quartz crystal do not only compensate for the crystal's natural temperature characteristics but also any other influences on the crystal such as ageing as well as from other oscillating circuit elements. In addition, the method also improves frequency sensitivity in inductance measurements. The experimental results show that through high temperature compensation improvement of the quartz crystal characteristics, this switching method theoretically enables a 2 pH resolution. It converts inductance to frequency in the range of 85–100 ?H to 2–560 kHz. PMID:25325334

  4. Damped quantum harmonic oscillator

    E-print Network

    A. Isar; A. Sandulescu

    2006-02-17

    In the framework of the Lindblad theory for open quantum systems the damping of the harmonic oscillator is studied. A generalization of the fundamental constraints on quantum mechanical diffusion coefficients which appear in the master equation for the damped quantum oscillator is presented; the Schr\\"odinger and Heisenberg representations of the Lindblad equation are given explicitly. On the basis of these representations it is shown that various master equations for the damped quantum oscillator used in the literature are particular cases of the Lindblad equation and that the majority of these equations are not satisfying the constraints on quantum mechanical diffusion coefficients. Analytical expressions for the first two moments of coordinate and momentum are also obtained by using the characteristic function of the Lindblad master equation. The master equation is transformed into Fokker-Planck equations for quasiprobability distributions. A comparative study is made for the Glauber $P$ representation, the antinormal ordering $Q$ representation and the Wigner $W$ representation. It is proven that the variances for the damped harmonic oscillator found with these representations are the same. By solving the Fokker-Planck equations in the steady state, it is shown that the quasiprobability distributions are two-dimensional Gaussians with widths determined by the diffusion coefficients. The density matrix is represented via a generating function, which is obtained by solving a time-dependent linear partial differential equation derived from the master equation. Illustrative examples for specific initial conditions of the density matrix are provided.

  5. Harmonic generation at high intensities

    SciTech Connect

    Schafer, K.J.; Krause, J.L.; Kulander, K.C.

    1993-06-01

    Atomic electrons subject to intense laser fields can absorb many photons, leading either to multiphoton ionization or the emission of a single, energetic photon which can be a high multiple of the laser frequency. The latter process, high-order harmonic generation, has been observed experimentally using a range of laser wavelengths and intensities over the past several years. Harmonic generation spectra have a generic form: a steep decline for the low order harmonics, followed by a plateau extending to high harmonic order, and finally an abrupt cutoff beyond which no harmonics are discernible. During the plateau the harmonic production is a very weak function of the process order. Harmonic generation is a promising source of coherent, tunable radiation in the XUV to soft X-ray range which could have a variety of scientific and possibly technological applications. Its conversion from an interesting multiphoton phenomenon to a useful laboratory radiation source requires a complete understanding of both its microscopic and macroscopic aspects. We present some recent results on the response of single atoms at intensities relevant to the short pulse experiments. The calculations employ time-dependent methods, which we briefly review in the next section. Following that we discuss the behavior of the harmonics as a function of laser intensity. Two features are notable: the slow scaling of the harmonic intensities with laser intensity, and the rapid variation in the phase of the individual harmonics with respect to harmonic order. We then give a simple empirical formula that predicts the extent of the plateau for a given ionization potential, wavelength and intensity.

  6. Tunable middle infrared radiation with HgGa 2S 4 crystal

    NASA Astrophysics Data System (ADS)

    Das, S.; Chatterjee, U.; Ghosh, C.; Gangopadhyay, S.; Andreev, Yu. M.; Lanskii, G.; Badikov, V. V.

    2006-03-01

    Optical properties of orange phased HgGa2S4 crystal is investigated. Generation of tunable middle infrared radiation by second harmonic of tunable CO2 laser radiation has been demonstrated. Second harmonic conversion efficiency with respect to other infrared crystal has also been discussed.

  7. Radiant energy to electric energy converter

    NASA Technical Reports Server (NTRS)

    Sher, Arden (Inventor)

    1980-01-01

    Radiant energy is converted into electric energy by irradiating a capacitor including an ionic dielectric. The dielectric is a sintered crystal superionic conductor, e.g., lanthanum trifluoride, lanthanum trichloride, or silver bromide, so that a multiplicity of crystallites exist between electrodes of the capacitor. The radiant energy cyclically irradiates the dielectric so that the dielectric exhibits a cyclic photocapacitive like effect. Adjacent crystallites have abutting surfaces that enable the crystallites to effectively form a multiplicity of series capacitor elements between the electrodes. Each of the capacitor elements has a dipole layer only on or near its surface. The capacitor is initially charged to a voltage just below the dielectric breakdown voltage by connecting it across a DC source causing a current to flow through a charging resistor to the dielectric. The device can be utilized as a radiant energy detector or as a solar energy cell.

  8. MODEL HARMONIZATION POTENTIAL AND BENEFITS

    EPA Science Inventory

    The IPCS Harmonization Project, which is currently ongoing under the auspices of the WHO, in the context of chemical risk assessment or exposure modeling, does not imply global standardization. Instead, harmonization is thought of as an effort to strive for consistency among appr...

  9. Harmonic Series Meets Fibonacci Sequence

    ERIC Educational Resources Information Center

    Chen, Hongwei; Kennedy, Chris

    2012-01-01

    The terms of a conditionally convergent series may be rearranged to converge to any prescribed real value. What if the harmonic series is grouped into Fibonacci length blocks? Or the harmonic series is arranged in alternating Fibonacci length blocks? Or rearranged and alternated into separate blocks of even and odd terms of Fibonacci length?

  10. Diamond turning of L-arginine phosphate, a new organic crystal

    SciTech Connect

    Fuchs, B.A.; Syn, K.; Velsko, S.P. )

    1989-10-15

    We have demonstrated that single point diamond turning can be used to generate high optical quality finished surfaces on a new organic nonlinear crystal, L-arginine phosphate (LAP). The proper choice of cutting conditions can produce surfaces with {lt}5-A rms local roughness. Local softening or melting near the cutting tool tip may play a key role in the machining process by ensuring that material is removed by ductile cutting rather than brittle fracture. At the same time, the low melting temperature of LAP makes lubrication and cooling especially important to prevent extensive melting and tool fouling. In spite of the presence of a weak cleavage plane in LAP, the surface quality is relatively insensitive to crystallographic orientation. Tool wear is apparently negligible, so that surface flatness is governed by the stability of the diamond turning machine. These results suggest that it may be possible to fabricate large aperture LAP harmonic converters for use in inertial confinement fusion lasers.

  11. Second harmonic generation from ZnO films and nanostructures

    NASA Astrophysics Data System (ADS)

    Larciprete, Maria Cristina; Centini, Marco

    2015-09-01

    Zinc oxide ZnO is a n-type semiconductor having a wide direct band gap (3.37 eV) as well as a non-centrosymmetric crystal structure resulting from hexagonal wurtzite phase. Its wide transparency range along with its second order nonlinear optical properties make it a promising material for efficient second harmonic generation processes and nonlinear optical applications in general. In this review, we present an extensive analysis of second harmonic generation from ZnO films and nanostructures. The literature survey on ZnO films will include some significant features affecting second harmonic generation efficiency, as crystalline structure, film thickness, surface contributes, and doping. In a different section, the most prominent challenges in harmonic generation from ZnO nanostructures are discussed, including ZnO nanowires, nanorods, and nanocrystals, to name a few. Similarly, the most relevant works regarding third harmonic generation from ZnO films and nanostructures are separately addressed. Finally, the conclusion part summarizes the current standing of published values for the nonlinear optical coefficients and for ZnO films and nanostructures, respectively.

  12. Wind/water energy converter

    NASA Technical Reports Server (NTRS)

    Paulkovich, J.

    1979-01-01

    Device will convert wind, water, tidal or wave energy into electrical or mechanical energy. Is comprised of windmill-like paddles or blades synchronously geared to orient themselves to wind direction for optimum energy extraction.

  13. Coherence convertibility for mixed states

    E-print Network

    Xiaofei Qi; Zhaofang Bai; Shuanping Du

    2015-05-27

    In this paper, by providing a class of coherence measures in finite dimensional systems, a sufficient and necessary condition for the existence of coherence transformations that convert one probability distribution of any pure states into another one is obtained.

  14. Radiation tolerant power converter controls

    NASA Astrophysics Data System (ADS)

    Todd, B.; Dinius, A.; King, Q.; Uznanski, S.

    2012-11-01

    The Large Hadron Collider (LHC) at the European Organisation for Nuclear Research (CERN) is the world's most powerful particle collider. The LHC has several thousand magnets, both warm and super-conducting, which are supplied with current by power converters. Each converter is controlled by a purpose-built electronic module called a Function Generator Controller (FGC). The FGC allows remote control of the power converter and forms the central part of a closed-loop control system where the power converter voltage is set, based on the converter output current and magnet-circuit characteristics. Some power converters and FGCs are located in areas which are exposed to beam-induced radiation. There are numerous radiation induced effects, some of which lead to a loss of control of the power converter, having a direct impact upon the accelerator's availability. Following the first long shut down (LS1), the LHC will be able to run with higher intensity beams and higher beam energy. This is expected to lead to significantly increased radiation induced effects in materials close to the accelerator, including the FGC. Recent radiation tests indicate that the current FGC would not be sufficiently reliable. A so-called FGClite is being designed to work reliably in the radiation environment in the post-LS1 era. This paper outlines the concepts of power converter controls for machines such as the LHC, introduces the risks related to radiation and a radiation tolerant project flow. The FGClite is then described, with its key concepts and challenges: aiming for high reliability in a radiation field.

  15. Galilean covariant harmonic oscillator

    NASA Technical Reports Server (NTRS)

    Horzela, Andrzej; Kapuscik, Edward

    1993-01-01

    A Galilean covariant approach to classical mechanics of a single particle is described. Within the proposed formalism, all non-covariant force laws defining acting forces which become to be defined covariantly by some differential equations are rejected. Such an approach leads out of the standard classical mechanics and gives an example of non-Newtonian mechanics. It is shown that the exactly solvable linear system of differential equations defining forces contains the Galilean covariant description of harmonic oscillator as its particular case. Additionally, it is demonstrated that in Galilean covariant classical mechanics the validity of the second Newton law of dynamics implies the Hooke law and vice versa. It is shown that the kinetic and total energies transform differently with respect to the Galilean transformations.

  16. Synchronous Discrete Harmonic Oscillator

    SciTech Connect

    Antippa, Adel F.; Dubois, Daniel M.

    2008-10-17

    We introduce the synchronous discrete harmonic oscillator, and present an analytical, numerical and graphical study of its characteristics. The oscillator is synchronous when the time T for one revolution covering an angle of 2{pi} in phase space, is an integral multiple N of the discrete time step {delta}t. It is fully synchronous when N is even. It is pseudo-synchronous when T/{delta}t is rational. In the energy conserving hyperincursive representation, the phase space trajectories are perfectly stable at all time scales, and in both synchronous and pseudo-synchronous modes they cycle through a finite number of phase space points. Consequently, both the synchronous and the pseudo-synchronous hyperincursive modes of time-discretization provide a physically realistic and mathematically coherent, procedure for dynamic, background independent, discretization of spacetime. The procedure is applicable to any stable periodic dynamical system, and provokes an intrinsic correlation between space and time, whereby space-discretization is a direct consequence of background-independent time-discretization. Hence, synchronous discretization moves the formalism of classical mechanics towards that of special relativity. The frequency of the hyperincursive discrete harmonic oscillator is ''blue shifted'' relative to its continuum counterpart. The frequency shift has the precise value needed to make the speed of the system point in phase space independent of the discretizing time interval {delta}t. That is the speed of the system point is the same on the polygonal (in the discrete case) and the circular (in the continuum case) phase space trajectories.

  17. Passively Q-switched Nd:YAG/Cr4+:YAG bonded crystal microchip laser operating at 1112??nm and its application for second-harmonic generation.

    PubMed

    Fu, S G; Ouyang, X Y; Liu, X J

    2015-10-10

    A passively Q-switched Nd:YAG/Cr4+:YAG microchip laser operating at 1112 nm is demonstrated. Under a pump power of 5.5 W, a maximum average output power of 623 mW was obtained with T=6% output coupler, corresponding to an optical-to-optical conversion efficiency of 11.3% and a slope efficiency of 19.5%. The minimum pulse width was 2.8 ns, the pulse energy and peak power were 39.3 ?J and 14 kW, respectively. Additionally, based on the 1112 nm laser, a 230 mW 556 nm green-yellow laser was achieved within an LBO crystal. PMID:26479822

  18. Analysis of harmonic spline gravity models for Venus and Mars

    NASA Technical Reports Server (NTRS)

    Bowin, Carl

    1986-01-01

    Methodology utilizing harmonic splines for determining the true gravity field from Line-Of-Sight (LOS) acceleration data from planetary spacecraft missions was tested. As is well known, the LOS data incorporate errors in the zero reference level that appear to be inherent in the processing procedure used to obtain the LOS vectors. The proposed method offers a solution to this problem. The harmonic spline program was converted from the VAX 11/780 to the Ridge 32C computer. The problem with the matrix inversion routine that improved inversion of the data matrices used in the Optimum Estimate program for global Earth studies was solved. The problem of obtaining a successful matrix inversion for a single rev supplemented by data for the two adjacent revs still remains.

  19. Solid oxygen as converter for the production of ultra-cold neutrons

    E-print Network

    A. Frei; F. Böhle; R. Bozhanova; E. Gutsmiedl; T. Huber; J. Klenke; S. Paul; S. Wlokka

    2011-07-11

    We have investigated solid oxygen as a converter material for the production of ultra-cold neutrons. In a first series of experiments the crystal preparation was examined. An optically semi-transparent solid $\\alpha$-oxygen crystal has been prepared. In a second series of experiments such a crystal prepared indentically as in the first series of experiments has been exposed to the cold neutron flux of the MEPHISTO beam line of the FRM II. Ultra-cold neutrons produced inside the oxygen crystal have been extracted and the count rates have been measured at different converter temperatures. The results of these measurements give a clear signal of the superthermal UCN production mechanism in $\\alpha$-oxygen. The mean free loss length of UCN inside the crystal at a temperature of 5\\,K was determined to be in the order of $20\\,\\mathrm{cm}$.

  20. Synthesis, crystal growth and physical characterizations of organic nonlinear optical crystal: Ammonium hydrogen L-malate.

    PubMed

    Boopathi, K; Ramasamy, P

    2014-05-21

    An organic nonlinear optical crystal ammonium hydrogen l-malate (AHM) has been synthesized. Single crystals of AHM have successfully been grown by the slow evaporation solution method. Optically clear single crystals having dimensions up to 23×9×4mm(3) have been grown. Single crystal X-ray diffraction study confirms that the AHM crystallizes in orthorhombic crystal system with space group P212121. The powder X-ray diffraction pattern of the grown crystal has been recorded. FT-IR spectrum was recorded to identify the various functional groups of AHM. The UV-vis-NIR transmission was analyzed for grown crystal. Thermal analysis was performed to find out thermal stability of the compound. Vickers microhardness measurements were carried and also work hardening coefficient has been found. The crystalline perfection of the grown crystal has been analyzed by HRXRD measurements. The second harmonic efficiency of AHM was found to be 1.2 times that of KDP. PMID:24583470

  1. Relativistic harmonic oscillator revisited

    SciTech Connect

    Bars, Itzhak

    2009-02-15

    The familiar Fock space commonly used to describe the relativistic harmonic oscillator, for example, as part of string theory, is insufficient to describe all the states of the relativistic oscillator. We find that there are three different vacua leading to three disconnected Fock sectors, all constructed with the same creation-annihilation operators. These have different spacetime geometric properties as well as different algebraic symmetry properties or different quantum numbers. Two of these Fock spaces include negative norm ghosts (as in string theory), while the third one is completely free of ghosts. We discuss a gauge symmetry in a worldline theory approach that supplies appropriate constraints to remove all the ghosts from all Fock sectors of the single oscillator. The resulting ghost-free quantum spectrum in d+1 dimensions is then classified in unitary representations of the Lorentz group SO(d,1). Moreover, all states of the single oscillator put together make up a single infinite dimensional unitary representation of a hidden global symmetry SU(d,1), whose Casimir eigenvalues are computed. Possible applications of these new results in string theory and other areas of physics and mathematics are briefly mentioned.

  2. Crystallization Screens Crystallization Optimization

    E-print Network

    Lebendiker, Mario

    a local start-up company into an established business with a glo- bal distribution network. We deliver crystallization. High quality reagents and excellent customer service help the researcher to find tailor of tools for protein crystallization. High quality reagents and excellent customer service help

  3. Echo-Enabled Harmonic Generation

    SciTech Connect

    Stupakov, Gennady

    2010-08-25

    A recently proposed concept of the Echo-Enabled Harmonic Generation (EEHG) FEL uses two laser modulators in combination with two dispersion sections to generate a high-harmonic density modulation in a relativistic beam. This seeding technique holds promise of a one-stage soft x-ray FEL that radiates not only transversely but also longitudinally coherent pulses. Currently, an experimental verification of the concept is being conducted at the SLAC National Accelerator Laboratory aimed at the demonstration of the EEHG.

  4. Azimuthal anisotropy: The higher harmonics

    SciTech Connect

    Poskanzer, Arthur M.; STAR Collaboration

    2004-03-12

    We report the first observations of the fourth harmonic (v{sub 4}) in the azimuthal distribution of particles at RHIC. The measurement was done taking advantage of the large elliptic flow generated at RHIC. The integrated v{sub 4} is about a factor of 10 smaller than v{sub 2}. For the sixth (v{sub 6}) and eighth (v{sub 8}) harmonics upper limits on the magnitudes are reported.

  5. Echo-Enabled Harmonic Generation

    SciTech Connect

    Stupakov, Gennady; /SLAC

    2012-06-28

    A recently proposed concept of the Echo-Enabled Harmonic Generation (EEHG) FEL uses two laser modulators in combination with two dispersion sections to generate a high-harmonic density modulation in a relativistic beam. This seeding technique holds promise of a one-stage soft x-ray FEL that radiates not only transversely but also longitudinally coherent pulses. Currently, an experimental verification of the concept is being conducted at the SLAC National Accelerator Laboratory aimed at the demonstration of the EEHG.

  6. Relation of squeezed states between damped harmonic and simple harmonic oscillators

    NASA Technical Reports Server (NTRS)

    Um, Chung-In; Yeon, Kyu-Hwang; George, Thomas F.; Pandey, Lakshmi N.

    1993-01-01

    The minimum uncertainty and other relations are evaluated in the framework of the coherent states of the damped harmonic oscillator. It is shown that the coherent states of the damped harmonic oscillator are the squeezed coherent states of the simple harmonic oscillator. The unitary operator is also constructed, and this connects coherent states with damped harmonic and simple harmonic oscillators.

  7. High efficiency thermionic converter studies

    NASA Technical Reports Server (NTRS)

    Huffman, F. N.; Sommer, A. H.; Balestra, C. L.; Briere, T. R.; Lieb, D.; Oettinger, P. E.; Goodale, D. B.

    1977-01-01

    Research in thermionic energy conversion technology is reported. The objectives were to produce converters suitable for use in out of core space reactors, radioisotope generators, and solar satellites. The development of emitter electrodes that operate at low cesium pressure, stable low work function collector electrodes, and more efficient means of space charge neutralization were investigated to improve thermionic converter performance. Potential improvements in collector properties were noted with evaporated thin film barium oxide coatings. Experiments with cesium carbonate suggest this substance may provide optimum combinations of cesium and oxygen for thermionic conversion.

  8. High-order harmonic generation in plasmas from nanoparticle and mixed metal targets at 1-kHz repetition rate

    NASA Astrophysics Data System (ADS)

    Wöstmann, Michael; Redkin, Pavel V.; Zheng, Jiaan; Witte, Henrik; Ganeev, Rashid A.; Zacharias, Helmut

    2015-07-01

    High-order harmonic generation in laser-produced plasmas from nanoparticle and mixed metal targets is studied using a femtosecond Ti:sapphire laser operating at 1-kHz repetition rate. Mixed plasmas from brass and plasmas from nanoparticles (Al, carbon) are investigated and compared to their monatomic counterparts of Zn, Cu, and Al. The dependence on the delay between the heating ablation pulse and the driving converting pulse is studied for a light (carbon) and a heavy atom (silver) target. Further, we report on a comparative measurement of the efficiencies and the photon flux from argon gas harmonics and carbon plasma harmonics. For our conditions, the 13th harmonic is generated in a carbon plasma with an efficiency of ? = 5.3 × 10-7 and yields a flux of about 9.8 × 1010 photons s-1, about 40 % higher than the corresponding harmonic flux in Ar gas under otherwise identical conditions.

  9. Half-Bridge Type Immittance Converter

    NASA Astrophysics Data System (ADS)

    Irie, Hisaichi; Takayama, Nobuyuki

    The immittance converter has the input impedance that is proportional to the admittance of the load connected across output terminals. Therefore, in this converter, the output current is proportional to the input voltage and the input current is proportional to the output voltage. Consequently, it converts a constant voltage source into a constant current source and a constant current source into a constant voltage source. In this paper, we propose a new type immittance converter, named half-bridge type immittance converter, consists of a tapped transformer and a pair of L, C. The new immittance converter is developed from the hybrid type immittance converter, and has almost same characteristics of that.

  10. Averaged DC Link Voltage Control and its Compensation Method of Output Voltage Error of Direct AC/AC Converters

    NASA Astrophysics Data System (ADS)

    Shizu, Keiichiro; Azuma, Satoshi

    Direct AC/AC converters have been investigated for miniaturization, high efficiency and harmonics reduction of mains current. These converters are classified into direct switch AC/AC converter (matrix converter) and PWM rectifier-inverter AC/AC converter in view of each circuit configuration. Firstly, this paper proposes averaged DC link voltage control of direct AC/AC converters, and details of the control method are described. In this method, averaged DC link voltage is derived from two selecting phase-to-phase mains voltages and the duty ratio of these selecting voltages for each modulation period. The averaged DC link voltage is used for the calculation of modulation index at each output phase. Secondly, this paper discusses a compensation method of output voltage error from commutation in case of applying the averaged DC link voltage control. Generally, the output voltage error occurs in direct AC/AC converters from commutation sequence consisting of two or four steps. And the compensation method reduces the error by analyzing commutation pattern created by the averaged DC link voltage control. Finally, experimental results are demonstrated, and it is confirmed that the harmonic distortion of the output current is efficiently reduced with the proposed compensation method.

  11. Parametric study of laser photovoltaic energy converters

    NASA Technical Reports Server (NTRS)

    Walker, G. H.; Heinbockel, J. H.

    1987-01-01

    Photovoltaic converters are of interest for converting laser power to electrical power in a space-based laser power system. This paper describes a model for photovoltaic laser converters and the application of this model to a neodymium laser silicon photovoltaic converter system. A parametric study which defines the sensitivity of the photovoltaic parameters is described. An optimized silicon photovoltaic converter has an efficiency greater than 50 percent for 1000 W/sq cm of neodymium laser radiation.

  12. Charge-pump voltage converter

    DOEpatents

    Brainard, John P. (Albuquerque, NM); Christenson, Todd R. (Albuquerque, NM)

    2009-11-03

    A charge-pump voltage converter for converting a low voltage provided by a low-voltage source to a higher voltage. Charge is inductively generated on a transfer rotor electrode during its transit past an inductor stator electrode and subsequently transferred by the rotating rotor to a collector stator electrode for storage or use. Repetition of the charge transfer process leads to a build-up of voltage on a charge-receiving device. Connection of multiple charge-pump voltage converters in series can generate higher voltages, and connection of multiple charge-pump voltage converters in parallel can generate higher currents. Microelectromechanical (MEMS) embodiments of this invention provide a small and compact high-voltage (several hundred V) voltage source starting with a few-V initial voltage source. The microscale size of many embodiments of this invention make it ideally suited for MEMS- and other micro-applications where integration of the voltage or charge source in a small package is highly desirable.

  13. Converting Petroleum Coke to Electricity 

    E-print Network

    Pavone, A.

    1992-01-01

    is the coking unit, more cokers are being built, and existing cokers are being operated to maximum capacity utilization. SRI recently completed an assignment for a refiner interested in converting the by-product fluid coke from his unit to electricity...

  14. CONVERTING ABANDONED LANDS TO CROPLAND

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Because of economic conditions, areas of cropland in Ukraine have been left unused for several years. These abandoned lands are now infested with perennial weeds. Producers are interested in converting these lands back to cropland with no-till systems to preserve soil benefits gained by not tillin...

  15. Efficient broadband second-harmonic generation by dispersive achromatic nonlinear conversion using only prisms

    SciTech Connect

    Richman, B.A.; Bisson, S.E.; Trebino, R.

    1998-04-01

    Using a lossless dispersive apparatus consisting of six prisms, optimized to match a second-harmonic crystal phase-matching angle versus wavelength to second order, we efficiently doubled tunable fundamental light near 660nm over a range of 80nm, using a 4-mm-long type I {beta}-barium borate crystal without tuning the crystal angle. Another set of six prisms after the crystal realigned the propagation directions of the various second-harmonic frequencies to be collinear to within 1/4 spot diameter in position and 200 {mu}rad in angle. The measured conversion efficiency of a 40-mJ, 5-ns fundamental pulse was 10{percent}. {copyright} {ital 1998} {ital Optical Society of America}

  16. Characteristics of an equidistant firing system in 12-pulse converter bridges for HVDC

    NASA Astrophysics Data System (ADS)

    Juslin, K.; Laiho, Y.; Vauhkonen, V.

    1981-05-01

    The construction of a simulation model for a twelve pulse HVDC transmission line is discussed. The realized equidistant pulse phase control system is suitable for the operation in weak or strongly unbalanced ac systems from the viewpoint of harmonic instability and suppression of abnormal harmonic currents. The phase of the firing pulses is proportional to an absolute level of the control voltage, and the operation with a constant control angle is possible. The synchronism with an ac system is guaranteed by a phase-locked loop, not by the main control loop. Thus quick and ideal response is obtaind. The measurements show that this kind of grid conrol is stable also in many faulty conditions. Abnormal harmonic generation of the converter is very small compared with the traditional systems by utilizing this kind of grid control.

  17. Mesoscopic harmonic mapping of electromechanical response in a relaxor ferroelectric

    NASA Astrophysics Data System (ADS)

    Vasudevan, Rama K.; Zhang, Shujun; Ding, Jilai; Okatan, M. Baris; Jesse, Stephen; Kalinin, Sergei V.; Bassiri-Gharb, Nazanin

    2015-06-01

    Relaxor-ferroelectrics are renowned for very large electrostrictive response, enabling applications in transducers, actuators, and energy harvesters. However, insight into the dissimilar contributions (polarization rotation, wall motion) to the electromechanical response from electrostrictive strain, and separation of such contributions from linear piezoelectric response are largely ignored at the mesoscale. Here, we employ a band-excitation piezoresponse force microscopy (BE-PFM) technique to explore the first and second harmonics of the piezoelectric response in prototypical relaxor-ferroelectric 0.72Pb(Mg1/3Nb2/3)O3-0.28PbTiO3 (PMN-0.28PT) single crystals. Third order polynomial fitting of the second harmonic reveals considerable correlation between the cubic coefficient map and the first harmonic piezoresponse amplitude. These results are interpreted under a modified Rayleigh framework, as evidence for domain wall contributions to enhanced electromechanical response. These studies highlight the contribution of domain wall motion in the electromechanical response of relaxor ferroelectrics, and further show the utility of harmonic BE-PFM measurements in spatially mapping the mesoscopic variability inherent in disordered systems.

  18. Potentials of LiGa(S 1-xSe x) 2 mixed crystals for optical frequency conversion

    NASA Astrophysics Data System (ADS)

    Huang, J.-J.; Atuchin, V. V.; Andreev, Yu. M.; Lanskii, G. V.; Pervukhina, N. V.

    2006-07-01

    Phase-matching conditions are considered for second harmonic generation (SHG) and optical parametric generation in LiGa(S 1-xSe x) 2 mixed crystals as a function of chemical composition under the supposition of linear dependence of refractive indices on x. It has been shown that by tuning x over the range 0-1 the SHG can be realized in XY plane for ?=2.1-7.8 ?m pumping at ?=43-90°, in YZ plane for ?=2.1-2.2 and 4.8-7.8 ?m pumping at ?=0-90°, and in XZ plane for ?=1.6-11.7 ?m pumping at ?=0-57°. The LiGa(S 1-xSe x) 2 solid solutions are also attractive for design of tunable femtosecond pulse frequency converters with saving of pump pulse duration.

  19. Nonlinear optical response of a two-dimensional atomic crystal.

    PubMed

    Merano, Michele

    2016-01-01

    The theory of Bloembergen and Pershan for the light waves at the boundary of nonlinear media is extended to a nonlinear two-dimensional (2D) atomic crystal, i.e., a single planar atomic lattice, placed between linear bulk media. The crystal is treated as a zero-thickness interface, a real 2D system. Harmonic waves emanate from it. Generalization of the laws of reflection and refraction give the direction and the intensity of the harmonic waves. As a particular case that contains all the essential physical features, second-order harmonic generation is considered. The theory, due to its simplicity that stems from the special character of a single planar atomic lattice, is able to elucidate and explain the rich experimental details of harmonic generation from a 2D atomic crystal. PMID:26696190

  20. Harmonic Analysis of the Output Voltage of a Third-Harmonic-Injected Inverter for LSM Drives

    NASA Astrophysics Data System (ADS)

    Shigeeda, Hidenori; Okui, Akinobu; Akagi, Hirofumi

    The superconducting magnetic levitation railway system (MAGLEV) under development in Japan uses a pulse-width-modulation (PWM) inverter for driving a linear synchronous motor (LSM). The inverter output voltage contains non-negligible harmonics which cause harmonic resonances in the LSM system, and therefore harmonics of the output voltage have been analyzed in order to control such harmonic resonances. This paper applies a third-harmonic injection method to the inverter for the purpose of enhancing the output voltage without changing the circuit configuration. It performs harmonic analysis of the output voltage of the inverter based on the third-harmonic injection. Validity of the harmonic analysis is verified by computer simulation.

