Sample records for high average powers

  1. High average power supercontinuum sources

    Indian Academy of Sciences (India)

    J C Travers


    The physical mechanisms and basic experimental techniques for the creation of high average spectral power supercontinuum sources is briefly reviewed. We focus on the use of high-power ytterbium-doped fibre lasers as pump sources, and the use of highly nonlinear photonic crystal fibres as the nonlinear medium. The most common experimental arrangements are described, including both continuous wave fibre laser systems with over 100 W pump power, and picosecond mode-locked, master oscillator power fibre amplifier systems, with over 10 kW peak pump power. These systems can produce broadband supercontinua with over 50 and 1 mW/nm average spectral power, respectively. Techniques for numerical modelling of the supercontinuum sources are presented and used to illustrate some supercontinuum dynamics. Some recent experimental results are presented.

  2. High-Average Power Facilities

    Energy Technology Data Exchange (ETDEWEB)

    Dowell, David H.; /SLAC; Power, John G.; /Argonne


    There has been significant progress in the development of high-power facilities in recent years yet major challenges remain. The task of WG4 was to identify which facilities were capable of addressing the outstanding R&D issues presently preventing high-power operation. To this end, information from each of the facilities represented at the workshop was tabulated and the results are presented herein. A brief description of the major challenges is given, but the detailed elaboration can be found in the other three working group summaries.

  3. High Average Power Yb:YAG Laser

    Energy Technology Data Exchange (ETDEWEB)

    Zapata, L E; Beach, R J; Payne, S A


    We are working on a composite thin-disk laser design that can be scaled as a source of high brightness laser power for tactical engagement and other high average power applications. The key component is a diffusion-bonded composite comprising a thin gain-medium and thicker cladding that is strikingly robust and resolves prior difficulties with high average power pumping/cooling and the rejection of amplified spontaneous emission (ASE). In contrast to high power rods or slabs, the one-dimensional nature of the cooling geometry and the edge-pump geometry scale gracefully to very high average power. The crucial design ideas have been verified experimentally. Progress this last year included: extraction with high beam quality using a telescopic resonator, a heterogeneous thin film coating prescription that meets the unusual requirements demanded by this laser architecture, thermal management with our first generation cooler. Progress was also made in design of a second-generation laser.

  4. High average-power induction linacs

    Energy Technology Data Exchange (ETDEWEB)

    Prono, D.S.; Barrett, D.; Bowles, E.; Caporaso, G.J.; Chen, Yu-Jiuan; Clark, J.C.; Coffield, F.; Newton, M.A.; Nexsen, W.; Ravenscroft, D.


    Induction linear accelerators (LIAs) are inherently capable of accelerating several thousand amperes of /approximately/ 50-ns duration pulses to > 100 MeV. In this paper we report progress and status in the areas of duty factor and stray power management. These technologies are vital if LIAs are to attain high average power operation. 13 figs.

  5. High Average Power Optical FEL Amplifiers

    CERN Document Server

    Ben-Zvi, I; Litvinenko, V


    Historically, the first demonstration of the FEL was in an amplifier configuration at Stanford University. There were other notable instances of amplifying a seed laser, such as the LLNL amplifier and the BNL ATF High-Gain Harmonic Generation FEL. However, for the most part FELs are operated as oscillators or self amplified spontaneous emission devices. Yet, in wavelength regimes where a conventional laser seed can be used, the FEL can be used as an amplifier. One promising application is for very high average power generation, for instance a 100 kW average power FEL. The high electron beam power, high brightness and high efficiency that can be achieved with photoinjectors and superconducting energy recovery linacs combine well with the high-gain FEL amplifier to produce unprecedented average power FELs with some advantages. In addition to the general features of the high average power FEL amplifier, we will look at a 100 kW class FEL amplifier is being designed to operate on the 0.5 ampere Energy Recovery Li...

  6. Materials for high average power lasers

    Energy Technology Data Exchange (ETDEWEB)

    Marion, J.E.; Pertica, A.J.


    Unique materials properties requirements for solid state high average power (HAP) lasers dictate a materials development research program. A review of the desirable laser, optical and thermo-mechanical properties for HAP lasers precedes an assessment of the development status for crystalline and glass hosts optimized for HAP lasers. 24 refs., 7 figs., 1 tab.

  7. Industrial Applications of High Average Power FELS

    CERN Document Server

    Shinn, Michelle D


    The use of lasers for material processing continues to expand, and the annual sales of such lasers exceeds $1 B (US). Large scale (many m2) processing of materials require the economical production of laser powers of the tens of kilowatts, and therefore are not yet commercial processes, although they have been demonstrated. The development of FELs based on superconducting RF (SRF) linac technology provides a scaleable path to laser outputs above 50 kW in the IR, rendering these applications economically viable, since the cost/photon drops as the output power increases. This approach also enables high average power ~ 1 kW output in the UV spectrum. Such FELs will provide quasi-cw (PRFs in the tens of MHz), of ultrafast (pulsewidth ~ 1 ps) output with very high beam quality. This talk will provide an overview of applications tests by our facility's users such as pulsed laser deposition, laser ablation, and laser surface modification, as well as present plans that will be tested with our upgraded FELs. These upg...

  8. Eighth CW and High Average Power RF Workshop

    CERN Document Server


    We are pleased to announce the next Continuous Wave and High Average RF Power Workshop, CWRF2014, to take place at Hotel NH Trieste, Trieste, Italy from 13 to 16 May, 2014. This is the eighth in the CWRF workshop series and will be hosted by Elettra - Sincrotrone Trieste S.C.p.A. ( CWRF2014 will provide an opportunity for designers and users of CW and high average power RF systems to meet and interact in a convivial environment to share experiences and ideas on applications which utilize high-power klystrons, gridded tubes, combined solid-state architectures, high-voltage power supplies, high-voltage modulators, high-power combiners, circulators, cavities, power couplers and tuners. New ideas for high-power RF system upgrades and novel ways of RF power generation and distribution will also be discussed. CWRF2014 sessions will start on Tuesday morning and will conclude on Friday lunchtime. A visit to Elettra and FERMI will be organized during the workshop. ORGANIZING COMMITTEE (OC): Al...

  9. Thermal effects in high average power optical parametric amplifiers. (United States)

    Rothhardt, Jan; Demmler, Stefan; Hädrich, Steffen; Peschel, Thomas; Limpert, Jens; Tünnermann, Andreas


    Optical parametric amplifiers (OPAs) have the reputation of being average power scalable due to the instantaneous nature of the parametric process (zero quantum defect). This Letter reveals serious challenges originating from thermal load in the nonlinear crystal caused by absorption. We investigate these thermal effects in high average power OPAs based on beta barium borate. Absorption of both pump and idler waves is identified to contribute significantly to heating of the nonlinear crystal. A temperature increase of up to 148 K with respect to the environment is observed and mechanical tensile stress up to 40 MPa is found, indicating a high risk of crystal fracture under such conditions. By restricting the idler to a wavelength range far from absorption bands and removing the crystal coating we reduce the peak temperature and the resulting temperature gradient significantly. Guidelines for further power scaling of OPAs and other nonlinear devices are given.

  10. High-average-power diode-pumped Yb: YAG lasers

    Energy Technology Data Exchange (ETDEWEB)

    Avizonis, P V; Beach, R; Bibeau, C M; Emanuel, M A; Harris, D G; Honea, E C; Monroe, R S; Payne, S A; Skidmore, J A; Sutton, S B


    A scaleable diode end-pumping technology for high-average-power slab and rod lasers has been under development for the past several years at Lawrence Livermore National Laboratory (LLNL). This technology has particular application to high average power Yb:YAG lasers that utilize a rod configured gain element. Previously, this rod configured approach has achieved average output powers in a single 5 cm long by 2 mm diameter Yb:YAG rod of 430 W cw and 280 W q-switched. High beam quality (M{sup 2} = 2.4) q-switched operation has also been demonstrated at over 180 W of average output power. More recently, using a dual rod configuration consisting of two, 5 cm long by 2 mm diameter laser rods with birefringence compensation, we have achieved 1080 W of cw output with an M{sup 2} value of 13.5 at an optical-to-optical conversion efficiency of 27.5%. With the same dual rod laser operated in a q-switched mode, we have also demonstrated 532 W of average power with an M{sup 2} < 2.5 at 17% optical-to-optical conversion efficiency. These q-switched results were obtained at a 10 kHz repetition rate and resulted in 77 nsec pulse durations. These improved levels of operational performance have been achieved as a result of technology advancements made in several areas that will be covered in this manuscript. These enhancements to our architecture include: (1) Hollow lens ducts that enable the use of advanced cavity architectures permitting birefringence compensation and the ability to run in large aperture-filling near-diffraction-limited modes. (2) Compound laser rods with flanged-nonabsorbing-endcaps fabricated by diffusion bonding. (3) Techniques for suppressing amplified spontaneous emission (ASE) and parasitics in the polished barrel rods.

  11. Potential of high-average-power solid state lasers

    Energy Technology Data Exchange (ETDEWEB)

    Emmett, J.L.; Krupke, W.F.; Sooy, W.R.


    We discuss the possibility of extending solid state laser technology to high average power and of improving the efficiency of such lasers sufficiently to make them reasonable candidates for a number of demanding applications. A variety of new design concepts, materials, and techniques have emerged over the past decade that, collectively, suggest that the traditional technical limitations on power (a few hundred watts or less) and efficiency (less than 1%) can be removed. The core idea is configuring the laser medium in relatively thin, large-area plates, rather than using the traditional low-aspect-ratio rods or blocks. This presents a large surface area for cooling, and assures that deposited heat is relatively close to a cooled surface. It also minimizes the laser volume distorted by edge effects. The feasibility of such configurations is supported by recent developments in materials, fabrication processes, and optical pumps. Two types of lasers can, in principle, utilize this sheet-like gain configuration in such a way that phase and gain profiles are uniformly sampled and, to first order, yield high-quality (undistorted) beams. The zig-zag laser does this with a single plate, and should be capable of power levels up to several kilowatts. The disk laser is designed around a large number of plates, and should be capable of scaling to arbitrarily high power levels.

  12. A high average power electro-optic switch using KTP

    Energy Technology Data Exchange (ETDEWEB)

    Ebbers, C.A.; Cook, W.M.; Velsko, S.P.


    High damage threshold, high thermal conductivity, and small thermo-optic coefficients make KTiOPO{sub 4} (KTP) an attractive material for use in a high average power Q-switch. However, electro-chromic damage and refractive index homogeneity have prevented the utilization of KTP in such a device in the past. This work shows that electro-chromic damage is effectively suppressed using capacitive coupling, and a KTP crystal can be Q-switched for 1.5 {times} 10{sup 9} shots without any detectable electro-chromic damage. In addition, KTP with the high uniformity and large aperture size needed for a KTP electro-optic Q-switch can be obtained from flux crystals grown at constant temperature. A thermally compensated, dual crystal KTP Q-switch, which successfully produced 50 mJ pulses with a pulse width of 8 ns (FWHM), has been constructed. In addition, in off-line testing the Q-switch showed less than 7% depolarization at an average power loading of 3.2 kW/cm{sup 2}.

  13. A high-average-power FEL for industrial applications

    Energy Technology Data Exchange (ETDEWEB)

    Dylla, H.F.; Benson, S.; Bisognano, J.


    CEBAF has developed a comprehensive conceptual design of an industrial user facility based on a kilowatt UV (150-1000 nm) and IR (2-25 micron) FEL driven by a recirculating, energy-recovering 200 MeV superconducting radio-frequency (SRF) accelerator. FEL users{endash}CEBAF`s partners in the Laser Processing Consortium, including AT&T, DuPont, IBM, Northrop-Grumman, 3M, and Xerox{endash}plan to develop applications such as polymer surface processing, metals and ceramics micromachining, and metal surface processing, with the overall effort leading to later scale-up to industrial systems at 50-100 kW. Representative applications are described. The proposed high-average-power FEL overcomes limitations of conventional laser sources in available power, cost-effectiveness, tunability and pulse structure. 4 refs., 3 figs., 2 tabs.

  14. High Average Current Electron Guns for High-Power FELs (United States)


    FELs 10 Appendix B: Thermionic Injectors 11 Appendix C: Grid Fields and Bunch Emittance 13 Appendix D: PARMELA Simulation of an IOT Gun 16...Inductive Output Tube ( IOT ) amplifiers [32-34] and can generate average currents of ~1 A, peak currents of ~ 5-10 A, cathode-anode voltages of ~ 35...of grid wires, centered at z = zG and x = ±a, ±3a, ±5a, ..., is given by <D(JC,Z) = - X n = ±l.±3. Fa(x,z) Gn(x,z) ( C3 ) where *0 = (1 / 2


    Energy Technology Data Exchange (ETDEWEB)

    Douglas, David; Evtushenko, Pavel; Gubeli, Joseph; Hernandez-Garcia, Carlos; Legg, Robert; Neil, George; Powers, Thomas; Shinn, Michelle D; Tennant, Christopher


    Having produced 14 kW of average power at {approx}2 microns, JLAB has shifted its focus to the ultraviolet portion of the spectrum. This presentation will describe the JLab UV Demo FEL, present specifics of its driver ERL, and discuss the latest experimental results from FEL experiments and machine operations.

  16. Active cooling of pulse compression diffraction gratings for high energy, high average power ultrafast lasers. (United States)

    Alessi, David A; Rosso, Paul A; Nguyen, Hoang T; Aasen, Michael D; Britten, Jerald A; Haefner, Constantin


    Laser energy absorption and subsequent heat removal from diffraction gratings in chirped pulse compressors poses a significant challenge in high repetition rate, high peak power laser development. In order to understand the average power limitations, we have modeled the time-resolved thermo-mechanical properties of current and advanced diffraction gratings. We have also developed and demonstrated a technique of actively cooling Petawatt scale, gold compressor gratings to operate at 600W of average power - a 15x increase over the highest average power petawatt laser currently in operation. Combining this technique with low absorption multilayer dielectric gratings developed in our group would enable pulse compressors for petawatt peak power lasers operating at average powers well above 40kW.

  17. Picosecond mid-infrared amplifier for high average power.

    CSIR Research Space (South Africa)

    Botha, LR


    Full Text Available are similar. The saturation fluence for a multi level system can be written as z PhEsat σ υ 2 = With σ the stimulated emission cross section and P the pressure of the laser. 1/z... is essentially the average number of populated rotational levels. For our case z=0.07 and 181054.1 −×=σ cm2. Thus for a 10 atm laser the saturation fluence is: 2 18 1334 /1173 07.01017/12 10109.210626.6 cmmJxEsat = ××× ××× = − − The maximum...

  18. Diode-Pumped High Energy and High Average Power All-Solid-State Picosecond Amplifier Systems

    Directory of Open Access Journals (Sweden)

    Jiaxing Liu


    Full Text Available We present our research on the high energy picosecond laser operating at a repetition rate of 1 kHz and the high average power picosecond laser running at 100 kHz based on bulk Nd-doped crystals. With diode-pumped solid state (DPSS hybrid amplifiers consisting of a picosecond oscillator, a regenerative amplifier, end-pumped single-pass amplifiers, and a side-pumped amplifier, an output energy of 64.8 mJ at a repetition rate of 1 kHz was achieved. An average power of 37.5 W at a repetition rate of 100 kHz pumped by continuous wave laser diodes was obtained. Compact, stable and high power DPSS laser amplifier systems with good beam qualities are excellent picosecond sources for high power optical parametric chirped pulse amplification (OPCPA and high-efficiency laser processing.

  19. Diode-Pumped High Energy and High Average Power All-Solid-State Picosecond Amplifier Systems


    Jiaxing Liu; Wei Wang; Zhaohua Wang; Zhiguo Lv; Zhiyuan Zhang; Zhiyi Wei


    We present our research on the high energy picosecond laser operating at a repetition rate of 1 kHz and the high average power picosecond laser running at 100 kHz based on bulk Nd-doped crystals. With diode-pumped solid state (DPSS) hybrid amplifiers consisting of a picosecond oscillator, a regenerative amplifier, end-pumped single-pass amplifiers, and a side-pumped amplifier, an output energy of 64.8 mJ at a repetition rate of 1 kHz was achieved. An average power of 37.5 W at a repetition ra...

  20. High average power coherent vuv generation at 10 MHz repetition frequency by intracavity high harmonic generation. (United States)

    Ozawa, Akira; Zhao, Zhigang; Kuwata-Gonokami, Makoto; Kobayashi, Yohei


    Intracavity high harmonic generation was utilized to generate high average-power coherent radiation at vacuum ultraviolet (vuv) wavelengths. A ytterbium-doped fiber-laser based master-oscillator power-amplifier (MOPA) system with a 10 MHz repetition frequency was developed and used as a driving laser for an external cavity. A series of odd-order harmonic radiations was generated extending down to ∼ 30 nm (41 eV in photon energy). The 7th harmonic radiation generated was centered at 149 nm and had an average output power of up to 0.5 mW. In this way, we developed a sub-mW coherent vuv-laser with a 10 MHz repetition frequency, which, if used as an excitation laser source for photo-electron spectroscopy, could improve the signal count-rate without deterioration of the spectral-resolution caused by space-charge effects.

  1. Crossatron switch as thyratron replacement in high repetition rate, high average power modulators (United States)

    Sullivan, J. S.


    The Crossatron is a cold cathode, low pressure, gas discharge switch with opening and closing capabilities. Due to its cold cathode operation, the Crossatron may offer lifetime advantages compared to the hydrogen thyratron. Unfortunately, little information regarding Crossatron lifetime and performance in high repetition rate, high average power, pulse modulators exists. Four prototype Crossatron devices, fabricated by Hughes Aircraft, were obtained to evaluate their performance and lifetime in high repetition rate, high average power, pulse modulators that had previously been equipped with hydrogen thyratrons. The prototype Crossatrons were evaluated over a range of operating parameters. Various grid drive, keep alive power levels and triggering schemes were employed in the tests. Switch parameters such as trigger time, anode fall time, jitter, recovery time, peak di/dt, switch efficiency, and the gas pumping effect of the discharge were observed. One Crossatron prototype was also subjected to lifetime tests that accumulated tens of billions of pulses. Lifetime data will be compared to various thyratron models tested similarly.

  2. High-throughput machining using high average power ultrashort pulse lasers and ultrafast polygon scanner (United States)

    Schille, Joerg; Schneider, Lutz; Streek, André; Kloetzer, Sascha; Loeschner, Udo


    In this paper, high-throughput ultrashort pulse laser machining is investigated on various industrial grade metals (Aluminium, Copper, Stainless steel) and Al2O3 ceramic at unprecedented processing speeds. This is achieved by using a high pulse repetition frequency picosecond laser with maximum average output power of 270 W in conjunction with a unique, in-house developed two-axis polygon scanner. Initially, different concepts of polygon scanners are engineered and tested to find out the optimal architecture for ultrafast and precision laser beam scanning. Remarkable 1,000 m/s scan speed is achieved on the substrate, and thanks to the resulting low pulse overlap, thermal accumulation and plasma absorption effects are avoided at up to 20 MHz pulse repetition frequencies. In order to identify optimum processing conditions for efficient high-average power laser machining, the depths of cavities produced under varied parameter settings are analyzed and, from the results obtained, the characteristic removal values are specified. The maximum removal rate is achieved as high as 27.8 mm3/min for Aluminium, 21.4 mm3/min for Copper, 15.3 mm3/min for Stainless steel and 129.1 mm3/min for Al2O3 when full available laser power is irradiated at optimum pulse repetition frequency.

  3. Performance and production requirements for the optical components in a high-average-power laser system

    Energy Technology Data Exchange (ETDEWEB)

    Chow, R.; Doss, F.W.; Taylor, J.R.; Wong, J.N.


    Optical components needed for high-average-power lasers, such as those developed for Atomic Vapor Laser Isotope Separation (AVLIS), require high levels of performance and reliability. Over the past two decades, optical component requirements for this purpose have been optimized and performance and reliability have been demonstrated. Many of the optical components that are exposed to the high power laser light affect the quality of the beam as it is transported through the system. The specifications for these optics are described including a few parameters not previously reported and some component manufacturing and testing experience. Key words: High-average-power laser, coating efficiency, absorption, optical components

  4. Improved performance of high average power semiconductor arrays for applications in diode pumped solid state lasers

    Energy Technology Data Exchange (ETDEWEB)

    Beach, R.; Emanuel, M.; Benett, W.; Freitas, B.; Ciarlo, D.; Carlson, N.; Sutton, S.; Skidmore, J.; Solarz, R.


    The average power performance capability of semiconductor diode laser arrays has improved dramatically over the past several years. These performance improvements, combined with cost reductions pursued by LLNL and others in the fabrication and packaging of diode lasers, have continued to reduce the price per average watt of laser diode radiation. Presently, we are at the point where the manufacturers of commercial high average power solid state laser systems used in material processing applications can now seriously consider the replacement of their flashlamp pumps with laser diode pump sources. Additionally, a low cost technique developed and demonstrated at LLNL for optically conditioning the output radiation of diode laser arrays has enabled a new and scalable average power diode-end-pumping architecture that can be simply implemented in diode pumped solid state laser systems (DPSSL`s). This development allows the high average power DPSSL designer to look beyond the Nd ion for the first time. Along with high average power DPSSL`s which are appropriate for material processing applications, low and intermediate average power DPSSL`s are now realizable at low enough costs to be attractive for use in many medical, electronic, and lithographic applications.

  5. High Average Power Diode Pumped Solid State Lasers: Power Scaling With High Spectral and Spatial Coherence (United States)


    sensing and coherent LIDAR systems, will require kW class lasers in the near future. The zigzag slab architecture [2], with its nearly one-dimensional... photodetectors ; PM1, PM2, PM3: thermal power meters; HBS1: 1064 nm holographic beam sampler; HBS2: 532-nm holographic beam sampler; LD: laser diode; CCD: charge...recombining pairs is measured by a photodetector . This measurement shows higher PL intensity as the material is improved by reducing defect density. We tried

  6. Kilowatt high average power narrow-linewidth nanosecond all-fiber laser

    Institute of Scientific and Technical Information of China (English)

    Rongtao; Su; Pu; Zhou; Xiaolin; Wang; Rumao; Tao; Xiaojun; Xu


    A high power narrow-linewidth nanosecond all-fiber laser based on the master oscillator power amplifier(MOPA)configuration is demonstrated. A pulsed seed with high repetition rate of 10 MHz was generated by modulating a continuous-wave(CW) single-frequency fiber laser at ~1064 nm by using an electro-optic intensity modulator(EOIM).After multi-stage cascaded power amplification, the average power was boosted to be kilowatt level. The pulses from the main amplifier had a pulse width of ~3 ns and an average/peak power of 913 W/28.6 kW. Further power scaling of the pulses was limited by stimulated Raman scattering(SRS) for the moment, method for SRS suppression and further power scaling was briefly discussed.

  7. High-Average-Power Diffraction Pulse-Compression Gratings Enabling Next-Generation Ultrafast Laser Systems

    Energy Technology Data Exchange (ETDEWEB)

    Alessi, D. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)


    Pulse compressors for ultrafast lasers have been identified as a technology gap in the push towards high peak power systems with high average powers for industrial and scientific applications. Gratings for ultrashort (sub-150fs) pulse compressors are metallic and can absorb a significant percentage of laser energy resulting in up to 40% loss as well as thermal issues which degrade on-target performance. We have developed a next generation gold grating technology which we have scaled to the petawatt-size. This resulted in improvements in efficiency, uniformity and processing as compared to previous substrate etched gratings for high average power. This new design has a deposited dielectric material for the grating ridge rather than etching directly into the glass substrate. It has been observed that average powers as low as 1W in a compressor can cause distortions in the on-target beam. We have developed and tested a method of actively cooling diffraction gratings which, in the case of gold gratings, can support a petawatt peak power laser with up to 600W average power. We demonstrated thermo-mechanical modeling of a grating in its use environment and benchmarked with experimental measurement. Multilayer dielectric (MLD) gratings are not yet used for these high peak power, ultrashort pulse durations due to their design challenges. We have designed and fabricated broad bandwidth, low dispersion MLD gratings suitable for delivering 30 fs pulses at high average power. This new grating design requires the use of a novel Out Of Plane (OOP) compressor, which we have modeled, designed, built and tested. This prototype compressor yielded a transmission of 90% for a pulse with 45 nm bandwidth, and free of spatial and angular chirp. In order to evaluate gratings and compressors built in this project we have commissioned a joule-class ultrafast Ti:Sapphire laser system. Combining the grating cooling and MLD technologies developed here could enable petawatt laser systems to

  8. High-gain Yb:YAG amplifier for ultrashort pulse laser at high-average power (United States)

    Vetrovec, John; Copeland, Drew A.; Litt, Amardeep S.; Du, Detao


    We report on a Yb:YAG laser amplifier for ultrashort pulse applications at kW-class average power. The laser uses two large-aperture, disk-type gain elements fabricated from composite ceramic YAG material, and a multi-pass extraction architecture to obtain high gain in a chirped-pulse amplification system. The disks are edge-pumped, thus allowing for reduced doping of host material with laser ions, which translates to lower lasing threshold and lower heat dissipation in the Yb:YAG material. The latter makes it possible to amplify a near diffraction-limited seed without significant thermo-optical distortions. This work presents results of testing the laser amplifier with relay optics configured for energy extraction with up to 40 passes through the disks. Applications for the ultrashort pulse laser amplifier include producing laser-induced plasma channel, laser material ablation, and laser acceleration of atomic particles.