  1. Crystal Creations.

    ERIC Educational Resources Information Center

    Whipple, Nona; Whitmore, Sherry

    1989-01-01

    Presents a many-faceted learning approach to the study of crystals. Provides instructions for performing activities including crystal growth and patterns, creating miniature simulations of crystal-containing rock formations, charcoal and sponge gardens, and snowflakes. (RT)

  2. Crystal Meth

    MedlinePLUS

    ... for: Navigation Home / Stories of Hope / Crystal meth Crystal meth Story Of Hope By giovanni January 3rd, ... about my drug addiction having to deal with Crystal meth. I am now in recovery and fighting ...

  3. Resonant third harmonic generation of KrF laser in Ar gas

    SciTech Connect

    Rakowski, R.; Barna, A.; Suta, T.; Földes, I. B.; Bohus, J.; Szatmári, S.; Miko?ajczyk, J.; Bartnik, A.; Fiedorowicz, H.; Verona, C.; Verona Rinati, G.; Margarone, D.; Nowak, T.; and others

    2014-12-15

    Investigations of emission of harmonics from argon gas jet irradiated by 700 fs, 5 mJ pulses from a KrF laser are presented. Harmonics conversion was optimized by varying the experimental geometry and the nozzle size. For the collection of the harmonic radiation silicon and solar-blind diamond semiconductor detectors equipped with charge preamplifiers were applied. The possibility of using a single-crystal CVD diamond detector for separate measurement of the 3rd harmonic in the presence of a strong pumping radiation was explored. Our experiments show that the earlier suggested 0.7% conversion efficiency can really be obtained, but only in the case when phase matching is optimized with an elongated gas target length corresponding to the length of coherence.

  4. Resonant third harmonic generation of KrF laser in Ar gas.

    PubMed

    Rakowski, R; Barna, A; Suta, T; Bohus, J; Földes, I B; Szatmári, S; Miko?ajczyk, J; Bartnik, A; Fiedorowicz, H; Verona, C; Verona Rinati, G; Margarone, D; Nowak, T; Rosi?ski, M; Ry?, L

    2014-12-01

    Investigations of emission of harmonics from argon gas jet irradiated by 700 fs, 5 mJ pulses from a KrF laser are presented. Harmonics conversion was optimized by varying the experimental geometry and the nozzle size. For the collection of the harmonic radiation silicon and solar-blind diamond semiconductor detectors equipped with charge preamplifiers were applied. The possibility of using a single-crystal CVD diamond detector for separate measurement of the 3rd harmonic in the presence of a strong pumping radiation was explored. Our experiments show that the earlier suggested 0.7% conversion efficiency can really be obtained, but only in the case when phase matching is optimized with an elongated gas target length corresponding to the length of coherence. PMID:25554270

  5. Harmonic resolution as a holographic quantum number

    SciTech Connect

    Bousso, Raphael

    2004-01-31

    The Bekenstein bound takes the holographic principle into the realm of flat space, promising new insights on the relation of non-gravitational physics to quantum gravity. This makes it important to obtain a precise formulation of the bound. Conventionally, one specifies two macroscopic quantities, mass and spatial width, which cannot be simultaneously diagonalized. Thus, the counting of compatible states is not sharply defined. The resolution of this and other formal difficulties leads naturally to a definition in terms of discretized light-cone quantization. In this form, the area difference specified in the covariant bound converts to a single quantum number, the harmonic resolution K. The Bekenstein bound then states that the Fock space sector with K units of longitudinal momentum contains no more than exp(2 pi^2 K) independent discrete states. This conjecture can be tested unambiguously for a given Lagrangian, and it appears to hold true for realistic field theories, including models arising from string compactifications. For large K, it makes contact with more conventional but less well-defined formulations.

  6. Harmonic Balance Computations of Fan Aeroelastic Stability

    NASA Technical Reports Server (NTRS)

    Bakhle, Milind A.; Reddy, T. S. R.

    2010-01-01

    A harmonic balance (HB) aeroelastic analysis, which has been recently developed, was used to determine the aeroelastic stability (flutter) characteristics of an experimental fan. To assess the numerical accuracy of this HB aeroelastic analysis, a time-domain aeroelastic analysis was also used to determine the aeroelastic stability characteristics of the same fan. Both of these three-dimensional analysis codes model the unsteady flowfield due to blade vibrations using the Reynolds-averaged Navier-Stokes (RANS) equations. In the HB analysis, the unsteady flow equations are converted to a HB form and solved using a pseudo-time marching method. In the time-domain analysis, the unsteady flow equations are solved using an implicit time-marching approach. Steady and unsteady computations for two vibration modes were carried out at two rotational speeds: 100 percent (design) and 70 percent (part-speed). The steady and unsteady results obtained from the two analysis methods compare well, thus verifying the recently developed HB aeroelastic analysis. Based on the results, the experimental fan was found to have no aeroelastic instability (flutter) at the conditions examined in this study.

  7. Electromagnetic space-time crystals. II. Fractal computational approach

    E-print Network

    G. N. Borzdov

    2014-10-20

    A fractal approach to numerical analysis of electromagnetic space-time crystals, created by three standing plane harmonic waves with mutually orthogonal phase planes and the same frequency, is presented. Finite models of electromagnetic crystals are introduced, which make possible to obtain various approximate solutions of the Dirac equation. A criterion for evaluating accuracy of these approximate solutions is suggested.

  8. Method for reducing energy losses in laser crystals

    DOEpatents

    Atherton, L.J.; DeYoreo, J.J.; Roberts, D.H.

    1992-03-24

    A process for reducing energy losses in crystals is disclosed which comprises: a. heating a crystal to a temperature sufficiently high as to cause dissolution of microscopic inclusions into the crystal, thereby converting said inclusions into point-defects, and b. maintaining said crystal at a given temperature for a period of time sufficient to cause said point-defects to diffuse out of said crystal. Also disclosed are crystals treated by the process, and lasers utilizing the crystals as a source of light. 12 figs.

  9. Method for reducing energy losses in laser crystals

    DOEpatents

    Atherton, L. Jeffrey (Pleasanton, CA); DeYoreo, James J. (Livermore, CA); Roberts, David H. (Pleasanton, CA)

    1992-01-01

    A process for reducing energy losses in crystals is disclosed which comprises: a. heating a crystal to a temperature sufficiently high as to cause dissolution of microscopic inclusions into the crystal, thereby converting said inclusions into point-defects, and b. maintaining said crystal at a given temperature for a period of time sufficient to cause said point-defects to diffuse out of said crystal. Also disclosed are crystals treated by the process, and lasers utilizing the crystals as a source of light.

  10. Portable convertible blast effects shield

    DOEpatents

    Pastrnak, John W. (Livermore, CA); Hollaway, Rocky (Modesto, CA); Henning, Carl D. (Livermore, CA); Deteresa, Steve (Livermore, CA); Grundler, Walter (Hayward, CA); Hagler, Lisle B. (Berkeley, CA); Kokko, Edwin (Dublin, CA); Switzer, Vernon A (Livermore, CA)

    2007-05-22

    A rapidly deployable portable convertible blast effects shield/ballistic shield includes a set two or more telescoping cylindrical rings operably connected to each other to convert between a telescopically-collapsed configuration for storage and transport, and a telescopically-extended upright configuration forming an expanded inner volume. In a first embodiment, the upright configuration provides blast effects shielding, such as against blast pressures, shrapnel, and/or fire balls. And in a second embodiment, the upright configuration provides ballistic shielding, such as against incoming weapons fire, shrapnel, etc. Each ring has a high-strength material construction, such as a composite fiber and matrix material, capable of substantially inhibiting blast effects and impinging projectiles from passing through the shield. And the set of rings are releasably securable to each other in the telescopically-extended upright configuration, such as by click locks.

  11. Portable convertible blast effects shield

    DOEpatents

    Pastrnak, John W. (Livermore, CA); Hollaway, Rocky (Modesto, CA); Henning, Carl D. (Livermore, CA); Deteresa, Steve (Livermore, CA); Grundler, Walter (Hayward, CA); Hagler,; Lisle B. (Berkeley, CA); Kokko, Edwin (Dublin, CA); Switzer, Vernon A (Livermore, CA)

    2010-10-26

    A rapidly deployable portable convertible blast effects shield/ballistic shield includes a set two or more telescoping cylindrical rings operably connected to each other to convert between a telescopically-collapsed configuration for storage and transport, and a telescopically-extended upright configuration forming an expanded inner volume. In a first embodiment, the upright configuration provides blast effects shielding, such as against blast pressures, shrapnel, and/or fire balls. And in a second embodiment, the upright configuration provides ballistic shielding, such as against incoming weapons fire, shrapnel, etc. Each ring has a high-strength material construction, such as a composite fiber and matrix material, capable of substantially inhibiting blast effects and impinging projectiles from passing through the shield. And the set of rings are releasably securable to each other in the telescopically-extended upright configuration, such as by click locks.

  12. Portable convertible blast effects shield

    DOEpatents

    Pastrnak, John W. (Livermore, CA); Hollaway, Rocky (Modesto, CA); Henning, Carl D. (Livermore, CA); Deteresa, Steve (Livermore, CA); Grundler, Walter (Hayward, CA); Hagler, Lisle B. (Berkeley, CA); Kokko, Edwin (Dublin, CA); Switzer, Vernon A. (Livermore, CA)

    2011-03-15

    A rapidly deployable portable convertible blast effects shield/ballistic shield includes a set two or more frusto-conically-tapered telescoping rings operably connected to each other to convert between a telescopically-collapsed configuration for storage and transport, and a telescopically-extended upright configuration forming an expanded inner volume. In a first embodiment, the upright configuration provides blast effects shielding, such as against blast pressures, shrapnel, and/or fire balls. And in a second embodiment, the upright configuration provides ballistic shielding, such as against incoming weapons fire, shrapnel, etc. Each ring has a high-strength material construction, such as a composite fiber and matrix material, capable of substantially inhibiting blast effects and impinging projectiles from passing through the shield. And the set of rings are releasably securable to each other in the telescopically-extended upright configuration by the friction fit of adjacent pairs of frusto-conically-tapered rings to each other.

  13. Vibration converter with magnetic levitation

    NASA Astrophysics Data System (ADS)

    Gladilin, A. V.; Pirogov, V. A.; Golyamina, I. P.; Kulaev, U. V.; Kurbatov, P. A.; Kurbatova, E. P.

    2015-05-01

    The paper presents a mathematical model, the results of computational and theoretical research, and the feasibility of creating a vibration converter with full magnetic levitation in the suspension of a high-temperature superconductor (HTSC). The axial and radial stability of the active part of the converter is provided by the interaction of the magnetic field of ring-shaped permanent magnets and a hollow cylinder made of the ceramic HTSC material. The force is created by a system of current-carrying coils whose magnetic field is polarized by permanent magnets and interacts with induced currents in the superconducting cylinder. The case of transition to the superconducting state of HTSC material in the field of the permanent magnets (FC mode) is considered. The data confirm the outlook for the proposed technical solutions.

  14. Harmonic nanoparticles for regenerative research.

    PubMed

    Ronzoni, Flavio; Magouroux, Thibaud; Vernet, Remi; Extermann, Jérôme; Crotty, Darragh; Prina-Mello, Adriele; Ciepielewski, Daniel; Volkov, Yuri; Bonacina, Luigi; Wolf, Jean-Pierre; Jaconi, Marisa

    2014-01-01

    In this visualized experiment, protocol details are provided for in vitro labeling of human embryonic stem cells (hESC) with second harmonic generation nanoparticles (HNPs). The latter are a new family of probes recently introduced for labeling biological samples for multi-photon imaging. HNPs are capable of doubling the frequency of excitation light by the nonlinear optical process of second harmonic generation with no restriction on the excitation wavelength. Multi-photon based methodologies for hESC differentiation into cardiac clusters (maintained as long term air-liquid cultures) are presented in detail. In particular, evidence on how to maximize the intense second harmonic (SH) emission of isolated HNPs during 3D monitoring of beating cardiac tissue in 3D is shown. The analysis of the resulting images to retrieve 3D displacement patterns is also detailed. PMID:24836220

  15. Multi-MW 22.8 GHz Harmonic Multiplier - RF Power Source for High-Gradient Accelerator R&D

    SciTech Connect

    Jay L. Hirshfield

    2012-07-26

    Electrodynamic and particle simulation studies have been carried out to optimize design of a two-cavity harmonic frequency multiplier, in which a linear electron beam is energized by rotating fields near cyclotron resonance in a TE111 cavity in a uniform magnetic field, and in which the beam then radiates coherently at the nth harmonic into a TEn11 output cavity. Examples are worked out in detail for 7th and 2nd harmonic converters, showing RF-to-RF conversion efficiencies of 45% and 88%, respectively at 19.992 GHz (K-band) and 5.712 GHz (C-band), for a drive frequency of 2.856 GHz. Details are shown of RF infrastructure (S-band klystron, modulator) and harmonic converter components (drive cavity, output cavities, electron beam source and modulator, beam collector) for the two harmonic converters to be tested. Details are also given for the two-frequency (S- and C-band) coherent multi-MW test stand for RF breakdown and RF gun studies.

  16. High efficiency thermionic converter studies

    NASA Technical Reports Server (NTRS)

    Huffman, F. N.; Sommer, A. H.; Balestra, C. L.; Briere, D. P.; Oettinger, P. E.

    1976-01-01

    The objective is to improve thermionic converter performance by means of reduced interelectrode losses, greater emitter capabilities, and lower collector work functions until the converter performance level is suitable for out-of-core space reactors and radioisotope generators. Electrode screening experiments have identified several promising collector materials. Back emission work function measurements of a ZnO collector in a thermionic diode have given values less than 1.3 eV. Diode tests were conducted over the range of temperatures of interest for space power applications. Enhanced mode converter experiments have included triodes operated in both the surface ionization and plasmatron modes. Pulsed triodes were studied as a function of pulse length, pulse potential, inert gas fill pressure, cesium pressure, spacing, emitter temperature and collector temperature. Current amplifications (i.e., mean output current/mean grid current) of several hundred were observed up to output current densities of one amp/sq cm. These data correspond to an equivalent arc drop less than 0.1 eV.

  17. Localization and vector spherical harmonics

    NASA Astrophysics Data System (ADS)

    von Brecht, James H.

    2016-01-01

    This paper establishes the following localization property for vector spherical harmonics: a wide class of non-local, vector-valued operators reduce to local, multiplication-type operations when applied to a vector spherical harmonic. As localization occurs in a very precise, quantifiable and explicitly computable fashion, the localization property provides a set of useful formulae for analyzing vector-valued fractional diffusion and non-local differential equations defined on S d - 1. As such analyses require a detailed understanding of operators for which localization occurs, we provide several applications of the result in the context of non-local differential equations.

  18. Low work function silicon collector for thermionic converters

    NASA Technical Reports Server (NTRS)

    Chang, K. H.; Shimada, K.

    1976-01-01

    To improve the efficiency of present thermionic converters, single crystal silicon was investigated as a low work function collector material. The experiments were conducted in a test vehicle which resembled an actual thermionic converter. Work function as low as 1.0eV was obtained with an n-type silicon. The stabilities of the activated surfaces at elevated temperatures were tested by raising the collector temperature up to 829 K. By increasing the Cs arrival rate, it was possible to restore the originally activated low work function of the surface at elevated surface temperatures. These results, plotted in the form of Rasor-Warner curve, show a behavior similar to that of metal electrode except that the minimum work function was much lower with silicon than with metals.

  19. Plasmonic grating as a nonlinear converter-coupler.

    PubMed

    Talebi, Nahid; Shahabadi, Mahmoud; Khunsin, Worawut; Vogelgesang, Ralf

    2012-01-16

    The paper introduces a wavelength converter composed of a metallic finite 2-dimensional particle grating on top of an optical waveguide. The particles sustain plasmonic resonances which will result in the near-field enhancement and therefore, high conversion efficiency. Due to near-field interaction of the grating field with the propagating modes of the waveguide, the generated third harmonic wave is phase-matched to a propagating mode of the waveguide, while the fundamental frequency component is not coupled into the output waveguide of the structure. The performance of this structure is numerically investigated using a full-wave transmission line method for the linear analysis and a three-dimensional finite-difference time-domain method for the nonlinear analysis. PMID:22274484

  20. Large wind energy converter: Growian 3 MW

    NASA Technical Reports Server (NTRS)

    Koerber, F.; Thiele, H. A.

    1979-01-01

    The main features of the Growian wind energy converter are presented. Energy yield, environmental impact, and construction of the energy converter are discussed. Reliability of the windpowered system is assessed.

  1. Harmonic generation from indium-rich plasmas

    SciTech Connect

    Ganeev, R. A.; Kulagin, I. A.; Singhal, H.; Naik, P. A.; Arora, V.; Chakravarty, U.; Chakera, J. A.; Khan, R. A.; Raghuramaiah, M.; Gupta, P. D.; Redkin, P. V.

    2006-12-15

    An experimental study of high-order harmonic generation in In, InSb, InP, and InGaP plasmas using femtosecond laser radiation with variable chirp is presented. Intensity enhancement of the 13th and 21st harmonics compared to the neighboring harmonics by a factor of 200 and 10, respectively, is observed. It is shown that the harmonic spectrum from indium-containing plasma plumes can be considerably modified by controlling the chirp of the driving laser pulse.

  2. Method for Controlling a Multilevel Cascade BTB System Using Bidirectional Isolated DC/DC Converters

    NASA Astrophysics Data System (ADS)

    Kitada, Ryohei; Akagi, Hirofumi

    This paper discusses a 6.6-kV next-generation BTB system in which bidirectional isolated dc/dc converters are combined with modular multilevel cascade converters. The system consists of N converter cells cascaded in each phase at both front ends. Each converter cell consists of a bidirectional isolated dc/dc converter and two voltage-source H-bridge PWM converters. This circuit configuration can be adopted to significantly reduce harmonic voltages and currents because the voltage steps are extremely low. In a conventional power conversion system, bulky line-frequency transformers are employed. On the other hand, in the present system, light and compact high-frequency transformers are used for providing galvanic isolation. Thus, the overall physical size and weight are reduced. The authors design, construct, and test a single-phase 120-V, 3.3-kW downscaled model with N=3, in order to verify the feasibility and effectiveness. The downscaled model helps to develop an operable 6.6-kV system with focus on control and performance.

  3. Covariant harmonic oscillators: 1973 revisited

    NASA Technical Reports Server (NTRS)

    Noz, M. E.

    1993-01-01

    Using the relativistic harmonic oscillator, a physical basis is given to the phenomenological wave function of Yukawa which is covariant and normalizable. It is shown that this wave function can be interpreted in terms of the unitary irreducible representations of the Poincare group. The transformation properties of these covariant wave functions are also demonstrated.

  4. CONVERTIBLE BONDS IN A DEFAULTABLE DIFFUSION MODEL

    E-print Network

    Jeanblanc, Monique

    CONVERTIBLE BONDS IN A DEFAULTABLE DIFFUSION MODEL Tomasz R. Bielecki Department of Applied Research Grant PS12918. #12;2 Convertible Bonds in a Defaultable Diffusion Model 1 Introduction In [4), such as Convertible Bonds (CB), and we provided a rigorous decomposition of a CB into a bond component and a (game

  5. SWITCHED-CAPACITOR VOLTAGE CONVERTERS WITH REGULATORS

    E-print Network

    Berns, Hans-Gerd

    LT1054 SWITCHED-CAPACITOR VOLTAGE CONVERTERS WITH REGULATORS SLVS033E ­ FEBRUARY 1990 ­ REVISED-to-Pin Compatible With the LTC1044/7660 description The LT1054 is a bipolar, switched-capacitor voltage converter regulation, a feature not previously available in switched-capacitor voltage converters. By adding

  6. 12 CFR 1.6 - Convertible securities.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 12 Banks and Banking 1 2011-01-01 2011-01-01 false Convertible securities. 1.6 Section 1.6 Banks and Banking COMPTROLLER OF THE CURRENCY, DEPARTMENT OF THE TREASURY INVESTMENT SECURITIES § 1.6 Convertible securities. A national bank may not purchase securities convertible into stock at the option...

  7. 12 CFR 1.6 - Convertible securities.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 12 Banks and Banking 1 2013-01-01 2013-01-01 false Convertible securities. 1.6 Section 1.6 Banks and Banking COMPTROLLER OF THE CURRENCY, DEPARTMENT OF THE TREASURY INVESTMENT SECURITIES § 1.6 Convertible securities. A national bank may not purchase securities convertible into stock at the option...

  8. Motion Planning with Gamma-Harmonic Potential

    E-print Network

    Masoud, Ahmad A.

    Motion Planning with Gamma-Harmonic Potential Fields AHMAD A. MASOUD, Member, IEEE King Fahad University of Petroleum and Minerals This paper extends the capabilities of the harmonic potential field (HPF flowing in a nonhomogeneous conducting medium. The resulting potential field is known as the gamma-harmonic

  9. Harmonic Functions of Subordinate Killed Brownian Motion

    E-print Network

    Vondraèek, Zoran

    Harmonic Functions of Subordinate Killed Brownian Motion J. Glover, Z. Pop-Stojanovic, M. Rao, H is intrinsic ultracontractive, all nonnegative harmonic functions of the subordinate killed Brownian motion harmonic functions of the subordinate killed Brownian motion in D. AMS 2000 Mathematics Subject

  10. Harmonic generation with temporally focused ultrashort pulses

    E-print Network

    Silberberg, Yaron

    Harmonic generation with temporally focused ultrashort pulses Dan Oron and Yaron Silberberg of harmonic generation with temporally focused ultrashort pulses are explored both theoreti- cally and experimentally. Analyzing the phase-matching conditions for harmonic generation we find a corre- spondence

  11. An Introduction of Infinity Harmonic Changyou Wang

    E-print Network

    Wang, Changyou

    An Introduction of Infinity Harmonic Functions Changyou Wang University of Kentucky Lexington, KY on the analysis of infinity harmonic functions, a subject that has received considerable interests very recently characterizations of infinity harmonic functions. He presents the celebrated theorem by R. Jensen [17

  12. Quantum mechanics of the damped harmonic oscillator

    E-print Network

    Blasone, Massimo

    645 Quantum mechanics of the damped harmonic oscillator Massimo Blasone and Petr Jizba Abstract: We quantize the system of a damped harmonic oscillator coupled to its time- reversed image, known as Bateman of the simplest dissipative system -- the damped harmonic oscillator (DHO) -- is not an easy task [1], and indeed

  13. Auxiliary resonant DC tank converter

    DOEpatents

    Peng, Fang Z. (Knoxville, TN)

    2000-01-01

    An auxiliary resonant dc tank (ARDCT) converter is provided for achieving soft-switching in a power converter. An ARDCT circuit is coupled directly across a dc bus to the inverter to generate a resonant dc bus voltage, including upper and lower resonant capacitors connected in series as a resonant leg, first and second dc tank capacitors connected in series as a tank leg, and an auxiliary resonant circuit comprising a series combination of a resonant inductor and a pair of auxiliary switching devices. The ARDCT circuit further includes first clamping means for holding the resonant dc bus voltage to the dc tank voltage of the tank leg, and second clamping means for clamping the resonant dc bus voltage to zero during a resonant period. The ARDCT circuit resonantly brings the dc bus voltage to zero in order to provide a zero-voltage switching opportunity for the inverter, then quickly rebounds the dc bus voltage back to the dc tank voltage after the inverter changes state. The auxiliary switching devices are turned on and off under zero-current conditions. The ARDCT circuit only absorbs ripples of the inverter dc bus current, thus having less current stress. In addition, since the ARDCT circuit is coupled in parallel with the dc power supply and the inverter for merely assisting soft-switching of the inverter without participating in real dc power transmission and power conversion, malfunction and failure of the tank circuit will not affect the functional operation of the inverter; thus a highly reliable converter system is expected.

  14. Investigation of Second- and Third-Harmonic Generation in Few-Layer Gallium Selenide by Multiphoton Microscopy

    PubMed Central

    Karvonen, Lasse; Säynätjoki, Antti; Mehravar, Soroush; Rodriguez, Raul D.; Hartmann, Susanne; Zahn, Dietrich R. T.; Honkanen, Seppo; Norwood, Robert A.; Peyghambarian, N.; Kieu, Khanh; Lipsanen, Harri; Riikonen, Juha

    2015-01-01

    Gallium selenide (GaSe) is a layered semiconductor and a well-known nonlinear optical crystal. The discovery of graphene has created a new vast research field focusing on two-dimensional materials. We report on the nonlinear optical properties of few-layer GaSe using multiphoton microscopy. Both second- and third-harmonic generation from few-layer GaSe flakes were observed. Unexpectedly, even the peak at the wavelength of 390?nm, corresponding to the fourth-harmonic generation or the sum frequency generation from third-harmonic generation and pump light, was detected during the spectral measurements in thin GaSe flakes. PMID:25989113

  15. Structural ordering and glass forming of soft spherical particles with harmonic repulsions

    SciTech Connect

    Sun, Bin; Sun, Zhiwei; Ouyang, Wenze Xu, Shenghua

    2014-04-07

    We carry out dissipative particle dynamics simulations to investigate the dynamic process of phase transformation in the system with harmonic repulsion particles. Just below the melting point, the system undergoes liquid state, face-centered cubic crystallization, body-centered cubic crystallization, and reentrant melting phase transition upon compression, which is in good agreement with the phase diagram constructed previously via thermodynamic integration. However, when the temperature is decreased sufficiently, the system is trapped into an amorphous and frustrated glass state in the region of intermediate density, where the solid phase and crystal structure should be thermodynamically most stable.

  16. Mode conversion and absorption of fast waves at high ion cyclotron harmonics in inhomogeneous magnetic fields

    SciTech Connect

    Cho, Suwon; Kwak, Jong-Gu

    2014-04-15

    The propagation and absorption of high harmonic fast waves is of interest for non-inductive current drives in fusion experiments. The fast wave can be coupled with the ion Bernstein wave that propagates in the high magnetic field side of an ion cyclotron harmonic resonance layer. This coupling and the absorption are analyzed using the hot plasma dispersion relation and a wave equation that was converted from an approximate dispersion relation for the case where ?{sub i}=k{sub ?}{sup 2}?{sub i}{sup 2}/2?1 (where k{sub ?} is the perpendicular wave number and ?{sub i} is the ion Larmor radius). It is found that both reflection and conversion may occur near the harmonic resonance layer but that they decrease rapidly, giving rise to a sharp increase in the absorption as the parallel wave number increases.

  17. Workshop 4 Converter cooling & recuperation

    SciTech Connect

    Iles, P.; Hindman, D.

    1995-01-05

    Cooling the PV converter increases the overall TPV system efficiency, and more than offsets the losses incurred in providing cooling systems. Convective air flow methods may be sufficient, and several standard water cooling systems, including thermo-syphon radiators, capillary pumps or microchannel plates, are available. Recuperation is used to increase system efficiency, rather than to increase the emitter temperature. Recuperators operating at comparable high temperatures, such as in high temperature turbines have worked effectively. {copyright} {ital 1995} {ital American} {ital Institute} {ital of} {ital Physics}.

  18. Power Converters and Power Quality

    E-print Network

    Kahle, K

    2015-01-01

    This paper discusses the subject of power quality for power converters. The first part gives an overview of most of the common disturbances and power quality issues in electrical networks for particle accelerators, and explains their consequences for accelerator operation. The propagation of asymmetrical network disturbances into a network is analysed. Quantitative parameters for network disturbances in a typical network are presented, and immunity levels for users’ electrical equipment are proposed. The second part of this paper discusses the technologies and strategies used in particle accelerator networks for power quality improvement . Particular focus is given to networks supplying loads with cycling active and reactive power

  19. Liquid-metal magnetohydrodynamic converter

    SciTech Connect

    Aladiev, I.T.; Dikhashidze, M.A.; Dzhamardzhashvili, V.A.; Teplov, S.V.; Tskhvirashvili, D.G.

    1981-06-16

    A liquid-metal magnetohydrodynamic converter is disclosed that is comprised of hydraulically interconnected components as a heat source a two-phase nozzle, a separator, a magnetohydrodynamic generator, a liquid diffuser, and a heat-regenerating means, said components being arranged successively so as to form a loop. The two-phase nozzle is provided with steam-bleeding units located in different sections over its length and having the outlets thereof coupled to steam inlets of the heat-regenerating means. A steam diffuser and a condenser are hydraulically interconnected and coupled to the separator and the steam inlet of the heat-regenerating means, respectively.

  20. Liquid-metal magnetohydrodynamic converter

    SciTech Connect

    Aladiev, I. T.; Dzhamardzhashvili, V. A.

    1981-09-01

    A liquid-metal magnetohydrodynamic converter is described that is comprised of such hydraulically interconnected components as a heat source, a two-phase nozzle, a separator, a liquid diffuser, a liquid metal cooler, a magnetohydrodynamic generator and a means for heating and delivering liquid metal supplied from the cooler, all of said components being arranged successively so as to form a loop. A steam diffuser and a condenser are interconnected and hydraulically coupled to the separator and the means for heating and delivering liquid metal supplied from the cooler, respectively.

  1. Photovoltaic converters for solar-pumped lasers

    NASA Technical Reports Server (NTRS)

    Walker, Gilbert H.; Heinbockel, John H.

    1988-01-01

    The authors describe a mathematical parametric study of converters used to convert laser radiation to electricity for space-based laser power systems. Two different lasers, the 1.06-micron Nd laser and the 1.315-micron iodine laser, are used in the vertical junction converter. The calculated efficiency is 50 percent for a 100-junction Si photovoltaic converter when used with a Nd laser. The calculated efficiency for a 1000-junction Ga(0.53)In(0.47)As photovoltaic converter is 43 percent when used with an iodine laser.

  2. Elimination of Harmonics in a Multilevel Converter using the Theory of Symmetric

    E-print Network

    Tolbert, Leon M.

    of dc voltages. For example, the output of solar cells are dc voltages, and if this energy is to be fed for connecting such distributed dc energy sources (solar cells, fuel cells, the rectified output of wind turbines be solved which in turn greatly reduces the computational burden. In con- trast to results reported

  3. Converting from CVF to AAF

    NASA Technical Reports Server (NTRS)

    Gladden, Roy E.; Khanampompan, Teerapat; Edmonds, Karina

    2008-01-01

    A computer program called dsn config converter automates what had been a manual process for updating the multimission adaptation file (multi.aaf) used by a multiple-mission-command-sequence-generating process comprised of a combination of the AUTOGEN and APGEN programs mentioned in the immediately preceding article. The program converts the dsn_config.cvf file that provides DSN (Deep Space Network) antenna configuration code mappings from a context variable file (CVF) format used in another part of the command generation process to an APGEN activity file (AAF) format used by AUTOGEN and APGEN. Whereas previously, the information in the dsn_config.cvf file was manually encoded into the multi.aaf file, now the program automatically generates a dsn_config.aaf file from the dsn_config.cvf file. As part of this development effort the multi.aaf file was adapted to use the new dsn_config.aaf representations. Through this automation a tedious error-prone step has now been replaced by a quick and robust step.

  4. Coherent Visible-Light-Generation Enhancement in Silicon-Based Nanoplasmonic Waveguides via Third-Harmonic Conversion.

    PubMed

    Sederberg, S; Elezzabi, A Y

    2015-06-01

    We report visible third-harmonic conversion at ?=517 nm in subwavelength silicon-based nanoplasmonic waveguides at an unprecedented conversion efficiency of 2.3×10^{-5}. This marks both the highest third-harmonic conversion efficiency in a silicon-based or nanoplasmonic structure and the smallest silicon waveguide structure demonstrated to date. The high conversion efficiency is attributed to tight electric field confinement and strong light-matter coupling arising from surface plasmon modes in the nanoplasmonic waveguide, enabling efficient nonlinear optical mixing over micrometer length scales. The nonresonant geometry of the waveguide enables the entire ?=1550 nm femtosecond pulse spectrum to be converted to its third harmonic, which may be easily extended to the entire visible spectrum. We envisage that third-harmonic generation in silicon-based nanoplasmonic waveguides could provide a platform for integrated, broadband visible light sources and entangled triplet photons on future hybrid electronic-silicon photonic chips. PMID:26196643

  5. Second harmonic generation in the moving media

    E-print Network

    Ghalandari, Mahboubeh

    2015-01-01

    Because of the importance of second harmonic generation in some nonlinear media, in this paper, we investigated induced second harmonic generation in diamond where there is no intrinsic second order susceptibility, X(2). The electric field is proposed to introduce moving susceptibility of the second order and induce second harmonic generation. Then, spatiotemporal (QPM) is applied to optimize the induced second harmonic generation. Numerical results reveals that in this way, the induced second harmonic is found at the frequency of omega (2) = 2 omega(0) + or - Delta omega rather than omega (0).

  6. Kolakoski sequence as an element to radiate giant forward and backward second harmonic signals

    NASA Astrophysics Data System (ADS)

    Parvini, T. S.; Tehranchi, M. M.; Hamidi, S. M.; Sarkarati, S.

    2015-11-01

    We propose a novel type of aperiodic one-dimensional photonic crystal structures which can be used for generating giant forward and backward second harmonic signals. The studied structure is formed by stacking together the air and nonlinear layers according to the Kolakoski self-generation scheme in which each nonlinear layer contains a pair of antiparallel 180° poled LiNbO3 crystal layers. For different generation stages of the structure, conversion efficiencies of forward and backward second harmonic waves have been calculated by nonlinear transfer matrix method. Numerical simulations show that conversion efficiencies in the Kolakoski-based multilayer are larger than the perfect ones for at least one order of magnitude. Especially for 33rd and 39th generation stages, forward second harmonic wave are 42 and 19 times larger, respectively. In this paper, we validate the strong fundamental field enhancement and localization within Kolakoski-based multilayer due to periodicity breaking which consequently leads to very strong radiation of backward and forward second harmonic signals. Following the applications of analogous aperiodic structures, we expect that Kolakosi-based multilayer can play a role in optical parametric devices such as multicolor second harmonic generators with high efficiency.

  7. Thermal optimization of second harmonic generation at high pump powers.

    PubMed

    Sahm, Alexander; Uebernickel, Mirko; Paschke, Katrin; Erbert, Götz; Tränkle, Günther

    2011-11-01

    We measure the temperature distribution of a 3 cm long periodically poled LiNbO? crystal in a single-pass second harmonic generation (SHG) setup at 488 nm. By means of three resistance heaters and directly mounted Pt100 sensors the crystal is subdivided in three sections. 9.4 W infrared pump light and 1.3 W of SHG light cause a de-homogenized temperature distribution of 0.2 K between the middle and back section. A sectional offset heating is used to homogenize the temperature in those two sections and thus increasing the conversion efficiency. A 15% higher SHG output power matching the prediction of our theoretical model is achieved. PMID:22109182

  8. Lorentz Harmonics, Squeeze Harmonics, and their Physical Applications

    E-print Network

    Young S. Kim; Marilyn E. Noz

    2011-02-19

    Among the symmetries in physics, the rotation symmetry is most familiar to us. It is known that the spherical harmonics serve useful purposes when the world is rotated. Squeeze transformations are also becoming more prominent in physics, particularly in optical sciences and in high-energy physics. As can be seen from Dirac's light-cone coordinate system, Lorentz boosts are squeeze transformations. Thus the squeeze transformation is one of the fundamental transformations in Einstein's Lorentz-covariant world. It is possible to define a complete set of orthonormal functions defined for one Lorentz frame. It is shown that the same set can be used for other Lorentz frames. Transformation properties are discussed. Physical applications are discussed in both optics and high-energy physics. It is shown that the Lorentz harmonics provide the mathematical basis for squeezed states of light. It is shown also that the same set of harmonics can be used for understanding Lorentz-boosted hadrons in high-energy physics. It is thus possible to transmit physics from one branch of physics to the other branch using the mathematical basis common to them.

  9. Second harmonic generation study of local polar inhomogeneities in Pb3(MgNb2)O9

    NASA Astrophysics Data System (ADS)

    Pugachev, A. M.; Kovalevskii, V. I.; Malinovskii, V. K.; Malitskaya, M. A.; Raevskaya, S. I.; Raevskii, I. P.; Surovtsev, N. V.

    2015-03-01

    The temperature dependence of the second harmonic generation in the lead magnesium niobate (Pb3(MgNb2)O9) crystal has been studied. It has been shown that the second harmonic generation in the crystal occurs in local non-centrosymmetric regions in the sample bulk, whereas a similar response from a fine powder is caused by effects associated with decreasing grain sizes. Maximum changes in polarization in local regions occur near the Vogel-Fulcher temperature in the range of 200-270 K. In the same temperature range, according to the published data, gradual freezing of polar regions and the formation of an infinite cluster is assumed.

  10. Highly efficient second-harmonic generation of intense femtosecond pulses with a significant effect of cubic nonlinearity

    SciTech Connect

    Mironov, S Yu; Ginzburg, V N; Lozhkarev, V V; Luchinin, G A; Kirsanov, Aleksei V; Yakovlev, I V; Khazanov, Efim A; Shaykin, A A

    2011-11-30

    A highly efficient (73%) second-harmonic generation of femtosecond pulses in a 1-mm-thick KDP crystal at a fundamentalharmonic peak intensity of 2 TW cm{sup -2} has been demonstrated experimentally. In a 0.5-mm-thick KDP crystal, a 50% efficiency has been reached at a peak intensity of 3.5 TW cm{sup -2}. We examine the key factors that limit the conversion efficiency and present numerical simulation results on further temporal compression of second-harmonic pulses.

  11. Data harmonization and model performance

    NASA Astrophysics Data System (ADS)

    The Joint Committee on Urban Storm Drainage of the International Association for Hydraulic Research (IAHR) and International Association on Water Pollution Research and Control (IAWPRC) was formed in 1982. The current committee members are (no more than two from a country): B. C. Yen, Chairman (USA); P. Harremoes, Vice Chairman (Denmark); R. K. Price, Secretary (UK); P. J. Colyer (UK), M. Desbordes (France), W. C. Huber (USA), K. Krauth (FRG), A. Sjoberg (Sweden), and T. Sueishi (Japan).The IAHR/IAWPRC Joint Committee is forming a Task Group on Data Harmonization and Model Performance. One objective is to promote international urban drainage data harmonization for easy data and information exchange. Another objective is to publicize available models and data internationally. Comments and suggestions concerning the formation and charge of the Task Group are welcome and should be sent to: B. C. Yen, Dept. of Civil Engineering, Univ. of Illinois, 208 N. Romine St., Urbana, IL 61801.

  12. Axisymmetric generalized harmonic evolution code

    SciTech Connect

    Sorkin, Evgeny

    2010-04-15

    We describe the first axisymmetric numerical code based on the generalized harmonic formulation of the Einstein equations, which is regular at the axis. We test the code by investigating gravitational collapse of distributions of complex scalar field in a Kaluza-Klein spacetime. One of the key issues of the harmonic formulation is the choice of the gauge source functions, and we conclude that a damped-wave gauge is remarkably robust in this case. Our preliminary study indicates that evolution of regular initial data leads to formation both of black holes with spherical and cylindrical horizon topologies. Intriguingly, we find evidence that near threshold for black hole formation the number of outcomes proliferates. Specifically, the collapsing matter splits into individual pulses, two of which travel in the opposite directions along the compact dimension and one which is ejected radially from the axis. Depending on the initial conditions, a curvature singularity develops inside the pulses.

  13. Harmon Craig (1926-2003)

    NASA Astrophysics Data System (ADS)

    Weiss, Ray

    Harmon Craig, one of the great pioneers of isotope geochemistry died on 14 March after suffering a massive heart attack at his home in La Jolla, California. He was one day shy of his 77th birthday. Through an academic career of more than fifty years, Craig—or simply “Harmon,” as he was known throughout the world of geochemistry—made a remarkable number of fundamental and far-reaching contributions in a wide range of important areas concerned with the chemical and physical processes by which the solid Earth, the oceans, the atmosphere, and the solar system interact. While his research was broad in scope, it was also characterized by a strong emphasis on meticulous field and laboratory work, and on original and insightful interpretations of the resulting observations.

  14. {D}-Deformed Harmonic Oscillators

    NASA Astrophysics Data System (ADS)

    Bagarello, F.; Gargano, F.; Volpe, D.

    2015-11-01

    We analyze systematically several deformations arising from two-dimensional harmonic oscillators which can be described in terms of {D}-pseudo bosons. They all give rise to exactly solvable models, described by non self-adjoint hamiltonians whose eigenvalues and eigenvectors can be found adopting the quite general framework of the so-called {D}-pseudo bosons. In particular, we show that several models previously introduced in the literature perfectly fit into this scheme.

  15. Harmonic oscillator and nuclear pseudospin

    SciTech Connect

    Lisboa, Ronai; Malheiro, Manuel; Castro, Antonio S. de; Alberto, Pedro; Fiolhais, Manuel

    2004-12-02

    A generalized relativistic harmonic oscillator for spin 1/2 particles is studied. The Dirac Hamiltonian contains a scalar S and a vector V quadratic potentials in the radial coordinate, as well as a tensor potential U, linear in r. Setting either {sigma} = S + V or {delta} = V - S to zero, analytical solutions for bound states are found. The eingenenergies and their nonrelativistic limits are presented and particular cases are discussed, especially the case {sigma} = 0, for which pseudospin symmetry is exact.

  16. Theoretical and experimental study of optical second harmonic generation in new chiral thiolates salts

    NASA Astrophysics Data System (ADS)

    Sylla, M.; Giffard, M.; Mabon, G.; Cubillan, N.; Castellano, O.; Hernandez, J.; Soscun, H.; Nguyen Phu, X.

    2006-11-01

    The second harmonic generation ability of new chiral thiolate salts is investigated. Aromatic thiolate anions ArS - are expected from semi-empirical calculations with PM3 parameterization of the MNDO Hamiltonian to possess higher intrinsic polarizabilities than the parent neutral thiols ArSH. Salts associating (hyper)polarizable aromatic thiolate anions with chiral cations, which ensure the noncentrosymmetry necessary to have second-order nonlinear optical effects have been synthesized. The first hyperpolarizabilities, ?, of the salts are measured using hyper-Rayleigh scattering technique. Second harmonic generation powder tests (Kurtz and Perry method) carried out on various salts studied, were positive indicating that these materials crystallize in noncentrosymmetric space groups.

  17. Thermionic converter emitter support arrangement

    DOEpatents

    Allen, Daniel T. (La Jolla, CA)

    1990-01-01

    A support is provided for use in a therminonic converter to support an end of an emitter to keep it out of contact with a surrounding collector while allowing the emitter end to move axially as its temperature changes. The emitter end (34) is supported by a spring structure (44) that includes a pair of Belleville springs, and the spring structure is supported by a support structure (42) fixed to the housing that includes the collector. The support structure is in the form of a sandwich with a small metal spring-engaging element (74) at the front end, a larger metal main support (76) at the rear end that is attached to the housing, and with a ceramic layer (80) between them that is bonded by hot isostatic pressing to the metal element and metal main support. The spring structure can include a loose wafer (120) captured between the Belleville springs.

  18. Thermionic converter emitter support arrangement

    DOEpatents

    Allen, Daniel T. (La Jolla, CA)

    1990-01-01

    A support is provided for use in a thermionic converter to support an end an emitter to keep it out of contact with a surrounding collector while allowing the emitter end to move axially at its temperatures changes. The emitter end (34) is supported by a spring structure (44) that includes a pair of Belleville springs, and the spring structure is supported by a support structure (42) fixed to the housing that includes the collector. The support structure is in the form of a sandwich with a small metal spring-engaging element (74) at the front end, a larger metal main support (76) at the rear end that is attached to the housng, and with a ceramic layer (80) between them that is bonded by hot isostatic pressing to the metal element and metal main support. The spring structure can include a loose wafer (120) captured between the Belleville springs.

  19. Cryogenic Power Converter Module Performance

    NASA Astrophysics Data System (ADS)

    Hennessy, M. J.; Mueller, E. K.; Mueller, O.; Park, J. N.; Neal, R. R.

    2006-03-01

    Several cryogenic power converter modules were built and tested, including a low-voltage, high-power series based on Cryo-MOSFETs and a high-voltage, high-power series based on Cryo-IGBTs. Half-bridge modules were manufactured and demonstrated in liquid nitrogen. The hardware is such that several half-bridge modules can be interconnected to form a multiphase full bridge. Conduction losses in the MOSFET modules were reduced by more than an order of magnitude. Switching powers up to 340 kW were achieved in the MOSFET modules, and 720 kW was demonstrated in the IGBT series. These modules can be utilized in fully integrated, megawatt-level cryogenic power systems.

  20. A zero power harmonic transponder sensor for ubiquitous wireless ?L liquid-volume monitoring.

    PubMed

    Huang, Haiyu; Chen, Pai-Yen; Hung, Cheng-Hsien; Gharpurey, Ranjit; Akinwande, Deji

    2016-01-01

    Autonomous liquid-volume monitoring is crucial in ubiquitous healthcare. However, conventional approach is based on either human visual observation or expensive detectors, which are costly for future pervasive monitoring. Here we introduce a novel approach based on passive harmonic transponder antenna sensor and frequency hopping spread spectrum (FHSS) pattern analysis, to provide a very low cost wireless ?L-resolution liquid-volume monitoring without battery or digital circuits. In our conceptual demonstration, the harmonic transponder comprises of a passive nonlinear frequency multiplier connected to a metamaterial-inspired 3-D antenna designed to be highly sensitive to the liquid-volume within a confined region. The transponder first receives some FHSS signal from an interrogator, then converts such signal to its harmonic band and re-radiates through the antenna sensor. The harmonic signal is picked up by a sniffer receiver and decoded through pattern analysis of the high dimensional FHSS signal strength data. A robust, zero power, absolute accuracy wireless liquid-volume monitoring is realized in the presence of strong direct coupling, background scatters, distance variance as well as near-field human-body interference. The concepts of passive harmonic transponder sensor, metamaterial-inspired antenna sensor, and FHSS pattern analysis based sensor decoding may help establishing cost-effective, energy-efficient and intelligent wireless pervasive healthcare monitoring platforms. PMID:26732251

  1. Crystal growth of organics for nonlinear optical applications

    NASA Technical Reports Server (NTRS)

    Singh, N. B.; Mazelsky, R.

    1993-01-01

    The crystal growth and characterization of organic and inorganic nonlinear optical materials were extensively studied. For example, inorganic crystals such as thallium arsenic selenide were studied in our laboratory for several years and crystals in sizes over 2.5 cm in diameter are available. Organic crystals are suitable for the ultraviolet and near infrared region, but are relatively less developed than their inorganic counterparts. Very high values of the second harmonic conversion efficiency and the electro-optic coefficient were reported for organic compounds. Single crystals of a binary organic alloy based on m.NA and CNA were grown and higher second harmonic conversion efficiency than the values reported for m.NA were observed.

  2. Virtual Crystallizer

    SciTech Connect

    Land, T A; Dylla-Spears, R; Thorsness, C B

    2006-08-29

    Large dihydrogen phosphate (KDP) crystals are grown in large crystallizers to provide raw material for the manufacture of optical components for large laser systems. It is a challenge to grow crystal with sufficient mass and geometric properties to allow large optical plates to be cut from them. In addition, KDP has long been the canonical solution crystal for study of growth processes. To assist in the production of the crystals and the understanding of crystal growth phenomena, analysis of growth habits of large KDP crystals has been studied, small scale kinetic experiments have been performed, mass transfer rates in model systems have been measured, and computational-fluid-mechanics tools have been used to develop an engineering model of the crystal growth process. The model has been tested by looking at its ability to simulate the growth of nine KDP boules that all weighed more than 200 kg.

  3. Crystal Systems.

    ERIC Educational Resources Information Center

    Schomaker, Verner; Lingafelter, E. C.

    1985-01-01

    Discusses characteristics of crystal systems, comparing (in table format) crystal systems with lattice types, number of restrictions, nature of the restrictions, and other lattices that can accidently show the same metrical symmetry. (JN)

  4. Performance of Power Converters at Cryogenic Temperatures

    NASA Technical Reports Server (NTRS)

    Elbuluk, Malik E.; Gerber, Scott; Hammoud, Ahmad; Patterson, Richard L.

    2001-01-01

    Power converters capable of operation at cryogenic temperatures are anticipated to play an important role in the power system architecture of future NASA deep space missions. Design of such converters to survive cryogenic temperatures will improve the power system performance and reduce development and launch costs. Aerospace power systems are mainly a DC distribution network. Therefore, DC/DC and DC/AC converters provide the outputs needed to different loads at various power levels. Recently, research efforts have been performed at the NASA Glenn Research Center (GRC) to design and evaluate DC/DC converters that are capable of operating at cryogenic temperatures. This paper presents a summary of the research performed to evaluate the low temperature performance of five DC/DC converters. Various parameters were investigated as a function of temperature in the range of 20 to -196 C. Data pertaining to the output voltage regulation and efficiency of the converters is presented and discussed.

  5. Radiation-Tolerant DC-DC Converters

    NASA Technical Reports Server (NTRS)

    Skutt, Glenn; Sable, Dan; Leslie, Leonard; Graham, Shawn

    2012-01-01

    A document discusses power converters suitable for space use that meet the DSCC MIL-PRF-38534 Appendix G radiation hardness level P classification. A method for qualifying commercially produced electronic parts for DC-DC converters per the Defense Supply Center Columbus (DSCC) radiation hardened assurance requirements was developed. Development and compliance testing of standard hybrid converters suitable for space use were completed for missions with total dose radiation requirements of up to 30 kRad. This innovation provides the same overall performance as standard hybrid converters, but includes assurance of radiation- tolerant design through components and design compliance testing. This availability of design-certified radiation-tolerant converters can significantly reduce total cost and delivery time for power converters for space applications that fit the appropriate DSCC classification (30 kRad).

  6. Application of a Series-Connected Hybrid Multi-Converter System to STATCOM

    NASA Astrophysics Data System (ADS)

    Li, Dongsheng; Fukuda, Shoji

    This paper gives an analysis and design of a static synchronous compensator (STATCOM) using a series-connected hybrid multi-converter system. The hybrid multi-converter system consists of two GTO converters and an IGBT converter connected in series by transformers. The proposed STATCOM has advantages that the harmonic components of the output voltage/current would be less than a conventional configuration STATCOM composed of a 12-, 24-, or 48-pulse converter; the total switching losses would be less than a PWM STATCOM; and the response would be as rapid as a PWM STATCOM. One problem of the hybrid configuration STATCOM is that it tends to operate in an over-modulation range if a considerable compensating reference change occurs. To solve this problem, this paper also proposes a variable DC voltage control strategy, where the DC voltage is adaptively adjusted in accordance with the required reactive power. The validity of the proposed configuration STATCOM and control strategies are verified by simulation and experimental results.

  7. Crystal growing

    NASA Technical Reports Server (NTRS)

    Neville, J. P.

    1990-01-01

    One objective is to demonstrate the way crystals grow and how they affect the behavior of material. Another objective is to compare the growth of crystals in metals and nonmetals. The procedures, which involve a supersaturated solution of a salt that will separate into crystals on cooling and the pouring off of an eutectic solution to expose the crystals formed by a solid solution when an alloy of two metals forms a solid and eutectic solution on cooling, are described.

  8. Ocean floor mounting of wave energy converters

    DOEpatents

    Siegel, Stefan G

    2015-01-20

    A system for mounting a set of wave energy converters in the ocean includes a pole attached to a floor of an ocean and a slider mounted on the pole in a manner that permits the slider to move vertically along the pole and rotate about the pole. The wave energy converters can then be mounted on the slider to allow adjustment of the depth and orientation of the wave energy converters.

  9. Generation of green frequency comb from chirped ?{sup (2)} nonlinear photonic crystals

    SciTech Connect

    Lai, C.-M.; Chang, K.-H.; Yang, Z.-Y.; Fu, S.-H.; Tsai, S.-T.; Hsu, C.-W.; Peng, L.-H.; Yu, N. E.; Boudrioua, A.; Kung, A. H.

    2014-12-01

    Spectrally broad frequency comb generation over 510–555?nm range was reported on chirped quasi-phase-matching (QPM) ?{sup (2)} nonlinear photonic crystals of 12?mm length with periodicity stepwise increased from 5.9??m to 7.1??m. When pumped with nanosecond infrared (IR) frequency comb derived from a QPM optical parametric oscillator (OPO) and spanned over 1040?nm to 1090?nm wavelength range, the 520?nm to 545?nm up-converted green spectra were shown to consist of contributions from (a) second-harmonic generation among the signal or the idler modes, and (b) sum-frequency generation (SFG) from the neighboring pairs of the signal or the idler modes. These mechanisms led the up-converted green frequency comb to have the same mode spacing of 450?GHz as that in the IR-OPO pump comb. As the pump was further detuned from the aforementioned near-degeneracy point and moved toward the signal (1020–1040?nm) and the idler (1090–1110?nm) spectral range, the above QPM parametric processes were preserved in the chirped QPM devices to support up-converted green generation in the 510–520?nm and the 545–555?nm spectral regime. Additional 530–535?nm green spectral generation was also observed due to concurrence of multi-wavelength SFG processes between the (signal, idler) mode pairs. These mechanisms facilitate the chirped QPM device to support a single-pass up-conversion efficiency ?10% when subject to an IR-OPO pump comb with 200 mW average power operated near- or off- the degeneracy point.

  10. Generation of green frequency comb from chirped ?(2) nonlinear photonic crystals

    NASA Astrophysics Data System (ADS)

    Lai, C.-M.; Chang, K.-H.; Yang, Z.-Y.; Fu, S.-H.; Tsai, S.-T.; Hsu, C.-W.; Yu, N. E.; Boudrioua, A.; Kung, A. H.; Peng, L.-H.

    2014-12-01

    Spectrally broad frequency comb generation over 510-555 nm range was reported on chirped quasi-phase-matching (QPM) ?(2) nonlinear photonic crystals of 12 mm length with periodicity stepwise increased from 5.9 ?m to 7.1 ?m. When pumped with nanosecond infrared (IR) frequency comb derived from a QPM optical parametric oscillator (OPO) and spanned over 1040 nm to 1090 nm wavelength range, the 520 nm to 545 nm up-converted green spectra were shown to consist of contributions from (a) second-harmonic generation among the signal or the idler modes, and (b) sum-frequency generation (SFG) from the neighboring pairs of the signal or the idler modes. These mechanisms led the up-converted green frequency comb to have the same mode spacing of 450 GHz as that in the IR-OPO pump comb. As the pump was further detuned from the aforementioned near-degeneracy point and moved toward the signal (1020-1040 nm) and the idler (1090-1110 nm) spectral range, the above QPM parametric processes were preserved in the chirped QPM devices to support up-converted green generation in the 510-520 nm and the 545-555 nm spectral regime. Additional 530-535 nm green spectral generation was also observed due to concurrence of multi-wavelength SFG processes between the (signal, idler) mode pairs. These mechanisms facilitate the chirped QPM device to support a single-pass up-conversion efficiency ˜10% when subject to an IR-OPO pump comb with 200 mW average power operated near- or off- the degeneracy point.

  11. Speed converter for SLAR video signals

    NASA Astrophysics Data System (ADS)

    Selmeci, J.; Bozsoki, I.; Hetenyi, T.

    A relatively simple speed converter is described that can slow down the high-speed burst of a side-looking airborne radar (SLAR) signal to the pulse repetition time so that it can be digitized by a simple medium speed successive approximation type analog-to-digital converter. The basic element of the speed converter is a CCD analog delay line which can sample the analog input with the required high speed and have a much lower readout speed. The speed converter also has application to digital storage oscilloscopes with up to 50 MHz sampling frequency.

  12. DC/DC Converter Stability Testing Study

    NASA Technical Reports Server (NTRS)

    Wang, Bright L.

    2008-01-01

    This report presents study results on hybrid DC/DC converter stability testing methods. An input impedance measurement method and a gain/phase margin measurement method were evaluated to be effective to determine front-end oscillation and feedback loop oscillation. In particular, certain channel power levels of converter input noises have been found to have high degree correlation with the gain/phase margins. It becomes a potential new method to evaluate stability levels of all type of DC/DC converters by utilizing the spectral analysis on converter input noises.

  13. All-prism achromatic phase matching for tunable second-harmonic generation

    SciTech Connect

    Richman, Bruce A.; Bisson, Scott E.; Trebino, Rick; Jacobson, Alexander

    1999-05-01

    Achromatic phase matching (APM) involves dispersing the light entering a nonlinear optical crystal so that a wide range of wavelengths is simultaneously phase matched. We constructed an APM apparatus consisting of six prisms, the final dispersion angle of which was optimized to match to second order in wavelength the type I phase-matching angle of {beta} barium borate (BBO). With this apparatus, we doubled tunable fundamental light from 620 to 700 nm in wavelength using a 4-mm-long BBO crystal. An analogous set of six prisms after the BBO crystal, optimized to second order in second-harmonic wavelength, realigned the output second-harmonic beams. Computer simulations predict that adjustment of a single prism can compensate angular misalignment of any or all the prisms before the crystal, and similarly for the prisms after the crystal. We demonstrated such compensations with the experimental device. The simulations also indicate that the phase-matching wavelength band can be shifted and optimized for different crystal lengths. {copyright} 1999 Optical Society of America

  14. Growth and characterization of new organic nonlinear optical crystal (R)-2-cyano-N-(1-phenylethyl) acetamide

    NASA Astrophysics Data System (ADS)

    Hemaraju, B. C.; Madhukar, B. S.; Bhadregowda, D. G.; Gnana Prakash, A. P.

    2014-04-01

    (R)-2-Cyano-N-(1-phenylethyl) acetamide (RCNPA) single crystals were grown by slow evaporation of the aqueous solution at room temperature (300K) using ethanol. The grown crystals were characterized by single crystal X-ray diffraction, powder X-ray diffraction, FTIR, UV-Vis-NIR transmittance, scanning electron microscopy (SEM) and powder second harmonic generation (SHG).

  15. Growth and characterization of new organic nonlinear optical crystal (R)-2-cyano-N-(1-phenylethyl) acetamide

    SciTech Connect

    Hemaraju, B. C.; Gnana Prakash, A. P.; Madhukar, B. S.; Bhadregowda, D. G.

    2014-04-24

    (R)-2-Cyano-N-(1-phenylethyl) acetamide (RCNPA) single crystals were grown by slow evaporation of the aqueous solution at room temperature (300K) using ethanol. The grown crystals were characterized by single crystal X-ray diffraction, powder X-ray diffraction, FTIR, UV-Vis-NIR transmittance, scanning electron microscopy (SEM) and powder second harmonic generation (SHG)

  16. Killing vector fields and harmonic superfield theories

    SciTech Connect

    Groeger, Josua

    2014-09-15

    The harmonic action functional allows a natural generalisation to semi-Riemannian supergeometry, also referred to as harmonic, which resembles the supersymmetric sigma models studied in high energy physics. We show that Killing vector fields are infinitesimal supersymmetries of this harmonic action and prove three different Noether theorems in this context. En passant, we provide a homogeneous treatment of five characterisations of Killing vector fields on semi-Riemannian supermanifolds, thus filling a gap in the literature.

  17. Power Quality/Harmonic Detection: Harmonic Control in Electric Power Systems for the Telecommunications Industry 

    E-print Network

    Felkner, L. J.; Waggoner, R. M.

    1993-01-01

    The control of harmonics in power systems continues to be a major concern in the telecommunications industry. AC/DC telecommunication conversion equipment has rarely been thought of as playing a major role in the harmonic interaction problem. Yet...

  18. Vacuum-insulated catalytic converter

    DOEpatents

    Benson, David K. (Golden, CO)

    2001-01-01

    A catalytic converter has an inner canister that contains catalyst-coated substrates and an outer canister that encloses an annular, variable vacuum insulation chamber surrounding the inner canister. An annular tank containing phase-change material for heat storage and release is positioned in the variable vacuum insulation chamber a distance spaced part from the inner canister. A reversible hydrogen getter in the variable vacuum insulation chamber, preferably on a surface of the heat storage tank, releases hydrogen into the variable vacuum insulation chamber to conduct heat when the phase-change material is hot and absorbs the hydrogen to limit heat transfer to radiation when the phase-change material is cool. A porous zeolite trap in the inner canister absorbs and retains hydrocarbons from the exhaust gases when the catalyst-coated substrates and zeolite trap are cold and releases the hydrocarbons for reaction on the catalyst-coated substrate when the zeolite trap and catalyst-coated substrate get hot.