  9. High average power picosecond pulse generation from a thulium-doped all-fiber MOPA system. (United States)

    Liu, Jiang; Wang, Qian; Wang, Pu


    We report a stable highly-integrated high power picosecond thulium-doped all-fiber MOPA system without using conventional chirped pulse amplification technique. The master oscillator was passively mode-locked by a SESAM to generate average power of 15 mW at a fundamental repetition rate of 103 MHz in a short linear cavity, and a uniform narrow bandwidth FBG is employed to stabilize the passively mode-locked laser operation. Two-stage double-clad thulium-doped all-fiber amplifiers were used directly to boost average power to 20.7 W. The laser center wavelength was 1962.8 nm and the pulse width was 18 ps. The single pulse energy and peak-power after the amplication were 200 nJ and 11.2 kW respectively. To the best of our knowledge, this is the highest average power ever reported for a picosecond thulium-doped all-fiber MOPA system.

  10. Temperature-insensitive frequency tripling for generating high-average power UV lasers. (United States)

    Zhong, Haizhe; Yuan, Peng; Wen, Shuangchun; Qian, Liejia


    Aimed for generating high-average power ultraviolet (UV) lasers via third-harmonic generation (THG) consisting of frequency doubling and tripling stages, we numerically and experimentally demonstrate a novel frequency tripling scheme capable of supporting temperature-insensitive phase-matching (PM). Two cascaded tripling crystals, with opposite signs of the temperature derivation of phase-mismatch, are proposed and theoretically studied for improving the temperature-acceptance of PM. The proof-of-principle tripling experiment using two crystals of LBO and BBO shows that the temperature acceptance can be ~1.5 times larger than that of using a single tripling crystal. In addition, the phase shift caused by air dispersion, along with its influence on the temperature-insensitive PM, are also discussed. To illustrate the potential applications of proposed two-crystal tripling design in the high-average-power regime, full numerical simulations for the tripling process, are implemented based on the realistic crystals. The demonstrated two-crystal tripling scheme may provide a promising route to high-average-power THG in the UV region.

  11. High-throughput machining using a high-average power ultrashort pulse laser and high-speed polygon scanner (United States)

    Schille, Joerg; Schneider, Lutz; Streek, André; Kloetzer, Sascha; Loeschner, Udo


    High-throughput ultrashort pulse laser machining is investigated on various industrial grade metals (aluminum, copper, and stainless steel) and Al2O3 ceramic at unprecedented processing speeds. This is achieved by using a high-average power picosecond laser in conjunction with a unique, in-house developed polygon mirror-based biaxial scanning system. Therefore, different concepts of polygon scanners are engineered and tested to find the best architecture for high-speed and precision laser beam scanning. In order to identify the optimum conditions for efficient processing when using high-average laser powers, the depths of cavities made in the samples by varying the processing parameter settings are analyzed and, from the results obtained, the characteristic removal values are specified. For overlapping pulses of optimum fluence, the removal rate is as high as 27.8 mm3/min for aluminum, 21.4 mm3/min for copper, 15.3 mm3/min for stainless steel, and 129.1 mm3/min for Al2O3, when a laser beam of 187 W average laser powers irradiates. On stainless steel, it is demonstrated that the removal rate increases to 23.3 mm3/min when the laser beam is very fast moving. This is thanks to the low pulse overlap as achieved with 800 m/s beam deflection speed; thus, laser beam shielding can be avoided even when irradiating high-repetitive 20-MHz pulses.

  12. High average power CO II laser MOPA system for Tin target LPP EUV light source (United States)

    Ariga, Tatsuya; Hoshino, Hideo; Endo, Akira


    Extreme ultraviolet lithography (EUVL) is the candidate for next generation lithography to be introduced by the semiconductor industry to HVM (high volume manufacturing) in 2013. The power of the EUVL light source has to be at least 115W at a wavelength of 13.5nm. A laser produced plasma (LPP) is the main candidate for this light source but a cost effective laser driver is the key requirement for the realization of this concept. We are currently developing a high power and high repetition rate CO II laser system to achieve 50 W intermediate focus EUV power with a Tin droplet target. We have achieved CE of 2.8% with solid Tin wire target by a transversely excited atmospheric (TEA) CO II laser MOPA system with pulse width, pulse energy and pulse repetition rate as 10~15 ns, 30 mJ and 10 Hz, respectively. A CO II laser system with a short pulse length less than 15 ns, a nominal average power of a few kW, and a repetition rate of 100 kHz, based on RF-excited, fast axial flow CO II laser amplifiers is under development. Output power of about 3 kW has been achieved with a pulse length of 15 ns at 130 kHz repletion rate in a small signal amplification condition with P(20) single line. The phase distortion of the laser beam after amplification is negligible and the beam can be focused to about 150μm diameter in 1/e2. The CO II laser system is reported on short pulse amplification performance using RF-excited fast axial flow lasers as amplifiers. And the CO II laser average output power scaling is shown towards 5~10 kW with pulse width of 15 ns from a MOPA system.

  13. New generation of high average power industry grade ultrafast ytterbium fiber lasers (United States)

    Yusim, Alex; Samartsev, Igor; Shkurikhin, Oleg; Myasnikov, Daniil; Bordenyuk, Andrey; Platonov, Nikolai; Kancharla, Vijay; Gapontsev, Valentin


    We report an industrial grade picosecond and femtosecond pulse Yb fiber lasers with >100 μJ pulse energy and hundreds of Watts of average power for improved laser machining speed of sapphire and glass. This highly efficient laser offers >25% wall plug efficiency within a compact 3U rack-mountable configuration plus a long >2m fiber delivery cable. Reconfigurable features such as controllable repetition rate, fine pulse duration control, burst mode operation and adjustable pulse energy permit the customer to tailor the laser to their application.

  14. Dual-scale turbulence in filamenting laser beams at high average power

    CERN Document Server

    Schubert, Elise; Mongin, Denis; Kasparian, Jérôme; Wolf, Jean-Pierre; Klingebiel, Sandro; Schultze, Marcel; Metzger, Thomas; Michel, Knut


    We investigate the self-induced turbulence of high repetition rate laser filaments over a wide range of average powers (1 mW to 100 W) and its sensitivity to external atmospheric turbulence. Although both externally-imposed and self-generated turbulences can have comparable magnitudes, they act on different temporal and spatial scales. While the former drives the shot-to-shot motion at the millisecond time scale, the latter acts on the 0.5 s scale. As a consequence, their effects are decoupled, preventing beam stabilization by the thermally-induced low-density channel produced by the laser filaments.

  15. High energy, high average power solid state green or UV laser (United States)

    Hackel, Lloyd A.; Norton, Mary; Dane, C. Brent


    A system for producing a green or UV output beam for illuminating a large area with relatively high beam fluence. A Nd:glass laser produces a near-infrared output by means of an oscillator that generates a high quality but low power output and then multi-pass through and amplification in a zig-zag slab amplifier and wavefront correction in a phase conjugator at the midway point of the multi-pass amplification. The green or UV output is generated by means of conversion crystals that follow final propagation through the zig-zag slab amplifier.

  16. Optimisation of high average power optical parametric generation using a photonic crystal fiber. (United States)

    Sloanes, Trefor; McEwan, Ken; Lowans, Brian; Michaille, Laurent


    In this paper the length of a photonic crystal fiber is optimised to perform high average output power parametric generation with maximum efficiency. It is shown that the fiber length has to be increased up to 150 m, well beyond the walk-off distance between the pump and signal/idler, to optimize the generation efficiency. In this regime, the Raman process can take over from four-wave mixing and lead to supercontinuum generation. It is shown that the parametric wavelength conversion is directional; probably due to small variations in the core dimensions along the fiber length. The fiber exhibits up to 40% conversion efficiency, with the idler (0.9 microm) and the signal (1.3 microm) having a combined output power of over 1.5 W.

  17. Status of HiLASE project: High average power pulsed DPSSL systems for research and industry

    Directory of Open Access Journals (Sweden)

    Mocek T.


    Full Text Available We introduce the Czech national R&D project HiLASE which focuses on strategic development of advanced high-repetition rate, diode pumped solid state laser (DPSSL systems that may find use in research, high-tech industry and in the future European large-scale facilities such as HiPER and ELI. Within HiLASE we explore two major concepts: thin-disk and cryogenically cooled multislab amplifiers capable of delivering average output powers above 1 kW level in picosecond-to-nanosecond pulsed regime. In particular, we have started a programme of technology development to demonstrate the scalability of multislab concept up to the kJ level at repetition rate of 1–10 Hz.

  18. Status of HiLASE project: High average power pulsed DPSSL systems for research and industry (United States)

    Mocek, T.; Divoky, M.; Smrz, M.; Sawicka, M.; Chyla, M.; Sikocinski, P.; Vohnikova, H.; Severova, P.; Lucianetti, A.; Novak, J.; Rus, B.


    We introduce the Czech national R&D project HiLASE which focuses on strategic development of advanced high-repetition rate, diode pumped solid state laser (DPSSL) systems that may find use in research, high-tech industry and in the future European large-scale facilities such as HiPER and ELI. Within HiLASE we explore two major concepts: thin-disk and cryogenically cooled multislab amplifiers capable of delivering average output powers above 1 kW level in picosecond-to-nanosecond pulsed regime. In particular, we have started a programme of technology development to demonstrate the scalability of multislab concept up to the kJ level at repetition rate of 1-10 Hz.

  19. The Mercury Project: A High Average Power, Gas-Cooled Laser For Inertial Fusion Energy Development

    Energy Technology Data Exchange (ETDEWEB)

    Bayramian, A; Armstrong, P; Ault, E; Beach, R; Bibeau, C; Caird, J; Campbell, R; Chai, B; Dawson, J; Ebbers, C; Erlandson, A; Fei, Y; Freitas, B; Kent, R; Liao, Z; Ladran, T; Menapace, J; Molander, B; Payne, S; Peterson, N; Randles, M; Schaffers, K; Sutton, S; Tassano, J; Telford, S; Utterback, E


    Hundred-joule, kilowatt-class lasers based on diode-pumped solid-state technologies, are being developed worldwide for laser-plasma interactions and as prototypes for fusion energy drivers. The goal of the Mercury Laser Project is to develop key technologies within an architectural framework that demonstrates basic building blocks for scaling to larger multi-kilojoule systems for inertial fusion energy (IFE) applications. Mercury has requirements that include: scalability to IFE beamlines, 10 Hz repetition rate, high efficiency, and 10{sup 9} shot reliability. The Mercury laser has operated continuously for several hours at 55 J and 10 Hz with fourteen 4 x 6 cm{sup 2} ytterbium doped strontium fluoroapatite (Yb:S-FAP) amplifier slabs pumped by eight 100 kW diode arrays. The 1047 nm fundamental wavelength was converted to 523 nm at 160 W average power with 73% conversion efficiency using yttrium calcium oxy-borate (YCOB).

  20. Cryogenic nanosecond and picosecond high average and peak power(HAPP) pump lasers for ultrafast applications

    Institute of Scientific and Technical Information of China (English)

    David C.Brown; Sten Tornegrd; Joseph Kolis


    Using cryogenic laser technology, it is now possible to design and demonstrate lasers that have concomitant high average and peak powers, with near-diffraction-limited beam quality. We refer to these new laser systems as HAPP lasers. In this paper, we review important laser crystal materials properties at cryogenic temperature, with an emphasis on Yb lasers, and discuss the important design considerations, including the laser-induced damage threshold, nonlinear effects and thermal effects. A comprehensive model is presented to describe diode pulsed pumping with arbitrary duration and repetition rate, and is used with the Frantz–Nodvik equation to describe, to first order, the performance of HAPP laser systems. A computer code with representative results is also described.

  1. High average power Q-switched 1314 nm two-crystal Nd:YLF laser

    CSIR Research Space (South Africa)

    Botha, RC


    Full Text Available . 40, No. 4 / OPTICS LETTERS High average power Q-switched 1314 nm two-crystal Nd:YLF laser R. C. Botha,1,2,* W. Koen,3 M. J. D. Esser,3,4 C. Bollig,3,5 W. L. Combrinck,1,6 H. M. von Bergmann,2 and H. J. Strauss3 1HartRAO, P.O. Box 443..., Krugersdorp, 1740 South Africa 2Stellenbosch University, P/Bag X1, Matieland, 7602 South Africa 3National Laser Centre, CSIR, PO Box 395, Pretoria, 0001 South Africa 4Formerly at CSIR, now at Heriot-Watt University, EH14 4AS Edinburgh, UK 5Formerly at CSIR...

  2. High speed laser drilling of metals using a high repetition rate, high average power ultrafast fiber CPA system. (United States)

    Ancona, A; Röser, F; Rademaker, K; Limpert, J; Nolte, S; Tünnermann, A


    We present an experimental study on the drilling of metal targets with ultrashort laser pulses at high repetition rates (from 50 kHz up to 975 kHz) and high average powers (up to 68 Watts), using an ytterbium-doped fiber CPA system. The number of pulses to drill through steel and copper sheets with thicknesses up to 1 mm have been measured as a function of the repetition rate and the pulse energy. Two distinctive effects, influencing the drilling efficiency at high repetition rates, have been experimentally found and studied: particle shielding and heat accumulation. While the shielding of subsequent pulses due to the ejected particles leads to a reduced ablation efficiency, this effect is counteracted by heat accumulation. The experimental data are in good qualitative agreement with simulations of the heat accumulation effect and previous studies on the particle emission. However, for materials with a high thermal conductivity as copper, both effects are negligible for the investigated processing parameters. Therefore, the full power of the fiber CPA system can be exploited, which allows to trepan high-quality holes in 0.5mm-thick copper samples with breakthrough times as low as 75 ms.

  3. Numerical Investigation of Thermal Effect in Plasma Electrode Pockels Cell for High Average Power

    Institute of Scientific and Technical Information of China (English)

    CAO Ding-Xiang; ZHANG Xiong-Jun; ZHENG Wan-Guo; HE Shao-Bo; SUI Zhan


    @@ The average power of a Pockels cell is limited by thermal effects arising from the optical absorption of the laser pulse. These thermal effects can be managed by configuring the switch as a plasma-electrode thin plate Pockels cell, which works under heat-capacity operation. Simulation results show that, based on KD*P (in thickness 0.5cm) at an average power loading of 1 kW, the aperture integrated depolarization loss at 1.06 um is less than 10% in 5min working time.

  4. High-average-power and high-beam-quality Innoslab picosecond laser amplifier. (United States)

    Xu, Liu; Zhang, Hengli; Mao, Yefei; Yan, Ying; Fan, Zhongwei; Xin, Jianguo


    We demonstrated a laser-diode, end-pumped picosecond amplifier. With effective shaping of the seed laser, we achieved 73 W amplified laser output at the pump power of 255 W, and the optical-optical efficiency was about 28%. The beam propagation factors M(2) measured at the output power of 60 W in the horizontal direction and the vertical direction were 1.5 and 1.4, respectively.

  5. Generation and applications of high average power Mid-IR supercontinuum in chalcogenide fibres

    DEFF Research Database (Denmark)

    Petersen, Christian Rosenberg


    Mid-infrared supercontinuum with up to 54.8 mW average power, and maximum bandwidth of 1.77-8.66 μm is demonstrated as a result of pumping tapered chalcogenide photonic crystal fibers with a MHz parametric source at 4 μm....

  6. Thermal distortion and birefringence in repetition-rate plasma electrode Pockels cell for high average power

    Institute of Scientific and Technical Information of China (English)

    Dingxiang Cao; Xiongjun Zhang; Wanguo Zheng; Shaobo He; Zhan Sui


    We numerically study thermally induced birefringence and distortion in plasma electrode Pockels cell based on KD*P as the electro-optic material. This device can repetitively operate under the heat capacity mode.Simulation results indicate that the excellent switching performances and low wave-front distortion are achieved within several tens seconds working time at average power in excess of 1 kW.

  7. Design of a high average-power FEL driven by an existing 20 MV electrostatic-accelerator

    Energy Technology Data Exchange (ETDEWEB)

    Kimel, I.; Elias, L.R. [Univ. of Central Florida, Orlando, FL (United States)


    There are some important applications where high average-power radiation is required. Two examples are industrial machining and space power-beaming. Unfortunately, up to date no FEL has been able to show more than 10 Watts of average power. To remedy this situation we started a program geared towards the development of high average-power FELs. As a first step we are building in our CREOL laboratory, a compact FEL which will generate close to 1 kW in CW operation. As the next step we are also engaged in the design of a much higher average-power system based on a 20 MV electrostatic accelerator. This FEL will be capable of operating CW with a power output of 60 kW. The idea is to perform a high power demonstration using the existing 20 MV electrostatic accelerator at the Tandar facility in Buenos Aires. This machine has been dedicated to accelerate heavy ions for experiments and applications in nuclear and atomic physics. The necessary adaptations required to utilize the machine to accelerate electrons will be described. An important aspect of the design of the 20 MV system, is the electron beam optics through almost 30 meters of accelerating and decelerating tubes as well as the undulator. Of equal importance is a careful design of the long resonator with mirrors able to withstand high power loading with proper heat dissipation features.

  8. Femtosecond and picosecond laser drilling of metals at high repetition rates and average powers. (United States)

    Ancona, A; Döring, S; Jauregui, C; Röser, F; Limpert, J; Nolte, S; Tünnermann, A


    The influence of pulse duration on the laser drilling of metals at repetition rates of up to 1 MHz and average powers of up to 70 W has been experimentally investigated using an ytterbium-doped-fiber chirped-pulse amplification system with pulses from 800 fs to 19 ps. At a few hundred kilohertz particle shielding causes an increase in the number of pulses for breakthrough, depending on the pulse energy and duration. At higher repetition rates, the heat accumulation effect overbalances particle shielding, but significant melt ejection affects the hole quality. Using femtosecond pulses, heat accumulation starts at higher repetition rates, and the ablation efficiency is higher compared with picosecond pulses.

  9. High-average-power high-beam-quality vis-UV sources based on kinetically enhanced copper vapor lasers (United States)

    Brown, Daniel J. W.; Withford, Michael J.; Carman, Robert J.; Mildren, Richard P.; Piper, James A.


    Investigations of the factors that limit average power scaling of elemental copper vapor lasers (CVLs) have demonstrated that decay of the electron density in the interpulse period is critical in restricting pulse repetition rate and laser aperture scaling. We have recently developed the 'kinetic enhancement' (or KE) technique to overcome these limitations, whereby optimal plasma conditions are engineered using low concentrations of HCl/H2 additive gases in the Ne buffer. Dissociative electron attachment of HCl and subsequent mutual neutralization of Cl- and Cu+ promote rapid plasma relaxation and fast recovery of Cu densities, permitting operation at elevated Cu densities and pulse rates for given apertures. Using this approach, we have demonstrated increases in output power and efficiency of a factor of 2 or higher over conventional CVLs of the same size. For a 38 mm- bore KE-CVL, output powers up to 150 W have been achieved at 22 kHz, corresponding to record specific powers (80 mW/cm3) for such a 'small/medium-scale' device. In addition, kinetic enhancement significantly extends the gain duration and restores gain on-axis, even for high pulse rates, thereby promoting substantial increases (5 - 10x) in high- beam-quality power levels when operating with unstable resonators. This has enabled us to achieve much higher powers in second-harmonic generation from the visible copper laser output to the ultraviolet (e.g. 5 W at 255 nm from a small- scale KE-CVL). Our approach to developing KE-CVLs including computer modeling and experimental studies will be reviewed, and most recent results in pulse rate scaling and scaling of high-beam-quality power using oscillator-amplifier configurations, will be presented.

  10. High average power picosecond pulse and supercontinuum generation from a thulium-doped, all-fiber amplifier. (United States)

    Liu, Jiang; Xu, Jia; Liu, Kun; Tan, Fangzhou; Wang, Pu


    We demonstrate a high-power, picosecond, thulium-doped, all-fiber master oscillator power amplifier with average power of 120.4 W. The compact fiber oscillator is carefully designed with high repetition rate for the purpose of overcoming the detrimental effects of fiber nonlinearity in the later fiber amplifiers. The pulse duration of 16 ps at 333.75 MHz repetition rate results in a peak power of 22.5 kW in the final fiber power amplifier. To the best of our knowledge, this is the first demonstration of average power exceeding 100 W from an ultrashort pulse laser at 2 μm wavelength. On the other hand, by decreasing the fiber oscillator repetition rate and pulse duration for enhancing the fiber nonlinearity effects, we also demonstrate a high-power supercontinuum source with average power of 36 W from 1.95 μm to beyond 2.4 μm in the final fiber power amplifier.

  11. NEO-LISP: Deflecting near-Earth objects using high average power, repetitively pulsed lasers (United States)

    Phipps, C. R.; Michaelis, M. M.

    Several kinds of Near-Earth objects exist for which one would like to cause modest orbit perturbations, but which are inaccessible to normal means of interception because of their number, distance or the lack of early warning. For these objects, LISP (Laser Impulse Space Propulsion) is an appropriate technique for rapidly applying the required mechanical impulse from a ground-based station. In order of increasing laser energy required, examples are: (1) repositioning specially prepared geosynchronous satellites for an enhanced lifetime; (2) causing selected items of space junk to re-enter and burn up in the atmosphere on a computed trajectory; and (3) safely deflecting Earth-directed comet nuclei and earth-crossing asteroids (ECA's) a few tens of meters in size (the most hazardous size). They will discuss each of these problems in turn and show that each application is best matched by its own matrix of LISP laser pulse width, pulse repetition rate, wavelength and average power. The latter ranges from 100W to 3GW for the cases considered. They will also discuss means of achieving the active beam phase error correction during passage through the atmosphere and very large exit pupil in the optical system which are required in each of these cases.

  12. High average power and energy microsecond pulse generation from an erbium-doped fluoride fiber MOPA system. (United States)

    Luo, Hongyu; Li, Jianfneg; Xie, Jitao; Zhai, Bo; Wei, Chen; Liu, Yong


    We reported a high average power and energy microsecond pulse erbium-doped fluoride fiber MOPA system centered at 2786.8 nm. The master oscillator was a passively Q-switched erbium-doped fluoride fiber laser based on SESAM in a linear cavity. Then a one-stage erbium-doped fluoride fiber amplifier was used to boost its average output power to 4.2 W and pulse energy to 58.87 μJ. The pulse duration and repetition rate were 2.29 µs and 71.73 kHz, respectively. To the best of our knowledge, the achieved average output power and pulse energy are the recorded levels for the passively Q-switched fiber lasers at 3 μm wavelength region.

  13. High-repetition rate industrial TEA CO2 laser with average output power of 1.5 kW (United States)

    Wan, Chongyi; Liu, Shiming; Zhou, Jinwen; Qi, Jilan; Yang, Xiaola; Wu, Jin; Tan, Rongqing; Wang, Lichun; Mei, Qichu


    High power high repetition rate TEA CO2 laser has potential importance in material processing such as shock hardening, glazing, drilling, welding, and cutting for high damage threshold materials, as well as in chemical reaction and isotope separation. This paper describes a transverse-flow closed-cycle UV-preionized TEA CO2 laser with peak pulse power of 20 MW, maximum average power of 1.5 KW at repetition rate of 300 HZ. The laser has compact constructure of gas flow circulation system using tangential fans. With addition of small amounts of H2 and CO to the normal CO2-N2-He gas mixture, one filling sealed operating lifetime is up to millions of pulses. A novel spark gap switch has been developed for very high repetition rate laser discharge in the condition of high pulse power.

  14. Optical Fibre Beam Delivery of High Average Power NEODYMIUM:YAG Laser Radiation (United States)

    Boechat, Alvaro A. P.

    Available from UMI in association with The British Library. This thesis presents a study of the waveguiding properties of large core (200-1000mum core diameter), relatively short length (5-50m) multimode optical fibres used for delivery of Nd:YAG laser radiation at a wavelength of 1.06mum. A major objective of the study was to provide design information for beam delivery systems used in high power materials processing application. Experimental and theoretical investigation of the optical losses produced by bending the fibre lead to a model which can be used to predict the magnitude of the bend loss as a function of launching conditions, bend geometry and fibre parameters. The study confirms the importance of using large numerical aperture, small core diameter fibres to minimise losses. It has been shown that the beam output near field profile from a fibre is a function of the launching conditions. Theoretical and experimental study of the effect for both step and graded index fibres is presented. Geometric optics and phase space theory was used to develop a model in which a relationship between input and output beam quality from a graded index fibre was established. The results showed that there is an optimum launching condition for which the beam quality may be preserved for fibres with quadratic index profiles. The effect of curvature induced mode coupling on beam quality has been studied experimentally, and compared with intrinsic mode coupling effects. The study was supported by the development of a simple theoretical mode coupling model. Finally, a new monitoring technique for beam delivery systems was developed, based on detection of power in the fibre cladding. Applications include determining laser -fibre coupling efficiency, fibre integrity monitoring, and providing real time process information.

  15. Design of an L-band normally conducting RF gun cavity for high peak and average RF power (United States)

    Paramonov, V.; Philipp, S.; Rybakov, I.; Skassyrskaya, A.; Stephan, F.


    To provide high quality electron bunches for linear accelerators used in free electron lasers and particle colliders, RF gun cavities operate with extreme electric fields, resulting in a high pulsed RF power. The main L-band superconducting linacs of such facilities also require a long RF pulse length, resulting in a high average dissipated RF power in the gun cavity. The newly developed cavity based on the proven advantages of the existing DESY RF gun cavities, underwent significant changes. The shape of the cells is optimized to reduce the maximal surface electric field and RF loss power. Furthermore, the cavity is equipped with an RF probe to measure the field amplitude and phase. The elaborated cooling circuit design results in a lower temperature rise on the cavity RF surface and permits higher dissipated RF power. The paper presents the main solutions and results of the cavity design.

  16. Overview of the HiLASE project: high average power pulsed DPSSL systems for research and industry

    Institute of Scientific and Technical Information of China (English)

    M.Divoky; M.Smrz; M.Chyla; P.Sikocinski; P.Severova; O.Novak; J.Huynh; S.S.Nagisetty; T.Miura; J.Pila; O.Slezak; M.Sawicka; V.Jambunathan; J.Vanda; A.Endo; A.Lucianetti; D.Rostohar; P.D.Mason; P.J.Phillips; K.Ertel; S.Banerjee; C.Hernandez-Gomez; J.L.Collier; T.Mocek


    An overview of the Czech national R&D project HiLASE(High average power pulsed laser) is presented. The project focuses on the development of advanced high repetition rate, diode pumped solid state laser(DPSSL) systems with energies in the range from mJ to 100 J and repetition rates in the range from 10 Hz to 100 kHz. Some applications of these lasers in research and hi-tech industry are also presented.

  17. Investigation of laser diode face-pumped high average power heat capacity laser

    Institute of Scientific and Technical Information of China (English)

    Shenjin Zhang; Shouhuan Zhou; Xiaojun Tang; Guojiang Bi; Huachang LV


    The three-dimensional (3D) pump intensity distribution in medium of the laser diode (LD) pumped highaverage power heat capacity laser is simulated by the ray tracing method, and the divergence characteristicsof fast axis and slow axis of LD are simultaneously considered. The transient 3D temperature and stressdistributions are also simulated by the finite element method (FEM) with considering the uneven heatsource distribution in medium. A LD face-pumped Nd:GGG heat capacity laser is designed. The averageoutput power is 1.49 kW with an optical-optical efficiency of 24.1%.

  18. High Average Power Raman Conversion in Diamond: ’Eyesafe’ Output and Fiber Laser Conversion (United States)


    power. The efficiencies and brightness achieved are found to be higher than expected by current theories for thermal effects in diamond. The project...understand the importance of other cavity parameters on laser behaviour in order to assist with future optimization of designs. We thus developed a model...three areas not originally planned in the proposal. 1) Raman beam combination The technique of Raman beam combination, which has been investigated

  19. Edge-facet pumped, multi-aperture, thin-disk laser geometry for very high average power output scaling

    Energy Technology Data Exchange (ETDEWEB)

    Zapata, Luis E.


    The average power output of a laser is scaled, to first order, by increasing the transverse dimension of the gain medium while increasing the thickness of an index matched light guide proportionately. Strategic facets cut at the edges of the laminated gain medium provide a method by which the pump light introduced through edges of the composite structure is trapped and passes through the gain medium repeatedly. Spontaneous emission escapes the laser volume via these facets. A multi-faceted disk geometry with grooves cut into the thickness of the gain medium is optimized to passively reject spontaneous emission generated within the laser material, which would otherwise be trapped and amplified within the high index composite disk. Such geometry allows the useful size of the laser aperture to be increased, enabling the average laser output power to be scaled.

  20. Solid State Raman Materials Characterization for High Average Power 1.3 micrometer Laser Frequency Shift (United States)


    reflectivity at 1067 rim wavelength. Solid state phototrop filter based on gallium -scandium- gadolinium garnet doped with chromium was used as a passive Q-switch... gadolinium tungstate, KGd(W0 4)2 exhibited efficient Raman properties . In spite of the fact that its Raman gain coefficient at 1064 nm (6 cm/GW) is twice less...studied by high- temperature Raman scattering (HTRS) technique. According to [1], the lattice cell of KGd(W04) 2 low - temperature modification is a base

  1. Method for optical pumping of thin laser media at high average power

    Energy Technology Data Exchange (ETDEWEB)

    Zapata, Luis E. (Livermore, CA); Beach, Raymond J. (Livermore, CA); Honea, Eric C. (Sunol, CA); Payne, Stephen A. (Castro Valley, CA)


    A thin, planar laser material is bonded to a light guide of an index-matched material forming a composite disk. Diode array or other pump light is introduced into the composite disk through the edges of the disk. Pump light trapped within the composite disk depletes as it multi-passes the laser medium before reaching an opposing edge of the disk. The resulting compound optical structure efficiently delivers concentrated pump light and to a laser medium of minimum thickness. The external face of the laser medium is used for cooling. A high performance cooler attached to the external face of the laser medium rejects heat. Laser beam extraction is parallel to the heat flux to minimize optical distortions.

  2. TECATE - a code for anisotropic thermoelasticity in high-average-power laser technology. Phase 1 final report

    Energy Technology Data Exchange (ETDEWEB)

    Gelinas, R.J.; Doss, S.K.; Carlson, N.N.


    This report describes a totally Eulerian code for anisotropic thermoelasticity (code name TECATE) which may be used in evaluations of prospective crystal media for high-average-power lasers. The present TECATE code version computes steady-state distributions of material temperatures, stresses, strains, and displacement fields in 2-D slab geometry. Numerous heat source and coolant boundary condition options are available in the TECATE code for laser design considerations. Anisotropic analogues of plane stress and plane strain evaluations can be executed for any and all crystal symmetry classes. As with all new and/or large physics codes, it is likely that some code imperfections will emerge at some point in time.

  3. Plasma wakefield excitation by incoherent laser pulses: a path towards high-average power laser-plasma accelerators

    CERN Document Server

    Benedetti, C; Esarey, E; Leemans, W P


    In a laser plasma accelerator (LPA), a short and intense laser pulse propagating in a plasma drives a wakefield (a plasma wave with a relativistic phase velocity) that can sustain extremely large electric fields, enabling compact accelerating structures. Potential LPA applications include compact radiation sources and high energy linear colliders. We propose and study plasma wave excitation by an incoherent combination of a large number of low energy laser pulses (i.e., without constraining the pulse phases). We show that, in spite of the incoherent nature of electromagnetic fields within the volume occupied by the pulses, the excited wakefield is regular and its amplitude is comparable or equal to that obtained using a single, coherent pulse with the same energy. These results provide a path to the next generation of LPA-based applications, where incoherently combined multiple pulses may enable high repetition rate, high average power LPAs.

  4. Process optimization in high-average-power ultrashort pulse laser microfabrication: how laser process parameters influence efficiency, throughput and quality (United States)

    Schille, Joerg; Schneider, Lutz; Loeschner, Udo


    In this paper, laser processing of technical grade stainless steel and copper using high-average-power ultrashort pulse lasers is studied in order to gain deeper insight into material removal for microfabrication. A high-pulse repetition frequency picosecond and femtosecond laser is used in conjunction with high-performance galvanometer scanners and an in-house developed two-axis polygon scanner system. By varying the processing parameters such as wavelength, pulse length, fluence and repetition rate, cavities of standardized geometry are fabricated and analyzed. From the depths of the cavities produced, the ablation rate and removal efficiency are estimated. In addition, the quality of the cavities is evaluated by means of scanning electron microscope micrographs or rather surface roughness measurements. From the results obtained, the influence of the machining parameters on material removal and machining quality is discussed. In addition, it is shown that both material removal rate and quality increase by using femtosecond compared to picosecond laser pulses. On stainless steel, a maximum throughput of 6.81 mm3/min is achieved with 32 W femtosecond laser powers; if using 187 W picosecond laser powers, the maximum is 15.04 mm3/min, respectively. On copper, the maximum throughputs are 6.1 mm3/min and 21.4 mm3/min, obtained with 32 W femtosecond and 187 W picosecond laser powers. The findings indicate that ultrashort pulses in the mid-fluence regime yield most efficient material removal. In conclusion, from the results of this analysis, a range of optimum processing parameters are derived feasible to enhance machining efficiency, throughput and quality in high-rate micromachining. The work carried out here clearly opens the way to significant industrial applications.

  5. Status of the High Average Power Diode-Pumped Solid State Laser Development at HiLASE

    Directory of Open Access Journals (Sweden)

    Ondřej Novák


    Full Text Available An overview of the latest developments of kilowatt-level diode pumped solid state lasers for advanced applications at the HiLASE Centre is presented. An overview of subcontracted and in-house-developed laser beamlines is presented. The aim of development is to build kW-class beamlines delivering picosecond pulses between 1- and 100-kHz repetition rates and high-energy nanosecond pulses at 10 Hz. The picosecond beamlines are based on Yb:YAG thin-disk amplifiers and chirped pulse amplification. The current status of the beamlines’ performance is reported. The advantages of zero-phonon line and pulsed pumping are demonstrated with respect to efficiency, thin disk temperature and beam quality. New diagnostics methods supporting the high average power lasers’ development, such as the high-resolution spectroscopy of Yb-doped materials, in situ thin disk deformation measurements, single-shot M2 measurement, realization of wavefront correction by a deformable mirror and the laser performance of a new mixed garnet ceramics, are described. The energetic, thermal and fluid-mechanical numerical modeling for the optimization of the multi-slab amplifiers is also described.

  6. Performance study of highly efficient 520 W average power long pulse ceramic Nd:YAG rod laser (United States)

    Choubey, Ambar; Vishwakarma, S. C.; Ali, Sabir; Jain, R. K.; Upadhyaya, B. N.; Oak, S. M.


    We report the performance study of a 2% atomic doped ceramic Nd:YAG rod for long pulse laser operation in the millisecond regime with pulse duration in the range of 0.5-20 ms. A maximum average output power of 520 W with 180 J maximum pulse energy has been achieved with a slope efficiency of 5.4% using a dual rod configuration, which is the highest for typical lamp pumped ceramic Nd:YAG lasers. The laser output characteristics of the ceramic Nd:YAG rod were revealed to be nearly equivalent or superior to those of high-quality single crystal Nd:YAG rod. The laser pump chamber and resonator were designed and optimized to achieve a high efficiency and good beam quality with a beam parameter product of 16 mm mrad (M2˜47). The laser output beam was efficiently coupled through a 400 μm core diameter optical fiber with 90% overall transmission efficiency. This ceramic Nd:YAG laser will be useful for various material processing applications in industry.

  7. High-average-power 2 μm few-cycle optical parametric chirped pulse amplifier at 100 kHz repetition rate. (United States)

    Shamir, Yariv; Rothhardt, Jan; Hädrich, Steffen; Demmler, Stefan; Tschernajew, Maxim; Limpert, Jens; Tünnermann, Andreas


    Sources of long wavelengths few-cycle high repetition rate pulses are becoming increasingly important for a plethora of applications, e.g., in high-field physics. Here, we report on the realization of a tunable optical parametric chirped pulse amplifier at 100 kHz repetition rate. At a central wavelength of 2 μm, the system delivered 33 fs pulses and a 6 W average power corresponding to 60 μJ pulse energy with gigawatt-level peak powers. Idler absorption and its crystal heating is experimentally investigated for a BBO. Strategies for further power scaling to several tens of watts of average power are discussed.

  8. High-Throughput Laser Peening of Metals Using a High-Average-Power Nd: Glass Laser System

    Energy Technology Data Exchange (ETDEWEB)

    Dane, C.B.; Hackel, L.A.; Halpin, J.; Daly, J.; Harrisson, J.; Harris, J.


    Laser shot peening, a surface treatment for metals, is known to induce residual compressive stresses to depths of over 1 mm providing improved component resistance to various forms of failure. Recent information also suggests that thermal relaxation of the laser induced stress is significantly less than that experienced by other forms of surface stressing that involve significantly higher levels of cold work. We have developed a unique solid state laser technology employing Nd:glass amplifier slabs and SBS phase conjugation that enables this process to move into high throughput production processing.

  9. Computations of longitudinal electron dynamics in the recirculating cw RF accelerator-recuperator for the high average power FEL (United States)

    Sokolov, A. S.; Vinokurov, N. A.


    The use of optimal longitudinal phase-energy motion conditions for bunched electrons in a recirculating RF accelerator gives the possibility to increase the final electron peak current and, correspondingly, the FEL gain. The computer code RECFEL, developed for simulations of the longitudinal compression of electron bunches with high average current, essentially loading the cw RF cavities of the recirculator-recuperator, is briefly described and illustrated by some computational results.

  10. High average power 1314 nm Nd:YLF laser, passively Q-switched with V:YAG

    CSIR Research Space (South Africa)

    Botha, RC


    Full Text Available Stellenbosch University, P/Bag X1, Matieland 7602, South Africa 3National Laser Centre, Council for Scientific and Industrial Research, P.O. Box 395, Pretoria 0001, South Africa 4Physics Department, Carl von Ossietzky University, Oldenburg 26111, Germany 5...-shifted to the 1.5 μm region, which is useful for applications requiring eye-safe operation at high powers, such as Lidar and free-space optical com- munication [1]. Furthermore, 1314.0 nm (specifically the 657.0 nm harmonic) is required to probe the relevant...

  11. Spatial models for probabilistic prediction of wind power with application to annual-average and high temporal resolution data

    DEFF Research Database (Denmark)

    Lenzi, Amanda; Pinson, Pierre; Clemmensen, Line Katrine Harder;


    Producing accurate spatial predictions for wind power generation together with a quantification of uncertainties is required to plan and design optimal networks of wind farms. Toward this aim, we propose spatial models for predicting wind power generation at two different time scales: for annual...... that our method makes it possible to obtain fast and accurate predictions from posterior marginals for wind power generation. The proposed method is applicable in scientific areas as diverse as climatology, environmental sciences, earth sciences and epidemiology....

  12. Development of laser diode-pumped high average power solid-state laser for the pumping of Ti:sapphire CPA system

    Energy Technology Data Exchange (ETDEWEB)

    Maruyama, Yoichiro; Tei, Kazuyoku; Kato, Masaaki; Niwa, Yoshito; Harayama, Sayaka; Oba, Masaki; Matoba, Tohru; Arisawa, Takashi; Takuma, Hiroshi [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment


    Laser diode pumped all solid state, high repetition frequency (PRF) and high energy Nd:YAG laser using zigzag slab crystals has been developed for the pumping source of Ti:sapphire CPA system. The pumping laser installs two main amplifiers which compose ring type amplifier configuration. The maximum amplification gain of the amplifier system is 140 and the condition of saturated amplification is achieved with this high gain. The average power of fundamental laser radiation is 250 W at the PRF of 200 Hz and the pulse duration is around 20 ns. The average power of second harmonic is 105 W at the PRF of 170 Hz and the pulse duration is about 16 ns. The beam profile of the second harmonic is near top hat and will be suitable for the pumping of Ti:sapphire laser crystal. The wall plug efficiency of the laser is 2.0 %. (author)

  13. Investigation on repetition rate and pulse duration influences on ablation efficiency of metals using a high average power Yb-doped ultrafast laser

    Directory of Open Access Journals (Sweden)

    Lopez J.


    Full Text Available Ultrafast lasers provide an outstanding processing quality but their main drawback is the low removal rate per pulse compared to longer pulses. This limitation could be overcome by increasing both average power and repetition rate. In this paper, we report on the influence of high repetition rate and pulse duration on both ablation efficiency and processing quality on metals. All trials have been performed with a single tunable ultrafast laser (350 fs to 10ps.

  14. Terbium gallium garnet ceramic-based Faraday isolator with compensation of thermally induced depolarization for high-energy pulsed lasers with kilowatt average power (United States)

    Yasuhara, Ryo; Snetkov, Ilya; Starobor, Alexey; Palashov, Oleg


    A scalable aperture Faraday isolator for high-energy pulsed lasers with kW-level average power was demonstrated using terbium gallium garnet ceramics with water cooling and compensation of thermally induced depolarization in a magnetic field. An isolation ratio of 35 dB (depolarization ratio γ of 3.4 × 10-4) was experimentally observed at a maximum laser power of 740 W. By using this result, we estimated that this isolator maintains an isolation ratio of 30 dB for laser powers of up to 2.7 kW. Our results provide the solution for achieving optical isolation in high-energy (100 J to kJ) laser systems with a repetition rate greater than 10 Hz.

  15. Development of a kilowatt-class, joule-level ultrafast laser for driving compact high average power coherent EUV/soft x-ray sources (United States)

    Reagan, Brendan A.; Baumgarten, Cory M.; Pedicone, Michael A.; Bravo, Herman; Yin, Liang; Woolston, Mark; Wang, Hanchen; Menoni, Carmen S.; Rocca, Jorge J.


    Our recent progress in the development of high energy / high average power, chirped pulse amplification laser systems based on diode-pumped, cryogenically-cooled Yb:YAG amplifiers is discussed, including the demonstration of a laser that produces 1 Joule, sub-10 picosecond duration, λ = 1.03μm pulses at 500 Hz repetition rate. This compact, all-diodepumped laser combines a mode-locked Yb:KYW oscillator and a water-cooled Yb:YAG preamplifer with two cryogenic power amplification stages to produce 1.5 Joule pulses with high beam quality which are subsequently compressed. This laser system occupies an optical table area of less than 1.5x3m2. This laser was employed to pump plasma-based soft x-ray lasers at λ = 10-20nm at repetition rates >=100 Hz. To accomplish this, temporally-shaped pulses were focused at grazing incidence into a high aspect ratio line focus using cylindrical optics on a high shot capacity rotating metal target. This results in an elongated plasma amplifier that produces microjoule pulses at several narrow-linewidth EUV wavelengths between λ = 109Å and 189Å. The resulting fraction of a milliwatt average powers are the highest reported to date for a compact, coherent source operating at these wavelengths, to the best of our knowledge.

  16. Residual thermal stress of a mounted KDP crystal after cooling and its effects on second harmonic generation of a high-average-power laser (United States)

    Su, Ruifeng; Liu, Haitao; Liang, Yingchun; Yu, Fuli


    Thermal problems are huge challenges for solid state lasers that are interested in high output power, cooling of the nonlinear optics is insufficient to completely solve the problem of thermally induced stress, as residual thermal stress remains after cooling, which is first proposed, to the best of our knowledge. In this paper a comprehensive model incorporating principles of thermodynamics, mechanics and optics is proposed, and it is used to study the residual thermal stress of a mounted KDP crystal after cooling process from mechanical perspective, along with the effects of the residual thermal stress on the second harmonic generation (SHG) efficiency of a high-average-power laser. Effects of the structural parameters of the mounting configuration of the KDP crystal on the residual thermal stress are characterized, as well as the SHG efficiency. The numerical results demonstrate the feasibility of solving the problems of residual thermal stress from the perspective on structural design of mounting configuration.

  17. All-fiber high-average power nanosecond-pulsed master-oscillator power amplifier at 2  μm with mJ-level pulse energy. (United States)

    Wang, Xiong; Jin, Xiaoxi; Zhou, Pu; Wang, Xiaolin; Xiao, Hu; Liu, Zejin


    We present a high-power nanosecond-pulsed Tm-doped fiber amplifier at 1.971 μm based on a master-oscillator power amplifier (MOPA) configuration. When the repetition rate is 500 kHz and the pulse width is 63.3 ns, the average power reaches 238 W, the peak power reaches 7.06 kW, and the pulse energy is 0.477 mJ. When the pulse train's repetition rate is 300 kHz with a pulse width of 63.7 ns, the average power reaches 197 W, the peak power reaches 9.73 kW, and the pulse energy is 0.66 mJ. When the pulse train's repetition rate is 200 kHz with a pulse width of 58.2 ns, the average power reaches 150 W, the peak power reaches 12.1 kW, and the pulse energy is 0.749 mJ. The spectral linewidths of the pulse trains are 0.15, 0.14, and 0.10 nm for 500 kHz repetition rate, 300 kHz repetition rate, and 200 kHz repetition rate, respectively. To the best of our knowledge, this is the first demonstration of high-power nanosecond-pulsed MOPA at 2 μm with the maximum average power reaching 238 W, the maximum peak power reaching 12.1 kW, and the maximum pulse energy reaching 0.749 mJ.


    Energy Technology Data Exchange (ETDEWEB)

    Jordan, Kevin; Allison, Trent; Evans, Richard; Coleman, James; Grippo, Albert


    A fully integrated Machine Protection System (MPS) is critical to efficient commissioning and safe operation of all high current accelerators. The Jefferson Lab FEL [1,2] has multiple electron beam paths and many different types of diagnostic insertion devices. The MPS [3] needs to monitor both the status of these devices and the magnet settings which define the beam path. The matrix of these devices and beam paths are programmed into gate arrays, the output of the matrix is an allowable maximum average power limit. This power limit is enforced by the drive laser for the photocathode gun. The Beam Loss Monitors (BLMs), RF status, and laser safety system status are also inputs to the control matrix. There are 8 Machine Modes (electron path) and 8 Beam Modes (average power limits) that define the safe operating limits for the FEL. Combinations outside of this matrix are unsafe and the beam is inhibited. The power limits range from no beam to 2 megawatts of electron beam power.

  19. Performance of MgO:PPLN, KTA, and KNbO₃ for mid-wave infrared broadband parametric amplification at high average power. (United States)

    Baudisch, M; Hemmer, M; Pires, H; Biegert, J


    The performance of potassium niobate (KNbO₃), MgO-doped periodically poled lithium niobate (MgO:PPLN), and potassium titanyl arsenate (KTA) were experimentally compared for broadband mid-wave infrared parametric amplification at a high repetition rate. The seed pulses, with an energy of 6.5 μJ, were amplified using 410 μJ pump energy at 1064 nm to a maximum pulse energy of 28.9 μJ at 3 μm wavelength and at a 160 kHz repetition rate in MgO:PPLN while supporting a transform limited duration of 73 fs. The high average powers of the interacting beams used in this study revealed average power-induced processes that limit the scaling of optical parametric amplification in MgO:PPLN; the pump peak intensity was limited to 3.8  GW/cm² due to nonpermanent beam reshaping, whereas in KNbO₃ an absorption-induced temperature gradient in the crystal led to permanent internal distortions in the crystal structure when operated above a pump peak intensity of 14.4  GW/cm².

  20. Power Efficiency Improvements through Peak-to-Average Power Ratio Reduction and Power Amplifier Linearization

    Directory of Open Access Journals (Sweden)

    Zhou G Tong


    Full Text Available Many modern communication signal formats, such as orthogonal frequency-division multiplexing (OFDM and code-division multiple access (CDMA, have high peak-to-average power ratios (PARs. A signal with a high PAR not only is vulnerable in the presence of nonlinear components such as power amplifiers (PAs, but also leads to low transmission power efficiency. Selected mapping (SLM and clipping are well-known PAR reduction techniques. We propose to combine SLM with threshold clipping and digital baseband predistortion to improve the overall efficiency of the transmission system. Testbed experiments demonstrate the effectiveness of the proposed approach.

  1. High-average power THG of a diode-pumped Nd:YAG laser at 355 nm generated by LiB3O5 crystal

    Institute of Scientific and Technical Information of China (English)

    Yong Bi(毕勇); Yan Feng(冯衍); Huarong Gong(巩华荣); Hongbo Zhang(张鸿博); Zuyan Xu(许祖彦)


    More than 6 W average power ultraviolet radiation at 355 nm was generated in LiB3O5 (LBO) crystalthrough the frequency mixing of the fundamental and second harmonic radiation of a Nd:YAG laser. Thisperformance was achieved with 38% optical-to-optical conversion efficiency (532 nm to 355 nm).