  19. High voltage photovoltaic power converter

    DOEpatents

    Haigh, Ronald E. (Arvada, CO); Wojtczuk, Steve (Cambridge, MA); Jacobson, Gerard F. (Livermore, CA); Hagans, Karla G. (Livermore, CA)

    2001-01-01

    An array of independently connected photovoltaic cells on a semi-insulating substrate contains reflective coatings between the cells to enhance efficiency. A uniform, flat top laser beam profile is illuminated upon the array to produce electrical current having high voltage. An essentially wireless system includes a laser energy source being fed through optic fiber and cast upon the photovoltaic cell array to prevent stray electrical signals prior to use of the current from the array. Direct bandgap, single crystal semiconductor materials, such as GaAs, are commonly used in the array. Useful applications of the system include locations where high voltages are provided to confined spaces such as in explosive detonation, accelerators, photo cathodes and medical appliances.

  20. XUV frequency combs based on intracavity high harmonic generation

    NASA Astrophysics Data System (ADS)

    Jones, R. Jason

    2014-05-01

    Intracavity high harmonic generation utilizing femtosecond enhancement cavities (fsEC's) has been established as an efficient route for the generation of femtosecond frequency combs in the vacuum-ultraviolet (VUV) to the extreme-ultraviolet (XUV) spectral regions. Such VUV/XUV frequency combs enable precision spectroscopy of atomic and potentially molecular spectra in an otherwise difficult to access spectral region. An improved understanding of the intracavity ionization dynamics that currently limit pulse enhancement has enabled a new generation of XUV frequency comb sources with significantly higher powers, at the >10 microwatt level per harmonic order extending below 50nm. We have developed a novel time-resolved pump-probe measurement technique to monitor and characterize the intracavity ionization dynamics by utilizing the sensitive response of the fsEC resonance itself to plasma induced nonlinear phase shifts. In recent work, we have developed a high power dual-frequency comb system based on Yb-fiber laser technology. The two phase-coherent frequency combs can be up-converted to the VUV/XUV using the fsEC. Dual-comb spectroscopy has already been established as a powerful spectroscopic method in the infrared. It's extension to the VUV/XUV spectral region will enable robust and high precision direct frequency comb spectroscopy of complex atomic and molecular structure in this spectral region.

  1. Echo-Enabled Harmonic Generation for Seeded FELs

    SciTech Connect

    Stupakov, G.; /SLAC

    2011-05-19

    In the x-ray wavelengths, the two leading FEL concepts are the self-amplified spontaneous emission (SASE) configuration and the high-gain harmonic generation (HGHG) scheme. While the radiation from a SASE FEL is coherent transversely, it typically has rather limited temporal coherence. Alternatively, the HGHG scheme allows generation of fully coherent radiation by up-converting the frequency of a high-power seed laser. However, due to the relatively low up-frequency conversion efficiency, multiple stages of HGHG FEL are needed in order to generate x-rays from a UV laser. The up-frequency conversion efficiency can be greatly improved with the recently proposed echo-enabled harmonic generation (EEHG) technique. In this work we will present the concept of EEHG, and address some practically important issues that affect the performance of the seeding. We show how the EEHG can be incorporated in the FEL scheme and what is the expected performance of the EEHG seeded FEL. We will then briefly describe the first proof-of-principle EEHG experiment carried out at the Next Linear Collider Test Accelerator (NLCTA) at SLAC. We will also discuss latest advances in the echo-scheme approach, and refer to subsequent modifications of the original concept.

  2. Characterization of Second Harmonic Afterburner Radiation at the LCLS

    SciTech Connect

    Nuhn, Heinz-Dieter

    2010-09-14

    During commissioning of the Linac Coherent Light Source (LCLS) x-ray Free Electron Laser (FEL) at the SLAC National Accelerator Laboratory it was shown that saturation lengths much shorter than the installed length of the undulator line can routinely be achieved. This frees undulator segments that can be used to provide enhanced spectral properties and at the same time, test the concept of FEL Afterburners. In December 2009 a project was initiated to convert undulator segments at the down-beam end of the undulator line into Second Harmonic Afterburners (SHAB) to enhance LCLS radiation levels in the 10-20 keV energy range. This is being accomplished by replacement of gap-shims increasing the fixed gaps from 6.8 mm to 9.9 mm, which reduces their K values from 3.50 to 2.25 and makes the segments resonant at the second harmonic of the upstream unmodified undulators. This paper reports experimental results of the commissioning of the SHAB extension to LCLS.

  3. Harmonic Generation from Laser-Irradiated Clusters

    E-print Network

    Kundu, M; Bauer, D

    2007-01-01

    The harmonic emission from cluster nanoplasmas subject to short, intense infrared laser pulses is analyzed by means of particle-in-cell simulations. A pronounced resonant enhancement of the low-order harmonic yields is found when the Mie plasma frequency of the ionizing and expanding cluster resonates with the respective harmonic frequency. We show that a strong, nonlinear resonant coupling of the cluster electrons with the laser field inhibits coherent electron motion, suppressing the emitted radiation and restricting the spectrum to only low-order harmonics. A pump-probe scheme is suggested to monitor the ionization dynamics of the expanding clusters.

  4. Harmonic generation from laser-irradiated clusters

    SciTech Connect

    Kundu, M.; Bauer, D.; Popruzhenko, S. V.

    2007-09-15

    The harmonic emission from cluster nanoplasmas subject to short, intense infrared laser pulses is analyzed by means of particle-in-cell simulations. A pronounced resonant enhancement of the low-order harmonic yields is found when the Mie plasma frequency of the ionizing and expanding cluster resonates with the respective harmonic frequency. We show that a strong, nonlinear resonant coupling of the cluster electrons with the laser field inhibits coherent electron motion, suppressing the emitted radiation and restricting the spectrum to only low-order harmonics. A pump-probe scheme is suggested to monitor the ionization dynamics of the expanding clusters.

  5. Nonlinear harmonic generation by diurnal tides

    NASA Astrophysics Data System (ADS)

    Wunsch, Scott

    2015-09-01

    Recent observations from the South China Sea have demonstrated that semi-diurnal tides sometimes generate a double-frequency harmonic. Similar harmonic generation has been found in laboratory experiments and numerical simulations of internal wave beams refracting into a pycnocline. Here, a weakly nonlinear theory of internal wave refraction is applied to oceanic internal tides in an idealized stratification profile. The steady state harmonic amplitude is calculated as a function of the tidal frequency and the pycnocline characteristics. The results indicate that harmonic generation by nonlinear refraction of semi-diurnal tides is consistent with the South China Sea observations.

  6. Enhanced harmonic generation in aperiodic optical superlattices

    NASA Astrophysics Data System (ADS)

    Gu, Ben-Yuan; Dong, Bi-Zhen; Zhang, Yan; Yang, Guo-Zhen

    1999-10-01

    We find that harmonic generation can be enhanced with aperiodic optical superlattice (AOS) structures realized by inverting poled ferroelectric domains in sample. The optimal design of the AOS can be achieved with use of the simulated annealing method. The constructed AOSs can implement multiple wavelength second-harmonic generation and the coupled third-harmonic generation with an identical effective nonlinear coefficient. The simulations show that the constructed AOSs can enhance harmonic generation compared with the Fibonacci optical superlattice. The physical origin of this enhancement is ascribed to the constructive interference effect.

  7. High harmonic cusptron device with an inverted structure

    SciTech Connect

    Kim, J.; Faith, J.; Kuo, S.P.

    1994-12-31

    An e-beam driven coherent radiation source operating at high cyclotron harmonic is designed. This device, called inverted cusptron, has a coaxial line configuration structured with both slotted central line and outer conductor. It used a cusp-magnetic field to convert a hollow e-beam produced from an annular thermionic cathode into an e-layer as the radiation source. The advantageous feature of the tube is that the central cylindrical tube of the structure can be used as input-output ports for an amplifier setup. A particle simulation code is developed to study the interaction between the electrons in the e-layer and the mode fields of the tube. The optimum design parameters such as the dimensions of the tube, electron beam energy, and magnetic field in order to obtain the maximum efficiency of the device for the TE{sub 02} 2{pi} mode are determined by the results of simulations. Five harmonics (N = 6, 8, 10, 12, 16) are considered, and the corresponding tube parameters are tabulated. It is found that the efficiency of the tube is insensitive to the relative position between the inner and outer slots. On the other hand, it is strongly dependent on the configuration of the cathode ring. Considering an electron beam produced by a 1/4 ring cathode (i.e. a 90{degree} arc length), the optimum conversion efficiencies of the five tubes are calculated to be 25%, 23%, 16%, 11%, and 9% respectively at an output frequency around 20GHz. The experiment to test the sixteenth harmonic tube has been set up. The preliminary experimental results will also be reported.

  8. Deriving projective hyperspace from harmonic

    SciTech Connect

    Jain, Dharmesh; Siegel, Warren

    2009-08-15

    We derive actions for projective N=2 superspace ('hyperspace') from those for harmonic hyperspace, including that for non-Abelian Yang-Mills theory (a new result). The method uses Wick rotation of the sphere from complex conjugate coordinates to real, null ones, which can be treated as independent. The result can be considered 'holographic' in that the dimension of the internal (R symmetry) space is reduced from 2 to 1, by solving equations of motion or gauge conditions for dependence on the other coordinate. The auxiliary nature of the redundant dimension makes the hypergraph rules and evaluation almost identical.

  9. Making space for harmonic oscillators

    SciTech Connect

    Michelotti, Leo; /Fermilab

    2004-11-01

    If we restrict the number of harmonic oscillator energy eigenstates to some finite value, N, then the discrete spectrum of the corresponding position operator comprise the roots of the Hermite polynomial H{sub N+1}. Its range is just large enough to accommodate classical motion at high energy. A negative energy term must be added to the Hamiltonian which affects only the last eigenstate, |N>, suggesting it is concentrated at the extrema of this finite ''space''. Calculations support a conjecture that, in the limit of large N, the global distribution of points approaches the differential form for classical action.

  10. Harmonic potential and hadron spectroscopy

    E-print Network

    Rafael Tumanyan

    2009-05-28

    The quark-gluon sea in the hadrons is considered as periodically correlated. Energy levels of Shrodinger equation with harmonic potential is used for describing of the spectrum of hadron masses. In the considered cases the effective potential operating on each particle of ensemble, under certain conditions becomes square-law on displacement from a equilibrium point. It can become an explanation of popularity of oscillator potential for the description of a spectrum of masses of elementary particles. The analysis shows that levels of periodic potential better agreed to the spectrum of hadron masses, than levels of other potentials used for an explanation of a spectrum of masses.

  11. Symmetries of coupled harmonic oscillators

    NASA Technical Reports Server (NTRS)

    Han, D.; Kim, Y. S.

    1993-01-01

    It is shown that the system of two coupled harmonic oscillators possesses many interesting symmetries. It is noted that the symmetry of a single oscillator is that of the three-parameter group Sp(2). Thus two uncoupled oscillator exhibits a direct product of two Sp(2) groups, with six parameters. The coupling can be achieved through a rotation in the two-dimensional space of two oscillator coordinates. The closure of the commutation relations for the generators leads to the ten-parameter group Sp(4) which is locally isomorphic to the deSitter group O(3,2).

  12. The nonlinear optical response of a two-dimensional atomic crystal

    E-print Network

    Merano, Michele

    2015-01-01

    The theory of Bloembergen and Persham for the light waves at the boundary of nonlinear media is applied to a nonlinear two-dimensional atomic crystal placed in between linear bulk media. The crystal is treated as a zero-thickness interface, a real two-dimensional system. Harmonic waves emanate from it. Generalization of the laws of reflection and refraction give the direction and the intensity of the harmonic waves. The nonlinear polarization of these special materials is very sensitive to the substrate on which they are deposited. Experiments on second harmonic generation of a $\\rm MoS_{2}$ monolayer are discussed to elucidate this point.

  13. Time interleaved counter analog to digital converters 

    E-print Network

    Danesh, Seyed Amir Ali

    2011-11-22

    The work explores extending time interleaving in A/D converters, by applying a high-level of parallelism to one of the slowest and simplest types of data-converters, the counter ADC. The motivation for the work is to ...

  14. Power Converters Secure Electronics in Harsh Environments

    NASA Technical Reports Server (NTRS)

    2013-01-01

    In order to harden power converters for the rigors of space, NASA awarded multiple SBIR contracts to Blacksburg, Virginia-based VPT Inc. The resulting hybrid DC-DC converters have proven valuable in aerospace applications, and as a result the company has generated millions in revenue from the product line and created four high-tech jobs to handle production.

  15. High Precision Current Measurement for Power Converters

    E-print Network

    Cerqueira Bastos, M

    2015-01-01

    The accurate measurement of power converter currents is essential to controlling and delivering stable and repeatable currents to magnets in particle accelerators. This paper reviews the most commonly used devices for the measurement of power converter currents and discusses test and calibration methods.

  16. Passive Resonant Bidirectional Converter with Galvanic Barrier

    NASA Technical Reports Server (NTRS)

    Rosenblad, Nathan S. (Inventor)

    2014-01-01

    A passive resonant bidirectional converter system that transports energy across a galvanic barrier includes a converter using at least first and second converter sections, each section including a pair of transfer terminals, a center tapped winding; a chopper circuit interconnected between the center tapped winding and one of the transfer terminals; an inductance feed winding interconnected between the other of the transfer terminals and the center tap and a resonant tank circuit including at least the inductance of the center tap winding and the parasitic capacitance of the chopper circuit for operating the converter section at resonance; the center tapped windings of the first and second converter sections being disposed on a first common winding core and the inductance feed windings of the first and second converter sections being disposed on a second common winding core for automatically synchronizing the resonant oscillation of the first and second converter sections and transferring energy between the converter sections until the voltage across the pairs of transfer terminals achieves the turns ratio of the center tapped windings.

  17. RF digital-to-analog converter

    DOEpatents

    Conway, P.H.; Yu, D.U.L.

    1995-02-28

    A digital-to-analog converter is disclosed for producing an RF output signal proportional to a digital input word of N bits from an RF reference input, N being an integer greater or equal to 2. The converter comprises a plurality of power splitters, power combiners and a plurality of mixers or RF switches connected in a predetermined configuration. 18 figs.

  18. RF digital-to-analog converter

    DOEpatents

    Conway, Patrick H. (Rancho Palos Verdes, CA); Yu, David U. L. (Rancho Palos Verdes, CA)

    1995-01-01

    A digital-to analogue converter for producing an RF output signal proportional to a digital input word of N bits from an RF reference input, N being an integer greater or equal to 2. The converter comprises a plurality of power splitters, power combiners and a plurality of mixers or RF switches connected in a predetermined configuration.

  19. Controller for a wave energy converter

    DOEpatents

    Wilson, David G.; Bull, Diana L.; Robinett, III, Rush D.

    2015-09-22

    A wave energy converter (WEC) is described, the WEC including a power take off (PTO) that converts relative motion of bodies of the WEC into electrical energy. A controller controls operation of the PTO, causing the PTO to act as a motor to widen a wave frequency spectrum that is usable to generate electrical energy.

  20. (Convertible) Undeniable Signatures without Random Oracles

    E-print Network

    International Association for Cryptologic Research (IACR)

    (Convertible) Undeniable Signatures without Random Oracles Tsz Hon Yuen 1 , Man Ho Au 1 , Joseph K a convertible undeniable signature scheme without random oracles. Our construction is based on the Waters the existing undeniable signatures without random oracles due to Laguillaumie and Vergnaud. Keywords

  1. (Convertible) Undeniable Signatures without Random Oracles

    E-print Network

    International Association for Cryptologic Research (IACR)

    (Convertible) Undeniable Signatures without Random Oracles Tsz Hon Yuen1 , Man Ho Au1 , Joseph K a convertible undeniable signature scheme without random oracles. Our construction is based on the Waters the existing undeniable signatures without random oracles due to Laguillaumie and Vergnaud. Keywords

  2. Radiation Effects on DC-DC Converters

    NASA Technical Reports Server (NTRS)

    Zhang, De-Xin; AbdulMazid, M. D.; Attia, John O.; Kankam, Mark D. (Technical Monitor)

    2001-01-01

    In this work, several DC-DC converters were designed and built. The converters are Buck Buck-Boost, Cuk, Flyback, and full-bridge zero-voltage switched. The total ionizing dose radiation and single event effects on the converters were investigated. The experimental results for the TID effects tests show that the voltages of the Buck Buck-Boost, Cuk, and Flyback converters increase as total dose increased when using power MOSFET IRF250 as a switching transistor. The change in output voltage with total dose is highest for the Buck converter and the lowest for Flyback converter. The trend of increase in output voltages with total dose in the present work agrees with those of the literature. The trends of the experimental results also agree with those obtained from PSPICE simulation. For the full-bridge zero-voltage switch converter, it was observed that the dc-dc converter with IRF250 power MOSFET did not show a significant change of output voltage with total dose. In addition, for the dc-dc converter with FSF254R4 radiation-hardened power MOSFET, the output voltage did not change significantly with total dose. The experimental results were confirmed by PSPICE simulation that showed that FB-ZVS converter with IRF250 power MOSFET's was not affected with the increase in total ionizing dose. Single Event Effects (SEE) radiation tests were performed on FB-ZVS converters. It was observed that the FB-ZVS converter with the IRF250 power MOSFET, when the device was irradiated with Krypton ion with ion-energy of 150 MeV and LET of 41.3 MeV-square cm/mg, the output voltage increased with the increase in fluence. However, for Krypton with ion-energy of 600 MeV and LET of 33.65 MeV-square cm/mg, and two out of four transistors of the converter were permanently damaged. The dc-dc converter with FSF254R4 radiation hardened power MOSFET's did not show significant change at the output voltage with fluence while being irradiated by Krypton with ion energy of 1.20 GeV and LET of 25.97 MeV-square cm/mg. This might be due to fact that the device is radiation hardened.

  3. Evaluations of uranium-nitride fueled converters.

    NASA Technical Reports Server (NTRS)

    Shimada, K.; Cassell, P. L.

    1971-01-01

    Evaluation of two uranium-nitride (UN) fueled converters was initiated at the Jet Propulsion Laboratory to investigate the effect of fuel on the converter performance while being operated out-of-core. The initial tests were performed with the dynamic data acquisition system that was developed at the Laboratory. Parametric tests of these converters were to obtain: (1) static volt-ampere curves, (2) dynamic volt-ampere curves, and (3) the electrode work functions. The power outputs were 9.3 W/sq cm for the rhenium converter and 3.8 W/sq cm for the tungsten converter at 0.6 V when the emitter surface temperature was 2000 K, according to the static volt-ampere curves.

  4. Modelling, analyses and design of switching converters

    NASA Technical Reports Server (NTRS)

    Cuk, S. M.; Middlebrook, R. D.

    1978-01-01

    A state-space averaging method for modelling switching dc-to-dc converters for both continuous and discontinuous conduction mode is developed. In each case the starting point is the unified state-space representation, and the end result is a complete linear circuit model, for each conduction mode, which correctly represents all essential features, namely, the input, output, and transfer properties (static dc as well as dynamic ac small-signal). While the method is generally applicable to any switching converter, it is extensively illustrated for the three common power stages (buck, boost, and buck-boost). The results for these converters are then easily tabulated owing to the fixed equivalent circuit topology of their canonical circuit model. The insights that emerge from the general state-space modelling approach lead to the design of new converter topologies through the study of generic properties of the cascade connection of basic buck and boost converters.

  5. Continuous-wave Cascaded-Harmonic Generation and Multi-Photon Raman Lasing in Lithium Niobate Whispering-Gallery Resonators

    E-print Network

    Moore, Jeremy; Carmon, Tal; Jarrahi, Mona

    2011-01-01

    We report experimental demonstration of continuous-wave cascaded-harmonic generation and Raman lasing in a millimeter-scale lithium niobate whispering-gallery resonator pumped at a telecommunication-compatible infrared wavelength. Intensity enhancement through multiple recirculations in the whispering-gallery resonator and quasi phase-matching through a nonuniform crystal poling enable simultaneous cascaded-harmonic generation up to the fourth-harmonic accompanied by stimulated Raman, two-photon, three-photon, and four-photon Raman scattering corresponding the molecular vibrational wavenumbers 632 cm-1 and 255 cm-1 in z-cut lithium niobate at pump power levels as low as 200mW. We demonstrate simultaneous cascaded-harmonic generation and Raman lasing by observing the spectrum of the scattered light from the resonator and by capturing the image of the decoupled light from the resonator on a color CCD camera.

  6. Simultaneous type I and type II ?erenkov-phase matched second-harmonic generation in disordered nonlinear photonic structures.

    PubMed

    Ayoub, Mousa; Paßlick, Markus; Imbrock, Jörg; Denz, Cornelia

    2015-11-01

    We observe simultaneous type I and II ?erenkov-phase matched second-harmonic generation in a disordered nonlinear photonic crystal. The mean width of the disordered ferroelectric domains and the laser beam width are adjusted to be on the same length scale. We analyze the polarization properties, emission angles and intensities of each process. PMID:26561107

  7. Lysozyme Crystal

    NASA Technical Reports Server (NTRS)

    2004-01-01

    To the crystallographer, this may not be a diamond but it is just as priceless. A Lysozyme crystal grown in orbit looks great under a microscope, but the real test is X-ray crystallography. The colors are caused by polarizing filters. Proteins can form crystals generated by rows and columns of molecules that form up like soldiers on a parade ground. Shining X-rays through a crystal will produce a pattern of dots that can be decoded to reveal the arrangement of the atoms in the molecules making up the crystal. Like the troops in formation, uniformity and order are everything in X-ray crystallography. X-rays have much shorter wavelengths than visible light, so the best looking crystals under the microscope won't necessarily pass muster under the X-rays. In order to have crystals to use for X-ray diffraction studies, crystals need to be fairly large and well ordered. Scientists also need lots of crystals since exposure to air, the process of X-raying them, and other factors destroy them. Growing protein crystals in space has yielded striking results. Lysozyme's structure is well known and it has become a standard in many crystallization studies on Earth and in space.

  8. Spectral behavior of second harmonic signals from organic and non-organic materials in multiphoton microscopy

    PubMed Central

    Ehmke, Tobias; Knebl, Andreas; Reiss, Stephan; Fischinger, Isaak R.; Seiler, Theo G.; Stachs, Oliver; Heisterkamp, Alexander

    2015-01-01

    Multimodal nonlinear microscopy allows imaging of highly ordered biological tissue due to spectral separation of nonlinear signals. This requires certain knowledge about the spectral distribution of the different nonlinear signals. In contrast to several publications we demonstrate a factor of 122 relating the full width at half maximum of a gaussian laser pulse spectrum to the corresponding second harmonic pulse spectrum in the spatial domain by using a simple theoretical model. Experiments on monopotassium phosphate crystals (KDP-crystals) and on porcine corneal tissue support our theoretical predictions. Furthermore, no differences in spectral width were found for epi- and trans-detection of the second harmonic signal. Overall, these results may help to build an optimized multiphoton setup for spectral separation of nonlinear signals. PMID:26339527

  9. Spectral behavior of second harmonic signals from organic and non-organic materials in multiphoton microscopy

    NASA Astrophysics Data System (ADS)

    Ehmke, Tobias; Knebl, Andreas; Reiss, Stephan; Fischinger, Isaak R.; Seiler, Theo G.; Stachs, Oliver; Heisterkamp, Alexander

    2015-08-01

    Multimodal nonlinear microscopy allows imaging of highly ordered biological tissue due to spectral separation of nonlinear signals. This requires certain knowledge about the spectral distribution of the different nonlinear signals. In contrast to several publications we demonstrate a factor of /1 2 ?{ 2 } relating the full width at half maximum of a gaussian laser pulse spectrum to the corresponding second harmonic pulse spectrum in the spatial domain by using a simple theoretical model. Experiments on monopotassium phosphate crystals (KDP-crystals) and on porcine corneal tissue support our theoretical predictions. Furthermore, no differences in spectral width were found for epi- and trans-detection of the second harmonic signal. Overall, these results may help to build an optimized multiphoton setup for spectral separation of nonlinear signals.

  10. Current Generated Harmonics and Their Effect Upon Electrical Industrial Systems 

    E-print Network

    Alexander, H. R.; Rogge, D. S.

    1995-01-01

    This paper provides a general overview of harmonics and addresses the causes of current generated harmonics in electrical systems. In addition, problems caused by current generated harmonics and their affects upon different types of electrical...

  11. RNA Crystallization

    NASA Technical Reports Server (NTRS)

    Golden, Barbara L.; Kundrot, Craig E.

    2003-01-01

    RNA molecules may be crystallized using variations of the methods developed for protein crystallography. As the technology has become available to syntheisize and purify RNA molecules in the quantities and with the quality that is required for crystallography, the field of RNA structure has exploded. The first consideration when crystallizing an RNA is the sequence, which may be varied in a rational way to enhance crystallizability or prevent formation of alternate structures. Once a sequence has been designed, the RNA may be synthesized chemically by solid-state synthesis, or it may be produced enzymatically using RNA polymerase and an appropriate DNA template. Purification of milligram quantities of RNA can be accomplished by HPLC or gel electrophoresis. As with proteins, crystallization of RNA is usually accomplished by vapor diffusion techniques. There are several considerations that are either unique to RNA crystallization or more important for RNA crystallization. Techniques for design, synthesis, purification, and crystallization of RNAs will be reviewed here.

  12. Sunspots and Their Simple Harmonic Motion

    ERIC Educational Resources Information Center

    Ribeiro, C. I.

    2013-01-01

    In this paper an example of a simple harmonic motion, the apparent motion of sunspots due to the Sun's rotation, is described, which can be used to teach this subject to high-school students. Using real images of the Sun, students can calculate the star's rotation period with the simple harmonic motion mathematical expression.

  13. SHTOOLS: Tools for Working with Spherical Harmonics

    NASA Astrophysics Data System (ADS)

    Wieczorek, Mark

    2011-10-01

    SHTOOLS is an archive of fortran 95 based software that can be used to perform (among others) spherical harmonic transforms and reconstructions, rotations of spherical harmonic coefficients, and multitaper spectral analyses on the sphere. While several collections of code currently exist for working with data expressed in spherical harmonics, this one is unique for several reasons: It can accommodate any standard normalization of the spherical harmonic functions ("geodesy" 4? normalized, Schmidt semi-normalized, orthonormalized, and unnormalized).Either real or complex spherical harmonics can be employed.Spherical harmonic transforms are calculated by exact quadrature rules using either (1) the sampling theorem of Driscoll and Healy (1994) where data are equally sampled (or spaced) in latitude and longitude, or (2) Gauss-Legendre quadrature. A least squares inversion routine for irregularly sampled data is included as well.One can choose to use or exclude the Condon-Shortley phase factor of (-1)m with the associated Legendre functions.The spherical harmonic transforms are proven to be accurate to approximately degree 2800, corresponding to a spatial resolution of better than 4 arc minutes.Routines are included for performing localized multitaper spectral analyses.Routines are included for performing standard gravity calculations, such as computation of the geoid and the determination of the potential associated with finite-amplitude topography.The routines are fast. Spherical harmonic transforms and reconstructions take on the order of 1 second for bandwidths less than 600 and about 3 minutes for bandwidths close to 2800.

  14. HARMONIC CYCLOTRON HEATING IN THE TOROIDAL OCTUPOLE

    E-print Network

    Sprott, Julien Clinton

    HARMONIC CYCLOTRON HEATING IN THE TOROIDAL OCTUPOLE J. C. Sprott October 1976 Plasma Studies PLP without consent of the author and maj or professor. #12;-2- Previous calculations of cyclotron resonance the harmonic cyclotron heating of both electrons and ions. It is well known (see, for example, O. Eldridge

  15. Effective bandwidth extension by combined harmonics

    NASA Astrophysics Data System (ADS)

    Clement, Gregory T.; Nomura, Hideyuki; Adachi, Hideo; Kamakura, Tomoo

    2012-09-01

    Originating from signal compression techniques in radar, a wide range of ultrasound encoded excitation approaches have been developed for increasing signal strength. These techniques have been extended to nonlinear applications by isolating higher harmonic signal components, thus offering higher signal-to-noise ratios along with the harmonic's increased radial focusing abilities and a potentially broader bandwidth relative to the fundamental. Unfortunately, such techniques can suffer artifacts caused by overlap between the harmonics. We have been investigating an alternative approach to nonlinear compression that combines the fundamental and higher harmonics, effectively treating them as a single band. This extended bandwidth permits a significant increase in the ability to compress a signal. Successfully implemented, the method would permit enhanced image resolution while benefiting from the increased SNR offered by encoding. Pulse-inverted sum and difference signals are first used to isolate even and odd harmonics. Matched filters specific to the source geometry and the transmit signal are then separately applied to each harmonic band. Verification experiments are performed using up the third harmonic resulting from an underwater chirp excitation. Analysis of signal peaks after scattering indicates increased compression using the extended bandwidth as compared to standard fundamental and 2nd-harmonic chirp compression. Further optimization of the compression by altering the transmission signal is also investigated. Overall, results establish the feasibility of extended bandwidth signal compression for simultaneously increasing SNR and signal resolution.

  16. Harmonic oscillator states in aberration optics

    NASA Technical Reports Server (NTRS)

    Wolf, Kurt Bernardo

    1993-01-01

    The states of the three-dimensional quantum harmonic oscillator classify optical aberrations of axis-symmetric systems due to the isomorphism between the two mathematical structures. Cartesian quanta and angular momentum classifications have their corresponding aberration classifications. The operation of concatenation of optical elements introduces a new operation between harmonic oscillator states.

  17. Harmonic morphisms from homogeneous Hadamard manifolds

    E-print Network

    Gudmundsson, Sigmundur

    2010-01-01

    We present a new method for manufacturing complex-valued harmonic morphisms from a wide class of Riemannian Lie groups. This yields new solutions from an important family of homogeneous Hadamard manifolds. We also give a new method for constructing left-invariant foliations on a large class of Lie groups producing harmonic morphisms

  18. Practical Tools to Foster Harmonic Understanding

    ERIC Educational Resources Information Center

    Johnson, Erik

    2013-01-01

    Among the elements required to develop a comprehensive understanding of music is students' ability to perceive, recognize, and label the harmonies they hear. Harmonic dictation is among the strategies that teachers have traditionally chosen to help students develop harmonic awareness. However, the highly idiosyncratic ways that students approach…

  19. Harmonic considerations for electrical distribution feeders

    NASA Astrophysics Data System (ADS)

    1988-03-01

    Harmonics on the electric power distribution system can cause motor overheating, capacitor failures,watt-hour meter error, and relay malfunctions. The degree of problems caused by harmonics is greatly dependent on the characteristics of the distribution feeder, which can absorb a considerable percentage of its capacity in harmonic currents without ill effects. However, power factor correction capacitors can cause resonances near harmonic voltages that can result in intolerable distortion. Both motor loads and resistive loads can decrease the effect of resonance significantly. This report describes useful techniques to analyze, suppress, and measure harmonics on distribution feeders. Applicable areas for manual analysis and computer analysis are explained. The basic formulae are presented as well as sophisticated computer methods. Emphasis is placed on the fundamental principle. Models of harmonic-producing devices are presented and their limitations discussed. Most distribution feeder harmonics analyses can be performed using simple current source models. Filtering of specific loads and general, dispersed load is discussed. The fundamental principle in filtering distribution feeders is to shorten the harmonic current path. 3-dimensional plots enhance the understanding of the filtering action. Equipment and procedures for making measurements are described.