  2. Plasma wakefields driven by an incoherent combination of laser pulses: a path towards high-average power laser-plasma accelerators

    Energy Technology Data Exchange (ETDEWEB)

    Benedetti, C.; Schroeder, C.B.; Esarey, E.; Leemans, W.P.


    he wakefield generated in a plasma by incoherently combining a large number of low energy laser pulses (i.e.,without constraining the pulse phases) is studied analytically and by means of fully-self-consistent particle-in-cell simulations. The structure of the wakefield has been characterized and its amplitude compared with the amplitude of the wake generated by a single (coherent) laser pulse. We show that, in spite of the incoherent nature of the wakefield within the volume occupied by the laser pulses, behind this region the structure of the wakefield can be regular with an amplitude comparable or equal to that obtained from a single pulse with the same energy. Wake generation requires that the incoherent structure in the laser energy density produced by the combined pulses exists on a time scale short compared to the plasma period. Incoherent combination of multiple laser pulses may enable a technologically simpler path to high-repetition rate, high-average power laser-plasma accelerators and associated applications.

  3. Optimization of X-ray sources from a high-average-power ND:Glass laser-produced plasma for proximity lithography

    Energy Technology Data Exchange (ETDEWEB)

    Celliers, P.; Da Silva, L.B.; Dane, C.B. [and others


    The concept of a laser-based proximity lithography system for electronic microcircuit production has advanced to the point where a detailed design of a prototype system capable of exposing wafers at 40 wafer levels per hr is technically feasible with high-average-power laser technology. In proximity x-ray lithography, a photoresist composed of polymethyl- methacrylate (PMMA) or similar material is exposed to x rays transmitted through a mask placed near the photoresist, a procedure which is similar to making a photographic contact print. The mask contains a pattern of opaque metal features, with line widths as small as 0.12 {mu}m, placed on a thin (1-{mu}m thick) Si membrane. During the exposure, the shadow of the mask projected onto the resist produces in the physical and chemical properties of the resist a pattern of variation with the same size and shape as the features contained in the metal mask. This pattern can be further processed to produce microscopic structures in the Si substrate. The main application envisioned for this technology is the production of electronic microcircuits with spatial features significantly smaller than currently achievable with conventional optical lithographic techniques (0.12 {micro}m vs 0.25 {micro}m). This article describes work on optimizing a laser-produced plasma x-ray source intended for microcircuit production by proximity lithography.

  4. Optimization of x-ray sources for proximity lithography produced by a high average power Nd:glass laser{sup a}

    Energy Technology Data Exchange (ETDEWEB)

    Celliers, P.; Da Silva, L.B.; Dane, C.B.; Mrowka, S.; Norton, M.; Harder, J.; Hackel, L.; Matthews, D.L. [Lawrence Livermore National Laboratory, University of California, Livermore, California 94550 (United States); Fiedorowicz, H.; Bartnik, A. [Laser Plasma Interaction Section, Military University of Technology, Institute of Optoelectronics, 01-489 Warsaw 49 (Poland); Maldonado, J.R. [IBM Microelectronics, Hopewell Junction, New York 12533 (United States); Abate, J.A. [AT& T Bell Laboratories, Murray Hill, New Jersey 07974 (United States)


    We measured the conversion efficiency of laser pulse energy into keV x rays from a variety of solid planar targets and a Xe gas puff target irradiated using a high average power Nd:glass slab laser capable of delivering 13 ns full width at half-maximum pulses at up to 20 J at 1.053 {mu}m and 12 J at 0.53 {mu}m. Targets were chosen to optimize emission in the 10{endash}15 A wavelength band, including {ital L}-shell emission from materials with atomic numbers in the range {ital Z}=24{endash}30 and {ital M}-shell emission from Xe ({ital Z}=54). With 1.053 {mu}m a maximum conversion of 11{percent} into 2{pi} sr was measured from solid Xe targets. At 0.527 {mu}m efficiencies of 12{percent}{endash}18{percent}/(2{pi} sr) were measured for all of the solid targets in the same wavelength band. The x-ray conversion efficiency from the Xe gas puff target was considerably lower, at about 3{percent}/(2{pi} sr) when irradiated with 1.053 {mu}m. {copyright} {ital 1996 American Institute of Physics.}

  5. Diode-pumped continuous-wave and femtosecond Cr:LiCAF lasers with high average power in the near infrared, visible and near ultraviolet


    Demirbas, Umit; Baali, Ilyes; Acar, Durmus Alp Emre; Leitenstorfer, Alfred


    We demonstrate continuous-wave (cw), cw frequency-doubled, cw mode-locked and Q-switched mode-locked operation of multimode diode-pumped Cr:LiCAF lasers with record average powers. Up to 2.54 W of cw output is obtained around 805 nm at an absorbed pump power of 5.5 W. Using intracavity frequency doubling with a BBO crystal, 0.9 W are generated around 402 nm, corresponding to an optical-to-optical conversion efficiency of 12%. With an intracavity birefringent tuning plate, the fundamental and ...

  6. Diode-pumped continuous-wave and femtosecond Cr:LiCAF lasers with high average power in the near infrared, visible and near ultraviolet. (United States)

    Demirbas, Umit; Baali, Ilyes; Acar, Durmus Alp Emre; Leitenstorfer, Alfred


    We demonstrate continuous-wave (cw), cw frequency-doubled, cw mode-locked and Q-switched mode-locked operation of multimode diode-pumped Cr:LiCAF lasers with record average powers. Up to 2.54 W of cw output is obtained around 805 nm at an absorbed pump power of 5.5 W. Using intracavity frequency doubling with a BBO crystal, 0.9 W are generated around 402 nm, corresponding to an optical-to-optical conversion efficiency of 12%. With an intracavity birefringent tuning plate, the fundamental and frequency-doubled laser output is tuned continuously in a broad wavelength range from 745 nm to 885 nm and from 375 to 440 nm, respectively. A saturable Bragg reflector is used to initiate and sustain mode locking. In the cw mode-locked regime, the Cr:LiCAF laser produces 105-fs long pulses near 810 nm with an average power of 0.75 W. The repetition rate is 96.4 MHz, resulting in pulse energies of 7.7 nJ and peak powers of 65 kW. In Q-switched mode-locked operation, pulses with energies above 150 nJ are generated.

  7. Scalability of components for kW-level average power few-cycle lasers. (United States)

    Hädrich, Steffen; Rothhardt, Jan; Demmler, Stefan; Tschernajew, Maxim; Hoffmann, Armin; Krebs, Manuel; Liem, Andreas; de Vries, Oliver; Plötner, Marco; Fabian, Simone; Schreiber, Thomas; Limpert, Jens; Tünnermann, Andreas


    In this paper, the average power scalability of components that can be used for intense few-cycle lasers based on nonlinear compression of modern femtosecond solid-state lasers is investigated. The key components of such a setup, namely, the gas-filled waveguides, laser windows, chirped mirrors for pulse compression and low dispersion mirrors for beam collimation, focusing, and beam steering are tested under high-average-power operation using a kilowatt cw laser. We demonstrate the long-term stable transmission of kW-level average power through a hollow capillary and a Kagome-type photonic crystal fiber. In addition, we show that sapphire substrates significantly improve the average power capability of metal-coated mirrors. Ultimately, ultrabroadband dielectric mirrors show negligible heating up to 1 kW of average power. In summary, a technology for scaling of few-cycle lasers up to 1 kW of average power and beyond is presented.

  8. Energy and average power scalable optical parametric chirped-pulse amplification in yttrium calcium oxyborate. (United States)

    Liao, Zhi M; Jovanovic, Igor; Ebbers, Chris A; Fei, Yiting; Chai, Bruce


    Optical parametric chirped-pulse amplification (OPCPA) in nonlinear crystals has the potential to produce extremes of peak and average power but is limited either in energy by crystal growth issues or in average power by crystal thermo-optic characteristics. Recently, large (7.5 cm diameter x 25 cm length) crystals of yttrium calcium oxyborate (YCOB) have been grown and utilized for high-average-power second-harmonic generation. Further, YCOB has the necessary thermo-optic properties required for scaling OPCPA systems to high peak and average power operation for wavelengths near 1 microm. We report what is believed to be the first use of YCOB for OPCPA. Scalability to higher peak and average power is addressed.

  9. Power Allocation for Fading Channels with Peak-to-Average Power Constraints

    CERN Document Server

    Nguyen, Khoa D; Rasmussen, Lars K


    Power allocation with peak-to-average power ratio constraints is investigated for transmission over Nakagami-m fading channels with arbitrary input distributions. In the case of delay-limited block-fading channels, we find the solution to the minimum outage power allocation scheme with peak-to-average power constraints and arbitrary input distributions, and show that the signal-to-noise ratio exponent for any finite peak-to-average power ratio is the same as that of the peak-power limited problem, resulting in an error floor. In the case of the ergodic fully-interleaved channel, we find the power allocation rule that yields the maximal information rate for an arbitrary input distribution and show that capacities with peak-to-average power ratio constraints, even for small ratios, are very close to capacities without peak-power restrictions.

  10. High Brightness, High Average Current Injector Development at Cornell

    CERN Document Server

    Sinclair, C K


    Cornell University is constructing a 100 mA average current, high brightness electron injector for a planned Energy Recovery Linac (ERL) hard X-ray synchrotron radiation source. This injector will employ a very high voltage DC gun with a negative electron affinity photoemission cathode. Relatively long duration electron pulses from the photocathode will be drift bunched, and accelerated to 5-15 MeV with five two-cell, 1300 MHz superconducting cavities. The total beam power will be limited to 575 kW by the DC and RF power sources. A genetic algorithm based computational optimization of this injector has resulted in simulated rms normalized emittances of 0.1 mm-mrad at 80 pC/bunch, and 0.7 mm-mrad at 1 nC/bunch. The many technical issues and their design solutions will be discussed. Construction of the gun and the SRF cavities is well underway. The schedule for completion, and the planned measurements, will be presented.

  11. Longitudinal temperature distribution in an end-pumped solid-state amplifier medium: application to a high average power diode pumped Yb:YAG thin disk amplifier. (United States)

    Bourdet, Gilbert L; Yu, Haiwu


    We propose a simple analytical derivation making it possible to compute a one-dimensional temperature variation in an end-pumped solid-state laser. This derivation takes into account the pump intensity variation along the crystal, the doping concentration, and temperature dependence of the thermal conductivity. We then compare this simulation with the one usually used, which does not take into account any of these dependences. The results show that, at room temperature, the two methods are in good agreement, but at a cryogenic temperature where the thermal conductivity varies fast with temperature, a large discrepancy is found, and the conventional computations underestimate both the average temperature and the longitudinal gradient.

  12. Diffusion Bonded KTiOPO4 Crystal for the Second Harmonic Generation of High Average Power Zigzag Slab Nd:YAG Laser (United States)

    Tei, Kazuyoku; Kato, Masaaki; Matsuoka, Fumiaki; Niwa, Yosito; Maruyama, Yoichiro; Matoba, Tohru; Arisawa, Takasi


    For the second harmonic generation (SHG) of a high-repetition rate and high pulse energy zigzag slab Nd:YAG laser, the direct bonding of two KTiPO4 (KTP) crystals is carried out and their characteristics are studied using the zigzag slab laser that produces 2.1 J energy pulses with a beam having a rectangular cross section at a pulse repetition rate of 100 Hz. Although an angle mismatch of four minutes between two tuning curves is observed for the bonded crystals, the energy conversion efficiency is the same as that of a single KTP crystal. The second harmonic produced is 1 J.

  13. Capacity Achieving Modulation for Fixed Constellations with Average Power Constraint

    CERN Document Server

    Bocherer, Georg; Mathar, Rudolf


    The capacity achieving probability mass function (PMF) of a finite signal constellation with an average power constraint is in most cases non-uniform. A common approach to generate non-uniform input PMFs is Huffman shaping, which consists of first approximating the capacity achieving PMF by a sampled Gaussian density and then to calculate the Huffman code of the sampled Gaussian density. The Huffman code is then used as a prefix-free modulation code. This approach showed good results in practice, can however lead to a significant gap to capacity. In this work, a method is proposed that efficiently constructs optimal prefix-free modulation codes for any finite signal constellation with average power constraint in additive noise. The proposed codes operate as close to capacity as desired. The major part of this work elaborates an analytical proof of this property. The proposed method is applied to 64-QAM in AWGN and numeric results are given, which show that, opposed to Huffman shaping, by using the proposed me...

  14. A New Type S-band High-average-power Broadband Klystron%一种新型S波段高平均功率宽带速调管

    Institute of Scientific and Technical Information of China (English)

    张兆传; 沈宝丽; 于晓娟; 张峰; 黄云平


    This paper presents the design considerations, the simulation results and the test results for a new type S-band high-average-power broadband klystron. In this paper, a method which is used for verifying the quality of an electron-optics-system of a high-average-power broadband klystron is proposed. And then the coordinate method using the 2.5D Arsenal-MSN code and the KLY6 code is also described, which deals with eliminating the potential output-power-sag and optimizing the parameters of the RF-interaction region for broadband klystrons. The further hot-test results prove that both of the methods are effective.%该文介绍了一种新型S波段高平均功率宽带速调管的主要设计思想、模拟计算结果和实验结果.文中提出了具有理想高频通过率的高平均功率宽带速调管电子光学系统的验证方法,以及联合使用2.5D Arsenal-MSN code和KLY6两种软件去除带内功率凹点和改善高频性能的方法.最终的实验测试结果表明,这些方法是有效的.

  15. FY2005 Progress Summary and FY2006 Program Plan Statement of Work and Deliverables for Development of High Average Power Diode-Pumped Solid State Lasers, and Complementary Technologies, for Applications in Energy and Defense

    Energy Technology Data Exchange (ETDEWEB)

    Ebbers, C


    The primary focus this year was to operate the system with two amplifiers populated with and pumped by eight high power diode arrays. The system was operated for extended run periods which enabled average power testing of components, diagnostics, and controls. These tests were highly successful, with a demonstrated energy level of over 55 joules for 4 cumulative hours at a repetition rate of 10 Hz (average power 0.55 kW). In addition, high average power second harmonic generation was demonstrated, achieving 227 W of 523.5 nm light (22.7 J, 10 Hz, 15 ns, 30 minutes) Plans to achieve higher energy levels and average powers are in progress. The dual amplifier system utilizes a 4-pass optical arrangement. The Yb:S-FAP slabs were mounted in aerodynamic aluminum vane structures to allow turbulent helium gas flow across the faces. Diagnostic packages that monitored beam performance were deployed during operation. The laser experiments involved injecting a seed beam from the front end into the system and making four passes through both amplifiers. Beam performance diagnostics monitored the beam on each pass to assess system parameters such as gain and nearfield intensity profiles. This year, an active mirror and wavefront sensor were procured and demonstrated in an off-line facility. The active mirror technology can correct for low order phase distortions at user specified operating conditions (such as repetition rates different than 10 Hz) and is a complementary technology to the static phase plates used in the system for higher order distortions. A picture of the laser system with amplifier No.2 (foreground) and amplifier No.1 (background) is shown in Fig. The control system and diagnostics were recently enhanced for faster processing and allow remote operation of the system. The growth and fabrication of the Yb:S-FAP slabs constituted another major element of our program objectives. Our goal was to produce at least fourteen 4x6 cm2 crystalline slabs. These

  16. High repetition TEA CO2 laser with average output power of 3.3 kW%平均功率3.3kW高重复频率TEA CO2激光器

    Institute of Scientific and Technical Information of China (English)

    文康; 谭荣清; 张阔海; 刘世明; 朱玉峰; 徐程; 王东蕾; 卢远添; 赵志龙


    研制了一台平均功率3.3 kW横向激励大气压(TEA)CO2激光器.激光器采用单节放电体积为5 cm×4 cm×90 cm的两节腔体串连的形式,印刷板电路预电离结构和闸流管开关放电电路,实现了激光器单脉冲能量输出,高重复频率工作.在重复频率150 Hz条件下,获得了3.3 kW平均输出功率.获得32.8 J单脉冲输出能量,电光转换效率达到15.4%.%A high average power TEA CO2 laser has been developed. Average output power of 3.3 kW is achieved at a repetition of 150 Hz. The TEA CO2 laser consists of two same laser modules, each of which has a 5 cm x 4 cm× 90 cm discharge volume. Several special technologies including Printed Circuit Board (PCB) pre-ionization and thyratron switch discharging circuit are employed. The laser realized large energy output, high repetition operating and high average power output. Laser output pulse energy is measured. The relationship between laser pulse energy and voltage at different gas pressures is obtained. The maximum of output pulse energy is 32.8 J. Electro-optical efficiency is calculated and the maximum of electro-optical efficiency is 15.4%. The laser pulse waveforms are measured at different gas pressures.

  17. Spatial filters for high average power lasers (United States)

    Erlandson, Alvin C


    A spatial filter includes a first filter element and a second filter element overlapping with the first filter element. The first filter element includes a first pair of cylindrical lenses separated by a first distance. Each of the first pair of cylindrical lenses has a first focal length. The first filter element also includes a first slit filter positioned between the first pair of cylindrical lenses. The second filter element includes a second pair of cylindrical lenses separated by a second distance. Each of the second pair of cylindrical lenses has a second focal length. The second filter element also includes a second slit filter positioned between the second pair of cylindrical lenses.

  18. FY2002 Progress Summary Program Plan, Statement of Work and Deliverables for Development of High Average Power Diode-Pumped Solid State Lasers, and Complementary Technologies, for Applications in Energy and Defense

    Energy Technology Data Exchange (ETDEWEB)

    Bayramian, A; Bibeau, C; Beach, R; Behrendt, B; Ebbers, C; Latkowski, J; Meier, W; Payne, S; Perkins, J; Schaffers, K; Skulina, K; Ditmire, T; Kelly, J; Waxer, L; Rudi, P; Randles, M; Witter, D; Meissner, H; Merissner, O


    The High Average Power Laser Program (HAPL) is a multi-institutional, coordinated effort to develop a high-energy, repetitively pulsed laser system for Inertial Fusion Energy and other DOE and DOD applications. This program is building a laser-fusion energy base to complement the laser-fusion science developed by DOE Defense programs over the past 25 years. The primary institutions responsible for overseeing and coordinating the research activities are the Naval Research Laboratory (NRL) and LLNL. The current LLNL proposal is a companion proposal to that submitted by NRL, for which the driver development element is focused on the krypton fluoride excimer laser option. Aside from the driver development aspect, the NRL and LLNL companion proposals pursue complementary activities with the associated rep-rated laser technologies relating to target fabrication, target injection, final optics, fusion chamber, materials and power plant economics. This report requests continued funding in FY02 to support LLNL in its program to build a 1kW, 100J, diode-pumped, crystalline laser. In addition, research in high gain laser target design, fusion chamber issues and survivability of the final optic element will be pursued. These technologies are crucial to the feasibility of inertial fusion energy power plants and also have relevance in rep-rated stewardship experiments.

  19. Optimizing average power in low quantum defect lasers. (United States)

    Bowman, S R


    Waste heat generation is a generic problem in high-power solid-state laser systems. One way to reduce heat loading while improving efficiency is to reduce the laser's quantum defect. This paper presents a simple analysis of low quantum defect laser materials. In these laser materials, the effects of fluorescent cooling and weak loss processes should not be ignored. Simple expressions are developed for efficiency and heating in a steady-state purely radiative material. These expressions are then extended to include weak losses and fluorescence reabsorption. Evaluation of these relations using ytterbium-doped YAG is used to illustrate several optimization schemes and the impact of realistic losses.

  20. Time Averaged Transmitter Power and Exposure to Electromagnetic Fields from Mobile Phone Base Stations

    Directory of Open Access Journals (Sweden)

    Alfred Bürgi


    Full Text Available Models for exposure assessment of high frequency electromagnetic fields from mobile phone base stations need the technical data of the base stations as input. One of these parameters, the Equivalent Radiated Power (ERP, is a time-varying quantity, depending on communication traffic. In order to determine temporal averages of the exposure, corresponding averages of the ERP have to be available. These can be determined as duty factors, the ratios of the time-averaged power to the maximum output power according to the transmitter setting. We determine duty factors for UMTS from the data of 37 base stations in the Swisscom network. The UMTS base stations sample contains sites from different regions of Switzerland and also different site types (rural/suburban/urban/hotspot. Averaged over all regions and site types, a UMTS duty factor  for the 24 h-average is obtained, i.e., the average output power corresponds to about a third of the maximum power. We also give duty factors for GSM based on simple approximations and a lower limit for LTE estimated from the base load on the signalling channels.

  1. Time averaged transmitter power and exposure to electromagnetic fields from mobile phone base stations. (United States)

    Bürgi, Alfred; Scanferla, Damiano; Lehmann, Hugo


    Models for exposure assessment of high frequency electromagnetic fields from mobile phone base stations need the technical data of the base stations as input. One of these parameters, the Equivalent Radiated Power (ERP), is a time-varying quantity, depending on communication traffic. In order to determine temporal averages of the exposure, corresponding averages of the ERP have to be available. These can be determined as duty factors, the ratios of the time-averaged power to the maximum output power according to the transmitter setting. We determine duty factors for UMTS from the data of 37 base stations in the Swisscom network. The UMTS base stations sample contains sites from different regions of Switzerland and also different site types (rural/suburban/urban/hotspot). Averaged over all regions and site types, a UMTS duty factor for the 24 h-average is obtained, i.e., the average output power corresponds to about a third of the maximum power. We also give duty factors for GSM based on simple approximations and a lower limit for LTE estimated from the base load on the signalling channels.

  2. April 25, 2003, FY2003 Progress Summary and FY2002 Program Plan, Statement of Work and Deliverables for Development of High Average Power Diode-Pumped Solid State Lasers,and Complementary Technologies, for Applications in Energy and Defense

    Energy Technology Data Exchange (ETDEWEB)

    Meier, W; Bibeau, C


    The High Average Power Laser Program (HAPL) is a multi-institutional, synergistic effort to develop inertial fusion energy (IFE). This program is building a physics and technology base to complement the laser-fusion science being pursued by DOE Defense programs in support of Stockpile Stewardship. The primary institutions responsible for overseeing and coordinating the research activities are the Naval Research Laboratory (NRL) and Lawrence Livermore National Laboratory (LLNL). The current LLNL proposal is a companion document to the one submitted by NRL, for which the driver development element is focused on the krypton fluoride excimer laser option. The NRL and LLNL proposals also jointly pursue complementary activities with the associated rep-rated laser technologies relating to target fabrication, target injection, final optics, fusion chamber, target physics, materials and power plant economics. This proposal requests continued funding in FY03 to support LLNL in its program to build a 1 kW, 100 J, diode-pumped, crystalline laser, as well as research into high gain fusion target design, fusion chamber issues, and survivability of the final optic element. These technologies are crucial to the feasibility of inertial fusion energy power plants and also have relevance in rep-rated stewardship experiments. The HAPL Program pursues technologies needed for laser-driven IFE. System level considerations indicate that a rep-rated laser technology will be needed, operating at 5-10 Hz. Since a total energy of {approx}2 MJ will ultimately be required to achieve suitable target gain with direct drive targets, the architecture must be scaleable. The Mercury Laser is intended to offer such an architecture. Mercury is a solid state laser that incorporates diodes, crystals and gas cooling technologies.

  3. The effect of an aerobic training program on the electrical remodeling of the heart: high-frequency components of the signal-averaged electrocardiogram are predictors of the maximal aerobic power

    Directory of Open Access Journals (Sweden)

    M. Marocolo


    Full Text Available Increased heart rate variability (HRV and high-frequency content of the terminal region of the ventricular activation of signal-averaged ECG (SAECG have been reported in athletes. The present study investigates HRV and SAECG parameters as predictors of maximal aerobic power (VO2max in athletes. HRV, SAECG and VO2max were determined in 18 high-performance long-distance (25 ± 6 years; 17 males runners 24 h after a training session. Clinical visits, ECG and VO2max determination were scheduled for all athletes during thew training period. A group of 18 untrained healthy volunteers matched for age, gender, and body surface area was included as controls. SAECG was acquired in the resting supine position for 15 min and processed to extract average RR interval (Mean-RR and root mean squared standard deviation (RMSSD of the difference of two consecutive normal RR intervals. SAECG variables analyzed in the vector magnitude with 40-250 Hz band-pass bi-directional filtering were: total and 40-µV terminal (LAS40 duration of ventricular activation, RMS voltage of total (RMST and of the 40-ms terminal region of ventricular activation. Linear and multivariate stepwise logistic regressions oriented by inter-group comparisons were adjusted in significant variables in order to predict VO2max, with a P < 0.05 considered to be significant. VO2max correlated significantly (P < 0.05 with RMST (r = 0.77, Mean-RR (r = 0.62, RMSSD (r = 0.47, and LAS40 (r = -0.39. RMST was the independent predictor of VO2max. In athletes, HRV and high-frequency components of the SAECG correlate with VO2max and the high-frequency content of SAECG is an independent predictor of VO2max.