  20. CW, single-frequency 229nm laser source for Cd-cooling by harmonic conversion

    NASA Astrophysics Data System (ADS)

    Kaneda, Yushi; Yarborough, J. M.; Merzlyak, Yevgeny

    2015-02-01

    More than 200mW of CW 229nm for Cd atom cooling application was generated by the 4th harmonic of a single frequency optically pumped semiconductor laser using a 10-mm long, Brewster-cut BBO crystal in an external cavity. With 650mW of 458nm input, 216mW of 229nm power was observed. Conversion efficiency from 458nm to 229nm was more than 33%.

  1. Protein Crystallization

    NASA Technical Reports Server (NTRS)

    Chernov, Alexander A.

    2005-01-01

    Nucleation, growth and perfection of protein crystals will be overviewed along with crystal mechanical properties. The knowledge is based on experiments using optical and force crystals behave similar to inorganic crystals, though with a difference in orders of magnitude in growing parameters. For example, the low incorporation rate of large biomolecules requires up to 100 times larger supersaturation to grow protein, rather than inorganic crystals. Nucleation is often poorly reproducible, partly because of turbulence accompanying the mixing of precipitant with protein solution. Light scattering reveals fluctuations of molecular cluster size, its growth, surface energies and increased clustering as protein ages. Growth most often occurs layer-by-layer resulting in faceted crystals. New molecular layer on crystal face is terminated by a step where molecular incorporation occurs. Quantitative data on the incorporation rate will be discussed. Rounded crystals with molecularly disordered interfaces will be explained. Defects in crystals compromise the x-ray diffraction resolution crucially needed to find the 3D atomic structure of biomolecules. The defects are immobile so that birth defects stay forever. All lattice defects known for inorganics are revealed in protein crystals. Contribution of molecular conformations to lattice disorder is important, but not studied. This contribution may be enhanced by stress field from other defects. Homologous impurities (e.g., dimers, acetylated molecules) are trapped more willingly by a growing crystal than foreign protein impurities. The trapped impurities induce internal stress eliminated in crystals exceeding a critical size (part of mni for ferritin, lysozyme). Lesser impurities are trapped from stagnant, as compared to the flowing, solution. Freezing may induce much more defects unless quickly amorphysizing intracrystalline water.

  2. Crystal Lake 

    E-print Network

    Unknown

    2011-09-05

    APPLICATION OF FREEZE CRYSTALLIZATION ROBERT G. GORGOL, MARKETING MANAGER, HPD INCORPORATED, NAPERVILLE, ILLINOIS ABSTRACT Industrial usc of frcezing for componcnt purification and separation is well understood, but commercial applications have becn... limitcd. Development of this process for commercial use has now bcen performed. The unique featurcs of frecze crystallization, low temperature operation, separation of organic and in-organic contaminants, can be put to use. Frccze crystallization can...

  3. Density- and wavefunction-normalized Cartesian spherical harmonics for l ? 20

    DOE PAGESBeta

    Michael, J. Robert; Volkov, Anatoliy

    2015-03-01

    The widely used pseudoatom formalism in experimental X-ray charge-density studies makes use of real spherical harmonics when describing the angular component of aspherical deformations of the atomic electron density in molecules and crystals. The analytical form of the density-normalized Cartesian spherical harmonic functions for up to l ? 7 and the corresponding normalization coefficients were reported previously by Paturle & Coppens. It was shown that the analytical form for normalization coefficients is available primarily forl ? 4. Only in very special cases it is possible to derive an analytical representation of the normalization coefficients for 4 l ? 7.more »In most cases for l > 4 the density normalization coefficients were calculated numerically to within seven significant figures. In this study we review the literature on the density-normalized spherical harmonics, clarify the existing notations, use the Paturle–Coppens method in the Wolfram Mathematicasoftware to derive the Cartesian spherical harmonics for l ? 20 and determine the density normalization coefficients to 35 significant figures, and computer-generate a Fortran90 code. The article primarily targets researchers who work in the field of experimental X-ray electron density, but may be of some use to all who are interested in Cartesian spherical harmonics.« less

  4. Harmonizing national with international standards in Japan

    SciTech Connect

    Hohki, Keiichi; Hammons, T.J.

    1996-05-01

    This paper presents a Japanese engineer`s view on harmonization of global standards as the key factor in maintaining and promoting free trade. Japan is endowed with almost no natural resources, and, for this reason, Japan must rely on international trade to sustain its standard of living. Japan fully recognizes that the maintenance and promotion of mutually beneficial free trade is indispensable for cooperation in an international society, and is essential for Japan`s survival. It is very clear that the promotion of the international harmonization of standards is the key factor in the maintenance and promotion of free trade. And Japan is one of the countries most eagerly hoping for its realization. The authors focus on three issues concerning the international harmonization of Japanese standards: (1) Efforts Japan has made for the harmonization of Japanese standards with international ones; (2) natural or tectonic circumstances unique to Japanese standards; and (3) relationship between standard harmonization and international trade.

  5. Synthesis, crystal growth and characterization of nonlinear optical organic crystal: p-Toluidinium p-toluenesulphonate

    SciTech Connect

    Vijayakumar, P.; Anandha Babu, G.; Ramasamy, P.

    2012-04-15

    Graphical abstract: p-Toluidinium p-toluenesulphonate (p-TTS) an organic nonlinear optical crystal has been grown from the aqueous solution by slow evaporation solution growth technique. Single crystal X-ray diffraction analysis reveals that p-TTS crystallizes in monoclinic crystal system. p-TTS single crystal belongs to negative birefringence crystal. Second harmonic conversion efficiency of p-TTS has been found to be 1.3 times higher than that of KDP. Multiple shot surface laser damage threshold is determined to be 0.30 GW/cm{sup 2} at 1064 nm laser radiation. Highlights: Black-Right-Pointing-Pointer It deals with the synthesis, growth and characterization of p-TTS an organic NLO crystal. Black-Right-Pointing-Pointer Wide optical transparency window between 280 nm and 1100 nm. Black-Right-Pointing-Pointer Negative birefringence crystal and dispersion of birefringence is negligibly small. Black-Right-Pointing-Pointer Thermal study reveals that the grown crystal is stable up to 210 Degree-Sign C. Black-Right-Pointing-Pointer Multiple shot surface laser damage threshold is 0.30 GW/cm{sup 2} at 1064 nm laser radiation. -- Abstract: p-Toluidinium p-toluenesulphonate (p-TTS) an organic nonlinear optical crystal has been grown from the aqueous solution by slow evaporation solution growth technique. Single crystal X-ray diffraction analysis reveals that p-TTS crystallizes in monoclinic crystal system. The structural perfection of the grown p-TTS single crystal has been analyzed by high-resolution X-ray diffraction rocking curve measurements. Fourier transform infrared spectral studies have been performed to identify the functional groups. The optical transmittance window and the lower cutoff wavelength of the grown crystals have been identified by UV-vis-IR studies. Birefringence of p-TTS crystal has been studied using channel spectrum measurement. The laser damage threshold value was measured using Nd:YAG laser. The second harmonic conversion efficiency of p-TTS has been determined using Kurtz powder technique. Thermo gravimetric and differential thermal analyses were used to study its thermal properties. Dielectric constant, dielectric loss and AC conductivity of the grown p-TTS single crystal has been studied.

  6. Mechanical phase matching of birefringent non-linear crystals.

    PubMed

    Deyra, Loïc; Balembois, François; Guilbaud, André; Villeval, Philippe; Georges, Patrick

    2014-09-22

    Second-order nonlinear processes such as second harmonic generation or parametric amplification have found numerous applications in the scientific and industrial world, from micromachining to petawatt laser facilities. These nonlinear interactions are mostly carried out in birefringent crystals because of their low cost and the possibility to operate at high powers Phase-matching configurations in birefringent crystals are determined by their refractive indexes. Here, we show that an important mechanical stress can be used to significantly change the phase-matching properties of a birefringent crystal. As an example, we demonstrate the shift of second harmonic non-critical phase matching wavelength of LiB3O5 (LBO) crystal at room temperature from 1200 nm to 1120 nm by applying compressive forces up to 100 MPa. We believe that this mechanical phase matching can be used as an additional degree of freedom to optimize nonlinear optical frequency mixing geometries. PMID:25321800

  7. Generation of tunable ultrafast ultraviolet third harmonic by collinear compensation of group-velocity mismatch

    NASA Astrophysics Data System (ADS)

    Meng, Xianghao; Liu, Huagang; Huang, Jianhong; Wu, Hongchun; Deng, Jing; Dai, Shutao; Weng, Wen; Lin, Wenxiong

    2015-10-01

    We demonstrate a high efficient frequency tripling configuration of Ti: sapphire amplifier system for wavelength-tunable ultrafast ultraviolet laser generation. A new nonlinear crystal Ba1-xB2-y-zO4SixAlyGaz and a type-II phase-matched ?-BaB2O4 crystal are employed for the second and the third harmonic generation, respectively. Significant improvement in conversion efficiency of frequency tripling is achieved by using a 65°-cut, 3-mm-long ?-BaB2O4 crystal as the collinear group velocity compensation plate. Tunable ultraviolet pulse within the wavelength range from 256.7 to 276.7 nm have been produced, with a maximum average power of 212 mW, corresponding to a conversion efficiency of 8.48% for the third harmonic generation with 2.5 W fundamental power. The maximum pulse energy of the third harmonic is up to 0.21 mJ and it is estimated that the peak power is above 1 GW at 266.7 nm.

  8. Synthesis, crystal growth and physiochemical characterization of organic NLO crystal: L-ornithinium dipicrate (LODP).

    PubMed

    Balaprabhakaran, S; Chandrasekaran, J; Babu, B; Thirumurugan, R; Anitha, K

    2015-02-01

    L-ornithinium dipicrate (LODP) has been synthesized and good quality single crystals were grown by slow evaporation method at room temperature. Single crystal XRD confirms that the grown crystal belongs to the monoclinic system with the noncentrosymmetric space group P21. Powder X-ray diffraction study confirms the crystalline nature of the compound. FTIR spectral analysis confirms the functional group in the synthesized compound. Thermogravimetric and differential thermal analyses reveal the thermal stability of the crystal. The optical absorption spectrum shows the absence of absorption between 475 nm and 800 nm. The dielectric measurements were carried out to estimate the dielectric parameters of the grown crystal in the frequency range from 50 Hz to 5 MHz at various temperatures. The second harmonic property has been investigated by Kurtz-Perry powder technique. The relative SHG efficiency of LODP is found to be 14.57 times greater than that of the reference material KDP. PMID:25448969

  9. Synthesis, crystal growth and physiochemical characterization of organic NLO crystal: L-ornithinium dipicrate (LODP)

    NASA Astrophysics Data System (ADS)

    Balaprabhakaran, S.; Chandrasekaran, J.; Babu, B.; Thirumurugan, R.; Anitha, K.

    2015-02-01

    L-ornithinium dipicrate (LODP) has been synthesized and good quality single crystals were grown by slow evaporation method at room temperature. Single crystal XRD confirms that the grown crystal belongs to the monoclinic system with the noncentrosymmetric space group P21. Powder X-ray diffraction study confirms the crystalline nature of the compound. FTIR spectral analysis confirms the functional group in the synthesized compound. Thermogravimetric and differential thermal analyses reveal the thermal stability of the crystal. The optical absorption spectrum shows the absence of absorption between 475 nm and 800 nm. The dielectric measurements were carried out to estimate the dielectric parameters of the grown crystal in the frequency range from 50 Hz to 5 MHz at various temperatures. The second harmonic property has been investigated by Kurtz-Perry powder technique. The relative SHG efficiency of LODP is found to be 14.57 times greater than that of the reference material KDP.

  10. Matrix laser IR-visible image converter

    SciTech Connect

    Lipatov, N I; Biryukov, A S

    2006-04-30

    A new type of a focal matrix IR-visible image converter is proposed. The pixel IR detectors of the matrix are tunable microcavities of VCSEL (vertical-cavity surface emitting laser) semiconductor microstructures. The image conversion is performed due to the displacements of highly reflecting cavity mirrors caused by thermoelastic stresses in their microsuspensions appearing upon absorption of IR radiation. Analysis of the possibilities of the converter shows that its sensitivity is 10{sup -3}-10{sup -2} K and the time response is 10{sup -4}-10{sup -3} s. These characteristics determine the practical application of the converter. (laser applications and other topics in quantum electronics)

  11. Operation of high power converters in parallel

    NASA Technical Reports Server (NTRS)

    Decker, D. K.; Inouye, L. Y.

    1993-01-01

    High power converters that are used in space power subsystems are limited in power handling capability due to component and thermal limitations. For applications, such as Space Station Freedom, where multi-kilowatts of power must be delivered to user loads, parallel operation of converters becomes an attractive option when considering overall power subsystem topologies. TRW developed three different unequal power sharing approaches for parallel operation of converters. These approaches, known as droop, master-slave, and proportional adjustment, are discussed and test results are presented.

  12. Harmonic Millimeter Wave Generation and Frequency Up-Conversion Using Optical Injection Locking and Brillouin Selective Sideband Amplification

    NASA Astrophysics Data System (ADS)

    Li, Wei; Zhu, Ning-Hua; Wang, Li-Xian; Liu, Jian-Guo; Qi, Xiao-Qiong; Xie, Liang

    2010-10-01

    Harmonic millimeter wave (mm-wave) generation and frequency up-conversion are experimentally demonstrated using optical injection locking and Brillouin selective sideband amplification (BSSA) induced by stimulated Brillouin scattering in a 10-km single-mode fiber. By using this method, we successfully generate third-harmonic mm-wave at 27 GHz (fLO = 9 GHz) with single sideband (SSB) modulation and up-convert the 2 GHz intermediate frequency signal into the mm-wave band with single mode modulation of the SSB modes. In addition, the mm-wave carrier obtains more than 23 dB power gain due to the BSSA. The transmission experiments show that the generated mm-wave and up-converted signals indicate strong immunity against the chromatic dispersion of the fibers.

  13. Point-based manifold harmonics.

    PubMed

    Liu, Yang; Prabhakaran, Balakrishnan; Guo, Xiaohu

    2012-10-01

    This paper proposes an algorithm to build a set of orthogonal Point-Based Manifold Harmonic Bases (PB-MHB) for spectral analysis over point-sampled manifold surfaces. To ensure that PB-MHB are orthogonal to each other, it is necessary to have symmetrizable discrete Laplace-Beltrami Operator (LBO) over the surfaces. Existing converging discrete LBO for point clouds, as proposed by Belkin et al., is not guaranteed to be symmetrizable. We build a new point-wisely discrete LBO over the point-sampled surface that is guaranteed to be symmetrizable, and prove its convergence. By solving the eigen problem related to the new operator, we define a set of orthogonal bases over the point cloud. Experiments show that the new operator is converging better than other symmetrizable discrete Laplacian operators (such as graph Laplacian) defined on point-sampled surfaces, and can provide orthogonal bases for further spectral geometric analysis and processing tasks. PMID:22879345

  14. Quantum wormholes and harmonic oscillators

    NASA Technical Reports Server (NTRS)

    Garay, Luis J.

    1993-01-01

    The quantum state of a wormhole can be represented by a path integral over all asymptotically Euclidean four-geometries and all matter fields which have prescribed values, the arguments of the wave function, on a three-surface which divides the space time manifold into two disconnected parts. Minisuperspace models which consist of a homogeneous massless scalar field coupled to a Friedmann-Robertson-Walker space time are considered. Once the path integral over the lapse function is performed, the requirement that the space time be asymptotically Euclidean can be accomplished by fixing the asymptotic gravitational momentum in the remaining path integral. It is argued that there does not exist any wave function which corresponds to asymptotic field configurations such that the effective gravitational constant is negative in the asymptotic region. Then, the wormhole wave functions can be written as linear combinations of harmonic oscillator wave functions.

  15. Electron cyclotron harmonic wave acceleration

    NASA Technical Reports Server (NTRS)

    Karimabadi, H.; Menyuk, C. R.; Sprangle, P.; Vlahos, L.

    1987-01-01

    A nonlinear analysis of particle acceleration in a finite bandwidth, obliquely propagating electromagnetic cyclotron wave is presented. It has been suggested by Sprangle and Vlahos in 1983 that the narrow bandwidth cyclotron radiation emitted by the unstable electron distribution inside a flaring solar loop can accelerate electrons outside the loop by the interaction of a monochromatic wave propagating along the ambient magnetic field with the ambient electrons. It is shown here that electrons gyrating and streaming along a uniform, static magnetic field can be accelerated by interacting with the fundamental or second harmonic of a monochromatic, obliquely propagating cyclotron wave. It is also shown that the acceleration is virtually unchanged when a wave with finite bandwidth is considered. This acceleration mechanism can explain the observed high-energy electrons in type III bursts.

  16. Modified Perfect Harmonics Cancellation Control of a Grid Interfaced SPV Power Generation

    NASA Astrophysics Data System (ADS)

    Singh, B.; Shahani, D. T.; Verma, A. K.

    2015-03-01

    This paper deals with a grid interfaced solar photo voltaic (SPV) power generating system with modified perfect harmonic cancellation (MPHC) control for power quality improvement in terms of mitigation of the current harmonics, power factor correction, control of point of common coupling (PCC) voltage with reactive power compensation and load balancing in a three phase distribution system. The proposed grid interfaced SPV system consists of a SPV array, a dc-dc boost converter and a voltage source converter (VSC) used for the compensation of other connected linear and nonlinear loads at PCC. The reference grid currents are estimated using MPHC method and control signals are derived by using pulse width modulation (PWM) current controller of VSC. The SPV power is fed to the common dc bus of VSC and dc-dc boost converter using maximum power point tracking (MPPT). The dc link voltage of VSC is regulated by using dc voltage proportional integral (PI) controller. The analysis of the proposed SPV power generating system is carried out under dc/ac short circuit and severe SPV-SX and SPV-TX intrusion.

  17. 100kW Energy Transfer Multiplexer Power Converter Prototype Development Project

    SciTech Connect

    S. Merrill Skeist; Richard H. Baker; Anthony G.P. Marini; DOE Project Officer - Keith Bennett

    2006-03-21

    Project Final Report for "100kW Energy Transfer Multiplexer Power Converter Prototype Development Project" prepared under DOE grant number DE-FG36-03GO13138. This project relates to the further development and prototype construction/evaluation for the Energy Transfer Multiplexer (ETM) power converter topology concept. The ETM uses a series resonant link to transfer energy from any phase of a multiphase input to any phase of a multiphase output, converting any input voltage and frequency to any output voltage and frequency. The basic form of the ETM converter consists of an eight (8)-switch matrix (six phase power switches and two ground power switches) and a series L-C resonant circuit. Electronic control of the switches allows energy to be transferred in the proper amount from any phase to any other phase. Depending upon the final circuit application, the switches may be either SCRs or IGBTs. The inherent characteristics of the ETM converter include the following: Power processing in either direction (bidirectional); Large voltage gain without the need of low frequency magnetics; High efficiency independent of output load and frequency; Wide bandwidth with fast transient response and; Operation as a current source. The ETM is able to synthesize true sinusoidal waveforms with low harmonic distortions. For a low power PM wind generation system, the ETM has the following characteristics and advantages: It provides voltage gain without the need of low frequency magnetics (DC inductors) and; It has constant high efficiency independent of the load. The ETM converter can be implemented into a PM wind power system with smaller size, reduced weight and lower cost. As a result of our analyses, the ETM offers wind power generation technology for the reduction of the cost and size as well as the increase in performance of low power, low wind speed power generation. This project is the further theoretical/analytical exploration of the ETM converter concept in relationship to PM wind power generator applications in the 100kW and under power range. The theoretical/analytical and bench scale work focuses on simplifying the basic ETM converter topology (in terms of parts count and complexity) for the specific application of the low power PM system. The project goals and objectives were for Spellman HV will develop a 100kW prototype ETM power converter based on paralleled lower ratings converters. The proposed configuration of this prototype is a 100kW rated converter comprised of four (4) 34kW rated modules connected in parallel (the fourth converter is included to demonstrate N+1 fault tolerance). This approach is more viable as there is lower technological risk involved in developing a 34kW-rated converter than a single 100kW unit. The modular system approach should have a lower deployment and service cost over a single unit system, because of the economics of scale (smaller units at a higher volume means lower manufacturing cost) and because of improved serviceability (a non-redundant power system with one failed module will still operate at a lower power level). There is also the added benefit that greater commercial application and acceptance should be achieved by having a modular system available in which fault tolerance (N+1 or 2N) is a feature. This modular approach would allow the output power to be increased by adding more paralleled converters. Thus, the maximum output power of the overall power system is a function of the interconnection medium (the hot swap connection subsystem), rather than the ratings of a single module. The project was implemented with Spellman HV acting as the program management and production assembly and test facility; The Baker Company acting as a technical consultant and resource when required; and dtm Associates acting as the design/development resource for the hardware development of the 100kW ETM converter prototype.

  18. The harmonic oscillator and the position dependent mass Schroedinger equation: isospectral partners and factorization operators

    SciTech Connect

    Morales, J.; Ovando, G.; Pena, J. J.

    2010-12-23

    One of the most important scientific contributions of Professor Marcos Moshinsky has been his study on the harmonic oscillator in quantum theory vis a vis the standard Schroedinger equation with constant mass [1]. However, a simple description of the motion of a particle interacting with an external environment such as happen in compositionally graded alloys consist of replacing the mass by the so-called effective mass that is in general variable and dependent on position. Therefore, honoring in memoriam Marcos Moshinsky, in this work we consider the position-dependent mass Schrodinger equations (PDMSE) for the harmonic oscillator potential model as former potential as well as with equi-spaced spectrum solutions, i.e. harmonic oscillator isospectral partners. To that purpose, the point canonical transformation method to convert a general second order differential equation (DE), of Sturm-Liouville type, into a Schroedinger-like standard equation is applied to the PDMSE. In that case, the former potential associated to the PDMSE and the potential involved in the Schroedinger-like standard equation are related through a Riccati-type relationship that includes the equivalent of the Witten superpotential to determine the exactly solvable positions-dependent mass distribution (PDMD)m(x). Even though the proposed approach is exemplified with the harmonic oscillator potential, the procedure is general and can be straightforwardly applied to other DEs.

  19. CMB map derived from the WMAP data through harmonic internal linear combination

    SciTech Connect

    Kim, Jaiseung; Naselsky, Pavel; Christensen, Per Rex

    2008-05-15

    We are presenting an internal linear combination CMB map, in which the foreground is reduced through harmonic variance minimization. We have derived our method by converting a general form of pixel-space approach into spherical harmonic space, maintaining full correspondence. By working in spherical harmonic space, spatial variability of linear weights is incorporated in a self-contained manner and our linear weights are continuous functions of position over the entire sky. The full correspondence to pixel-space approach enables straightforward physical interpretation on our approach. In variance minimization of a linear combination map, the existence of a cross term between residual foregrounds and CMB makes the linear combination of minimum variance differ from that of minimum foreground. We have developed an iterative foreground reduction method, where perturbative correction is made for the cross term. Our CMB map derived from the WMAP data is in better agreement with the WMAP best-fit {lambda}CDM model than the WMAP team's internal linear combination map. We find that our method's capacity to clean foreground is limited by the availability of enough spherical harmonic coefficients of good signal-to-noise ratio.

  20. The influence of thermal deformation processes on frequency conversion in an LBO crystal

    NASA Astrophysics Data System (ADS)

    Arapov, Yu D.; Dyakov, V. A.; Grechin, S. G.; Kasyanov, I. V.

    2014-12-01

    The influence of the thermal deformation process on frequency conversion in an LBO crystal is considered. The different temperature bandwidths at the harmonic generation of YAG:Nd laser radiation were obtained experimentally three times at different types of crystal fixation.

  1. Crystal Data

    National Institute of Standards and Technology Data Gateway

    SRD 3 NIST Crystal Data (PC database for purchase)   NIST Crystal Data contains chemical, physical, and crystallographic information useful to characterize more than 237,671 inorganic and organic crystalline materials. The data include the standard cell parameters, cell volume, space group number and symbol, calculated density, chemical formula, chemical name, and classification by chemical type.

  2. Damping assembly for a torque converter clutch

    SciTech Connect

    Dull, D.C.

    1989-12-26

    This patent describes a turbine damped torque converter and clutch. It comprises: a pressure plate; a torque converter turbine; a torque converter impeller; means including a control chamber for the pressure plate means for controlling the apply and release of the clutch for engaging the clutch with the impeller; a torque converter output shaft; a planetary gear arrangement including an input gear drivingly connected with the pressure plate, a reaction gear drivingly connected with the turbine, an output member drivingly connected with the output shaft and pinion gear means meshing with the input gear and the reaction gear for drivingly interconnecting the turbine and the pressure plate at a drive ratio of the turbine to the pressure plate of less than 1:1; and one-way drive means disposed between the turbine and the output shaft for preventing the turbine from overrunning the output shaft.

  3. Integrated optical analog-to-digital converter

    E-print Network

    Khilo, Anatol

    2008-01-01

    An optically-sampled frequency-demultiplexed wideband analog-to-digital converter (ADC) which has potential to exceed the performance of electronic ADCs by orders of magnitude is studied analytically and numerically. The ...

  4. New Perspectives on Wave Energy Converter Control 

    E-print Network

    Price, Alexandra A E

    2009-01-01

    This work examines some of the fundamental problems behind the control of wave energy converters (WECs). Several new perspectives are presented to aid the understanding of the problem and the interpretation of the ...

  5. Rotorcraft convertible engines for the 1980s

    NASA Technical Reports Server (NTRS)

    Eisenberg, J. D.

    1982-01-01

    Two rotorcraft studies were executed. The goal was to identify attractive techniques for implementing convertible powerplants for the ABC, Folded Tilt Rotor, and X-wing type high speed, high-L/D rotorcraft; to determine the DOC and fuel savings benefits achieved thereby; and to define research required to bring these powerplants into existence by the 1990's. These studies are reviewed herein and the different methods of approach are pointed out as well as the key findings. Fan shaft engines using variable inlet guide vanes or torque converters, and turboprop powerplants appear attractive. Savings in DOC and fuel consumption of over 15 percent are predicted in some cases as a result of convertible engine use rather than using separate engines for the thrust and the shaft functions. Areas of required research are fan performance (including noise), integrated engine/rotorcraft control, torque converters, turbine design, airflow for rotorcraft torque control, bleed for lift flow, and transmissions and clutches.

  6. Radio frequency digital to analog converter

    E-print Network

    Luschas, Susan, 1975-

    2003-01-01

    Dynamic performance of high speed, high resolution digital-to-analog converters (DACs) is limited by distortion at the data switching instants. Inter-symbol interference (ISI), imperfect timing synchronization and clock ...

  7. Improvement of up-converting phosphor technology-based biosensor

    NASA Astrophysics Data System (ADS)

    Xie, Chengke; Huang, Lihua; Zhang, Youbao; Guo, Xiaoxian; Qu, Jianfeng; Huang, Huijie

    2008-12-01

    A novel biosensor based on up-converting phosphor technology (UPT) was developed several years ago. It is a kind of optical biosensor using up-converting phosphor (UCP) particles as the biological marker. From then on, some improvements have been made for this UPT-based biosensor. The primary aspects of the improvement lie in the control system. On one hand, the hardware of the control system has been optimized, including replacing two single chip microcomputers (SCM) with only one, the optimal design of the keyboard interface circuit and the liquid crystal module (LCM) control circuit et al.. These result in lower power consumption and higher reliability. On the other hand, a novel signal processing algorithm is proposed in this paper, which can improve the automation and operating simplicity of the UPT-based biosensor. It has proved to have high sensitivity (~ng/ml), high stability and good repeatability (CV<5%), which is better than the former system. It can meet the need of some various applications such as rapid immunoassay, chemical and biological detection and so on.

  8. Solid-state power converter repeatability analysis

    E-print Network

    Dal Gobbo, Anthony

    2015-01-01

    This paper presents a method for evaluating power converter repeatability. The focus is on solid-state switch mode power converter for which the most problematic non-repeatability sources are the jitter of the drivers and of the switches leading to output voltage pulses bad repeatability. Both driver and switch turn-on and turn-off delay dispersion have been measured. These measurements confirm that the delay is Gaussian distributed and that the repeatability prediction method is valid.

  9. Relativistic plasma surfaces as an efficient second harmonic generator

    NASA Astrophysics Data System (ADS)

    Streeter, M. J. V.; Foster, P. S.; Cameron, F. H.; Borghesi, M.; Brenner, C.; Carroll, D. C.; Divall, E.; Dover, N. P.; Dromey, B.; Gallegos, P.; Green, J. S.; Hawkes, S.; Hooker, C. J.; Kar, S.; McKenna, P.; Nagel, S. R.; Najmudin, Z.; Palmer, C. A. J.; Prasad, R.; Quinn, K. E.; Rajeev, P. P.; Robinson, A. P. L.; Romagnani, L.; Schreiber, J.; Spindloe, C.; Ter-Avetisyan, S.; Tresca, O.; Zepf, M.; Neely, D.

    2011-02-01

    We report on the characterization of the specular reflection of 50 fs laser pulses in the intensity range 1017-1021 W cm-2 obliquely incident with p-polarization onto solid density plasmas. These measurements show that the absorbed energy fraction remains approximately constant and that second harmonic generation (SHG) achieves efficiencies of 22±8% for intensities approaching 1021 W cm-2. A simple model based on the relativistic oscillating mirror concept reproduces the observed intensity scaling, indicating that this is the dominant process involved for these conditions. This method may prove to be superior to SHG by sum frequency mixing in crystals as it is free from dispersion and retains high spatial coherence at high intensity.