  4. Composite Thin-Disk Laser Scaleable to 100 kW Average Power Output and Beyond

    Energy Technology Data Exchange (ETDEWEB)

    Zapata, L.; Beach, R.; Payne, S.


    By combining newly developed technologies to engineer composite laser components with state of the art diode laser pump delivery technologies, we are in a position to demonstrate high beam quality, continuous wave, laser radiation at scaleable high average powers. The crucial issues of our composite thin disk laser technology were demonstrated during a successful first light effort. The high continuous wave power levels that are now within reach make this system of high interest to future DoD initiatives in solid-state laser technology for the laser weapon arena.

  5. Measurement of time averaged power in HITU fields—effects of duty cycle and target distance (United States)

    Jenderka, K.-V.; Wilkens, V.


    The reliable description of the ultrasonic fields of high-intensity therapeutic ultrasound (HITU) devices is a prerequisite concerning the safe application of the method in the daily clinical routine. Since ultrasonic sensors used for the characterization of diagnostic fields are at high risk of being damaged in the strong therapeutic fields, the measurements are carried out in burst mode to reduce the acting temporal-average intensities. For the thorough investigation of possible differences between the excitation in continuous wave (cw) and burst mode, the temporal-average total acoustic output powers of two types of HITU transducers with f-numbers of approximately 1 and with working frequencies between 1.1 MHz and 3.3 MHz were investigated by means of a radiation force balance. The maximum cw equivalent power level was 300 W the duty cycles varied between 1% and 90%. In addition, the possible effect of the transducer-target distance was investigated. It was found that the different turn-on and turn-off behaviour of the transducers caused variations of the effective duty cycle, depending on the power level and the power amplifier used. The temporal-average power declined with increasing distance as expected, and no focal anomaly was detected.

  6. Efficient nonlinear companding scheme for substantial reduction in peak-to-average power ratio of OFDM

    Institute of Scientific and Technical Information of China (English)

    Kasun Bandara,Atul Sewaiwar,; Yeon-Ho Chung


    Orthogonal frequency division multiplexing (OFDM) produces a high peak-to-average power ratio (PAPR) that ad-versely affects high-speed OFDM data transmission. In order to reduce the high PAPR, an efficient nonlinear companding trans-form (NCT) function is proposed. With the proposed NCT function, the compression and expansion weights can be applied indepen-dently with suitably chosen function parameter values. As a re-sult, the proposed function can easily maintain the average signal power approximately unchanged during the companding process. In this regard, the proposed function is superior to previously pro-posed schemes. Also, the simulations show the outstanding PAPR reduction performance of the proposed function. It is demonstrated that the proposed scheme performs wel with nonlinear transmitter amplifiers and delivers superior error performance, compared with error function and exponential function based schemes.

  7. Image registration and averaging of low laser power two-photon fluorescence images of mouse retina. (United States)

    Alexander, Nathan S; Palczewska, Grazyna; Stremplewski, Patrycjusz; Wojtkowski, Maciej; Kern, Timothy S; Palczewski, Krzysztof


    Two-photon fluorescence microscopy (TPM) is now being used routinely to image live cells for extended periods deep within tissues, including the retina and other structures within the eye . However, very low laser power is a requirement to obtain TPM images of the retina safely. Unfortunately, a reduction in laser power also reduces the signal-to-noise ratio of collected images, making it difficult to visualize structural details. Here, image registration and averaging methods applied to TPM images of the eye in living animals (without the need for auxiliary hardware) demonstrate the structural information obtained with laser power down to 1 mW. Image registration provided between 1.4% and 13.0% improvement in image quality compared to averaging images without registrations when using a high-fluorescence template, and between 0.2% and 12.0% when employing the average of collected images as the template. Also, a diminishing return on image quality when more images were used to obtain the averaged image is shown. This work provides a foundation for obtaining informative TPM images with laser powers of 1 mW, compared to previous levels for imaging mice ranging between 6.3 mW [Palczewska G., Nat Med.20, 785 (2014) Sharma R., Biomed. Opt. Express4, 1285 (2013)].

  8. 28W average power hydrocarbon-free rubidium diode pumped alkali laser. (United States)

    Zweiback, Jason; Krupke, William F


    We present experimental results for a high-power diode pumped hydrocarbon-free rubidium laser with a scalable architecture. The laser consists of a liquid cooled, copper waveguide which serves to both guide the pump light and to provide a thermally conductive surface near the gain volume to remove heat. A laser diode stack, with a linewidth narrowed to approximately 0.35 nm with volume bragg gratings, is used to pump the cell. We have achieved 24W average power output using 4 atmospheres of naturally occurring helium ((4)He) as the buffer gas and 28W using 2.8 atmospheres of (3)He.

  9. Energetic sub-2-cycle laser with 216  W average power. (United States)

    Hädrich, Steffen; Kienel, Marco; Müller, Michael; Klenke, Arno; Rothhardt, Jan; Klas, Robert; Gottschall, Thomas; Eidam, Tino; Drozdy, András; Jójárt, Péter; Várallyay, Zoltán; Cormier, Eric; Osvay, Károly; Tünnermann, Andreas; Limpert, Jens


    Few-cycle lasers are essential for many research areas such as attosecond physics that promise to address fundamental questions in science and technology. Therefore, further advancements are connected to significant progress in the underlying laser technology. Here, two-stage nonlinear compression of a 660 W femtosecond fiber laser system is utilized to achieve unprecedented average power levels of energetic ultrashort or even few-cycle laser pulses. In a first compression step, 408 W, 320 μJ, 30 fs pulses are achieved, which can be further compressed to 216 W, 170 μJ, 6.3 fs pulses in a second compression stage. To the best of our knowledge, this is the highest average power few-cycle laser system presented so far. It is expected to significantly advance the fields of high harmonic generation and attosecond science.

  10. Cesium telluride cathodes for the next generation of high-average current high-brightness photoinjectors

    Energy Technology Data Exchange (ETDEWEB)

    Filippetto, D., E-mail:; Qian, H.; Sannibale, F. [Lawrence Berkeley National Laboratory, One Cyclotron Road, Berkeley, California 94720 (United States)


    We report on the performances of a Cs{sub 2}Te photocathode under extreme conditions of high peak time-dependent accelerating fields, continuous wave operations, and MHz pulse extraction with up to 0.3 mA average current. The measurements, performed in a normal conducting cavity, show extended lifetime and robustness, elucidate the main mechanisms for cathode degradation, and set the required system vacuum performance for compatibility with the operations of a high average power X-ray free electron laser user facility, opening the doors to the next generation of MHz-scale ultrafast scientific instruments.

  11. 53 W average power few-cycle fiber laser system generating soft x rays up to the water window. (United States)

    Rothhardt, Jan; Hädrich, Steffen; Klenke, Arno; Demmler, Stefan; Hoffmann, Armin; Gotschall, Thomas; Eidam, Tino; Krebs, Manuel; Limpert, Jens; Tünnermann, Andreas


    We report on a few-cycle laser system delivering sub-8-fs pulses with 353 μJ pulse energy and 25 GW of peak power at up to 150 kHz repetition rate. The corresponding average output power is as high as 53 W, which represents the highest average power obtained from any few-cycle laser architecture so far. The combination of both high average and high peak power provides unique opportunities for applications. We demonstrate high harmonic generation up to the water window and record-high photon flux in the soft x-ray spectral region. This tabletop source of high-photon flux soft x rays will, for example, enable coherent diffractive imaging with sub-10-nm resolution in the near future.

  12. Peak-to-Average Power Ratio Reduction based Varied Phase for MIMO-OFDM Systems

    Directory of Open Access Journals (Sweden)

    Lahcen Amhaimar


    Full Text Available One of the severe drawbacks of orthogonal fre-quency division multiplexing (OFDM is high Peak-to-Average Power Ratio (PAPR of transmitted OFDM signals. During modulation the sub-carriers are added together with same phase which increases the value of PAPR, leading to more interference and limits power efficiency of High Power Amplifier (HPA, it’s requires power amplifier’s (PAs with large linear oper-ating ranges but such PAs are difficult to design and costly to manufacture. Therefore, to reduce PAPR various methods have been proposed. As a promising scheme, partial transmit sequences (PTS provides an effective solution for PAPR reduction of OFDM signals. In this paper, we propose a PAPR reduction method for an OFDM system with variation of phases based on PTS schemes and Solid State Power Amplifiers (SSPA of Saleh model in conjunction with digital predistortion (DPD, in order to improve the performance in terms of PAPR, the HPA linearity and for the sake of mitigating the in-band distortion and the spectrum regrowth. The simulation results show that the proposed algorithm can not only reduces the PAPR significantly, but also improves the out-of-band radiation and decreases the computational complexity.

  13. Peak to Average Power Ratio Reduction of OFDM Signal by Combining Clipping with Walsh Hadamard Transform

    Directory of Open Access Journals (Sweden)

    Lavish Kansal


    Full Text Available Wireless communications have been developed widelyand rapidly in the modern world especially duringthe last decade. Orthogonal Frequency Division Multiplexing (OFDM has grown to a popularcommunication technique for high speed communication. Besides of the advantages, one of maindisadvantage of OFDM is high peak to average powerratio (PAPR. In this paper, a PAPR reductionmethod is proposed that is based on combining clipping with Walsh Hadamard Transform (WHT.WHT isa precoding technique which is having less complexity compared to the other existing power reductiontechniques and also it can reduce PAPR considerablyand results in no distortion. The performance of theproposed scheme is examined through computer simulations and it is found that power reductions areobtained.

  14. High Power Factor Power Design

    Directory of Open Access Journals (Sweden)

    Zhang Jing-yi


    Full Text Available The PFC circuit takes UCC28019 made by TI Company as the core of system control, realize the power factor correction circuit functions, and the circuit power factor can be measured. Through a variety of detection circuit, with the support SCM control. And 30V~36V output voltage regulator can be set; with over-current protection circuits function, and be able to automatically back. Output current, voltage, and little significant value are displayed by display modules.

  15. Analytical expressions for maximum wind turbine average power in a Rayleigh wind regime

    Energy Technology Data Exchange (ETDEWEB)

    Carlin, P.W.


    Average or expectation values for annual power of a wind turbine in a Rayleigh wind regime are calculated and plotted as a function of cut-out wind speed. This wind speed is expressed in multiples of the annual average wind speed at the turbine installation site. To provide a common basis for comparison of all real and imagined turbines, the Rayleigh-Betz wind machine is postulated. This machine is an ideal wind machine operating with the ideal Betz power coefficient of 0.593 in a Rayleigh probability wind regime. All other average annual powers are expressed in fractions of that power. Cases considered include: (1) an ideal machine with finite power and finite cutout speed, (2) real machines operating in variable speed mode at their maximum power coefficient, and (3) real machines operating at constant speed.

  16. High power fiber lasers

    Institute of Scientific and Technical Information of China (English)

    LOU Qi-hong; ZHOU Jun


    In this review article, the development of the double cladding optical fiber for high power fiber lasers is reviewed. The main technology for high power fiber lasers, including laser diode beam shaping, fiber laser pumping techniques, and amplification systems, are discussed in de-tail. 1050 W CW output and 133 W pulsed output are ob-tained in Shanghai Institute of Optics and Fine Mechanics, China. Finally, the applications of fiber lasers in industry are also reviewed.


    The ultra-high power transmission line techniques including both failure mechanisms and component design are discussed. Failures resulting from...a waveguide. In view of the many advantages of the low loss mode in circular waveguide for ultra-high power levels, a mode transducer and a two...percent of the peak power of a standard rectangular wave guide. Water cooling is provided for high average power operation. Analysis of mode sup pression

  18. A method for the estimation of p-mode parameters from averaged solar oscillation power spectra

    CERN Document Server

    Reiter, J; Kosovichev, A G; Schou, J; Scherrer, P H; Larson, T P


    A new fitting methodology is presented which is equally well suited for the estimation of low-, medium-, and high-degree mode parameters from $m$-averaged solar oscillation power spectra of widely differing spectral resolution. This method, which we call the "Windowed, MuLTiple-Peak, averaged spectrum", or WMLTP Method, constructs a theoretical profile by convolving the weighted sum of the profiles of the modes appearing in the fitting box with the power spectrum of the window function of the observing run using weights from a leakage matrix that takes into account both observational and physical effects, such as the distortion of modes by solar latitudinal differential rotation. We demonstrate that the WMLTP Method makes substantial improvements in the inferences of the properties of the solar oscillations in comparison with a previous method that employed a single profile to represent each spectral peak. We also present an inversion for the internal solar structure which is based upon 6,366 modes that we ha...

  19. Resonant High Power Combiners

    CERN Document Server

    Langlois, Michel; Peillex-Delphe, Guy


    Particle accelerators need radio frequency sources. Above 300 MHz, the amplifiers mostly used high power klystrons developed for this sole purpose. As for military equipment, users are drawn to buy "off the shelf" components rather than dedicated devices. IOTs have replaced most klystrons in TV transmitters and find their way in particle accelerators. They are less bulky, easier to replace, more efficient at reduced power. They are also far less powerful. What is the benefit of very compact sources if huge 3 dB couplers are needed to combine the power? To alleviate this drawback, we investigated a resonant combiner, operating in TM010 mode, able to combine 3 to 5 IOTs. Our IOTs being able to deliver 80 kW C.W. apiece, combined power would reach 400 kW minus the minor insertion loss. Values for matching and insertion loss are given. The behavior of the system in case of IOT failure is analyzed.

  20. Average density and porosity of high-strength lightweight concrete

    Directory of Open Access Journals (Sweden)

    A.S. Inozemtcev


    Full Text Available The analysis results of high-strength lightweight concrete (HSLWC structure are presented in this paper. The X-ray tomography, optical microscopy and other methods are used for researching of average density and porosity. It has been revealed that mixtures of HSLWC with density 1300…1500 kg/m3 have a homogeneous structure. The developed concrete has a uniform distribution of the hollow filler and a uniform layer of cement-mineral matrix. The highly saturated gas phase which is divided by denser large particles of quartz sand and products of cement hydration in the contact area allow forming a composite material with low average density, big porosity (up to 40% and high strength (compressive strength is more than 40 MPa. Special modifiers increase adhesion, compacts structure in the contact area, decrease water absorption of high-strength lightweight concrete (up to 1 % and ensure its high water resistance (water resistance coefficient is more than 0.95.

  1. Ultra low voltage and low power Static Random Access Memory design using average 6.5T technique

    Directory of Open Access Journals (Sweden)

    Nagalingam RAJESWARAN


    Full Text Available Power Stringent Static Random Access Memory (SRAM design is very much essential in embedded systems such as biomedical implants, automotive electronics and energy harvesting devices in which battery life, input power and execution delay are of main concern. With reduced supply voltage, SRAM cell design will go through severe stability issues. In this paper, we present a highly stable average nT SRAM cell for ultra-low power in 125nm technology. The distinct difference between the proposed technique and other conventional methods is about the data independent leakage in the read bit line which is achieved by newly introduced block mask transistors. An average 6.5T SRAM and average 8T SRAM are designed and compared with 6T SRAM, 8T SRAM, 9T SRAM, 10T SRAM and 14T SRAM cells. The result indicates that there is an appreciable decrease in power consumption and delay.

  2. Time-variant power spectral analysis of heart-rate time series by autoregressive moving average (ARMA) method

    Indian Academy of Sciences (India)

    V P S Naidu; M R S Reddy


    Frequency domain representation of a short-term heart-rate time series (HRTS) signal is a popular method for evaluating the cardiovascular control system. The spectral parameters, viz. percentage power in low frequency band (%PLF), percentage power in high frequency band (%PHF), power ratio of low frequency to high frequency (PRLH), peak power ratio of low frequency to high frequency (PPRLH) and total power (TP) are extrapolated from the averaged power spectrum of twenty-five healthy subjects, and 16 acute anterior-wall and nine acute inferior-wall myocardial infarction (MI) patients. It is observed that parasympathetic activity predominates in healthy subjects. From this observation we conclude that during acute myocardial infarction, the anterior wall MI has stimulated sympathetic activity, while the acute inferior wall MI has stimulated parasympathetic activity. Results obtained from ARMA-based analysis of heart-rate time series signals are capable of complementing the clinical examination results.

  3. Efficient Spectral Broadening in the 100-W Average Power Regime Using Gas Filled Kagome HC-PCF and Pulse Compression

    CERN Document Server

    Emaury, Florian; Debord, Benoit; Ghosh, Debashri; Diebold, Andreas; Gerome, Frederic; Suedmeyer, Thomas; Benabid, Fetah; Keller, Ursula


    We present nonlinear pulse compression of a high-power SESAM-modelocked thin-disk laser (TDL) using an Ar-filled hypocycloid-core Kagome Hollow-Core Photonic Crystal Fiber (HC-PCF). The output of the modelocked Yb:YAG TDL with 127 W average power, a pulse repetition rate of 7 MHz, and a pulse duration of 740 fs was spectrally broadened 16-fold while propagating in a Kagome HC-PCF containing 13 bar of static Argon gas. Subsequent compression tests performed using 8.4% of the full available power resulted in a pulse duration as short as 88 fs using the spectrally broadened output from the fiber. Compressing the full transmitted power through the fiber (118 W) could lead to a compressed output of >100 W of average power and >100 MW of peak power with an average power compression efficiency of 88%. This simple laser system with only one ultrafast laser oscillator and a simple single-pass fiber pulse compressor, generating both high peak power >100 MW and sub-100-fs pulses at megahertz repetition rate, is very int...

  4. High Power Picosecond Laser Pulse Recirculation

    Energy Technology Data Exchange (ETDEWEB)

    Shverdin, M Y; Jovanovic, I; Semenov, V A; Betts, S M; Brown, C; Gibson, D J; Shuttlesworth, R M; Hartemann, F V; Siders, C W; Barty, C P


    We demonstrate a nonlinear crystal-based short pulse recirculation cavity for trapping the second harmonic of an incident high power laser pulse. This scheme aims to increase the efficiency and flux of Compton-scattering based light sources. We demonstrate up to 36x average power enhancement of frequency doubled sub-millijoule picosecond pulses, and 17x average power enhancement of 177 mJ, 10 ps, 10 Hz pulses.

  5. High-power picosecond laser pulse recirculation. (United States)

    Shverdin, M Y; Jovanovic, I; Semenov, V A; Betts, S M; Brown, C; Gibson, D J; Shuttlesworth, R M; Hartemann, F V; Siders, C W; Barty, C P J


    We demonstrate a nonlinear crystal-based short pulse recirculation cavity for trapping the second harmonic of an incident high-power laser pulse. This scheme aims to increase the efficiency and flux of Compton-scattering-based light sources. We demonstrate up to 40x average power enhancement of frequency-doubled submillijoule picosecond pulses, and 17x average power enhancement of 177 mJ, 10 ps, 10 Hz pulses.

  6. High power microwaves

    CERN Document Server

    Benford, James; Schamiloglu, Edl


    Following in the footsteps of its popular predecessors, High Power Microwaves, Third Edition continues to provide a wide-angle, integrated view of the field of high power microwaves (HPMs). This third edition includes significant updates in every chapter as well as a new chapter on beamless systems that covers nonlinear transmission lines. Written by an experimentalist, a theorist, and an applied theorist, respectively, the book offers complementary perspectives on different source types. The authors address: * How HPM relates historically and technically to the conventional microwave field * The possible applications for HPM and the key criteria that HPM devices have to meet in order to be applied * How high power sources work, including their performance capabilities and limitations * The broad fundamental issues to be addressed in the future for a wide variety of source types The book is accessible to several audiences. Researchers currently in the field can widen their understanding of HPM. Present or pot...

  7. Simulation on Peak-to-Average Power Ratio for Orthogonal Frequency Division Multiplexing

    Institute of Scientific and Technical Information of China (English)

    SHAN Weifeng; MENG Baohong; LIU Ningning; LI Hui; ZHANG Hongwei


    Clipping is a simple and convenient PAPR (peak-to-average power ratio) reduction method for high speed OFDM (orthogonal frequency division multiplexing) communication system. In this paper, we propose a new PAPR reduction method for Wireless-MAN(metropolitan area network)-OFDM system based on IEEE 802.16, which is over-sampling clipping arithmetic. Simulation and performance of the over-samples clipping's PAPR reduction capability, BER effect is given. The simulation indicates that the PAPR of at least 99.9% OFDM symbol is below 6dB after 2 Nyquist rate clipping, and the performance of BER has 1dB SNR(signal noise ratio) loss. The results prove that this method has better capacity to reducing PAPR. So it can be well used in WMAN-OFDM system.

  8. Switching power converters medium and high power

    CERN Document Server

    Neacsu, Dorin O


    An examination of all of the multidisciplinary aspects of medium- and high-power converter systems, including basic power electronics, digital control and hardware, sensors, analog preprocessing of signals, protection devices and fault management, and pulse-width-modulation (PWM) algorithms, Switching Power Converters: Medium and High Power, Second Edition discusses the actual use of industrial technology and its related subassemblies and components, covering facets of implementation otherwise overlooked by theoretical textbooks. The updated Second Edition contains many new figures, as well as

  9. Optimum Power and Rate Allocation for Coded V-BLAST: Average Optimization

    CERN Document Server

    Kostina, Victoria


    An analytical framework for performance analysis and optimization of coded V-BLAST is developed. Average power and/or rate allocations to minimize the outage probability as well as their robustness and dual problems are investigated. Compact, closed-form expressions for the optimum allocations and corresponding system performance are given. The uniform power allocation is shown to be near optimum in the low outage regime in combination with the optimum rate allocation. The average rate allocation provides the largest performance improvement (extra diversity gain), and the average power allocation offers a modest SNR gain limited by the number of transmit antennas but does not increase the diversity gain. The dual problems are shown to have the same solutions as the primal ones. All these allocation strategies are shown to be robust. The reported results also apply to coded multiuser detection and channel equalization systems relying on successive interference cancelation.

  10. High Power Cryogenic Targets

    Energy Technology Data Exchange (ETDEWEB)

    Gregory Smith


    The development of high power cryogenic targets for use in parity violating electron scattering has been a crucial ingredient in the success of those experiments. As we chase the precision frontier, the demands and requirements for these targets have grown accordingly. We discuss the state of the art, and describe recent developments and strategies in the design of the next generation of these targets.

  11. Peak-to-average power ratio reduction in interleaved OFDMA systems

    KAUST Repository

    Al-Shuhail, Shamael


    Orthogonal frequency division multiple access (OFDMA) systems suffer from several impairments, and communication system engineers use powerful signal processing tools to combat these impairments and to keep up with the capacity/rate demands. One of these impairments is high peak-to-average power ratio (PAPR) and clipping is the simplest peak reduction scheme. However, in general, when multiple users are subjected to clipping, frequency domain clipping distortions spread over the spectrum of all users. This results in compromised performance and hence clipping distortions need to be mitigated at the receiver. Mitigating these distortions in multiuser case is not simple and requires complex clipping mitigation procedures at the receiver. However, it was observed that interleaved OFDMA presents a special structure that results in only self-inflicted clipping distortions (i.e., the distortions of a particular user do not interfere with other users). In this work, we prove analytically that distortions do not spread over multiple users (while utilizing interleaved carrier assignment in OFDMA) and construct a compressed sensing system that utilizes the sparsity of the clipping distortions and recovers it on each user. We provide numerical results that validate our analysis and show promising performance for the proposed clipping recovery scheme.

  12. Average Power Handling Capability of Microstrip Passive Circuits Considering Metal Housing and Environment Conditions


    Sánchez-Soriano, Miguel Ángel; Queré, Yves; Le Saux, Vincent; Quendo, Cédric; Cadiou, Stephane


    In this paper, the average power handling capability (APHC) of microstrip passive circuits considering the metal housing and environment conditions is investigated in detail. A systematic method is proposed for the computation of the APHC of microstrip circuits in open and enclosed metal housing configurations, typically used in microwave components. The method also yields an estimate of the maximum temperature in a microstrip circuit for a given input power. Closed-form equations accounting ...

  13. Very High Power THz Radiation Sources


    Carr, G.L.; Martin, M. C.; McKinney, W.R.; Jordan, K.; Neil, G. R.; Williams, G. P.


    We report the production of high power (20watts average, ∼ 1 Megawatt peak) broadbandTHz light based on coherent emission fromrelativistic electrons. Such sources areideal for imaging, for high power damagestudies and for studies of non-linearphenomena in this spectral range. Wedescribe the source, presenting theoreticalcalculations and their experimentalverification. For clarity we compare thissource with one based on ultrafast lasertechniques.