  10. Second-harmonic generation in zinc tris(thiourea) sulfate

    SciTech Connect

    Marcy, H.O.; Warren, L.F. ); Webb, M.S.; Ebbers, C.A.; Velsko, S.P. ); Kennedy, G.C.; Catella, G.C. )

    1992-08-20

    The linear and second-order nonlinear optical properties of single-crystal zinc tris(thiourea) sulfate, or ZTS, are determined. The deduced nonlinear coefficients are {vert bar} {ital d}{sub 31} {vert bar}=0.31, {vert bar} {ital d}{sub 32} {vert bar}=0.35, and {vert bar} {ital d}{sub 33} {vert bar}=0.23 pm/V compared with a {vert bar} {ital d}{sub 14} {vert bar} value of 0.39 pm/V for potassium dihydrogen phosphate. Because it exhibits a low angular sensitivity ({delta}{Delta}{ital k}/{delta}{theta}), ZTS may prove useful for type-II second-harmonic generation from 1.06 to 1.027 {mu}m. We present the phase-matching measurement data for ZTS and compare the calculated frequency conversion efficiency for ZTS with that of several other well-characterized materials.

  11. A high-fidelity harmonic drive model.

    SciTech Connect

    Preissner, C.; Royston, T. J.; Shu, D.

    2012-01-01

    In this paper, a new model of the harmonic drive transmission is presented. The purpose of this work is to better understand the transmission hysteresis behavior while constructing a new type of comprehensive harmonic drive model. The four dominant aspects of harmonic drive behavior - nonlinear viscous friction, nonlinear stiffness, hysteresis, and kinematic error - are all included in the model. The harmonic drive is taken to be a black box, and a dynamometer is used to observe the input/output relations of the transmission. This phenomenological approach does not require any specific knowledge of the internal kinematics. In a novel application, the Maxwell resistive-capacitor hysteresis model is applied to the harmonic drive. In this model, sets of linear stiffness elements in series with Coulomb friction elements are arranged in parallel to capture the hysteresis behavior of the transmission. The causal hysteresis model is combined with nonlinear viscous friction and spectral kinematic error models to accurately represent the harmonic drive behavior. Empirical measurements are presented to quantify all four aspects of the transmission behavior. These measurements motivate the formulation of the complete model. Simulation results are then compared to additional measurements of the harmonic drive performance.

  12. Correlated Emission Lasing in Harmonic Oscillators Coupled via a Single Three-Level Artificial Atom

    NASA Astrophysics Data System (ADS)

    Peng, Z. H.; Liu, Yu-xi; Peltonen, J. T.; Yamamoto, T.; Tsai, J. S.; Astafiev, O.

    2015-11-01

    A single superconducting artificial atom can be used for coupling electromagnetic fields up to the single-photon level due to an easily achieved strong coupling regime. Bringing a pair of harmonic oscillators into resonance with the transitions of a three-level atom converts atomic spontaneous processes into correlated emission dynamics. We present the experimental demonstration of two-mode correlated emission lasing in harmonic oscillators coupled via a fully controllable three-level superconducting quantum system (artificial atom). The correlation of emissions with two different colors reveals itself as equally narrowed linewidths and quenching of their mutual phase diffusion. The mutual linewidth is more than 4 orders of magnitude narrower than the Schawlow-Townes limit. The interference between the different color lasing fields demonstrates that the two-mode fields are strongly correlated.

  13. Near BPS skyrmions and restricted harmonic maps

    NASA Astrophysics Data System (ADS)

    Speight, J. M.

    2015-06-01

    Motivated by a class of near BPS Skyrme models introduced by Adam, Sánchez-Guillén and Wereszczy?ski, the following variant of the harmonic map problem is introduced: a map ? :(M, g) ?(N, h) between Riemannian manifolds is restricted harmonic if it locally extremizes E2 on its SDiff(M) orbit, where SDiff(M) denotes the group of volume preserving diffeomorphisms of (M, g), and E2 denotes the Dirichlet energy. It is conjectured that near BPS skyrmions tend to restricted harmonic maps in the BPS limit. It is shown that ? is restricted harmonic if and only if ?? h has exact divergence, and a linear stability theory of restricted harmonic maps is developed, from which it follows that all weakly conformal maps are stable restricted harmonic. Examples of restricted harmonic maps in every degree class R3 ? SU(2) and R2 ?S2 are constructed. It is shown that the axially symmetric BPS skyrmions on which all previous analytic studies of near BPS Skyrme models have been based, are not restricted harmonic, casting doubt on the phenomenological predictions of such studies. The problem of minimizing E2 for ? :Rk ? N over all linear volume preserving diffeomorphisms is solved explicitly, and a deformed axially symmetric family of Skyrme fields constructed which are candidates for approximate near BPS skyrmions at low baryon number. The notion of restricted harmonicity is generalized to restricted F-criticality where F is any functional on maps (M, g) ?(N, h) which is, in a precise sense, geometrically natural. The case where F is a linear combination of E2 and E4, the usual Skyrme term, is studied in detail, and it is shown that inverse stereographic projection R3 ?S3 ? SU(2) is stable restricted F-critical for every such F.

  14. On the uniqueness of harmonic coordinates

    E-print Network

    Jiri Bicak; Joseph Katz

    2005-03-04

    Harmonic coordinate conditions in stationary asymptotically flat spacetimes with matter sources have more than one solution. The solutions depend on the degree of smoothness of the metric and its first derivatives, which we wish to impose across the material boundary, and on the conditions at infinity and at a suitable point inside the matter. This is illustrated in detail by simple fully solvable examples of static spherically symmetric spacetimes in global harmonic coordinates. Examples of stationary electrovacuum spacetimes described simply in harmonic coordinates are also given. They can represent the exterior fields of material discs. The use of an appropriate background metric considerably simplifies the calculations.

  15. Crystal Furnace

    NASA Technical Reports Server (NTRS)

    1985-01-01

    A "melt recharging" technique which eliminates the cooldown and heating periods in a crystal "growing" crucible, resulted from a Jet Propulsion Laboratory (JPL)/Kayex Corporation program. Previously, the cost of growing the silicon solar cells had been very high. The JPL/Kayex system improved productivity by serially growing crystals from the same crucible using a melt recharger which made it possible to add raw silicon to an operating crucible. An isolation value, developed by Kayex, allowed the hopper to be lowered into the crucible without disturbing the inert gas atmosphere. The resulting product, a CG6000 crystal growing furnace, has become the company's major product.

  16. Preparation of spherically agglomerated crystals of aminophylline.

    PubMed

    Kawashima, Y; Aoki, S; Takenaka, H; Miyake, Y

    1984-10-01

    The spherically agglomerated crystals of aminophylline (theophylline-ethylenediamine complex) can be compounded directly into pharmaceutical formulations without further processing, e.g., granulation. Such crystals were prepared by mixing theophylline and ethylenediamine in a partially miscible solvent system, i.e., organic solvent-ethanol-water. The organic solvents used were chloroform, 1-hexanol, isopropyl acetate, isobutyl acetate, isoamyl acetate, benzene, toluene, n-hexane, or n-heptane. Spherical crystallization depended upon the solubility of theophylline in the solvent mixture. The resultant agglomerated crystals were identical with the theophylline-ethylenediamine complex by IR, X-ray, and differential scanning calorimetry analyses, and was the alpha-, beta-, or gamma-form when the water of crystallization was less than or equal to 0.5, 1.0, and 2.5 mol, respectively. When the amount of ethylenediamine used was less than 1.1 mL (0.0165 mol), the resultant agglomerated crystals were converted to anhydrous theophylline by washing with ethanol. When water was added to the system (greater than or equal to 0.3 mL, i.e., 0.0167 mol), water was occluded in the resultant agglomerates as water of crystallization. Ethylenediamine content in the agglomerated crystals could be controlled by changing the amount of ethylenediamine added in the crystallization solvent. PMID:6502490

  17. The harmonic explorer and its convergence to SLE(4)

    E-print Network

    Oded Schramm; Scott Sheffield

    2006-02-09

    The harmonic explorer is a random grid path. Very roughly, at each step the harmonic explorer takes a turn to the right with probability equal to the discrete harmonic measure of the left-hand side of the path from a point near the end of the current path. We prove that the harmonic explorer converges to SLE(4) as the grid gets finer.

  18. Dual aperture dipole magnet with second harmonic component

    DOEpatents

    Praeg, W.F.

    1983-08-31

    An improved dual aperture dipole electromagnet includes a second-harmonic frequency magnetic guide field winding which surrounds first harmonic frequency magnetic guide field windings associated with each aperture. The second harmonic winding and the first harmonic windings cooperate to produce resultant magnetic waveforms in the apertures which have extended acceleration and shortened reset portions of electromagnet operation.

  19. Dual aperture dipole magnet with second harmonic component

    DOEpatents

    Praeg, Walter F. (Palos Park, IL)

    1985-01-01

    An improved dual aperture dipole electromagnet includes a second-harmonic frequency magnetic guide field winding which surrounds first harmonic frequency magnetic guide field windings associated with each aperture. The second harmonic winding and the first harmonic windings cooperate to produce resultant magnetic waveforms in the apertures which have extended acceleration and shortened reset portions of electromagnet operation.

  20. A harmonic oscillator having “volleyball damping”

    NASA Astrophysics Data System (ADS)

    Mickens, R. E.; Oyedeji, K.; Rucker, S. A.

    2006-05-01

    Volleyball damping corresponds to linear damping up to a certain critical velocity, with zero damping above this value. The dynamics of a linear harmonic oscillator is investigated with this damping mechanism.

  1. High-harmonic generation in cavitated plasmas

    SciTech Connect

    Schroeder, C. B.; Esarey, E.; Comier-Michel, E.; Leemans, W. P.

    2008-05-15

    A method is proposed for producing coherent x-rays via high-harmonic generation using ultraintense lasers interacting with highly stripped ions in cavitated plasmas. This method relies on plasma cavitation by the wake of an intense drive beam (laser or electron beam) to produce an ion cavity. An ultrashort pulse laser propagating in the plasma-electron-free ion cavity generates laser harmonics. The longitudinal electron motion, which inhibits high-harmonic generation at high laser intensities, can be suppressed by the space-charge field in the ion cavity or by using a counterpropagating laser pulse. Periodic suppression of the longitudinal electron motion may also be used to quasi-phase-match. This method enables harmonic generation to be extended to the sub-A regime.

  2. Harmonic Lasing Characterization at Jefferson Lab

    SciTech Connect

    Stephen Benson; Michelle D. Shinn

    2006-08-27

    Harmonic lasing is normally suppressed because of lasing at the fundamental wavelength. It can, however, be achieved by using any of several methods that suppress fundamental lasing. In this paper we discuss two methods used at Jefferson Lab. The first is to use the characteristics of dielectric coatings to allow harmonic lasing at cavity lengths longer than the synchronous length for the fundamental. The second is to use a dielectric coating that has little reflectivity at the fundamental. This allows us to directly compare fundamental and harmonic lasing with the same optical resonator and electron beam. We present measurement carried out at Jefferson Lab using the IR Upgrade FEL operating at 0.53, 0.94, 1.04, 1.6, and 2.8 microns in which both schemes are used to produce lasing at both the 3rd and 5th harmonic of the fundamental.

  3. Harmonic quarks and their precise masses

    E-print Network

    Oleg A. Teplov

    2003-07-02

    An examination of charged two-quark meson masses hinted that the mass ratio of neighboring quarks could simply be a constant. The concept of a harmonic quark oscillator based on a quark-antiquark pair is introduced. Unstable symmetric state of the harmonic quark oscillator can be broken to an asymmetric state with the formation the neighboring quark of lesser mass due to a weak reaction. A new recurrent equation of quark masses is obtained and the model of harmonic quark family is developed. The quark masses in the model are bound together into one rigid chain. With the electromagnetic contribution taken into account the quark masses are calculated with the 0.03 percent inaccuracy. It follows from the model that the muon is a single u-quark mass state fixed as a lepton. The neutral pion is probably a stable harmonic oscillator based on a quark-antiquark u-pair.

  4. Harmonizing Systems and Software Cost Estimation

    E-print Network

    Wang, Gan

    2009-07-19

    The objective of this paper is to examine the gaps and overlaps between software and systems engineering cost models with intent to harmonize the estimates in engineering engineering estimation. In particular, we evaluate ...

  5. SEVENTH HARMONIC 20 GHz CO-GENERATOR

    SciTech Connect

    Hirshfield, Jay L

    2014-04-08

    To satisfy the need for multi-MW rf sources in frequency ranges where commercial sources do not exist, a study was undertaken on a class of devices based on gyro-harmonic frequency multiplication. This mechanism relies upon adding energy in gyrating motion to a linear electron beam that traverses a rotating-mode TE111-mode drive cavity in a dc magnetic field. The beam then drifts along the magnetic field into a second cavity, operating in the TEn11-mode tuned to the nth harmonic of the drive cavity. Studies of this configuration have been carried out for 2 < n < 7. Results are given for multi-MW, efficient operation of a 7th harmonic device operating at 20 GHz, and a 2nd harmonic device operating at 22.4 GHz.

  6. Limits of High Harmonic Generation conversion efficiency

    E-print Network

    Gkortsas, Vasileios-Marios

    2013-01-01

    High Harmonic Generation (HHG) is a fascinating phenomenon from both fundamental and technological point of view. It enables the generation of attosecond pulses and can have applications in EUV lithography and bio-microscopy. ...

  7. Imaging of Protein Crystals with Two-Photon Microscopy

    SciTech Connect

    Padayatti, Pius; Palczewska, Grazyna; Sun, Wenyu; Palczewski, Krzysztof; Salom, David

    2012-05-02

    Second-order nonlinear optical imaging of chiral crystals (SONICC), which portrays second-harmonic generation (SHG) by noncentrosymmetric crystals, is emerging as a powerful imaging technique for protein crystals in media opaque to visible light because of its high signal-to-noise ratio. Here we report the incorporation of both SONICC and two-photon excited fluorescence (TPEF) into one imaging system that allows visualization of crystals as small as 10 {mu}m in their longest dimension. Using this system, we then documented an inverse correlation between the level of symmetry in examined crystals and the intensity of their SHG. Moreover, because of blue-green TPEF exhibited by most tested protein crystals, we also could identify and image SHG-silent protein crystals. Our experimental data suggest that the TPEF in protein crystals is mainly caused by the oxidation of tryptophan residues. Additionally, we found that unspecific fluorescent dyes are able to bind to lysozyme crystals and enhance their detection by TPEF. We finally confirmed that the observed fluorescence was generated by a two-photon rather than a three-photon process. The capability for imaging small protein crystals in turbid or opaque media with nondamaging infrared light in a single system makes the combination of SHG and intrinsic visible TPEF a powerful tool for nondestructive protein crystal identification and characterization during crystallization trials.

  8. Understanding the damping of a quantum harmonic oscillator coupled to a two-level system using analogies to classical friction

    NASA Astrophysics Data System (ADS)

    Bhattacharya, M.; Stoutimore, M. J. A.; Osborn, K. D.; Mizel, Ari

    2012-09-01

    A quantum harmonic oscillator coupled to a two-level system provides a tractable model of many physical systems from atoms in an optical cavity, to superconducting qubits coupled to an oscillator, to quantum dots in a photonic crystal. When the system experiences damping, the problem becomes considerably more complicated. We demonstrate how to gain insight by drawing analogies to classical damping. Specifically, we show how a quantum harmonic oscillator coupled to a damped two-level system can display two types of frictional behavior, corresponding to classical motion in a fluid and motion on a rough surface. We further show that this system can be tuned continuously between these two regimes.

  9. Influence of small-scale self-focusing on second harmonic generation in an intense laser field

    SciTech Connect

    Ginzburg, V N; Lozhkarev, V V; Mironov, S Yu; Potemkin, A K; Khazanov, Efim A

    2010-08-27

    Linearised equations for the amplitudes of harmonic perturbations of strong waves in quadratic and cubic nonlinear media are obtained within the model of plane monochromatic waves. The dependences of the gains of noise components of the first and second harmonic waves upon frequency doubling on the B integral are found. The maximally admissible noise level in the fundamental radiation beam is calculated by the example of a 0.5-mm-long KDP crystal at the peak intensity of 4.5 TW cm{sup -2}. (nonlinear-optics phenomena)

  10. Higher-Order Harmonic Generation from Fullerene by Means of the Plasma Harmonic Method

    SciTech Connect

    Ganeev, R. A.; Bom, L. B. Elouga; Abdul-Hadi, J.; Ozaki, T.; Wong, M. C. H.; Brichta, J. P.; Bhardwaj, V. R.

    2009-01-09

    We demonstrate, for the first time, high-order harmonic generation from C{sub 60} by an intense femtosecond Ti:sapphire laser. Laser-produced plasmas from C{sub 60}-rich epoxy and C{sub 60} films were used as the nonlinear media. Harmonics up to the 19th order were observed. The harmonic yield from fullerene-rich plasma is about 25 times larger compared with those produced from a bulk carbon target. Structural studies of plasma debris confirm the presence and integrity of fullerenes within the plasma plume, indicating fullerenes as the source of high-order harmonics.

  11. Index calculation by means of harmonic expansion

    E-print Network

    Yosuke Imamura

    2015-10-28

    We review derivation of superconformal indices by means of supersymmetric localization and spherical harmonic expansion for 3d N=2, 4d N=1, and 6d N=(1,0) supersymmetric gauge theories. We demonstrate calculation of indices for vector multiplets in each dimensions by analysing energy eigenmodes in S^pxR. For the 6d index we consider the perturbative contribution only. We put focus on technical details of harmonic expansion rather than physical applications.

  12. HARMONIC CAVITY PERFORMANCE FOR NSLS-II

    SciTech Connect

    BLEDNYKH, A.; KRINSKY, S.; PODOBEDOV, B.; ROSE, J.; TOWNE, N.; WANG, J.M.

    2005-05-15

    NSLS-II is a 3 GeV ultra-high brightness storage ring planned to succeed the present NSLS rings at BNL. Ultralow emittance combined with short bunch length means that it is critical to minimize the effects of Touschek scattering and coherent instabilities. Improved lifetime and stability can be achieved by including a third-harmonic RF cavity in the baseline design. This paper describes the required harmonic RF parameters and the expected system performance.

  13. Quantum harmonic oscillator with superoscillating initial datum

    SciTech Connect

    Buniy, R. V.; Struppa, D. C.; Colombo, F.; Sabadini, I.

    2014-11-15

    In this paper, we study the evolution of superoscillating initial data for the quantum driven harmonic oscillator. Our main result shows that superoscillations are amplified by the harmonic potential and that the analytic solution develops a singularity in finite time. We also show that for a large class of solutions of the Schrödinger equation, superoscillating behavior at any given time implies superoscillating behavior at any other time.

  14. Index calculation by means of harmonic expansion

    E-print Network

    Imamura, Yosuke

    2015-01-01

    We review derivation of superconformal indices by means of supersymmetric localization and spherical harmonic expansion for 3d N=2, 4d N=1, and 6d N=(1,0) supersymmetric gauge theories. We demonstrate calculation of indices for vector multiplets in each dimensions by analysing energy eigenmodes in S^pxR. For the 6d index we consider the perturbative contribution only. We put focus on technical details of harmonic expansion rather than physical applications.

  15. Exact Wave Functions for Generalized Harmonic Oscillators

    E-print Network

    Nathan Lanfear; Raquel M. Lopez; Sergei K. Suslov

    2011-07-20

    We transform the time-dependent Schroedinger equation for the most general variable quadratic Hamiltonians into a standard autonomous form. As a result, the time-evolution of exact wave functions of generalized harmonic oscillators is determined in terms of solutions of certain Ermakov and Riccati-type systems. In addition, we show that the classical Arnold transformation is naturally connected with Ehrenfest's theorem for generalized harmonic oscillators.

  16. Conduit Processes Driving Pre-explosive Harmonic Tremor in the 2009 Redoubt Volcano Eruption

    NASA Astrophysics Data System (ADS)

    Summers, P.; Dunham, E. M.

    2013-12-01

    During the 2009 eruption of Redoubt Volcano, Alaska, gliding harmonic tremor was observed before many vulcanian explosions. Though harmonic tremor is relatively common at volcanoes, the high fundamental frequency of these tremors (up to 30 Hz) is unique and of particular interest. Hotovec et al. (JVGR, 2013) linked this tremor to rapidly repeating magnitude ~1 earthquakes located a few kilometers beneath the vent. These events might be occurring as brittle failure of the magma or as slip along the margins of an obstruction within the conduit. Using a frictional faulting model, Dmitrieva et al. (Nature Geoscience, 2013) converted the seismicity and tremor signals into an estimate of the history of shear stresses acting on the fault surface and causing slip. Stressing rates increased, in a nonlinear manner, from less than 1 MPa/s to about 20 MPa/s over the final ten minutes before the explosions. Here we investigate what conduit processes could plausibly be responsible for such high stressing rates. One possibility is that a blockage develops in the conduit prior to each explosion, perhaps from a crystal-rich magma plug or collapse of the conduit walls. This obstacle temporarily prevents upward flow of magma, while deeper influx from below thus compresses and pressurizes magma in the conduit beneath the blockage. This compression largely occurs between the base of the obstruction and the H2O exsolution depth, which petrologic estimates of volatile content and standard solubility laws suggest is nominally located about a kilometer or two deeper than the blockage. We solve the unsteady conduit flow equations (mass and momentum balance for a compressible, viscous mixture of gas and liquid). Gas exsolution is treated with Henry's law, and in our present models exsolution begins abruptly below a critical pressure. No flow is permitted past the blockage and the system is driven by steady influx at depth. We find that as magma accumulates within the conduit beneath the blockage, pressure on the base of the obstruction (which, through force balance, is proportional to shear stress on its margins) rises in a nonlinear manner. This is because the effective compressibility of the system decreases as the exsolution depth rises in response to increasing pressure. Preliminarily results suggest that this model can reproduce the nonlinear increase toward the very high stressing rates inferred from the seismicity and tremor data, without requiring additional temporal variations in magma influx rate. In the coming months, we plan to compare predicted volumes of magma accumulated in the pre-explosive period with estimates of erupted volume in each explosion. Additional constraints might also be placed on our model using geodetic deformation observations. We also plan to extend our modeling into the explosion phase itself, by rapidly removing the blockage to allow explosive depressurization of the magma column. That will provide predictions of exit velocities at the vent that could be compared with estimates from plume heights and related observations.

  17. Fabrication and life testing of thermionic converters

    NASA Technical Reports Server (NTRS)

    Yang, L.; Bruce, R.

    1973-01-01

    An unfueled converter containing a chloride-fluoride duplex tungsten emitter of 4.78 eV vacuum work function was tested for 46,647 hours at an emitter temperature of 1973 K and an electrode power output of about 8 watts/sq cm. The test demonstrated the superior and stable performance of the (110) oriented tungsten emitter at high temperatures. Three 90 UC-10 ZrC(C/U = 1.04, tungsten additive = 4 wt %) fueled converters were fabricated and tested at an emitter temperature of 1873 K. Converter containing chloride-arc-cast duplex tungsten cladding showed temperature thermionic performance and slower rate of performance drop than converter containing chloride-fluoride duplex tungsten cladding. This is believed to be due to the superior fuel component diffusion resistance of the arc-cast tungsten substrate used in the fuel cladding. It was shown that a converter containing a carbide fueled chloride-arc-cast duplex tungsten emitter with an initial electrode power output of 6.80 watts/sq cm could still deliver an electrode power output of 6.16 watts/sq cm after 18,632 hours of operation at an emitter temperature of 1873 K.

  18. Materials technology for Stirling space power converters

    NASA Astrophysics Data System (ADS)

    Baggenstoss, William; Mittendorf, Donald

    1992-07-01

    This program was conducted in support of the NASA LeRC development of the Stirling power converter (SPC) for space power applications. The objectives of this contract were: (1) to perform a technology review and analyses to support the evaluation of materials issues for the SPC; (2) to evaluate liquid metal compatibility issues of the SPC; (3) to evaluate and define a transient liquid phase diffusion bonding (TLPDB) process for the SPC joints to the Udimet 720 heater head; and (4) to evaluate alternative (to the TLPDB) joining techniques. In the technology review, several aspects of the current Stirling design were examined including the power converter assembly process, materials joining, gas bearings, and heat exchangers. The supporting analyses included GLIMPS power converter simulation in support of the materials studies, and system level analysis in support of the technology review. The liquid metal compatibility study evaluated process parameters for use in the Stirling power converter. The alternative joining techniques study looked at the applicability of various joining techniques to the Stirling power converter requirements.

  19. Isolated and soft-switched power converter

    DOEpatents

    Peng, Fang Zheng (Knoxville, TN); Adams, Donald Joe (Knoxville, TN)

    2002-01-01

    An isolated and soft-switched power converter is used for DC/DC and DC/DC/AC power conversion. The power converter includes two resonant tank circuits coupled back-to-back through an isolation transformer. Each resonant tank circuit includes a pair of resonant capacitors connected in series as a resonant leg, a pair of tank capacitors connected in series as a tank leg, and a pair of switching devices with anti-parallel clamping diodes coupled in series as resonant switches and clamping devices for the resonant leg. The power converter is well suited for DC/DC and DC/DC/AC power conversion applications in which high-voltage isolation, DC to DC voltage boost, bidirectional power flow, and a minimal number of conventional switching components are important design objectives. For example, the power converter is especially well suited to electric vehicle applications and load-side electric generation and storage systems, and other applications in which these objectives are important. The power converter may be used for many different applications, including electric vehicles, hybrid combustion/electric vehicles, fuel-cell powered vehicles with low-voltage starting, remote power sources utilizing low-voltage DC power sources, such as photovoltaics and others, electric power backup systems, and load-side electric storage and generation systems.

  20. Materials technology for Stirling space power converters

    NASA Technical Reports Server (NTRS)

    Baggenstoss, William; Mittendorf, Donald

    1992-01-01

    This program was conducted in support of the NASA LeRC development of the Stirling power converter (SPC) for space power applications. The objectives of this contract were: (1) to perform a technology review and analyses to support the evaluation of materials issues for the SPC; (2) to evaluate liquid metal compatibility issues of the SPC; (3) to evaluate and define a transient liquid phase diffusion bonding (TLPDB) process for the SPC joints to the Udimet 720 heater head; and (4) to evaluate alternative (to the TLPDB) joining techniques. In the technology review, several aspects of the current Stirling design were examined including the power converter assembly process, materials joining, gas bearings, and heat exchangers. The supporting analyses included GLIMPS power converter simulation in support of the materials studies, and system level analysis in support of the technology review. The liquid metal compatibility study evaluated process parameters for use in the Stirling power converter. The alternative joining techniques study looked at the applicability of various joining techniques to the Stirling power converter requirements.

  1. Sellmeier equations for green, yellow, and orange colored HgGa2S4 crystals

    NASA Astrophysics Data System (ADS)

    Wang, Tie-Jun; Kang, Zhi-Hui; Zhang, Hong-Zhi; Feng, Zhi-Shu; Wu, Feng-Guang; Zang, Hai-Yan; Jiang, Yun; Gao, Jin-Yue; Andreev, Yury; Lanskii, Grigory; Atuchin, Victor; Parasyuk, Oleg

    2007-04-01

    Modeling and experimental study on phase matching of second harmonic generation in different color HgGa2S4 crystals are carried out. Using the known Sellmeier equations, the dispersion relation with weighting proportionally to short-wavelength boundary of the crystal transparency band is proposed. Optimal dispersion relations and phase-matched conditions for different color HgGa2S4 crystals can be specified.

  2. Spherical Harmonic Analysis via Bayesian Inference

    NASA Astrophysics Data System (ADS)

    Muir, J. B.; Tkalcic, H.

    2014-12-01

    The real spherical harmonics form a compact, simple and commonly used set of basis functions for describing fields in tomographic inverse problems. It is therefore often useful to perform spherical harmonic analysis on data to represent it in the spherical harmonic parametrisation. Most existing algorithms, based on Fourier transforms, require that data be interpolated to a regular grid; this is not appropriate for the sparse, irregularly distributed data found in many geophysical applications. Instead, this work casts the problem of spherical harmonic analysis as an inverse problem, and applies the methods of Bayesian inference to overcome regularization problems in the inversion. This allows irregular data to be easily handled, and directly provides error estimates for the inverted spherical harmonic parameters. Synthetic tests have shown that this method easily handles relatively large amounts of added Gaussian noise. So far, this method has been applied to estimate the power in each harmonic degree for tomographic maps of the deep mantle based on PKP-PKIKP and PcP-P differential travel times, showing that they agree at global length scales despite local heterogeneity results being heavily influenced by data coverage. This potentially allows for simple heuristic arguments to constrain the global variation in core-mantle boundary topography based on the similarity between PKP and PcP derived tomographic maps.

  3. Solar thermophotovoltaic energy conversion systems with two-dimensional tantalum photonic crystal absorbers and emitters

    E-print Network

    Soljaèiæ, Marin

    Solar thermophotovoltaic energy conversion systems with two-dimensional tantalum photonic crystal) systems convert solar energy into electricity via thermally radiated photons at tailored wavelengths Elsevier B.V. All rights reserved. 1. Introduction Solar thermophotovoltaic (STPV) systems use

  4. Aalborg Universitet Efficiency and reliability improvement in wind turbine converters by grid converter

    E-print Network

    Munk-Nielsen, Stig

    was at the ground of the wind turbines development, and the synchronous generators are gaining significant attention are always welcome [3]. The generator is decoupled from the grid in the dc-link of the wind turbine converterAalborg Universitet Efficiency and reliability improvement in wind turbine converters by grid

  5. Infrared up-converting phosphors for bioassays.

    PubMed

    Corstjens, P L A M; Li, S; Zuiderwijk, M; Kardos, K; Abrams, W R; Niedbala, R S; Tanke, H J

    2005-04-01

    The development of up-converting phosphor reporter particles has added a powerful tool to modern detection technologies. Carefully constructed phosphor reporters have core-shell structures with surface functional groups suitable for standard bio-conjugations. These reporters are chemically stable, possess the unique property of infrared up-conversion, and are readily detected. In contrast to conventional fluorescent reporters, up-converting phosphor particles do not bleach and allow permanent excitation with simultaneous signal integration. A large anti-Stokes shift (up to 500 nm) separates discrete emission peaks from the infrared excitation source. Along with the unmatched contrast in biological specimens due to the absence of autofluorescence upon infrared excitation, up-converting phosphor technology (UPT) has unique properties for highly-sensitive particle-based assays. The production and characteristics of UPT reporter particles as well as their application in various bioassays is reviewed. PMID:16441160

  6. Solar energy recorder. [for converter site selection

    NASA Technical Reports Server (NTRS)

    Lollar, R. B.; Mandt, R. R.