  14. The average output power of a wind turbine in a turbulent wind

    Energy Technology Data Exchange (ETDEWEB)

    Rosen, A.; Sheinman, Y. (Faculty of Aerospace Engineering, Technion, Israel Institute of Technology, Haifa (Israel))


    Turbulence has an important influence on the average output power of a wind turbine taken over a certain period of time. The wind dynamics is coupled to the turbine dynamic characteristics and results in a fairly complicated behavior. Thus, the common 'static' model of calculating the average power, which is based on the turbine power curve and the average wind speed, may result in increasing errors. This paper presents three different models for calculating the average output power, taking into account the dynamic characteristics of the phenomenon. These models include direct time integration using accurate wind data and a detailed dynamic model of the turbine, a quasi-steady approach which is much simpler to apply and takes into account the wind dynamics, and an improved efficient model that also includes the influence of the dynamic characteristics of the turbine. The last improved model is based on a study of the turbine response to a sinusoidal gust. All models are compared with field measurements in order to study their accuracy. The comparison exhibits the importance of including all the dynamic effects in the calculations

  15. High Power Switching Transistor (United States)

    Hower, P. L.; Kao, Y. C.; Carnahan, D. C.


    Improved switching transistors handle 400-A peak currents and up to 1,200 V. Using large diameter silicon wafers with twice effective area as D60T, form basis for D7 family of power switching transistors. Package includes npn wafer, emitter preform, and base-contact insert. Applications are: 25to 50-kilowatt high-frequency dc/dc inverters, VSCF converters, and motor controllers for electrical vehicles.

  16. Non-chain pulsed DF laser with an average power of the order of 100 W (United States)

    Pan, Qikun; Xie, Jijiang; Wang, Chunrui; Shao, Chunlei; Shao, Mingzhen; Chen, Fei; Guo, Jin


    The design and performance of a closed-cycle repetitively pulsed DF laser are described. The Fitch circuit and thyratron switch are introduced to realize self-sustained volume discharge in SF6-D2 mixtures. The influences of gas parameters and charging voltage on output characteristics of non-chain pulsed DF laser are experimentally investigated. In order to improve the laser power stability over a long period of working time, zeolites with different apertures are used to scrub out the de-excitation particles produced in electric discharge. An average output power of the order of 100 W was obtained at an operating repetition rate of 50 Hz, with amplitude difference in laser pulses <8 %. And under the action of micropore alkaline zeolites, the average power fell by 20 % after the laser continuing working 100 s at repetition frequency of 50 Hz.

  17. Observer design for DC/DC power converters with bilinear averaged model

    NARCIS (Netherlands)

    Spinu, V.; Dam, M.C.A.; Lazar, M.


    Increased demand for high bandwidth and high efficiency made full state-feedback control solutions very attractive to power-electronics community. However, full state measurement is economically prohibitive for a large range of applications. Moreover, state measurements in switching power converters

  18. High-power electronics

    CERN Document Server

    Kapitsa, Petr Leonidovich


    High-Power Electronics, Volume 2 presents the electronic processes in devices of the magnetron type and electromagnetic oscillations in different systems. This book explores the problems of electronic energetics.Organized into 11 chapters, this volume begins with an overview of the motion of electrons in a flat model of the magnetron, taking into account the in-phase wave and the reverse wave. This text then examines the processes of transmission of electromagnetic waves of various polarization and the wave reflection from grids made of periodically distributed infinite metal conductors. Other

  19. High Power Dye Lasers (United States)


    art capabilities for developmental models of hydrogen thyratrons and solid state thyristors. Table II-l is a list of switches that have been... thyratron Table II-l Switch Ignitron GE, GL - 37207 Hydrogen Thyratron High Power Switches Peak Cur. (kA) RMS Cm. (A) 300 120 Max. Rep Rate...for 2 usec Pulse Cli„) 8 1. EG&G HY-5 2. EW. GHT9 3. EG&G Develop- mental model Thyristors 5 7.5 15 125 335 350 300 1000 300 RCA

  20. Yb-fiber-laser-based, 1.8 W average power, picosecond ultraviolet source at 266 nm. (United States)

    Chaitanya Kumar, S; Canals Casals, J; Sanchez Bautista, E; Devi, K; Ebrahim-Zadeh, M


    We report a compact, stable, high-power, picosecond ultraviolet (UV) source at 266 nm based on simple single-pass two-step fourth-harmonic generation (FHG) of a mode-locked Yb-fiber laser at 79.5 MHz in LiB3O5 (LBO) and β-BaB2O4. Using a 30-mm-long LBO crystal for single-pass second-harmonic generation, we achieve up to 9.1 W of average green power at 532 nm for 16.8 W of Yb-fiber power at a conversion efficiency of 54% in 16.2 ps pulses with a TEM00 spatial profile and passive power stability better than 0.5% rms over 16 h. The generated green radiation is then used for single-pass FHG into the UV, providing as much as 1.8 W of average power at 266 nm under the optimum focusing condition in the presence of spatial walk-off, at an overall FHG conversion efficiency of ∼11%. The generated UV output exhibits passive power stability better than 4.6% rms over 1.5 h and beam pointing stability better than 84 μrad over 1 h. The UV output beam has a circularity of >80% in high beam quality with the TEM00 mode profile. To the best of our knowledge, this is the first report of picosecond UV generation at 266 nm at megahertz repetition rates.


    Institute of Scientific and Technical Information of China (English)

    Jiang Tao; Zhu Guangxi


    A new scheme termed as Complement Block Coding (CBC) technique is proposed to reduce the Peak-to-Average Power Ratio (PAPR) of OFDM signals. Utilizing the complement bits which are added to the original information bits,this method can effectively reduce the PAPR of OFDM systems with random frame size N and the coding rate R ≤ (N - k)/N, where kis a positive integer and k ≤ N/2. The performance results obtained with CBC are given and compared with that of some well known schemes, such as Simple Block Coding (SBC), Modified Simple Block Coding (MSBC) and Simple Odd Parity Code (SOPC) for the same purpose. The results show that, at the same coding rate 3/4, the CBC can achieve almost the same performance as SBC, MSBC, but with lower complexity, and that the same performance can be obtained with higher coding rate by using CBC. At the same coding rate (N - 1)/N, the PAPR reduction of CBC is almost the twice as that of SOPC when N ≥ 16. Further more, the PAPR reductions with coding rate (N - 1)/N are almost the same as that with coding rate less than (N - 1)/N,so the proposed scheme CBC is more suitable for the large frame size with high coding rate and can provide error detection.

  2. A Hybrid Islanding Detection Technique Using Average Rate of Voltage Change and Real Power Shift

    DEFF Research Database (Denmark)

    Mahat, Pukar; Chen, Zhe; Bak-Jensen, Birgitte


    technique is proposed to solve this problem. An average rate of voltage change (passive technique) has been used to initiate a real power shift (active technique), which changes the eal power of distributed generation (DG), when the passive technique cannot have a clear discrimination between islanding......The mainly used islanding detection techniques may be classified as active and passive techniques. Passive techniques don't perturb the system but they have larger nondetection znes, whereas active techniques have smaller nondetection zones but they perturb the system. In this paper, a new hybrid...

  3. High power coaxial ubitron (United States)

    Balkcum, Adam J.

    In the ubitron, also known as the free electron laser, high power coherent radiation is generated from the interaction of an undulating electron beam with an electromagnetic signal and a static periodic magnetic wiggler field. These devices have experimentally produced high power spanning the microwave to x-ray regimes. Potential applications range from microwave radar to the study of solid state material properties. In this dissertation, the efficient production of high power microwaves (HPM) is investigated for a ubitron employing a coaxial circuit and wiggler. Designs for the particular applications of an advanced high gradient linear accelerator driver and a directed energy source are presented. The coaxial ubitron is inherently suited for the production of HPM. It utilizes an annular electron beam to drive the low loss, RF breakdown resistant TE01 mode of a large coaxial circuit. The device's large cross-sectional area greatly reduces RF wall heat loading and the current density loading at the cathode required to produce the moderate energy (500 keV) but high current (1-10 kA) annular electron beam. Focusing and wiggling of the beam is achieved using coaxial annular periodic permanent magnet (PPM) stacks without a solenoidal guide magnetic field. This wiggler configuration is compact, efficient and can propagate the multi-kiloampere electron beams required for many HPM applications. The coaxial PPM ubitron in a traveling wave amplifier, cavity oscillator and klystron configuration is investigated using linear theory and simulation codes. A condition for the dc electron beam stability in the coaxial wiggler is derived and verified using the 2-1/2 dimensional particle-in-cell code, MAGIC. New linear theories for the cavity start-oscillation current and gain in a klystron are derived. A self-consistent nonlinear theory for the ubitron-TWT and a new nonlinear theory for the ubitron oscillator are presented. These form the basis for simulation codes which, along

  4. Green-diode-pumped femtosecond Ti:Sapphire laser with up to 450 mW average power. (United States)

    Gürel, K; Wittwer, V J; Hoffmann, M; Saraceno, C J; Hakobyan, S; Resan, B; Rohrbacher, A; Weingarten, K; Schilt, S; Südmeyer, T


    We investigate power-scaling of green-diode-pumped Ti:Sapphire lasers in continuous-wave (CW) and mode-locked operation. In a first configuration with a total pump power of up to 2 W incident onto the crystal, we achieved a CW power of up to 440 mW and self-starting mode-locking with up to 200 mW average power in 68-fs pulses using semiconductor saturable absorber mirror (SESAM) as saturable absorber. In a second configuration with up to 3 W of pump power incident onto the crystal, we achieved up to 650 mW in CW operation and up to 450 mW in 58-fs pulses using Kerr-lens mode-locking (KLM). The shortest pulse duration was 39 fs, which was achieved at 350 mW average power using KLM. The mode-locked laser generates a pulse train at repetition rates around 400 MHz. No complex cooling system is required: neither the SESAM nor the Ti:Sapphire crystal is actively cooled, only air cooling is applied to the pump diodes using a small fan. Because of mass production for laser displays, we expect that prices for green laser diodes will become very favorable in the near future, opening the door for low-cost Ti:Sapphire lasers. This will be highly attractive for potential mass applications such as biomedical imaging and sensing.

  5. Development of a 16 kHz repetition rate, 110 W average power copper HyBrID laser

    Indian Academy of Sciences (India)

    R Biswal; P K Agrawal; G K Mishra; S V Nakhe; S K Dixit; J K Mittal


    This paper presents the design and performance analysis of an indigenously developed 110 W average output power copper HyBrID laser operating at 16 kHz pulse repetition rate. The laser active medium was confined within a fused silica tube of ∼ 6 cm diameter and ∼ 200 cm active length. An in-house developed high-power (∼ 10 kW) solid-state pulser was used as the electrical excitation source. A simple estimation of deposited electrical power, at the laser head, was carried out and based on it, the laser tube efficiency was found to be 2.9% at 70 W and 2.2% at 110 W laser power levels.

  6. High power beam analysis (United States)

    Aharon, Oren


    In various modern scientific and industrial laser applications, beam-shaping optics manipulates the laser spot size and its intensity distribution. However the designed laser spot frequently deviates from the design goal due to real life imperfections and effects, such as: input laser distortions, optical distortion, heating, overall instabilities, and non-linear effects. Lasers provide the ability to accurately deliver large amounts of energy to a target area with very high accuracy. Thus monitoring beam size power and beam location is of high importance for high quality results and repeatability. Depending on the combination of wavelength, beam size and pulse duration , laser energy is absorbed by the material surface, yielding into processes such as cutting, welding, surface treatment, brazing and many other applications. This article will cover the aspect of laser beam measurements, especially at the focal point where it matters the most. A brief introduction to the material processing interactions will be covered, followed by fundamentals of laser beam propagation, novel measurement techniques, actual measurement and brief conclusions.

  7. Short pulse mid-infrared amplifier for high average power

    CSIR Research Space (South Africa)

    Botha, LR


    Full Text Available Telephone number of main author: +27-12-841-3447 Fax number of main author: +27-12-841-3152 Complete mailing address of main author: L R Botha, P O Box 395, Building 46, 2 nd Floor, Pretoria, 0001, South Africa Topic Area: Gas lasers including metal....1  Hz. If the relationship 4.0 vt is used then pulses as short as 0.5 ps can be amplified. The gain bandwidth can be increased by using isotopic mixtures and consequently this will allow pulses shorter than 0.5ps to be amplified. Gas lasers...

  8. An Analytical and Experimental Investigation of Average Laser Power and Angular Scanning Speed Effects on Laser Tube Bending Process

    Directory of Open Access Journals (Sweden)

    Imhan Khalil Ibraheem


    Full Text Available Laser tube bending is a new technique of laser material forming to produce a complex and accurate shape due to its flexibility and high controllability. Moreover, the defects during conventional tube forming such as thinning, wrinkling, spring back and ovalization can be avoided in laser tube bending process, because there is no external force used. In this paper an analytical investigation has been conducted to analyses the effects of average laser power and laser scanning speed on laser tube bending process, the analytical results have been verified experimentally. The model used in this study is in the same trend of the experiment. The results show that the bending angle increased with the increasing of average laser power and decreased with the increasing of angular scanning speed.

  9. Application of Bayesian model averaging to measurements of the primordial power spectrum

    CERN Document Server

    Parkinson, David


    Cosmological parameter uncertainties are often stated assuming a particular model, neglecting the model uncertainty, even when Bayesian model selection is unable to identify a conclusive best model. Bayesian model averaging is a method for assessing parameter uncertainties in situations where there is also uncertainty in the underlying model. We apply model averaging to the estimation of the parameters associated with the primordial power spectra of curvature and tensor perturbations. We use CosmoNest and MultiNest to compute the model Evidences and posteriors, using cosmic microwave data from WMAP, ACBAR, BOOMERanG and CBI, plus large-scale structure data from the SDSS DR7. We find that the model-averaged 95% credible interval for the spectral index using all of the data is 0.940 < n_s < 1.000, where n_s is specified at a pivot scale 0.015 Mpc^{-1}. For the tensors model averaging can tighten the credible upper limit, depending on prior assumptions.

  10. A self-organizing power system stabilizer using Fuzzy Auto-Regressive Moving Average (FARMA) model

    Energy Technology Data Exchange (ETDEWEB)

    Park, Y.M.; Moon, U.C. [Seoul National Univ. (Korea, Republic of). Electrical Engineering Dept.; Lee, K.Y. [Pennsylvania State Univ., University Park, PA (United States). Electrical Engineering Dept.


    This paper presents a self-organizing power system stabilizer (SOPSS) which use the Fuzzy Auto-Regressive Moving Average (FARMA) model. The control rules and the membership functions of the proposed logic controller are generated automatically without using any plant model. The generated rules are stored in the fuzzy rule space and updated on-line by a self-organizing procedure. To show the effectiveness of the proposed controller, comparison with a conventional controller for one-machine infinite-bus system is presented.

  11. Compact high-power terahertz radiation source

    Directory of Open Access Journals (Sweden)

    G. A. Krafft


    Full Text Available In this paper a new type of THz radiation source, based on recirculating an electron beam through a high gradient superconducting radio frequency cavity, and using this beam to drive a standard electromagnetic undulator on the return leg, is discussed. Because the beam is recirculated and not stored, short bunches may be produced that radiate coherently in the undulator, yielding exceptionally high average THz power for relatively low average beam power. Deceleration from the coherent emission, and the detuning it causes, limits the charge-per-bunch possible in such a device.

  12. High power evaluation of X-band high power loads

    CERN Document Server

    Matsumoto, Shuji; Syratchev, Igor; Riddone, Germana; Wuensch, Walter


    Several types of X-band high power loads developed for several tens of MW range were designed, fabricated and used for high power tests at X-band facility of KEK. Some of them have been used for many years and few units showed possible deterioration of RF performance. Recently revised-design loads were made by CERN and the high power evaluation was performed at KEK. In this paper, the main requirements are recalled, together with the design features. The high power test results are analysed and presented

  13. High Efficiency Power Converter for Low Voltage High Power Applications

    DEFF Research Database (Denmark)

    Nymand, Morten

    , and remote power generation for light towers, camper vans, boats, beacons, and buoys etc. A review of current state-of-the-art is presented. The best performing converters achieve moderately high peak efficiencies at high input voltage and medium power level. However, system dimensioning and cost are often......The topic of this thesis is the design of high efficiency power electronic dc-to-dc converters for high-power, low-input-voltage to high-output-voltage applications. These converters are increasingly required for emerging sustainable energy systems such as fuel cell, battery or photo voltaic based...... determined by the performance at the system worst case operating point which is usually at minimum input voltage and maximum power. Except for the non-regulating V6 converters, all published solutions exhibit a very significant drop in conversion efficiency at minimum input voltage and maximum output power...

  14. Peak to Average Power Ratio Reduction of OFDM Signals Using Clipping and Iterative Processing Methods

    Directory of Open Access Journals (Sweden)

    Ahmed K. Hassan


    Full Text Available One of the serious problems in any wireless communication system using multi carrier modulation technique like Orthogonal Frequency Division Multiplexing (OFDM is its Peak to Average Power Ratio (PAPR.It limits the transmission power due to the limitation of dynamic range of Analog to Digital Converter and Digital to Analog Converter (ADC/DAC and power amplifiers at the transmitter, which in turn sets the limit over maximum achievable rate.This issue is especially important for mobile terminals to sustain longer battery life time. Therefore reducing PAPR can be regarded as an important issue to realize efficient and affordable mobile communication services.This paper presents an efficient PAPR reduction method for OFDM signal. This method is based on clipping and iterative processing. Iterative processing is performed to limit PAPR in time domain but the subtraction process of the peak that over PAPR threshold with the original signal is done in frequency domain, not in time like usual clipping technique. The results of this method is capable of reducing the PAPR significantly with minimum bit error rate (BER degradation.

  15. High Efficiency Power Converter for Low Voltage High Power Applications

    DEFF Research Database (Denmark)

    Nymand, Morten

    , and remote power generation for light towers, camper vans, boats, beacons, and buoys etc. In chapter 2, a review of current state-of-the-art is presented. The best performing converters achieve moderately high peak efficiencies at high input voltage and medium power level. However, system dimensioning...

  16. Twenty-watt average output power, picosecond thin-rod Yb:YAG regenerative chirped pulse amplifier with 200 mJ pulse energy


    MATSUBARA, Shinichi; TANAKA, Motoharu; TAKAMA, Masaki; KAWATO, Sakae; Kobayashi, Takao


    A high-average power, laser-diode-pumped, picosecond-pulse regenerative chirpedpulse amplifier was developed by using the thin-rod Yb:YAG laser architecture. An averageoutput power of 20 W was achieved at a repetition rate of 100 kHz with an output pulse width of 2ps.

  17. The monotonic increasing relationship between average powers of CMOS VLSI circuits with and without delay and its applications

    Institute of Scientific and Technical Information of China (English)

    骆祖莹; 闵应骅; 杨士元; 李晓维


    The authors theoretically describe the monotonic increasing relationship between averagepowers of a CMOS VLSI circuit with and without delay. The power of an ideal circuit without delay, whichcan be fast computed, has been used as the evaluation criterion for the power of a practical circuit withdelay, which needs more computing time, in such fields as fast estimation for the average power and themaximum power, and fast optimization for the Iow test power. The authors propose a novel simulationapproach that uses delay-free power to compact a long input vector pair sequence into a short sequenceand then, uses the compacted one to fast simulate the average (or maximum) power for a CMOS circuit. Incomparison with the traditional simulation approach that uses an un-compacted input sequence to simu-late the average (or maximum) power, experiment results demonstrate that in the field of fast estimationfor the average power, the present approach can be 6-10 times faster without significant loss in accuracy(less than 3.5% on average), and in the field of fast estimation for the maximum power, this approach canbe 6-8 times faster without significant loss in accuracy (less than 5% on average). In the field of fast op-timization for the test power, the authors propose a novel delay-free power optimization approach for thetest power. Experiment results demonstrate that, in comparison with the approach of direct optimizationand the approach of Hamming distance optimization, this approach is of the highest optimization effi-ciency because it needs shorter time (16.84%) to obtain a better optimization effect (reducing 35.11% testpower).

  18. The Jefferson Lab High Power Light Source

    Energy Technology Data Exchange (ETDEWEB)

    James R. Boyce


    Jefferson Lab has designed, built and operated two high average power free-electron lasers (FEL) using superconducting RF (SRF) technology and energy recovery techniques. Between 1999-2001 Jefferson Lab operated the IR Demo FEL. This device produced over 2 kW in the mid-infrared, in addition to producing world record average powers in the visible (50 W), ultraviolet (10 W) and terahertz range (50 W) for tunable, short-pulse (< ps) light. This FEL was the first high power demonstration of an accelerator configuration that is being exploited for a number of new accelerator-driven light source facilities that are currently under design or construction. The driver accelerator for the IR Demo FEL uses an Energy Recovered Linac (ERL) configuration that improves the energy efficiency and lowers both the capital and operating cost of such devices by recovering most of the power in the spent electron beam after optical power is extracted from the beam. The IR Demo FEL was de-commissioned in late 2001 for an upgraded FEL for extending the IR power to over 10 kW and the ultraviolet power to over 1 kW. The FEL Upgrade achieved 10 kW of average power in the mid-IR (6 microns) in July of 2004, and its IR operation currently is being extended down to 1 micron. In addition, we have demonstrated the capability of on/off cycling and recovering over a megawatt of electron beam power without diminishing machine performance. A complementary UV FEL will come on-line within the next year. This paper presents a summary of the FEL characteristics, user community accomplishments with the IR Demo, and planned user experiments.

  19. High-powered manoeuvres

    CERN Multimedia

    Anaïs Schaeffer


    This week, CERN received the latest new transformers for the SPS. Stored in pairs in 24-tonne steel containers, these transformers will replace the old models, which have been in place since 1981.     The transformers arrive at SPS's access point 4 (BA 4). During LS1, the TE-EPC Group will be replacing all of the transformers for the main converters of the SPS. This renewal campaign is being carried out as part of the accelerator consolidation programme, which began at the start of April and will come to an end in November. It involves 80 transformers: 64 with a power of 2.6 megavolt-amperes (MVA) for the dipole magnets, and 16 with 1.9 MVA for the quadrupoles. These new transformers were manufactured by an Italian company and are being installed outside the six access points of the SPS by the EN-HE Group, using CERN's 220-tonne crane. They will contribute to the upgrade of the SPS, which should thus continue to operate as the injector for the LHC until 2040....

  20. New Tone Reservation Technique for Peak to Average Power Ratio Reduction (United States)

    Wilharm, Joachim; Rohling, Hermann


    In Orthogonal Frequency Division Multiplexing (OFDM) the transmit signals have a highly fluctuating, non-constant envelope which is a technical challenge for the High Power Amplifier (HPA). Without any signal processing procedures the amplitude peaks of the transmit signal will be clipped by the HPA resulting in out-ofband radiation and in bit error rate (BER) performance degradation. The classical Tone Reservation (TR) technique calculates a correction signal in an iterative way to reduce the amplitude peaks. However this step leads to a high computational complexity. Therefore, in this paper an alternative TR technique is proposed. In this case a predefined signal pattern is shifted to any peak position inside the transmit signal and reduces thereby all amplitude peaks. This new procedure is able to outperform the classical TR technique and has a much lower computational complexity.


    Driver, G.E.


    High voltage, direct current power supplies are described for use with battery powered nuclear detection equipment. The particular advantages of the power supply described, are increased efficiency and reduced size and welght brought about by the use of transistors in the circuit. An important feature resides tn the employment of a pair of transistors in an alternatefiring oscillator circuit having a coupling transformer and other circuit components which are used for interconnecting the various electrodes of the transistors.

  2. An Effective Algorithm for Average Power Estimation of CMOS Sequential Chircuit

    Institute of Scientific and Technical Information of China (English)

    LIYueping; TANGPushan; ZHAOWenqing


    An incremental probabilistic algorithm is proposed for estimating average power of CMOS sequential circuit.We facilitate the flrst-order Taylor expansion to consider the spatial and temporal correlation among the internal nodes of the seauential circuits.Regarding finite state machines as non-decomposable and aperiodic Markov Chains,the steady-state probabilities exist.Consequently there have the steady probabilities of state lines.Thus the signal probability and switching activity of state line can be gotten through Picard-Peano iteration method.Sequential modules are separated from the whole circuit to shorten the runtime of our algorithm.We unroll the sequential module to accurately estimate the signal probability of state lines.Unilke the algorithms bassed on global BDD,the runtime of computing signal probability and switching activity of our algorithm does not depend on the circuit size.Experimental results show that our algorithm is much faster than the Monte-Carlo simulation method with the error below 10%.

  3. Technology development for high power induction accelerators

    Energy Technology Data Exchange (ETDEWEB)

    Birx, D.L.; Reginato, L.L.