    1974-01-01

    A serious obstacle to the large-scale terrestrial application of solar energy lies in the scarcity of reliable data on the amount of solar energy at candidate converter sites. This paper describes a system designed to monitor and record, automatically, the values of the direct and total (sun and sky) solar radiation which would be seen by either tracking or fixed-type solar converters. A further pressing need addressed by the system is the means for efficiency testing and evaluation of solar cells, solar collectors and solar concentrator systems, under outdoor exposure to natural sunlight and weather conditions for extended periods. The design was accomplished in support of the Marshall Space Flight Center, NASA, where design concepts and materials for large-scale terrestrial solar energy converters are currently being evaluated.

  7. Raman gains of ADP and KDP crystals

    NASA Astrophysics Data System (ADS)

    Zhou, Hai-Liang; Zhang, Qing-Hua; Wang, Bo; Xu, Xin-Guang; Wang, Zheng-Ping; Sun, Xun; Zhang, Fang; Zhang, Li-Song; Liu, Bao-An; Chai, Xiang-Xu

    2015-04-01

    In this paper, the Raman gain coefficients of ammonium dihydrogen phosphate (ADP) and potassium dihydrogen phosphate (KDP) crystals are measured. By using a pump source of a 30-ps, 532-nm laser, the gain coefficients of ADP and KDP are 1.22 cm/GW, and 0.91 cm/GW, respectively. While for a 20-ps, 355-nm pump laser, the gain coefficients of these two crystals are similar, which are 1.95 cm/GW for ADP and 1.86 for KDP. The present results indicate that for ultra-violet frequency conversion, the problem of stimulated Raman scattering for ADP crystal will not be more serious than that for KDP crystal. Considering other advantages such the larger nonlinear optical coefficient, higher laser damage threshold, and lower noncritical phase-matching temperature, it can be anticipated that ADP will be a powerful competitor to KDP in large aperture, high energy third-harmonic generation or fourth-harmonic generation applications. Project supported by the National Natural Science Foundation of China (Grant Nos. 51323002 and 51402173), the Independent Innovation Foundation of Shandong University, China (Grant Nos. IIFSDU and 2012JC016), the Program for New Century Excellent Talents in University, China (Grant No. NCET-10-0552), the Fund from the Key Laboratory of Neutron Physics, China Academy of Engineering Physics (Grant No. 2014BB07), and the Natural Science Foundation for Distinguished Young Scholar of Shandong Province, China (Grant No. JQ201218).

  8. Monomial Crystals and Partition Crystals

    E-print Network

    Tingley, Peter William

    Recently Fayers introduced a large family of combinatorial realizations of the fundamental crystal B(?[subscript 0]) for [^ over sl][subscript n], where the vertices are indexed by certain partitions. He showed that special ...

  9. Extraordinary Second Harmonic Generation in Tungsten Disulfide Monolayers

    PubMed Central

    Janisch, Corey; Wang, Yuanxi; Ma, Ding; Mehta, Nikhil; Elías, Ana Laura; Perea-López, Néstor; Terrones, Mauricio; Crespi, Vincent; Liu, Zhiwen

    2014-01-01

    We investigate Second Harmonic Generation (SHG) in monolayer WS2 both deposited on a SiO2/Si substrate or suspended using transmission electron microscopy grids. We find unusually large second order nonlinear susceptibility, with an estimated value of deff ~ 4.5?nm/V nearly three orders of magnitude larger than other common nonlinear crystals. In order to quantitatively characterize the nonlinear susceptibility of two-dimensional (2D) materials, we have developed a formalism to model SHG based on the Green's function with a 2D nonlinear sheet source. In addition, polarized SHG is demonstrated as a useful method to probe the structural symmetry and crystal orientation of 2D materials. To understand the large second order nonlinear susceptibility of monolayer WS2, density functional theory based calculation is performed. Our analysis suggests the origin of the large nonlinear susceptibility in resonance enhancement and a large joint density of states, and yields an estimate of the nonlinear susceptibility value deff = 0.77?nm/V for monolayer WS2, which shows good order-of-magnitude agreement with the experimental result. PMID:24984953

  10. Conformation, orientation and interaction in molecular monolayers: A surface second harmonic and sum frequency generation study

    SciTech Connect

    Superfine, R.; Huang, J.Y.; Shen, Y.R.

    1988-12-01

    We have used sum frequency generation (SFG) to study the order in a silane monolayer before and after the deposition of a coadsorbed liquid crystal monolayer. We observe an increase in the order of the chain of the silane molecule induced by the interpenetration of the liquid crystal molecules. By using second harmonic generation (SHG) and SFG, we have studied the orientation and conformation of the liquid crystal molecule on clean and silane coated glass surfaces. On both surfaces, the biphenyl group is tilted by 70{degree} with the alkyl chain end pointing away from the surface. The shift in the C-H stretch frequencies in the coadsorbed system indicates a significant interaction between molecules. 9 refs., 3 figs.

  11. WEC-Sim (Wave Energy Converter - SIMulator)

    SciTech Connect

    2014-11-26

    WEC-Sim (Wave Energy Converter SIMulator) is a code developed by Sandia National Laboratories and the National Renewable Energy Laboratory to model wave energy converters (WECs) when they are subject to operational waves. The code is a time-domain modeling tool developed in MATLAB/Simulink using the multi-body dynamics solver SimMechanics. In WEC-Sim, WECs are modeled by connecting rigid bodies to one another with joint or constraint blocks from the WEC-Sim library. WEC-Sim is a publicly available, open-source code to model WECs.

  12. WEC-Sim (Wave Energy Converter - SIMulator)

    Energy Science and Technology Software Center (ESTSC)

    2014-11-26

    WEC-Sim (Wave Energy Converter SIMulator) is a code developed by Sandia National Laboratories and the National Renewable Energy Laboratory to model wave energy converters (WECs) when they are subject to operational waves. The code is a time-domain modeling tool developed in MATLAB/Simulink using the multi-body dynamics solver SimMechanics. In WEC-Sim, WECs are modeled by connecting rigid bodies to one another with joint or constraint blocks from the WEC-Sim library. WEC-Sim is a publicly available, open-sourcemore »code to model WECs.« less

  13. Potential converter for laser-power beaming

    NASA Technical Reports Server (NTRS)

    Walker, Gilbert H.; Williams, Michael D.; Schuster, Gregory L.; Iles, Peter A.

    1991-01-01

    Future space missions, such as those associated with the Space Exploration Initiative (SEI), will require large amounts of power for operation of bases, rovers, and orbit transfer vehicles. One method for supplying this power is to beam power from a spaced based or Earth based laser power station to a receiver where laser photons can be converted to electricity. Previous research has described such laser power stations orbiting the Moon and beaming power to a receiver on the surface of the Moon by using arrays of diode lasers. Photovoltaic converters that can be efficiently used with these diode lasers are described.

  14. Synthesized C-band down-converter

    NASA Astrophysics Data System (ADS)

    Rothermich, E. W.; Williams, S. T.

    Problems involved in the design of a consumer-oriented C-band to 70-MHz single-conversion down-converter are discussed, with particular attention given to the solution of the problem of frequency drift, caused by exposure of the local oscillator to a wide range of temperatures, via frequency synthesis. Amplitude and phase requirements for image rejection are considered. A low-cost fully synthesized television receive-only down-converter has been developed using a UHF television prescaler, precision analog tuning circuitry, and microwave circuitry including the push-pull oscillator and subharmonically pumped mixer.

  15. Power converters for future LHC experiments

    NASA Astrophysics Data System (ADS)

    Alderighi, M.; Citterio, M.; Riva, M.; Latorre, S.; Costabeber, A.; Paccagnella, A.; Sichirollo, F.; Spiazzi, G.; Stellini, M.; Tenti, P.; Cova, P.; Delmonte, N.; Lanza, A.; Bernardoni, M.; Menozzi, R.; Baccaro, S.; Iannuzzo, F.; Sanseverino, A.; Busatto, G.; De Luca, V.; Velardi, F.

    2012-03-01

    The paper describes power switching converters suitable for possible power supply distribution networks for the upgraded detectors at the High Luminosity LHC collider. The proposed topologies have been selected by considering their tolerance to the highly hostile environment where the converters will operate as well as their limited electromagnetic noise emission. The analysis focuses on the description of the power supplies for noble liquid calorimeters, such as the Atlas LAr calorimeters, though several outcomes of this research can be applied to other detectors of the future LHC experiments. Experimental results carried on demonstrators are provided.

  16. Combination solar photovoltaic heat engine energy converter

    NASA Technical Reports Server (NTRS)

    Chubb, Donald L.

    1987-01-01

    A combination solar photovoltaic heat engine converter is proposed. Such a system is suitable for either terrestrial or space power applications. The combination system has a higher efficiency than either the photovoltaic array or the heat engine alone can attain. Advantages in concentrator and radiator area and receiver mass of the photovoltaic heat engine system over a heat-engine-only system are estimated. A mass and area comparison between the proposed space station organic Rankine power system and a combination PV-heat engine system is made. The critical problem for the proposed converter is the necessity for high temperature photovoltaic array operation. Estimates of the required photovoltaic temperature are presented.

  17. Solar energy converter using surface plasma waves

    NASA Technical Reports Server (NTRS)

    Anderson, L. M. (inventor)

    1984-01-01

    Sunlight is dispersed over a diffraction grating formed on the surface of a conducting film on a substrate. The angular dispersion controls the effective grating period so that a matching spectrum of surface plasmons is excited for parallel processing on the conducting film. The resulting surface plasmons carry energy to an array of inelastic tunnel diodes. This solar energy converter does not require different materials for each frequency band, and sunlight is directly converted to electricity in an efficient manner by extracting more energy from the more energetic photons.

  18. Organic nonlinear crystals and high power frequency conversion

    SciTech Connect

    Velsko, S.P.; Davis, L.; Wang, F.; Monaco, S.; Eimerl, D.

    1987-12-01

    We are searching for a new second- and third-harmonic generators among the salts of chiral organic acids and bases. We discuss the relevant properties of crystals from this group of compounds, including their nonlinear and phasematching characteristics, linear absorption, damage threshold and crystal growth. In addition, we summarize what is known concerning other nonlinear optical properties of these crystals, such as two-photon absorption, nonlinear refractive index, and stimulated Raman thresholds. A preliminary assessment is made of the potential of these materials for use in future high power, large aperture lasers such as those used for inertial confinement fusion experiments. 14 refs., 1 fig., 3 tabs.

  19. Organic Nonlinear Crystals And High Power Frequency Conversion

    NASA Astrophysics Data System (ADS)

    Velsko, Stephan P.; Davis, Laura; Wang, Francis; Monaco, Suzanne; Eimerl, David

    1988-02-01

    We are searching for new second and third harmonic generators among the salts of organic acids and bases. We discuss the relevant properties of crystals from this group of compounds, including their nonlinear and phasematching characteristics, linear absorption, damage threshold and crystal growth. In addition, we summarize what is known concerning other nonlinear optical properties of these crystals, such as two-photon absorption, nonlinear refractive index, and stimulated Raman thresholds. A preliminary assessment is made of the potential of these materials for use in future high power, large aperture lasers such as those used for inertial confinement fusion experiments.

  20. Proton and gamma radiation tests on nonlinear crystals.

    PubMed

    Roth, Ulrich; Tröbs, Michael; Graf, Thomas; Balmer, Jürg E; Weber, Heinz P

    2002-01-20

    We report on the results of proton and gamma irradiation tests performed on nonlinear crystals for second- (SHG) and third-harmonic generation. Beta-barium borate (BBO), lithium triborate (LBO), and KTP crystals were exposed to three different energies of proton radiation (8, 70, and 300 MeV) and incremental doses of gamma radiation (up to 139 krad) in order to investigate the change in SHG performance and transmission spectra. BBO and LBO crystals turned out to be a suitable choice for SHG under radiative conditions. PMID:11905572

  1. A Bidirectional High-Power-Quality Grid Interface With a Novel Bidirectional Noninverted Buck Boost Converter for PHEVs

    SciTech Connect

    Onar, Omer C

    2012-01-01

    Plug-in hybrid electric vehicles (PHEVs) will play a vital role in future sustainable transportation systems due to their potential in terms of energy security, decreased environmental impact, improved fuel economy, and better performance. Moreover, new regulations have been established to improve the collective gas mileage, cut greenhouse gas emissions, and reduce dependence on foreign oil. This paper primarily focuses on two major thrust areas of PHEVs. First, it introduces a grid-friendly bidirectional alternating current/direct current ac/dc dc/ac rectifier/inverter for facilitating vehicle-to-grid (V2G) integration of PHEVs. Second, it presents an integrated bidirectional noninverted buck boost converter that interfaces the energy storage device of the PHEV to the dc link in both grid-connected and driving modes. The proposed bidirectional converter has minimal grid-level disruptions in terms of power factor and total harmonic distortion, with less switching noise. The integrated bidirectional dc/dc converter assists the grid interface converter to track the charge/discharge power of the PHEV battery. In addition, while driving, the dc/dc converter provides a regulated dc link voltage to the motor drive and captures the braking energy during regenerative braking.

  2. Characterization of harmonic generation spectra in three-component Fibonacci optical superlattices

    NASA Astrophysics Data System (ADS)

    Liu, Xianjie; Wang, Zhenlin; Wu, Jun; Shen, Dezhong; Ming, Naiben

    1998-11-01

    The second-harmonic generation (SHG) and third-harmonic generation (THG) processes in a three-component Fibonacci optical superlattice (TCFOS) are studied. The TCFOS is made from a single crystal with quasiperiodic laminar ferroelectric domain structure. It is found that the TCFOS can provide more reciprocal vectors to compensate phase mismatch in optical parametric processes, which results in more intense peaks in the SHG and THG spectra of the quasiperiodic superlattice. The intense SHG and THG peaks can be labeled with three indices. In real space, the SHG and THG spectra exhibit self-similarity which is inherent to the superlattice. In reciprocal space, the self-similarity is destroyed due to the dispersion effect of the optical material. Dependence of the THG peak intensity within the TCFOS on the second-harmonic phase mismatch and the third-harmonic phase mismatch is discussed and presented. Numerical calculations show that an efficient THG can be achieved when THG quasi-phase-matching condition is satisfied even though the SHG is quasi-phase-mismatched.

  3. Diode-Pumped Nd:KGd(WO4)2 Laser: Lasing at Fundamental and Second Harmonic Frequencies

    NASA Astrophysics Data System (ADS)

    Bui, A. A.; Dashkevich, U. I.; Orlovich, V. A.; Khodasevich, I. A.

    2015-09-01

    High-power cw and quasi-cw lasing at the fundamental and second harmonic frequencies is obtained from Nd:KGd(WO 4 ) 2 lasers based on Np- and Ng-cut crystals pumped longitudinally by a diode laser at 879 nm. Because of different crystal lengths, the limiting pump power beyond which the crystals undergo thermomechanical damage is 26.8 W for the N p -cut and 17.3 W for the N g -cut. At these pump powers the cw outputs at ? = 1067.2 nm are 9.4 and 5.4 W, respectively, and the N g -cut crystal output is TEM 00 at the fundamental frequency. With quasicontinuous pumping at a 10% duty cycle the instantaneous laser power reaches ~11 W for both cuts with a periodic duration of 10-20 ms. The differential lasing efficiency relative to the absorbed pump power is 66.4% for cw lasing and 77.4% for quasi-cw operation. With intracavity frequency doubling using a KTP crystal, better results were obtained with the N g -cut crystal because of its simpler thermal lensing. The maximum second harmonic power was ~1.1 W for cw operation and ~2.6 W for quasi-cw operation with a diode laser power of 27.3 W.

  4. Molecular Alignment of Axially-Symmetric Sheared Polymer Network Liquid Crystals

    E-print Network

    Wu, Shin-Tson

    polarization converter, are discussed. Keywords: axially-symmetric and polymers; liquid-crystal devices 1. Cryst., Vol. 454, pp. 343=[745]­354=[756], 2006 Copyright # Taylor & Francis Group, LLC ISSN: 1542 as a tunable-focus negative lens and a spatial polarization converter. 2. SAMPLE FABRICATION To prepare a PNLC

  5. Single-mode, All-Solid-State Nd:YAG Laser Pumped UV Converter

    NASA Technical Reports Server (NTRS)

    Prasad, Narasimha S.; Armstrong, Darrell, J.; Edwards, William C.; Singh, Upendra N.

    2008-01-01

    In this paper, the status of a high-energy, all solid-state Nd:YAG laser pumped nonlinear optics based UV converter development is discussed. The high-energy UV transmitter technology is being developed for ozone sensing applications from space based platforms using differential lidar technique. The goal is to generate greater than 200 mJ/pulse with 10-50 Hz PRF at wavelengths of 308 nm and 320 nm. A diode-pumped, all-solid-state and single longitudinal mode Nd:YAG laser designed to provide conductively cooled operation at 1064 nm has been built and tested. Currently, this pump laser provides an output pulse energy of >1 J/pulse at 50 Hz PRF and a pulsewidth of 22 ns with an electrical-to-optical system efficiency of greater than 7% and a M(sup 2) value of <2. The single frequency UV converter arrangement basically consists of an IR Optical Parametric Oscillator (OPO) and a Sum Frequency Generator (SFG) setups that are pumped by 532 nm wavelength obtained via Second Harmonic Generation (SHG). In this paper, the operation of an inter cavity SFG with CW laser seeding scheme generating 320 nm wavelength is presented. Efforts are underway to improve conversion efficiency of this mJ class UV converter by modifying the spatial beam profile of the pump laser.

  6. High-frequency matrix converter with square wave input

    SciTech Connect

    Carr, Joseph Alexander; Balda, Juan Carlos

    2015-03-31

    A device for producing an alternating current output voltage from a high-frequency, square-wave input voltage comprising, high-frequency, square-wave input a matrix converter and a control system. The matrix converter comprises a plurality of electrical switches. The high-frequency input and the matrix converter are electrically connected to each other. The control system is connected to each switch of the matrix converter. The control system is electrically connected to the input of the matrix converter. The control system is configured to operate each electrical switch of the matrix converter converting a high-frequency, square-wave input voltage across the first input port of the matrix converter and the second input port of the matrix converter to an alternating current output voltage at the output of the matrix converter.

  7. Liquid Crystals

    NASA Technical Reports Server (NTRS)

    1990-01-01

    Thermochromic liquid crystals, or TLCs, are a type of liquid crystals that react to changes in temperature by changing color. The Hallcrest/NASA collaboration involved development of a new way to visualize boundary layer transition in flight and in wind tunnel testing of aircraft wing and body surfaces. TLCs offered a new and potentially better method of visualizing the boundary layer transition in flight. Hallcrest provided a liquid crystal formulation technique that afforded great control over the sensitivity of the liquid crystals to varying conditions. Method is of great use to industry, government and universities for aerodynamic and hydrodynamic testing. Company's principal line is temperature indicating devices for industrial use, such as non-destructive testing and flaw detection in electric/electronic systems, medical application, such as diagnostic systems, for retail sale, such as room, refrigerator, baby bath and aquarium thermometers, and for advertising and promotion specials. Additionally, Hallcrest manufactures TLC mixtures for cosmetic applications, and liquid crystal battery tester for Duracell batteries.

  8. Converting neutron stars into strange stars

    NASA Technical Reports Server (NTRS)

    Olinto, A. V.

    1991-01-01

    If strange matter is formed in the interior of a neutron star, it will convert the entire neutron star into a strange star. The proposed mechanisms are reviewed for strange matter seeding and the possible strange matter contamination of neutron star progenitors. The conversion process that follows seeding and the recent calculations of the conversion timescale are discussed.

  9. Convert natural gas into clean transportation fuels

    SciTech Connect

    Agee, M.A.

    1997-03-01

    A new process economically converts natural gas into synthetic transportation fuels that are free of sulfur, metals, aromatics and are clear in appearance. The process, developed by Syntroleum Corp., is energy self-sufficient and can be implemented in sizes small enough to fit a large number of the world`s gas fields. The process is described.

  10. Catalytic Converters Maintain Air Quality in Mines

    NASA Technical Reports Server (NTRS)

    2014-01-01

    At Langley Research Center, engineers developed a tin-oxide based washcoat to prevent oxygen buildup in carbon dioxide lasers used to detect wind shears. Airflow Catalyst Systems Inc. of Rochester, New York, licensed the technology and then adapted the washcoat for use as a catalytic converter to treat the exhaust from diesel mining equipment.

  11. Multilevel converters for large electric drives

    SciTech Connect

    Tolbert, L.M.; Peng, F.Z.

    1997-11-01

    Traditional two-level high frequency pulse width modulation (PWM) inverters for motor drives have several problems associated with their high frequency switching which produces common-mode voltage and high voltage change (dV/dt) rates to the motor windings. Multilevel inverters solve these problems because their devices can switch at a much lower frequency. Two different multilevel topologies are identified for use as a converter for electric drives, a cascade inverter with separate dc sources and a back-to-back diode clamped converter. The cascade inverter is a natural fit for large automotive all electric drives because of the high VA ratings possible and because it uses several levels of dc voltage sources which would be available from batteries or fuel cells. The back to back diode damped converter is ideal where a source of ac voltage is available such as a hybrid electric vehicle. Simulation and experimental results show the superiority of these two converters over PWM based drives.

  12. Hybrid switch for resonant power converters

    DOEpatents

    Lai, Jih-Sheng; Yu, Wensong

    2014-09-09

    A hybrid switch comprising two semiconductor switches connected in parallel but having different voltage drop characteristics as a function of current facilitates attainment of zero voltage switching and reduces conduction losses to complement reduction of switching losses achieved through zero voltage switching in power converters such as high-current inverters.

  13. Lathe converted for grinding aspheric surfaces

    NASA Technical Reports Server (NTRS)

    Larmer, J. W.; Levinsohn, M.; Mc Craw, D.; Pessagno, E. H.; Taub, F. J.

    1964-01-01

    A standard overarm tracing lathe converted by the addition of an independently driven diamond grinding wheel is used for grinding aspheric surfaces. The motion of the wheel is controlled by the lathe air tracer following the template which produces the desired aspheric profile.

  14. General Impedance Synthesis Using Simple Switching Converters

    E-print Network

    Tse, Chi K. "Michael"

    General Impedance Synthesis Using Simple Switching Converters Joe C. P. Liu, Chi K. Tse, Franki N Kong, Hong Kong Abstract-- A general impedance synthesizer using a minimum number of switching a lot of applications in power electronics. For instance, a resistance synthesizer can be used for power

  15. Assay for Angiotensin-Converting Enzyme.

    ERIC Educational Resources Information Center

    Russo, Salvatore F.

    1983-01-01

    Describes a three-hour experiment designed to introduce students to chemistry of the angiotensis-converting enzyme, illustrate design of a quenched fluorescence substrate, and examine considerations necessary in designing a clinical assay. Includes background information on the biochemistry of hypertension, reagents/materials needed, procedures…

  16. Single Inductor Dual Output Buck Converter 

    E-print Network

    Eachempatti, Haritha

    2010-07-14

    to regulate the battery voltage. In an SMPS, maximum area is taken by the passive components such as the inductor and the capacitor. This work demonstrates a single inductor used in a buck converter with two output voltages from an input battery with voltage...

  17. Interface Circuit for Multiple-Harmonic Analysis on Quartz Resonator Sensors to Investigate on Liquid Solution Microdroplets

    NASA Astrophysics Data System (ADS)

    Ferrari, M.; Ferrari, V.; Marioli, D.

    2009-05-01

    This work proposes an interface circuit which exploits a compact implementation of impedance measurement to innovatively analyze a quartz crystal resonator (QCR) sensor across a large number of harmonic overtones. The system measures the electrical admittance (real and imaginary parts) of the sensor, from which the series resonant frequency and the resonance damping are derived for each overtone. By probing the resonator at multiple harmonic modes, enhanced sensing capabilities can be conveniently achieved because a larger set of parameters can be measured with a single sensor. Experimental tests run with 5-MHz QCR sensors on which microdroplets of a sugar-water solution were deposited by a piezoelectric microdispenser show that the response patterns measured across different harmonics can be put in relation with the changes in the acoustic penetration depth into the loading medium.

  18. Rotationally invariant pattern recognition in a photorefractive joint transform correlator using circular harmonic filters and the wavelet transform

    NASA Astrophysics Data System (ADS)

    Zhang, H.; Cartwright, C. M.; Ding, M. S.; Wang, Z. Q.; Liang, B. L.; Gillespie, A.

    2001-08-01

    A photorefractive joint transform correlator using circular harmonic filters and the wavelet transform for high discriminant and rotationally invariant pattern recognition is reported. In the experimental implementation, a photorefractive crystal, BSO, is used as the dynamic holographic medium and a bank of wavelet functions, derived from a mother Mexican-hat wavelet have been selected to achieve a band-pass operation in the Fourier domain. The zero-order and second-order circular harmonic components are used in the investigation. It is shown that, with the proper dilation factors, there is a trade-off between peak correlation intensity and signal-to-noise ratio (SNR) with the wavelet transform filters. With the second-order circular harmonic, an improvement of 63% in the SNR is achieved with only a 4% loss in the peak correlation intensity.

  19. High-harmonic spectroscopy of molecular isomers

    SciTech Connect

    Wong, M. C. H.; Brichta, J.-P.; Bhardwaj, V. R.; Spanner, M.; Patchkovskii, S.

    2011-11-15

    We demonstrate that high-order-harmonic generation (HHG) spectroscopy can be used to probe stereoisomers of randomly oriented 1,2-dichloroethylene (C{sub 2}H{sub 2}Cl{sub 2}) and 2-butene (C{sub 4}H{sub 8}). The high-harmonic spectra of these isomers are distinguishable over a range of laser intensities and wavelengths. Time-dependent numerical calculations of angle-dependent ionization yields for 1,2-dichloroethylene suggest that the harmonic spectra of molecular isomers reflect differences in their strong-field ionization. The subcycle ionization yields for the cis isomer are an order of magnitude higher than those for the trans isomer. The sensitivity in discrimination of the harmonic spectra of cis- and trans- isomers is greater than 8 and 5 for 1,2-dichloroethylene and 2-butene, respectively. We show that HHG spectroscopy cannot differentiate the harmonic spectra of the two enantiomers of the chiral molecule propylene oxide (C{sub 3}H{sub 6}O).

  20. Entanglement of collectively interacting harmonic chains: An effective two-dimensional system

    NASA Astrophysics Data System (ADS)

    Unanyan, R. G.; Fleischhauer, M.; Bruß, D.

    2007-04-01

    We study the ground-state entanglement of one-dimensional harmonic chains that are coupled to each other by a collective interaction as realized, e.g., in an anisotropic ion crystal. Due to the collective type of coupling, where each chain interacts with every other one in the same way, the total system shows critical behavior in the direction orthogonal to the chains, while the isolated harmonic chains can be gapped and noncritical. We derive lower and most importantly upper bounds for the entanglement, quantified by the von Neumann entropy, between a compact block of oscillators and its environment. For sufficiently large size of the subsystems, the bounds coincide and show that the area law for entanglement is violated by a logarithmic correction.

  1. Stokes vector based polarization resolved second harmonic microscopy of starch granules

    PubMed Central

    Mazumder, Nirmal; Qiu, Jianjun; Foreman, Matthew R.; Romero, Carlos Macías; Török, Peter; Kao, Fu-Jen

    2013-01-01

    We report on the measurement and analysis of the polarization state of second harmonic signals generated by starch granules, using a four-channel photon counting based Stokes-polarimeter. Various polarization parameters, such as the degree of polarization (DOP), the degree of linear polarization (DOLP), the degree of circular polarization (DOCP), and anisotropy are extracted from the 2D second harmonic Stokes images of starch granules. The concentric shell structure of a starch granule forms a natural photonic crystal structure. By integration over all the solid angle, it will allow very similar SHG quantum efficiency regardless of the angle or the states of incident polarization. Given type I phase matching and the concentric shell structure of a starch granule, one can easily infer the polarization states of the input beam from the resulting SH micrograph. PMID:23577289

  2. Implementation and evaluation of a detector for forward propagated second harmonic signals.

    PubMed

    Moreno, Nuno; Feijó, José A; Cox, Guy

    2004-01-01

    Second harmonic generation (SHG) is emerging as an alternative non-linear imaging method. The fact that most commercial multi-photon microscopes can be easily adapted to image SHG makes it appealing to explore the kind of sample information given by SHG. Here we describe an SHG detection implementation designed to optimize the collection of forward propagating light. A Hamamatsu H957-08 PMT is inserted at the back-focal plane of the condenser on an inverted Nikon TE300, and controlled by the existing electronics of a BioRad 1024MP system. Evaluation of the performance was done on common SHG generating preparations, KH2PO4 crystals and collagen. We concluded that positioning a detector at the back focal plane of the condenser provides a highly efficient detection system for second harmonic signals, with many advantages over a detector sited at the lamp housing. PMID:15288652

  3. Optical second harmonic imaging as a diagnostic tool for monitoring epitaxial oxide thin-film growth

    NASA Astrophysics Data System (ADS)

    Rubano, Andrea; Günter, Tim; Lilienblum, Martin; Aruta, Carmela; Miletto Granozio, Fabio; Scotti di Uccio, Umberto; Marrucci, Lorenzo; Paparo, Domenico; Fiebig, Manfred

    2015-02-01

    Optical second harmonic generation is proposed as a tool for non-invasive, non-destructive, real-time, in-situ imaging of oxide epitaxial film growth. The films can be monitored by surface imaging with a lateral resolution of ?1 ?m on an area of size up to 1 cm2. We demonstrate the potential of the proposed technique by an ex-situ analysis of thin epitaxial SrTiO3 films grown on (1 1 0) NdGaO3 single crystals. Our data show that second harmonic generation provides complementary information to established in-situ monitoring techniques such as reflection high-energy electron diffraction. We demonstrate that this technique can reveal otherwise elusive in-plane inhomogeneities of electrostatic, chemical or structural nature. The presence of such inhomogeneities is independently confirmed by scanning probe microscopy.