    The marriage of Induction Linac technology with Nonlinear Magnetic Modulators has produced some unique capabilities. It appears possible to produce electron beams with average currents measured in amperes, at gradients exceeding 1 MeV/meter, and with power efficiencies approaching 50%. A 2 MeV, 5 kA electron accelerator has been constructed at the Lawrence Livermore National Laboratory (LLNL) to demonstrate these concepts and to provide a test facility for high brightness sources. The pulse drive for the accelerator is based on state-of-the-art magnetic pulse compressors with very high peak power capability, repetition rates exceeding a kilohertz and excellent reliability.

  4. Compact Source of Electron Beam with Energy of 200 kEv and Average Power of 2 kW

    CERN Document Server

    Kazarezov, Ivan; Balakin, Vladimir E; Bryazgin, Alex; Bulatov, Alexandre; Glazkov, Ivan; Kokin, Evgeny; Krainov, Gennady; Kuznetsov, Gennady I; Molokoedov, Andrey; Tuvik, Alfred


    The paper describes a compact electron beam source with average electron energy of 200 keV. The source operates with pulse power up to 2 MW under average power not higher than 2 kW, pulsed beam current up to 10 A, pulse duration up to 2 mks, and repetition rate up to 5 kHz. The electron beam is extracted through aluminium-beryllium alloy foil. The pulse duration and repetition rate can be changed from control desk. High-voltage generator for the source with output voltage up to 220 kV is realized using the voltage-doubling circuit which consists of 30 sections. The insulation type - gas, SF6 under pressure of 8 atm. The cooling of the foil supporting tubes is provided by a water-alcohol mixture from an independent source. The beam output window dimensions are 180?75 mm, the energy spread in the beam +10/-30%, the source weight is 80 kg.

  5. Partial Transition Sequence Algorithms for Reducing Peak to Average Power Ratio in the Next Generation Wireless Communications Systems

    Directory of Open Access Journals (Sweden)

    Mokhtaria Mesri


    Full Text Available The unprecedented scientific and technical advancements along with the ever-growing needs of humanity resulted in a revolution in the field of communication. Hence, single carrier waves are being replaced by multi-carrier systems like Orthogonal Frequency Division Multiplexing (OFDM and Generalized Frequency Division Multiplexing (GFDM which are nowadays commonly implemented. In the OFDM system, orthogonally placed subcarriers are used to carry the data from the transmitter to the receiver end. The presence of guard band in these systems helps in dealing with the problem of intersymbol interference (ISI and noise is minimized by the larger number of subcarriers. However, the large Peak to Average Power Ratio (PAPR of these signals has undesirable effects on the system. PAPR itself can cause interference and degradation of Bit Error Rate (BER. To reduce High Peak to Average Power Ratio and Bit Error Rate problems, more techniques are used. Furthermore, each technique has its own disadvantages, such as complexity in-band distortion and out-of-band radiation into OFDM and GFDM signals. In this paper, the emphasis will be put on the GFDM systems as well as on the methods that are meant to reduce the PAPR problem and improve efficiency.

  6. Efficient spectral broadening in the 100-W average power regime using gas-filled kagome HC-PCF and pulse compression. (United States)

    Emaury, Florian; Saraceno, Clara J; Debord, Benoit; Ghosh, Debashri; Diebold, Andreas; Gèrôme, Frederic; Südmeyer, Thomas; Benabid, Fetah; Keller, Ursula


    We present nonlinear pulse compression of a high-power SESAM-modelocked thin-disk laser (TDL) using an Ar-filled hypocycloid-core kagome hollow-core photonic crystal fiber (HC-PCF). The output of the modelocked Yb:YAG TDL with 127 W average power, a pulse repetition rate of 7 MHz, and a pulse duration of 740 fs was spectrally broadened 16-fold while propagating in a kagome HC-PCF containing 13 bar of static argon gas. Subsequent compression tests performed using 8.4% of the full available power resulted in a pulse duration as short as 88 fs using the spectrally broadened output from the fiber. Compressing the full transmitted power through the fiber (118 W) could lead to a compressed output of >100  W of average power and >100  MW of peak power with an average power compression efficiency of 88%. This simple laser system with only one ultrafast laser oscillator and a simple single-pass fiber pulse compressor, generating both high peak power >100  MW and sub-100-fs pulses at megahertz repetition rate, is very interesting for many applications such as high harmonic generation and attosecond science with improved signal-to-noise performance.

  7. Modular High Voltage Power Supply

    Energy Technology Data Exchange (ETDEWEB)

    Newell, Matthew R. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)


    The goal of this project is to develop a modular high voltage power supply that will meet the needs of safeguards applications and provide a modular plug and play supply for use with standard electronic racks.

  8. High Power Betavoltaic Technology Project (United States)

    National Aeronautics and Space Administration — The proposed innovation will dramatically improve the performance of tritium-powered betavoltaic batteries through the development of a high-aspect ratio, expanded...

  9. Femtosecond pulse generation at 50 W average powers from an Yb:KYW-Yb:YAG planar-waveguide MOPA

    Directory of Open Access Journals (Sweden)

    Baker H. J.


    Full Text Available An Yb:YAG planar-waveguide power amplifier seeded by an Yb:KYW master oscillator is reported. The system produced 700-fs pulses at 1032 nm at average output powers of 50 W and a frequency of 53 MHz.

  10. EURISOL High Power Targets

    CERN Document Server

    Kadi, Y; Lindroos, M; Ridikas, D; Stora, T; Tecchio, L; CERN. Geneva. BE Department


    Modern Nuclear Physics requires access to higher yields of rare isotopes, that relies on further development of the In-flight and Isotope Separation On-Line (ISOL) production methods. The limits of the In-Flight method will be applied via the next generation facilities FAIR in Germany, RIKEN in Japan and RIBF in the USA. The ISOL method will be explored at facilities including ISAC-TRIUMF in Canada, SPIRAL-2 in France, SPES in Italy, ISOLDE at CERN and eventually at the very ambitious multi-MW EURISOL facility. ISOL and in-flight facilities are complementary entities. While in-flight facilities excel in the production of very short lived radioisotopes independently of their chemical nature, ISOL facilities provide high Radioisotope Beam (RIB) intensities and excellent beam quality for 70 elements. Both production schemes are opening vast and rich fields of nuclear physics research. In this article we will introduce the targets planned for the EURISOL facility and highlight some of the technical and safety cha...

  11. Green-diode-pumped femtosecond Ti:Sapphire laser with up to 450 mW average power


    Gürel, Kutan; Wittwer, Valentin J; Hoffmann, Martin; Saraceno, Clara J.; Hakobyan, Sargis; Resan, B; Rohrbacher, A; Weingarten, K.; Schilt, Stéphane; Südmeyer, Thomas


    We investigate power-scaling of green-diode-pumped Ti:Sapphire lasers in continuous-wave (CW) and mode-locked operation. In a first configuration with a total pump power of up to 2 W incident onto the crystal, we achieved a CW power of up to 440 mW and self-starting mode-locking with up to 200 mW average power in 68-fs pulses using semiconductor saturable absorber mirror (SESAM) as saturable absorber. In a second configuration with up to 3 W of pump power incident onto the crystal, we achieve...

  12. Optimization and Annual Average Power Predictions of a Backward Bent Duct Buoy Oscillating Water Column Device Using the Wells Turbine


    Smith, Christopher; Willits, Steven; Bull, Diana; Fontaine, Arnold


    This paper presents work completed by The Applied Research Laboratory at The Pennsylvania State University, in conjunction with Sandia National Labs, on the optimization of the power conversion chain (PCC) design to maximize the Average Annual Electric Power (AAEP) output of an Oscillating Water Column (OWC) device. The design consists of two independent stages. First, the design of a floating OWC, a Backward Bent Duct Buoy (BBDB), and second the design of the PCC. The pneumatic power output ...

  13. The acute effect of lower-body training on average power output measured by loaded half-squat jump exercise

    Directory of Open Access Journals (Sweden)

    Matúš Krčmár


    Full Text Available Background: High muscular power output is required in many athletic endeavors in order for success to be achieved. In the scientific community postactivation potentiation and its effect on performance are often discussed. There are many studies where the effect of resistance exercise on motor performance (such as vertical jump performance and running speed has been investigated but only a few of them studied power output. Objective: The purpose of this study was to determine the acute responses to a 2 set loaded half-squat jumps and 2 set loaded back half-squat protocols designed to induce the acute maximum average power output during loaded half-squat jumps. Methods: A randomized cross-over design was used. 11 participants of this study performed 3 trials in randomized order separated by at least 48 hours where maximum average power output was measured. The specific conditioning activities were comprised of 2 sets and 4 repetitions of half-squat jumps, 2 sets and 4 repetitions of back half-squat exercises and a control protocol without an intervention by specific a conditioning activity. Participants were strength trained athletes with different sport specializations (e.g. ice-hockey, volleyball. Mean age of the athletes was 22 ± 1.8 years, body mass 80 ± 7.1 kg and body height 185 ± 6.5 cm. Analysis of variance with repeated measures was used to determine differences between pre- and post-condition in each protocol, as well as between conditioning protocols, and also effect size was used to evaluate practical significance. Results: Maximum average power was significantly enhanced after application of the half-squat jump condition protocol (1496.2 ± 194.5 to 1552 ± 196.1 W, Δ ~ 3.72%, p < .001 and after application of the back half-squat protocol (1500.7 ± 193.2 to 1556 ± 191.2 W, Δ ~ 3.68%, p < .001 after 10 min of rest. Power output after control protocol was

  14. High power ferrite microwave switch (United States)

    Bardash, I.; Roschak, N. K.


    A high power ferrite microwave switch was developed along with associated electronic driver circuits for operation in a spaceborne high power microwave transmitter in geostationary orbit. Three units were built and tested in a space environment to demonstrate conformance to the required performance characteristics. Each unit consisted of an input magic-tee hybrid, two non-reciprocal latching ferrite phase shifters, an out short-slot 3 db quadrature coupler, a dual driver electronic circuit, and input logic interface circuitry. The basic mode of operation of the high power ferrite microwave switch is identical to that of a four-port, differential phase shift, switchable circulator. By appropriately designing the phase shifters and electronic driver circuits to operate in the flux-transfer magnetization mode, power and temperature insensitive operation was achieved. A list of the realized characteristics of the developed units is given.

  15. Duration-tunable picosecond source at 560  nm with watt-level average power. (United States)

    Runcorn, T H; Murray, R T; Kelleher, E J R; Popov, S V; Taylor, J R


    A pulse source at 560 nm that is tunable in duration between 50 ps and 2.7 ns with >1  W of average power and near diffraction-limited beam quality is demonstrated. The source is based on efficient (up to 50%) second-harmonic generation in a periodically poled lithium tantalate crystal of a linearly polarized fiber-integrated Raman amplifier operating at 1120 nm. A duration-tunable ytterbium master-oscillator power-fiber amplifier is used to pulse-pump the Raman amplifier, which is seeded by a continuous-wave distributed-feedback laser diode at 1120 nm. The performance of the system using two different master oscillator schemes is compared. A pulse energy of up to 765 nJ is achieved with a conversion efficiency of 25% from the ytterbium fiber pump, demonstrating a compact and turn-key architecture for obtaining high peak-power radiation at 560 nm.

  16. High Power Amplifier and Power Supply (United States)

    Duong, Johnny; Stride, Scot; Harvey, Wayne; Haque, Inam; Packard, Newton; Ng, Quintin; Ispirian, Julie Y.; Waian, Christopher; Janes, Drew


    A document discusses the creation of a high-voltage power supply (HVPS) that is able to contain voltages up to -20 kV, keep electrical field strengths to below 200 V/mil (approximately equal to 7.87 kV/mm), and can provide a 200-nanosecond rise/fall time focus modulator swinging between cathode potential of 16.3 kV and -19.3 kV. This HVPS can protect the 95-GHz, pulsed extended interaction klystron (EIK) from arcs/discharges from all sources, including those from within the EIK fs vacuum envelope. This innovation has a multi-winding pulse transformer design, which uses new winding techniques to provide the same delays and rise/fall times (less than 10 nanoseconds) at different potential levels ranging from -20 kV to -16 kV. Another feature involves a high-voltage printed-wiring board that was corona-free at -20 kV DC with a 3- kV AC swing. The corona-free multilayer high-voltage board is used to simulate fields of less than 200 V/mil (approximately equal to 7.87 kV/mm) at 20 kV DC. Drive techniques for the modulator FETs (field-effect transistors) (four to 10 in a series) were created to change states (3,000-V swing) without abrupt steps, while still maintaining required delays and transition times. The packing scheme includes a potting mold to house a ten-stage modulator in the space that, in the past, only housed a four-stage modulator. Problems keeping heat down were solved using aluminum oxide substrate in the high-voltage section to limit temperature rise to less than 10 while withstanding -20 kV DC voltage and remaining corona-free.

  17. High power infrared QCLs: advances and applications (United States)

    Patel, C. Kumar N.


    QCLs are becoming the most important sources of laser radiation in the midwave infrared (MWIR) and longwave infrared (LWIR) regions because of their size, weight, power and reliability advantages over other laser sources in the same spectral regions. The availability of multiwatt RT operation QCLs from 3.5 μm to >16 μm with wall plug efficiency of 10% or higher is hastening the replacement of traditional sources such as OPOs and OPSELs in many applications. QCLs can replace CO2 lasers in many low power applications. Of the two leading groups in improvements in QCL performance, Pranalytica is the commercial organization that has been supplying the highest performance QCLs to various customers for over four year. Using a new QCL design concept, the non-resonant extraction [1], we have achieved CW/RT power of >4.7 W and WPE of >17% in the 4.4 μm - 5.0 μm region. In the LWIR region, we have recently demonstrated QCLs with CW/RT power exceeding 1 W with WPE of nearly 10 % in the 7.0 μm-10.0 μm region. In general, the high power CW/RT operation requires use of TECs to maintain QCLs at appropriate operating temperatures. However, TECs consume additional electrical power, which is not desirable for handheld, battery-operated applications, where system power conversion efficiency is more important than just the QCL chip level power conversion efficiency. In high duty cycle pulsed (quasi-CW) mode, the QCLs can be operated without TECs and have produced nearly the same average power as that available in CW mode with TECs. Multiwatt average powers are obtained even in ambient T>70°C, with true efficiency of electrical power-to-optical power conversion being above 10%. Because of the availability of QCLs with multiwatt power outputs and wavelength range covering a spectral region from ~3.5 μm to >16 μm, the QCLs have found instantaneous acceptance for insertion into multitude of defense and homeland security applications, including laser sources for infrared

  18. The JLab high power ERL light source

    Energy Technology Data Exchange (ETDEWEB)

    G.R. Neil; C. Behre; S.V. Benson; M. Bevins; G. Biallas; J. Boyce; J. Coleman; L.A. Dillon-Townes; D. Douglas; H.F. Dylla; R. Evans; A. Grippo; D. Gruber; J. Gubeli; D. Hardy; C. Hernandez-Garcia; K. Jordan; M.J. Kelley; L. Merminga; J. Mammosser; W. Moore; N. Nishimori; E. Pozdeyev; J. Preble; R. Rimmer; Michelle D. Shinn; T. Siggins; C. Tennant; R. Walker; G.P. Williams and S. Zhang


    A new THz/IR/UV photon source at Jefferson Lab is the first of a new generation of light sources based on an Energy-Recovered, (superconducting) Linac (ERL). The machine has a 160 MeV electron beam and an average current of 10 mA in 75 MHz repetition rate hundred femtosecond bunches. These electron bunches pass through a magnetic chicane and therefore emit synchrotron radiation. For wavelengths longer than the electron bunch the electrons radiate coherently a broadband THz {approx} half cycle pulse whose average brightness is > 5 orders of magnitude higher than synchrotron IR sources. Previous measurements showed 20 W of average power extracted[1]. The new facility offers simultaneous synchrotron light from the visible through the FIR along with broadband THz production of 100 fs pulses with >200 W of average power. The FELs also provide record-breaking laser power [2]: up to 10 kW of average power in the IR from 1 to 14 microns in 400 fs pulses at up to 74.85 MHz repetition rates and soon will produce similar pulses of 300-1000 nm light at up to 3 kW of average power from the UV FEL. These ultrashort pulses are ideal for maximizing the interaction with material surfaces. The optical beams are Gaussian with nearly perfect beam quality. See for details of the operating characteristics; a wide variety of pulse train configurations are feasible from 10 microseconds long at high repetition rates to continuous operation. The THz and IR system has been commissioned. The UV system is to follow in 2005. The light is transported to user laboratories for basic and applied research. Additional lasers synchronized to the FEL are also available. Past activities have included production of carbon nanotubes, studies of vibrational relaxation of interstitial hydrogen in silicon, pulsed laser deposition and ablation, nitriding of metals, and energy flow in proteins. This paper will present the status of the system and discuss some of the discoveries we have made

  19. High power neutron production targets

    Energy Technology Data Exchange (ETDEWEB)

    Wender, S. [Los Alamos National Lab., NM (United States)


    The author describes issues of concern in the design of targets and associated systems for high power neutron production facilities. The facilities include uses for neutron scattering, accelerator driven transmutation, accelerator production of tritium, short pulse spallation sources, and long pulse spallation sources. Each of these applications requires a source with different design needs and consequently different implementation in practise.

  20. 157 W all-fiber high-power picosecond laser. (United States)

    Song, Rui; Hou, Jing; Chen, Shengping; Yang, Weiqiang; Lu, Qisheng


    An all-fiber high-power picosecond laser is constructed in a master oscillator power amplifier configuration. The self-constructed fiber laser seed is passively mode locked by a semiconductor saturable absorber mirror. Average output power of 157 W is obtained after three stages of amplification at a fundamental repetition rate of 60 MHz. A short length of ytterbium double-clad fiber with a high doping level is used to suppress nonlinear effects. However, a stimulated Raman scattering (SRS) effect occurs owing to the 78 kW high peak power. A self-made all-fiber repetition rate increasing system is used to octuple the repetition rate and decrease the high peak power. Average output power of 156.6 W is obtained without SRS under the same pump power at a 480 MHz repetition rate with 0.6 nm line width.

  1. Increased mid-infrared supercontinuum bandwidth and average power by tapering large-mode-area chalcogenide photonic crystal fibers

    DEFF Research Database (Denmark)

    Petersen, Christian Rosenberg; Engelsholm, Rasmus Dybbro; Markos, Christos


    The trade-off between the spectral bandwidth and average output power from chalcogenide fiber-based mid-infrared supercontinuum sources is one of the major challenges towards practical application of the technology. In this paper we address this challenge through tapering of large-mode-area chalc...... m. (C) 2017 Optical Society of America...

  2. Significance of power average of sinusoidal and non-sinusoidal periodic excitations in nonlinear non-autonomous system

    Indian Academy of Sciences (India)



    Additional sinusoidal and different non-sinusoidal periodic perturbations applied to the periodically forced nonlinear oscillators decide the maintainance or inhibitance of chaos. It is observed that the weak amplitude of the sinusoidal force without phase is sufficient to inhibit chaos rather than the other non-sinusoidal forces and sinusoidal force with phase. Apart from sinusoidal force without phase, i.e., from various non-sinusoidal forces and sinusoidal force with phase, square force seems to be an effective weak perturbation to suppress chaos. The effectiveness of weak perturbation for suppressing chaos is understood with the total power average of the external forces applied to the system. In any chaotic system, the total power average of the external forces isconstant and is different for different nonlinear systems. This total power average decides the nature of the force to suppress chaos in the sense of weak perturbation. This has been a universal phenomenon for all the chaoticnon-autonomous systems. The results are confirmed by Melnikov method and numerical analysis. With the help of the total power average technique, one can say whether the chaos in that nonlinear system is to be supppressed or not.

  3. Icodextrin improves metabolic and fluid management in high and high-average transport diabetic patients. (United States)

    Paniagua, Ramón; Ventura, María-de-Jesús; Avila-Díaz, Marcela; Cisneros, Alejandra; Vicenté-Martínez, Marlén; Furlong, María-Del-Carmen; García-González, Zuzel; Villanueva, Diana; Orihuela, Oscar; Prado-Uribe, María-Del-Carmen; Alcántara, Guadalupe; Amato, Dante


    Icodextrin-based solutions (ICO) have clinical and theoretical advantages over glucose-based solutions (GLU) in fluid and metabolic management of diabetic peritoneal dialysis (PD) patients; however, these advantages have not yet been tested in a randomized fashion. To analyze the effects of ICO on metabolic and fluid control in high and high-average transport diabetic patients on continuous ambulatory PD (CAPD). A 12-month, multicenter, open-label, randomized controlled trial was conducted to compare ICO (n = 30) versus GLU (n = 29) in diabetic CAPD patients with high-average and high peritoneal transport characteristics. The basic daily schedule was 3 x 2 L GLU (1.5%) and either 1 x 2 L ICO (7.5%) or 1 x 2 L GLU (2.5%) for the long-dwell exchange, with substitution of 2.5% or 4.25% for 1.5% GLU being allowed when clinically necessary. Variables related to metabolic and fluid control were measured each month. Groups were similar at baseline in all measured variables. More than 66% of the patients using GLU, but only 9% using ICO, needed prescriptions of higher glucose concentration solutions. Ultrafiltration (UF) was higher (198 +/- 101 mL/day, p ICO group than in the GLU group over time. Changes from baseline were more pronounced in the ICO group than in the GLU group for extracellular fluid volume (0.23 +/- 1.38 vs -1.0 +/- 1.48 L, p ICO group had better metabolic control than those in the GLU group: glucose absorption was more reduced (-17 +/- 44 vs -64 +/- 35 g/day) as were insulin needs (3.6 +/- 3.4 vs - 9.1 +/- 4.7 U/day, p ICO group had fewer adverse events related to fluid and glucose control than patients in the GLU group. Icodextrin represents a significant advantage in the management of high transport diabetic patients on PD, improving peritoneal UF and fluid control and reducing the burden of glucose overexposure, thereby facilitating metabolic control.

  4. High temperature, high power piezoelectric composite transducers. (United States)

    Lee, Hyeong Jae; Zhang, Shujun; Bar-Cohen, Yoseph; Sherrit, Stewart


    Piezoelectric composites are a class of functional materials consisting of piezoelectric active materials and non-piezoelectric passive polymers, mechanically attached together to form different connectivities. These composites have several advantages compared to conventional piezoelectric ceramics and polymers, including improved electromechanical properties, mechanical flexibility and the ability to tailor properties by using several different connectivity patterns. These advantages have led to the improvement of overall transducer performance, such as transducer sensitivity and bandwidth, resulting in rapid implementation of piezoelectric composites in medical imaging ultrasounds and other acoustic transducers. Recently, new piezoelectric composite transducers have been developed with optimized composite components that have improved thermal stability and mechanical quality factors, making them promising candidates for high temperature, high power transducer applications, such as therapeutic ultrasound, high power ultrasonic wirebonding, high temperature non-destructive testing, and downhole energy harvesting. This paper will present recent developments of piezoelectric composite technology for high temperature and high power applications. The concerns and limitations of using piezoelectric composites will also be discussed, and the expected future research directions will be outlined.

  5. High Temperature, High Power Piezoelectric Composite Transducers

    Directory of Open Access Journals (Sweden)

    Hyeong Jae Lee


    Full Text Available Piezoelectric composites are a class of functional materials consisting of piezoelectric active materials and non-piezoelectric passive polymers, mechanically attached together to form different connectivities. These composites have several advantages compared to conventional piezoelectric ceramics and polymers, including improved electromechanical properties, mechanical flexibility and the ability to tailor properties by using several different connectivity patterns. These advantages have led to the improvement of overall transducer performance, such as transducer sensitivity and bandwidth, resulting in rapid implementation of piezoelectric composites in medical imaging ultrasounds and other acoustic transducers. Recently, new piezoelectric composite transducers have been developed with optimized composite components that have improved thermal stability and mechanical quality factors, making them promising candidates for high temperature, high power transducer applications, such as therapeutic ultrasound, high power ultrasonic wirebonding, high temperature non-destructive testing, and downhole energy harvesting. This paper will present recent developments of piezoelectric composite technology for high temperature and high power applications. The concerns and limitations of using piezoelectric composites will also be discussed, and the expected future research directions will be outlined.

  6. On the averaging area for incident power density for human exposure limits at frequencies over 6 GHz (United States)

    Hashimoto, Yota; Hirata, Akimasa; Morimoto, Ryota; Aonuma, Shinta; Laakso, Ilkka; Jokela, Kari; Foster, Kenneth R.