  4. Resonant high-order harmonic generation from plasma ablation: Laser intensity dependence of the harmonic intensity and phase

    SciTech Connect

    Milosevic, D. B.

    2010-02-15

    Experimentally observed strong enhancement of a single high-order harmonic in harmonic generation from low-ionized laser plasma ablation is explained as resonant harmonic generation. The resonant harmonic intensity increases regularly with the increase of the laser intensity, while the phase of the resonant harmonic is almost independent of the laser intensity. This is in sharp contrast with the usual plateau and cutoff harmonics, the intensity of which exhibits wild oscillations while its phase changes rapidly with the laser intensity. The temporal profile of a group of harmonics, which includes the resonant harmonic, has the form of a broad peak in each laser-field half cycle. These characteristics of resonant harmonics can have an important application in attoscience. We illustrate our results using examples of Sn and Sb plasmas.

  5. Extraction of small boat harmonic signatures from passive sonar.

    PubMed

    Ogden, George L; Zurk, Lisa M; Jones, Mark E; Peterson, Mary E

    2011-06-01

    This paper investigates the extraction of acoustic signatures from small boats using a passive sonar system. Noise radiated from a small boats consists of broadband noise and harmonically related tones that correspond to engine and propeller specifications. A signal processing method to automatically extract the harmonic structure of noise radiated from small boats is developed. The Harmonic Extraction and Analysis Tool (HEAT) estimates the instantaneous fundamental frequency of the harmonic tones, refines the fundamental frequency estimate using a Kalman filter, and automatically extracts the amplitudes of the harmonic tonals to generate a harmonic signature for the boat. Results are presented that show the HEAT algorithms ability to extract these signatures. PMID:21682400

  6. Resonance-enhanced harmonic generation in nanoparticle-containing plasmas

    NASA Astrophysics Data System (ADS)

    Ganeev, R. A.; Suzuki, M.; Yoneya, S.; Kuroda, H.

    2015-08-01

    We demonstrate the enhancement of a single harmonic of ultrashort pulses in nanoparticle-containing plasmas. The application of three laser-produced nanoparticle-containing plasmas (In2O3, Sn and Mn2O3) allowed the efficient generation of lower-order harmonics and the resonance enhancement of single (13th, 17th and 33rd) harmonics. The comparison of the harmonic spectra obtained using the plasmas produced on the bulk and nanoparticle-containing surfaces showed that similar enhancement of single harmonics occurs in the case of strong excitation of the latter targets, while weaker ablation of nanoparticles led to generation of featureless lower-order harmonic spectra.

  7. Simple harmonic error cancellation in time of flight range imaging.

    PubMed

    Streeter, Lee; Dorrington, Adrian A

    2015-11-15

    Amplitude modulated continuous wave (AMCW) time of flight (ToF) range imaging provides a full field of distance measurement, but common hardware is implemented with digital technology which leads to unwanted harmonic content, a principle source of error in the distance measurements. Existing strategies for correction of harmonics require auxiliary measurements and amplify noise. A small modification of the data acquisition procedure is described which, intrinsically, is invariant to at least one harmonic. The third harmonic, the main cause of harmonic error, is targeted. Compared to traditional measurements the third harmonic is eliminated with no significant increase in noise variance observed. PMID:26565882

  8. Degradation in finite-harmonic subcarrier demodulation

    NASA Technical Reports Server (NTRS)

    Feria, Y.; Townes, S.; Pham, T.

    1995-01-01

    Previous estimates on the degradations due to a subcarrier loop assume a square-wave subcarrier. This article provides a closed-form expression for the degradations due to the subcarrier loop when a finite number of harmonics are used to demodulate the subcarrier, as in the case of the buffered telemetry demodulator. We compared the degradations using a square wave and using finite harmonics in the subcarrier demodulation and found that, for a low loop signal-to-noise ratio, using finite harmonics leads to a lower degradation. The analysis is under the assumption that the phase noise in the subcarrier (SC) loop has a Tikhonov distribution. This assumption is valid for first-order loops.

  9. Second Harmonic Hectometric Radio Emission at Jupiter

    NASA Technical Reports Server (NTRS)

    Menietti, J. D.; Gurnett, D. A.; Groene, J. B.

    1998-01-01

    Galileo has been in orbit around Jupiter since December 1995. The plasma wave instrument on board the spacecraft has occasionally detected a rotationally modulated attenuation band in the hectometric (HOM) emission that most likely is due to scattering of the radiation from density fluctuations along the Io L-shell, as reported earlier. The occurrence of the attenuation band is likely to be dependent on Io activity and the presence of density scattering centers along the Io-L-shell as well as the location of the source region. Some of the attenuation bands show clear indications of second harmonic emission. Without polarization measurements, it is difficult to place constraints on the local generation conditions based on the cyclotron maser instability, but the results imply that second harmonic emission could be present in the decametric (DAM) radiation as well. A survey of the data has revealed about 30 examples of second harmonic HOM.

  10. Second Harmonic Hectometric Radio Emission at Jupiter

    NASA Technical Reports Server (NTRS)

    Menietti, J. D.; Gurnett, D. A.; Groene, J. B.

    1998-01-01

    Galileo has been in orbit around Jupiter since December 1995. The plasma wave instrument on board the spacecraft has occasionally detected a rotationally modulated attenuation band in the hectometric (HOM) emission that most likely is due to scattering of the radiation from density fluctuations along the Io L-shell, as reported earlier. The occurrence of the attenuation band is likely to be dependent on Io activity and the presence of density scattering centers along the Io L-shell as well as the location of the source region. Some of the attenuation bands show clear indications of second harmonic emission. Without polarization measurements, it is difficult to place constraints on the local generation conditions based on the cyclotron maser instability, but the results imply that second harmonic emission could be present in the decametric (DAM) radiation as well. A survey of the data has revealed about 30 examples of second harmonic HOM.

  11. Quantum dynamics of the damped harmonic oscillator

    NASA Astrophysics Data System (ADS)

    Philbin, T. G.

    2012-08-01

    The quantum theory of the damped harmonic oscillator has been a subject of continual investigation since the 1930s. The obstacle to quantization created by the dissipation of energy is usually dealt with by including a discrete set of additional harmonic oscillators as a reservoir. But a discrete reservoir cannot directly yield dynamics such as Ohmic damping (proportional to velocity) of the oscillator of interest. By using a continuum of oscillators as a reservoir, we canonically quantize the harmonic oscillator with Ohmic damping and also with general damping behaviour. The dynamics of a damped oscillator is determined by an arbitrary effective susceptibility that obeys the Kramers-Kronig relations. This approach offers an alternative description of nano-mechanical oscillators and opto-mechanical systems.

  12. Quantum dynamics of the damped harmonic oscillator

    E-print Network

    T. G. Philbin

    2012-05-11

    The quantum theory of the damped harmonic oscillator has been a subject of continual investigation since the 1930s. The obstacle to quantization created by the dissipation of energy is usually dealt with by including a discrete set of additional harmonic oscillators as a reservoir. But a discrete reservoir cannot directly yield dynamics such as Ohmic damping (proportional to velocity) of the oscillator of interest. By using a continuum of oscillators as a reservoir, we canonically quantize the harmonic oscillator with Ohmic damping and also with general damping behaviour. The dynamics of a damped oscillator is determined by an arbitrary effective susceptibility that obeys Kramers-Kronig relations. This approach offers an alternative description of nano-mechanical oscillators and opto-mechanical systems.

  13. Second International Workshop on Harmonic Oscillators

    NASA Technical Reports Server (NTRS)

    Han, Daesoo (editor); Wolf, Kurt Bernardo (editor)

    1995-01-01

    The Second International Workshop on Harmonic Oscillators was held at the Hotel Hacienda Cocoyoc from March 23 to 25, 1994. The Workshop gathered 67 participants; there were 10 invited lecturers, 30 plenary oral presentations, 15 posters, and plenty of discussion divided into the five sessions of this volume. The Organizing Committee was asked by the chairman of several Mexican funding agencies what exactly was meant by harmonic oscillators, and for what purpose the new research could be useful. Harmonic oscillators - as we explained - is a code name for a family of mathematical models based on the theory of Lie algebras and groups, with applications in a growing range of physical theories and technologies: molecular, atomic, nuclear and particle physics; quantum optics and communication theory.

  14. Microscopic optical buffering in a harmonic potential.

    PubMed

    Sumetsky, M

    2015-01-01

    In the early days of quantum mechanics, Schrödinger noticed that oscillations of a wave packet in a one-dimensional harmonic potential well are periodic and, in contrast to those in anharmonic potential wells, do not experience distortion over time. This original idea did not find applications up to now since an exact one-dimensional harmonic resonator does not exist in nature and has not been created artificially. However, an optical pulse propagating in a bottle microresonator (a dielectric cylinder with a nanoscale-high bump of the effective radius) can exactly imitate a quantum wave packet in the harmonic potential. Here, we propose a tuneable microresonator that can trap an optical pulse completely, hold it as long as the material losses permit, and release it without distortion. This result suggests the solution of the long standing problem of creating a microscopic optical buffer, the key element of the future optical signal processing devices. PMID:26689546

  15. The harmonic oscillator and nuclear physics

    NASA Technical Reports Server (NTRS)

    Rowe, D. J.

    1993-01-01

    The three-dimensional harmonic oscillator plays a central role in nuclear physics. It provides the underlying structure of the independent-particle shell model and gives rise to the dynamical group structures on which models of nuclear collective motion are based. It is shown that the three-dimensional harmonic oscillator features a rich variety of coherent states, including vibrations of the monopole, dipole, and quadrupole types, and rotations of the rigid flow, vortex flow, and irrotational flow types. Nuclear collective states exhibit all of these flows. It is also shown that the coherent state representations, which have their origins in applications to the dynamical groups of the simple harmonic oscillator, can be extended to vector coherent state representations with a much wider range of applicability. As a result, coherent state theory and vector coherent state theory become powerful tools in the application of algebraic methods in physics.

  16. High harmonic phase in molecular nitrogen

    SciTech Connect

    McFarland, Brian K.

    2009-10-17

    Electronic structure in atoms and molecules modulates the amplitude and phase of high harmonic generation (HHG). We report measurements of the high harmonic spectral amplitude and phase in N{sub 2}. The phase is measured interferometrically by beating the N{sub 2} harmonics with those of an Ar reference oscillator in a gas mixture. A rapid phase shift of 0.2{pi} is observed in the vicinity of the HHG spectral minimum, where a shift of {pi} had been presumed [J. Itatani et al., Nature 432, 867 (2004)]. We compare the phase measurements to a simulation of the HHG recombination step in N{sub 2} that is based on a simple interference model. The results of the simulation suggest that modifications beyond the simple interference model are needed to explain HHG spectra in molecules.

  17. Microscopic optical buffering in a harmonic potential

    PubMed Central

    Sumetsky, M.

    2015-01-01

    In the early days of quantum mechanics, Schrödinger noticed that oscillations of a wave packet in a one-dimensional harmonic potential well are periodic and, in contrast to those in anharmonic potential wells, do not experience distortion over time. This original idea did not find applications up to now since an exact one-dimensional harmonic resonator does not exist in nature and has not been created artificially. However, an optical pulse propagating in a bottle microresonator (a dielectric cylinder with a nanoscale-high bump of the effective radius) can exactly imitate a quantum wave packet in the harmonic potential. Here, we propose a tuneable microresonator that can trap an optical pulse completely, hold it as long as the material losses permit, and release it without distortion. This result suggests the solution of the long standing problem of creating a microscopic optical buffer, the key element of the future optical signal processing devices. PMID:26689546

  18. Microscopic optical buffering in a harmonic potential

    E-print Network

    Sumetsky, M

    2015-01-01

    In the early days of quantum mechanics, Schr\\"odinger noticed that oscillations of a wave packet in a one-dimensional harmonic potential well are periodic and, in contrast to those in anharmonic potential wells, do not experience distortion over time. This original idea did not find applications up to now since an exact one-dimensional harmonic resonator does not exist in nature and has not been created artificially. However, an optical pulse propagating in a bottle microresonator (a dielectric cylinder with a nanoscale-high bump of the effective radius) can exactly imitate a quantum wave packet in the harmonic potential. Here, we propose a tuneable microresonator that can trap an optical pulse completely, hold it as long as the material losses permit, and release it without distortion. This result suggests the solution of the long standing problem of creating a microscopic optical buffer, the key element of the future optical signal processing devices.

  19. Bioimpedance Harmonic Analysis as a Diagnostic Tool to Assess Regional Circulation and Neural Activity

    NASA Astrophysics Data System (ADS)

    Mudraya, I. S.; Revenko, S. V.; Khodyreva, L. A.; Markosyan, T. G.; Dudareva, A. A.; Ibragimov, A. R.; Romich, V. V.; Kirpatovsky, V. I.

    2013-04-01

    The novel technique based on harmonic analysis of bioimpedance microvariations with original hard- and software complex incorporating a high-resolution impedance converter was used to assess the neural activity and circulation in human urinary bladder and penis in patients with pelvic pain, erectile dysfunction, and overactive bladder. The therapeutic effects of shock wave therapy and Botulinum toxin detrusor injections were evaluated quantitatively according to the spectral peaks at low 0.1 Hz frequency (M for Mayer wave), respiratory (R) and cardiac (C) rhythms with their harmonics. Enhanced baseline regional neural activity identified according to M and R peaks was found to be presumably sympathetic in pelvic pain patients, and parasympathetic - in patients with overactive bladder. Total pulsatile activity and pulsatile resonances found in the bladder as well as in the penile spectrum characterised regional circulation and vascular tone. The abnormal spectral parameters characteristic of the patients with genitourinary diseases shifted to the norm in the cases of efficient therapy. Bioimpedance harmonic analysis seems to be a potent tool to assess regional peculiarities of circulatory and autonomic nervous activity in the course of patient treatment.

  20. Comparing Crystals

    ERIC Educational Resources Information Center

    Sharp, Janet; Hoiberg, Karen; Chumbley, Scott

    2003-01-01

    This standard lesson on identifying salt and sugar crystals expands into an opportunity for students to develop their observation, questioning, and modeling skills. Although sugar and salt may look similar, students discovered that they looked very different under a magnifying glass and behaved differently when dissolved in water. In addition,…

  1. Therapeutic Crystals

    ERIC Educational Resources Information Center

    Bond, Charles S.

    2014-01-01

    Some readers might not fully know what the difference is between crystallography, and the "new age" practice of dangling crystals around the body to capitalise on their healing energy. The latter is often considered to be superstition, while ironically, the former has actually resulted in real rationally-based healing of human diseases…

  2. Intracavity frequency doubling of a Nd:YAG laser with an organic nonlinear optical crystal. Interim report

    SciTech Connect

    Ducharme, S.; Risk, W.P.; Moerner, W.E.; Lee, V.Y.; Twieg, R.J.

    1990-03-13

    We have demonstrated intracavity second harmonic generation of green 532 nm light in a quasi-cw 1064 nm Nd:YAG laser using organic nonlinear optical crystals of DAN (4-(N,N-dimethylamino)-3-acetamidonitrobenzene) immersed in index matching fluid contained in an antireflection-coated cuvette. This technique permits crystals to be used directly from solution growth without polishing or antireflection coating them. Up to 0.56 mW peak power of 532 nm light was generated from 2.3 W of intracavity 1064 nm peak power in 100 microsecond pulses. We also report preliminary results on true cw intracavity harmonic generation with antireflection coated DAN crystals.

  3. Efficient 2(nd) and 4(th) harmonic generation of a single-frequency, continuous-wave fiber amplifier.

    PubMed

    Sudmeyer, Thomas; Imai, Yutaka; Masuda, Hisashi; Eguchi, Naoya; Saito, Masaki; Kubota, Shigeo

    2008-02-01

    We demonstrate efficient cavity-enhanced second and fourth harmonic generation of an air-cooled, continuous-wave (cw), single-frequency 1064 nm fiber-amplifier system. The second harmonic generator achieves up to 88% total external conversion efficiency, generating more than 20-W power at 532 nm wavelength in a diffraction-limited beam (M(2) < 1.05). The nonlinear medium is a critically phase-matched, 20-mm long, anti-reflection (AR) coated LBO crystal operated at 25 degrees C. The fourth harmonic generator is based on an AR-coated, Czochralski-grown beta-BaB(2)O(4) (BBO) crystal optimized for low loss and high damage threshold. Up to 12.2 W of 266-nm deep-UV (DUV) output is obtained using a 6-mm long critically phase-matched BBO operated at 40 degrees C. This power level is more than two times higher than previously reported for cw 266-nm generation. The total external conversion efficiency from the fundamental at 1064 nm to the fourth harmonic at 266 nm is >50%. PMID:18542230

  4. The application of the symmetry properties of optical second harmonic generation to studies of interfaces and gases

    SciTech Connect

    Feller, M.B.

    1991-11-01

    Optical second harmonic generation has proven to be a powerful tool for studying interfaces. The symmetry properties of the process allow for surface sensitivity not available with other optical methods. In this thesis, we take advantage of these symmetry properties SHG to study a variety of interesting systems not previously studied with this technique. We show that optical second harmonic generation is an effective surface probe with a submonolayer sensitivity for media without inversion symmetry. We demonstrate the technique at a gallium arsenide surface, exploiting the different symmetry properties of the bulk and surface of the crystal to isolate the surface contribution. We also demonstrate that optical second harmonic generation can be used to determine the anisotropic orientational distribution of a surface monolayer of molecules. We apply the technique to study homogeneously aligned liquid crystal cells. To further explore the LC-polymer interface, we used SHG to study the surface memory effect. The surface memory effect is the rendering of an isotropic interface anisotropic by putting it in contact with an anisotropic bulk. Last, we describe some preliminary measurements of a time-resolved spectroscopic study of the phenomenon of second harmonic generation in a gas. The construction of a 500 microjoule pulsed, tunable laser source is described.

  5. Second-harmonic frequency-resolved optical gating covering two and a half optical octaves using a single spectrometer

    NASA Astrophysics Data System (ADS)

    Marceau, C.; Thomas, S.; Kassimi, Y.; Gingras, G.; Witzel, B.

    2015-05-01

    We report the measurement of laser pulse shapes covering the range 580-3250 nm using second-harmonic generation frequency-resolved optical gating equipped with a single inexpensive visible-NIR miniature spectrometer and a single pair of homemade broadband beam splitters. Our experimental scheme exploits frequency up-conversion by BBO crystals and appropriate corrections for dispersion, beam splitter filtering and phase-matching efficiency. The signal and idler waves from a commercial optical parametric amplifier pumped by a Ti:Sapphire laser (26 fs, 1 kHz) have been characterized as well as their second harmonic. The pulse shapes out of a commercial difference frequency generation module mixing signal and idler have also been measured up to 3250 nm. The resulting pulses range from 20 to 120 fs, and their chirp characteristics are also exposed. Our approach is demonstrated over most of the doubling crystal transparency range.

  6. Spherical harmonic analysis of steady photospheric flows

    NASA Technical Reports Server (NTRS)

    Hathaway, David H.

    1987-01-01

    A technique is presented in which full disk Doppler velocity measurements are analyzed using spherical harmonic functions to determine the characteristics of the spectrum of spherical harmonic modes and the nature of steady photospheric flows. Synthetic data are constructed in order to test the technique. In spite of the mode mixing due to the lack of information about the motions on the backside of the sun, solar rotation and differential rotation can be accurately measured and monitored for secular changes, and meridional circulations with small amplitudes can be measured. Furthermore, limb shift measurements can be accurately obtained, and supergranules can be fully resolved and separated from giant cells by their spatial characteristics.

  7. Plasmon signatures in high harmonic generation

    E-print Network

    J. Zanghellini; Ch. Jungreuthmayer; T. Brabec

    2005-12-12

    High harmonic generation in polarizable multi-electron systems is investigated in the framework of multi-configuration time-dependent Hartree-Fock. The harmonic spectra exhibit two cut offs. The first cut off is in agreement with the well established, single active electron cut off law. The second cut off presents a signature of multi-electron dynamics. The strong laser field excites non-linear plasmon oscillations. Electrons that are ionized from one of the multi-plasmon states and recombine to the ground state gain additional energy, thereby creating the second plateau.

  8. Dark-field third-harmonic imaging

    NASA Astrophysics Data System (ADS)

    Doronina-Amitonova, L. V.; Lanin, A. A.; Fedotov, I. V.; Ivashkina, O. I.; Zots, M. A.; Fedotov, A. B.; Anokhin, K. V.; Zheltikov, A. M.

    2013-08-01

    Coherent cancellation of third-harmonic generation (THG) in a tightly focused laser beam is shown to enable a label-free imaging of individual neurons in representative brain tissues. The intrinsic coherence of third-harmonic buildup and cancellation combined with the nonlinear nature of the process enhances the locality of the dark signal in THG, translating into a remarkable sharpness of dark-field THG images. Unique advantages of this technique for high-contrast subcellular-resolution neuroimaging are demonstrated by comparing THG images of hippocampus and somatosensory cortex in a mouse brain with images visualizing fluorescent protein biomarkers.

  9. Nonlinear harmonic generation in distributed optical klystrons

    SciTech Connect

    H.P. Freund; George R. Neil

    2001-12-01

    A distributed optical klystron has the potential for dramatically shortening the total interaction length in high-gain free-electron lasers (INP 77-59, Novosibirsk, 1977; Nucl. Instr. and Meth A 304 (1991) 463) in comparison to a single-wiggler-segment configuration. This shortening can be even more dramatic if a nonlinear harmonic generation mechanism is used to reach the desired wavelength. An example operating at a 4.5{angstrom} fundamental and a 1.5{angstrom} harmonic is discussed.

  10. Growth and properties of benzil doped benzimidazole (BMZ) single crystals

    SciTech Connect

    Babu, R. Ramesh; Sukumar, M.; Vasudevan, V.; Crystal Growth and Crystallography Section, National Physical Laboratory, Krishnan Marg, New Delhi 110 012 ; Shakir, Mohd.; Ramamurthi, K.; Bhagavannarayana, G.

    2010-09-15

    In the present work, we have made an attempt to study the effect of benzil doping on the properties of benzimidazole single crystals. For this purpose we have grown pure and benzil doped benzimidazole single crystals by vertical Bridgman technique. The grown crystals were characterized by various characterization techniques. The presence of dopants confirmed by powder X-ray diffraction (XRD). Crystalline perfection of the grown crystals has been analysed by high-resolution X-ray diffraction (HRXRD). The transmittance, electrical property and mechanical strength have been analysed using UV-vis-NIR spectroscopic, dielectric and Vicker's hardness studies. The relative second harmonic generation efficiency of pure and doped benzimidazole crystals measured using Kurtz powder test.

  11. Growth and characterization of a novel nonlinear optical borate crystal - Yttrium calcium borate (YCB)

    NASA Astrophysics Data System (ADS)

    Arun Kumar, R.; Arivanandhan, M.; Dhanasekaran, R.; Hayakawa, Y.

    2013-06-01

    A new nonlinear optical single crystal yttrium calcium borate Y2CaB10O19 (YCB) was grown for the first time from its melt. The starting materials were prepared by the solid-state reaction method. The melting point of the synthesized material was identified to be 967 °C. YCB crystal exhibits monoclinic crystal structure with the space group C2. The crystalline perfection of the grown YCB crystal was found to be good. From the UV-VIS-NIR studies, the lower cutoff wavelength of the crystal occurs below 200 nm. The functional groups of the grown crystal were assigned using the FTIR data. The second harmonic generation (SHG) of the YCB crystal was observed using a Nd:YAG laser with a fundamental wavelength of 1064 nm. The laser damage threshold value of the YCB crystal was found to be very high - 10.5 GW/cm2.

  12. Frequency up-conversion in a mercury thiogallate crystal

    NASA Astrophysics Data System (ADS)

    Andreev, S. A.; Andreeva, N. P.; Badikov, V. V.; Matveev, I. N.; Pshenichnikov, S. M.

    1980-09-01

    The paper calculates the characteristics of a converter of CO2 laser radiation that is based on a mercury thiogallate (HgGa2S4) crystal pumped by YAG laser radiation. Experimental and theoretical results on the geometry and conversion efficiency are compared, and the IR-radiation resistance of HgGa2S4 crystals was determined. Measured conversion efficiency amounted to 60%.

  13. International Crystal Manufacturing

    E-print Network

    Berns, Hans-Gerd

    International Crystal Manufacturing CRYSTAL OSCILLATOR AND FILTER PRODUCTS International Crystal@icmfg.com #12;2 International Crystal Manufacturing, Inc. P.O. Box 26330 · Oklahoma City, OK 73126-0330 · Phone-800-322-9426 · www.icmfg.com · E-mail freeland@icmfg.com QUARTZ CRYSTALS Quartz Crystal Selection Guide

  14. A high efficiency photovoltaic module integrated converter with the asymmetrical half-bridge flyback converter

    SciTech Connect

    Kim, Heeje; Kim, Jongrak; Shin, Dongsul; Kim, Hosung; Lee, Kyungjun; Kim, Jonghyun; Yoo, Dongwook

    2010-08-15

    A module integrated converter (MIC) for a photovoltaic (PV) cell is important part of power conditioning system (PCS). It performs maximum power point tracking of a PV cell to generate the power as much as possible from solar energy. There are several methods for connection between the PV modules and the MICs. In order to avoid partial shading effects, converter-per-module approach was proposed. The MIC that performs maximum power point tracking (MPPT), if it is low efficiency, is no use. The MIC whose output is connected to the output of PV module was proposed for high efficiency. However, there are some problems. In this study, an asymmetrical half-bridge flyback converter is proposed instead of the original flyback converter with same method to solve the problems. The proposed MIC was built to verify the performance. The new topology using soft switching technique showed good performance for the efficiency. At the higher power, the efficiency of the proposed converter is higher than existing converter. (author)

  15. Component technology for stirling power converters

    NASA Technical Reports Server (NTRS)

    Thieme, Lanny G.

    1991-01-01

    NASA Lewis Research Center has organized a component technology program as part of the efforts to develop Stirling converter technology for space power applications. The Stirling Space Power Program is part of the NASA High Capacity Power Project of the Civil Space Technology Initiative (CSTI). NASA Lewis is also providing technical management for the DOE/Sandia program to develop Stirling converters for solar terrestrial power producing electricity for the utility grid. The primary contractors for the space power and solar terrestrial programs develop component technologies directly related to their goals. This Lewis component technology effort, while coordinated with the main programs, aims at longer term issues, advanced technologies, and independent assessments. An overview of work on linear alternators, engine/alternator/load interactions and controls, heat exchangers, materials, life and reliability, and bearings is presented.

  16. Strained quantum well photovoltaic energy converter

    NASA Technical Reports Server (NTRS)

    Freundlich, Alexandre (Inventor); Renaud, Philippe (Inventor); Vilela, Mauro Francisco (Inventor); Bensaoula, Abdelhak (Inventor)

    1998-01-01

    An indium phosphide photovoltaic cell is provided where one or more quantum wells are introduced between the conventional p-conductivity and n-conductivity indium phosphide layer. The approach allows the cell to convert the light over a wider range of wavelengths than a conventional single junction cell and in particular convert efficiently transparency losses of the indium phosphide conventional cell. The approach hence may be used to increase the cell current output. A method of fabrication of photovoltaic devices is provided where ternary InAsP and InGaAs alloys are used as well material in the quantum well region and results in an increase of the cell current output.

  17. Analog current mode analog/digital converter

    NASA Technical Reports Server (NTRS)

    Hadidi, Khayrollah (Inventor)

    1996-01-01

    An improved subranging or comparator circuit is provided for an analog-to-digital converter. As a subranging circuit, the circuit produces a residual signal representing the difference between an analog input signal and an analog of a digital representation. This is achieved by subdividing the digital representation into two or more parts and subtracting from the analog input signal analogs of each of the individual digital portions. In another aspect of the present invention, the subranging circuit comprises two sets of differential input pairs in which the transconductance of one differential input pair is scaled relative to the transconductance of the other differential input pair. As a consequence, the same resistor string may be used for two different digital-to-analog converters of the subranging circuit.

  18. The GLAST LAT Silicon Strip Tracker Converter

    SciTech Connect

    Johnson, R. P.

    2007-07-12

    The Tracker subsystem of the Large Area Telescope (LAT) science instrument of the Gamma-ray Large Area Space Telescope (GLAST) mission has been completed and tested. It is the central detector subsystem of the LAT and serves both to convert an incident gamma-ray into an electron-positron pair and to track the pair in order to measure the gamma-ray direction. It also provides the principal trigger for the LAT. The Tracker uses silicon strip detectors, read out by custom electronics, to detect charged particles. The detectors and electronics are packaged, along with tungsten converter foils, in 16 modular, high-precision carbon-composite structures. The test program has demonstrated that the system meets or surpasses all of its performance specifications as well as environmental requirements.

  19. MAGIC: Model and Graphic Information Converter

    NASA Technical Reports Server (NTRS)

    Herbert, W. C.

    2009-01-01

    MAGIC is a software tool capable of converting highly detailed 3D models from an open, standard format, VRML 2.0/97, into the proprietary DTS file format used by the Torque Game Engine from GarageGames. MAGIC is used to convert 3D simulations from authoritative sources into the data needed to run the simulations in NASA's Distributed Observer Network. The Distributed Observer Network (DON) is a simulation presentation tool built by NASA to facilitate the simulation sharing requirements of the Data Presentation and Visualization effort within the Constellation Program. DON is built on top of the Torque Game Engine (TGE) and has chosen TGE's Dynamix Three Space (DTS) file format to represent 3D objects within simulations.

  20. Flower-petal mode converter for NLC

    SciTech Connect

    Hoag, H.A.; Tantawi, S.G.; Callin, R.

    1993-04-01

    It is important to minimize power loss in the waveguide system connecting klystron, pulse-compressor, and accelerator in an X-Band NLC. However, existing designs of klystron output cavity circuits and accelerator input couplers utilize rectangular waveguide which has relatively high transmission loss. It is therefore necessary to convert to and from the low-loss mode in circular waveguide at each end of the system. A description is given of development work on high-power, high-vacuum `flower-petal` transducers, which convert the TE{sub 10} mode in rectangular guide to the TE{sub 01} mode in circular guide. A three-port modification of the flower petal device, which can be used as either a power combiner at the klystron or a power divider at the accelerator is also described.