    Incident power density is used as the dosimetric quantity to specify the restrictions on human exposure to electromagnetic fields at frequencies above 3 or 10 GHz in order to prevent excessive temperature elevation at the body surface. However, international standards and guidelines have different definitions for the size of the area over which the power density should be averaged. This study reports computational evaluation of the relationship between the size of the area over which incident power density is averaged and the local peak temperature elevation in a multi-layer model simulating a human body. Three wave sources are considered in the frequency range from 3 to 300 GHz: an ideal beam, a half-wave dipole antenna, and an antenna array. 1D analysis shows that averaging area of 20 mm  ×  20 mm is a good measure to correlate with the local peak temperature elevation when the field distribution is nearly uniform in that area. The averaging area is different from recommendations in the current international standards/guidelines, and not dependent on the frequency. For a non-uniform field distribution, such as a beam with small diameter, the incident power density should be compensated by multiplying a factor that can be derived from the ratio of the effective beam area to the averaging area. The findings in the present study suggest that the relationship obtained using the 1D approximation is applicable for deriving the relationship between the incident power density and the local temperature elevation.

  7. Average Transient Lifetime and Lyapunov Dimension for Transient Chaos in a High-Dimensional System

    Institute of Scientific and Technical Information of China (English)

    陈洪; 汤建新; 唐少炎; 向红; 陈新


    The average transient lifetime of a chaotic transient versus the Lyapunov dimension of a chaotic saddle is studied for high-dimensional nonlinear dynamical systems. Typically the average lifetime depends upon not only the system parameter but also the Lyapunov dimension of the chaotic saddle. The numerical example uses the delayed feedback differential equation.

  8. Frequency control in power systems with high wind power penetration

    Energy Technology Data Exchange (ETDEWEB)

    Tarnowski, German Claudio [Technical Univ. of Denmark (Denmark). Centre for Electric Technology; Vestas Wind Systems A/S, Alsve (Denmark); Kjaer, Philip Carne [Vestas Wind Systems A/S, Alsve (Denmark); Oestergaard, Jacob [Technical Univ. of Denmark (Denmark). Centre for Electric Technology; Soerensen, Poul E. [Risoe National Laboratory for Sustainable Energy, Roskilde (Denmark). Wind Energy Dept.


    The fluctuating nature of wind power introduces several challenges to reliable operation of power system. With high wind power penetration, conventional power plants are displaced and wind speed fluctuations introduce large power imbalances which lead to power system frequency control and operational problems. This paper analysis the impact of wind power in the frequency control of power systems for different amount of controllable variable speed wind turbines. Real measurements from short term wind power penetration tests in a power system are shown and used to study the amount of total regulating power needed from conventional power plants. Dynamic simulations with validated model of the power system support the studies. The paper also presents control concepts for wind power plants necessary to achieve characteristic of frequency response and active power balancing similarly to conventional power plants, therefore allowing higher wind power penetration. As the power system dependency on wind power increases, wind power generation has to contribute with dynamic response and control actions similarly to conventional power plants. (orig.)

  9. Average power density spectrum of Swift long gamma-ray bursts in the observer and in the source rest frames

    CERN Document Server

    Guidorzi, C; Amati, L; Campana, S; Orlandini, M; Romano, P; Stamatikos, M; Tagliaferri, G


    We calculate the average power density spectra (PDS) of 244 long gamma-ray bursts detected with the Swift Burst Alert Telescope in the 15-150 keV band from January 2005 to August 2011. For the first time we derived the average PDS in the source rest frame of 97 GRBs with known redshift. For 49 of them an average PDS was also obtained in a common source-frame energy band to account for the dependence of time profiles on energy. Previous results obtained on BATSE GRBs with unknown redshift showed that the average spectrum in the 25-2000 keV band could be modelled with a power-law with a 5/3 index over nearly two decades of frequency with a break at ~1 Hz. Depending on the normalisation and on the subset of GRBs considered, our results show analogous to steeper slopes (between 1.7 and 2.0) of the power-law. However, no clear evidence for the break at ~1 Hz was found, although the softer energy band of BAT compared with BATSE might account for that. We instead find a break at lower frequency corresponding to a ty...

  10. Vibrational resonance: a study with high-order word-series averaging

    CERN Document Server

    Murua, Ander


    We study a model problem describing vibrational resonance by means of a high-order averaging technique based on so-called word series. With the tech- nique applied here, the tasks of constructing the averaged system and the associ- ated change of variables are divided into two parts. It is first necessary to build recursively a set of so-called word basis functions and, after that, all the required manipulations involve only scalar coefficients that are computed by means of sim- ple recursions. As distinct from the situation with other approaches, with word- series, high-order averaged systems may be derived without having to compute the associated change of variables. In the system considered here, the construction of high-order averaged systems makes it possible to obtain very precise approxima- tions to the true dynamics.

  11. Validity of a Wearable Accelerometer Device to Measure Average Acceleration Values During High-Speed Running. (United States)

    Alexander, Jeremy P; Hopkinson, Trent L; Wundersitz, Daniel W T; Serpell, Benjamin G; Mara, Jocelyn K; Ball, Nick B


    Alexander, JP, Hopkinson, TL, Wundersitz, DWT, Serpell, BG, Mara, JK, and Ball, NB. Validity of a wearable accelerometer device to measure average acceleration values during high-speed running. J Strength Cond Res 30(11): 3007-3013, 2016-The aim of this study was to determine the validity of an accelerometer to measure average acceleration values during high-speed running. Thirteen subjects performed three sprint efforts over a 40-m distance (n = 39). Acceleration was measured using a 100-Hz triaxial accelerometer integrated within a wearable tracking device (SPI-HPU; GPSports). To provide a concurrent measure of acceleration, timing gates were positioned at 10-m intervals (0-40 m). Accelerometer data collected during 0-10 m and 10-20 m provided a measure of average acceleration values. Accelerometer data was recorded as the raw output and filtered by applying a 3-point moving average and a 10-point moving average. The accelerometer could not measure average acceleration values during high-speed running. The accelerometer significantly overestimated average acceleration values during both 0-10 m and 10-20 m, regardless of the data filtering technique (p < 0.001). Body mass significantly affected all accelerometer variables (p < 0.10, partial η = 0.091-0.219). Body mass and the absence of a gravity compensation formula affect the accuracy and practicality of accelerometers. Until GPSports-integrated accelerometers incorporate a gravity compensation formula, the usefulness of any accelerometer-derived algorithms is questionable.

  12. 340 W average power output of diode-pumped composite ceramic YAG/Nd:YAG disk laser (United States)

    Jia, Kai; Jiang, Yong; Yang, Feng; Deng, Bo; Hou, Tianjin; Guo, Jiawei; Chen, Dezhang; Wang, Hongyuan; Yang, Chuang; Peng, Chun


    We report on a diode-pumped composite ceramic disk laser in this paper. The composite ceramic YAG/Nd:YAG disk consists of 4 mm thick pure YAG and 2 mm thick Nd:YAG with 1.0 at.% doping concentration. The slope efficiency of the composite ceramic disk laser is 36.6% corresponding to the maximum optical-optical efficiency of 29.2%. Furthermore, 340 W average power output was achieved at the absorbed pump power of 1290 W.

  13. Preparation of high viscosity average molecular mass poly-L-lactide

    Institute of Scientific and Technical Information of China (English)

    ZHOU Zhi-hua; RUAN Jian-ming; ZOU Jian-peng; ZHOU Zhong-cheng; SHEN Xiong-jun


    Poly-L-lactide(PLLA) was synthesized by ring-opening polymerization from high purity L-lactide with tin octoate as initiator, and characterized by means of infrared, and 1H-nuclear magnetic resonance. The influences of initiator concentration,polymerization temperature and polymerization time on the viscosity average molecular mass of PLLA were investigated. The effects of different purification methods on the concentration of initiator and viscosity average molecular mass were also studied. PLLA with a viscosity average molecular mass of about 50.5×104 was obtained when polymerization was conducted for 24 h at 140 ℃ with the molar ratio of monomer to purification initator being 12 000. After purification, the concentration of tin octoate decreases; however,the effect of different purification methods on the viscosity average molecular mass of PLLA is different, and the obtained PLLA is a typical amorphous polymeric material. The crystallinity of PLLA decreases with the increase of viscosity average molecular mass.

  14. Electric Vehicles for Improved Operation of Power Systems with High Wind Power Penetration

    DEFF Research Database (Denmark)

    Larsen, Esben; Chandrashekhara, Divya K; Østergaard, Jacob


    In a power system with a high share of wind energy the wind fluctuation causes a variation in the power generation, which must be compensated from other sources. The situation in Denmark with a penetration of more than 20% wind in yearly average is presented. The introduction of electric drive ve...

  15. High power, high beam quality regenerative amplifier (United States)

    Hackel, L.A.; Dane, C.B.


    A regenerative laser amplifier system generates high peak power and high energy per pulse output beams enabling generation of X-rays used in X-ray lithography for manufacturing integrated circuits. The laser amplifier includes a ring shaped optical path with a limited number of components including a polarizer, a passive 90 degree phase rotator, a plurality of mirrors, a relay telescope, and a gain medium, the components being placed close to the image plane of the relay telescope to reduce diffraction or phase perturbations in order to limit high peak intensity spiking. In the ring, the beam makes two passes through the gain medium for each transit of the optical path to increase the amplifier gain to loss ratio. A beam input into the ring makes two passes around the ring, is diverted into an SBS phase conjugator and proceeds out of the SBS phase conjugator back through the ring in an equal but opposite direction for two passes, further reducing phase perturbations. A master oscillator inputs the beam through an isolation cell (Faraday or Pockels) which transmits the beam into the ring without polarization rotation. The isolation cell rotates polarization only in beams proceeding out of the ring to direct the beams out of the amplifier. The diffraction limited quality of the input beam is preserved in the amplifier so that a high power output beam having nearly the same diffraction limited quality is produced.

  16. High-power pulsed lasers

    Energy Technology Data Exchange (ETDEWEB)

    Holzrichter, J.F.


    The ideas that led to the successful construction and operation of large multibeam fusion lasers at the Lawrence Livermore Laboratory are reviewed. These lasers are based on the use of Nd:glass laser materials. However, most of the concepts are applicable to any laser being designed for fusion experimentation. This report is a summary of lectures given by the author at the 20th Scottish University Summer School in Physics, on Laser Plasma Interaction. This report includes basic concepts of the laser plasma system, a discussion of lasers that are useful for short-pulse, high-power operation, laser design constraints, optical diagnostics, and system organization.

  17. Crimes and the Bell Curve: The Role of People with High, Average, and Low Intelligence


    Burhan, Nik Ahmad Sufian; Kurniawan, Yohan; Sidek, Abdul Halim; Mohamad, Mohd Rosli


    The present study examines whether crime rates can be reduced by increasing the IQ of people with high, average, and low IQ. Previous studies have shown that as a determinant of the national level of income per capita growth and technological achievement, the IQ of the intellectual class (those at the 95th percentile of the Bell curve distribution of population intelligence) is more important than the IQ of those with average ability at the 50th percentile. Extending these findings, our study...

  18. Debugging on High-voltage Power Supply,Focusing Power Supply and Magnetic Field Power Supply

    Institute of Scientific and Technical Information of China (English)

    TU; Rui


    High-voltage power supply,focusing power supply and magnetic field power supply are the main parts of the power supply system of the EMIS(Electro-Magnetic Isotope Separator)supplying the ion source.In 2015,a high-voltage power supply,power supply for focusing and

  19. Femtosecond pulses at 50-W average power from an Yb:YAG planar waveguide amplifier seeded by an Yb:KYW oscillator. (United States)

    Leburn, Christopher G; Ramírez-Corral, Cristtel Y; Thomson, Ian J; Hall, Denis R; Baker, Howard J; Reid, Derryck T


    We report the demonstration of a high-power single-side-pumped Yb:YAG planar waveguide amplifier seeded by an Yb:KYW femtosecond laser. Five passes through the amplifier yielded 700-fs pulses with average powers of 50 W at 1030 nm. A numerical simulation of the amplifier implied values for the laser transition saturation intensity, the small-signal intensity gain coefficient and the gain bandwidth of 10.0 kW cm(-2), 1.6 cm(-1), and 3.7 nm respectively, and identified gain-narrowing as the dominant pulse-shaping mechanism.

  20. The Mercury Laser System-A scaleable average-power laser for fusion and beyond

    Energy Technology Data Exchange (ETDEWEB)

    Ebbers, C A; Moses, E I


    Nestled in a valley between the whitecaps of the Pacific and the snowcapped crests of the Sierra Nevada, Lawrence Livermore National Laboratory (LLNL) is home to the nearly complete National Ignition Facility (NIF). The purpose of NIF is to create a miniature star-on demand. An enormous amount of laser light energy (1.8 MJ in a pulse that is 20 ns in duration) will be focused into a small gold cylinder approximately the size of a pencil eraser. Centered in the gold cylinder (or hohlraum) will be a nearly perfect sphere filled with a complex mixture of hydrogen gas isotopes that is similar to the atmosphere of our Sun. During experiments, the laser light will hit the inside of the gold cylinder, heating the metal until it emits X-rays (similar to how your electric stove coil emits visible red light when heated). The X-rays will be used to compress the hydrogen-like gas with such pressure that the gas atoms will combine or 'fuse' together, producing the next heavier element (helium) and releasing energy in the form of energetic particles. 2010 will mark the first credible attempt at this world-changing event: the achievement of fusion energy 'break-even' on Earth using NIF, the world's largest laser! NIF is anticipated to eventually perform this immense technological accomplishment once per week, with the capability of firing up to six shots per day - eliminating the need for continued underground testing of our nation's nuclear stockpile, in addition to opening up new realms of science. But what about the day after NIF achieves ignition? Although NIF will achieve fusion energy break-even and gain, the facility is not designed to harness the enormous potential of fusion for energy generation. A fusion power plant, as opposed to a world-class engineering research facility, would require that the laser deliver drive pulses nearly 100,000 times more frequently - a rate closer to 10 shots per second as opposed to several shots per day.

  1. Development of a high average current polarized electron source with long cathode operational lifetime

    Energy Technology Data Exchange (ETDEWEB)

    C. K. Sinclair; P. A. Adderley; B. M. Dunham; J. C. Hansknecht; P. Hartmann; M. Poelker; J. S. Price; P. M. Rutt; W. J. Schneider; M. Steigerwald


    Substantially more than half of the electromagnetic nuclear physics experiments conducted at the Continuous Electron Beam Accelerator Facility of the Thomas Jefferson National Accelerator Facility (Jefferson Laboratory) require highly polarized electron beams, often at high average current. Spin-polarized electrons are produced by photoemission from various GaAs-based semiconductor photocathodes, using circularly polarized laser light with photon energy slightly larger than the semiconductor band gap. The photocathodes are prepared by activation of the clean semiconductor surface to negative electron affinity using cesium and oxidation. Historically, in many laboratories worldwide, these photocathodes have had short operational lifetimes at high average current, and have often deteriorated fairly quickly in ultrahigh vacuum even without electron beam delivery. At Jefferson Lab, we have developed a polarized electron source in which the photocathodes degrade exceptionally slowly without electron emission, and in which ion back bombardment is the predominant mechanism limiting the operational lifetime of the cathodes during electron emission. We have reproducibly obtained cathode 1/e dark lifetimes over two years, and 1/e charge density and charge lifetimes during electron beam delivery of over 2?105???C/cm2 and 200 C, respectively. This source is able to support uninterrupted high average current polarized beam delivery to three experimental halls simultaneously for many months at a time. Many of the techniques we report here are directly applicable to the development of GaAs photoemission electron guns to deliver high average current, high brightness unpolarized beams.

  2. Optimization and Annual Average Power Predictions of a Backward Bent Duct Buoy Oscillating Water Column Device Using the Wells Turbine.

    Energy Technology Data Exchange (ETDEWEB)

    Smith, Christopher S. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Bull, Diana L [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Willits, Steven M. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Fontaine, Arnold A. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)


    This Technical Report presents work completed by The Applied Research Laboratory at The Pennsylvania State University, in conjunction with Sandia National Labs, on the optimization of the power conversion chain (PCC) design to maximize the Average Annual Electric Power (AAEP) output of an Oscillating Water Column (OWC) device. The design consists of two independent stages. First, the design of a floating OWC, a Backward Bent Duct Buoy (BBDB), and second the design of the PCC. The pneumatic power output of the BBDB in random waves is optimized through the use of a hydrodynamically coupled, linear, frequency-domain, performance model that links the oscillating structure to internal air-pressure fluctuations. The PCC optimization is centered on the selection and sizing of a Wells Turbine and electric power generation equipment. The optimization of the PCC involves the following variables: the type of Wells Turbine (fixed or variable pitched, with and without guide vanes), the radius of the turbine, the optimal vent pressure, the sizing of the power electronics, and number of turbines. Also included in this Technical Report are further details on how rotor thrust and torque are estimated, along with further details on the type of variable frequency drive selected.

  3. Free-space optical communications with peak and average constraints: High SNR capacity approximation

    KAUST Repository

    Chaaban, Anas


    The capacity of the intensity-modulation direct-detection (IM-DD) free-space optical channel with both average and peak intensity constraints is studied. A new capacity lower bound is derived by using a truncated-Gaussian input distribution. Numerical evaluation shows that this capacity lower bound is nearly tight at high signal-to-noise ratio (SNR), while it is shown analytically that the gap to capacity upper bounds is a small constant at high SNR. In particular, the gap to the high-SNR asymptotic capacity of the channel under either a peak or an average constraint is small. This leads to a simple approximation of the high SNR capacity. Additionally, a new capacity upper bound is derived using sphere-packing arguments. This bound is tight at high SNR for a channel with a dominant peak constraint.

  4. Cooperative AF Relaying in Spectrum-Sharing Systems: Performance Analysis under Average Interference Power Constraints and Nakagami-m Fading

    KAUST Repository

    Xia, Minghua


    Since the electromagnetic spectrum resource becomes more and more scarce, improving spectral efficiency is extremely important for the sustainable development of wireless communication systems and services. Integrating cooperative relaying techniques into spectrum-sharing cognitive radio systems sheds new light on higher spectral efficiency. In this paper, we analyze the end-to-end performance of cooperative amplify-and-forward (AF) relaying in spectrum-sharing systems. In order to achieve the optimal end-to-end performance, the transmit powers of the secondary source and the relays are optimized with respect to average interference power constraints at primary users and Nakagami-$m$ fading parameters of interference channels (for mathematical tractability, the desired channels from secondary source to relay and from relay to secondary destination are assumed to be subject to Rayleigh fading). Also, both partial and opportunistic relay-selection strategies are exploited to further enhance system performance. Based on the exact distribution functions of the end-to-end signal-to-noise ratio (SNR) obtained herein, the outage probability, average symbol error probability, diversity order, and ergodic capacity of the system under study are analytically investigated. Our results show that system performance is dominated by the resource constraints and it improves slowly with increasing average SNR. Furthermore, larger Nakagami-m fading parameter on interference channels deteriorates system performance slightly. On the other hand, when interference power constraints are stringent, opportunistic relay selection can be exploited to improve system performance significantly. All analytical results are corroborated by simulation results and they are shown to be efficient tools for exact evaluation of system performance.

  5. Problem-Solving Processes of High and Average Performers in Physics. (United States)

    Coleman, Elaine B.; Shore, Bruce


    This study examined the problem-solving protocols of 21 students in a grade 11 enriched physics course as well as 3 adult "experts" in physics. Experts and high performing students made more correct metastatements and more references to prior knowledge than did average performing students. (DB)

  6. Total Quality Management (TQM) Practices and School Climate amongst High, Average and Low Performance Secondary Schools (United States)

    Ismail, Siti Noor


    Purpose: This study attempted to determine whether the dimensions of TQM practices are predictors of school climate. It aimed to identify the level of TQM practices and school climate in three different categories of schools, namely high, average and low performance schools. The study also sought to examine which dimensions of TQM practices…

  7. Sliding Mode Pulsed Averaging IC Drivers for High Brightness Light Emitting Diodes

    Energy Technology Data Exchange (ETDEWEB)

    Dr. Anatoly Shteynberg, PhD


    This project developed new Light Emitting Diode (LED) driver ICs associated with specific (uniquely operated) switching power supplies that optimize performance for High Brightness LEDs (HB-LEDs). The drivers utilize a digital control core with a newly developed nonlinear, hysteretic/sliding mode controller with mixed-signal processing. The drivers are flexible enough to allow both traditional microprocessor interface as well as other options such as “on the fly” adjustment of color and brightness. Some other unique features of the newly developed drivers include • AC Power Factor Correction; • High power efficiency; • Substantially fewer external components should be required, leading to substantial reduction of Bill of Materials (BOM). Thus, the LED drivers developed in this research : optimize LED performance by increasing power efficiency and power factor. Perhaps more remarkably, the LED drivers provide this improved performance at substantially reduced costs compared to the present LED power electronic driver circuits. Since one of the barriers to market penetration for HB-LEDs (in particular “white” light LEDs) is cost/lumen, this research makes important contributions in helping the advancement of SSL consumer acceptance and usage.

  8. Optics assembly for high power laser tools (United States)

    Fraze, Jason D.; Faircloth, Brian O.; Zediker, Mark S.


    There is provided a high power laser rotational optical assembly for use with, or in high power laser tools for performing high power laser operations. In particular, the optical assembly finds applications in performing high power laser operations on, and in, remote and difficult to access locations. The optical assembly has rotational seals and bearing configurations to avoid contamination of the laser beam path and optics.

  9. Optics assembly for high power laser tools

    Energy Technology Data Exchange (ETDEWEB)

    Fraze, Jason D.; Faircloth, Brian O.; Zediker, Mark S.


    There is provided a high power laser rotational optical assembly for use with, or in high power laser tools for performing high power laser operations. In particular, the optical assembly finds applications in performing high power laser operations on, and in, remote and difficult to access locations. The optical assembly has rotational seals and bearing configurations to avoid contamination of the laser beam path and optics.

  10. Relationship Between Selected Strength and Power Assessments to Peak and Average Velocity of the Drive Block in Offensive Line Play. (United States)

    Jacobson, Bert H; Conchola, Eric C; Smith, Doug B; Akehi, Kazuma; Glass, Rob G


    Jacobson, BH, Conchola, EC, Smith, DB, Akehi, K, and Glass, RG. Relationship between selected strength and power assessments to peak and average velocity of the drive block in offensive line play. J Strength Cond Res 30(8): 2202-2205, 2016-Typical strength training for football includes the squat and power clean (PC) and routinely measured variables include 1 repetition maximum (1RM) squat and 1RM PC along with the vertical jump (VJ) for power. However, little research exists regarding the association between the strength exercises and velocity of an actual on-the-field performance. The purpose of this study was to investigate the relationship of peak velocity (PV) and average velocity (AV) of the offensive line drive block to 1RM squat, 1RM PC, the VJ, body mass (BM), and body composition. One repetition maximum assessments for the squat and PC were recorded along with VJ height, BM, and percent body fat. These data were correlated with PV and AV while performing the drive block. Peal velocity and AV were assessed using a Tendo Power and Speed Analyzer as the linemen fired, from a 3-point stance into a stationary blocking dummy. Pearson product analysis yielded significant (p ≤ 0.05) correlations between PV and AV and the VJ, the squat, and the PC. A significant inverse association was found for both PV and AV and body fat. These data help to confirm that the typical exercises recommended for American football linemen is positively associated with both PV and AV needed for the drive block effectiveness. It is recommended that these exercises remain the focus of a weight room protocol and that ancillary exercises be built around these exercises. Additionally, efforts to reduce body fat are recommended.

  11. High-frequency averaging in semi-classical Hartree-type equations

    CERN Document Server

    Giannoulis, Johannes; Sparber, Christof


    We investigate the asymptotic behavior of solutions to semi-classical Schroedinger equations with nonlinearities of Hartree type. For a weakly nonlinear scaling, we show the validity of an asymptotic superposition principle for slowly modulated highly oscillatory pulses. The result is based on a high-frequency averaging effect due to the nonlocal nature of the Hartree potential, which inhibits the creation of new resonant waves. In the proof we make use of the framework of Wiener algebras.

  12. A Study on Estimation of Average Power Output Fluctuation of Clustered Photovoltaic Power Generation Systems in Urban District of a Few km2 (United States)

    Kato, Takeyoshi; Suzuoki, Yasuo

    The fluctuation of the total power output of clustered PV systems would be smaller than that of single PV system because of the time difference in the power output fluctuation among PV systems at different locations. This effect, so called smoothing-effect, must be taken into account properly when the impact of clustered PV systems on electric power system is assessed. If the average power output of clustered PV systems can be estimated from the power output of single PV system, it is very useful and helpful for the impact assessment. In this study, we propose a simple method to estimate the total power output fluctuation of clustered PV systems. In the proposed method, a smoothing effect is assumed to be caused as a result of two factors, i.e. time difference of overhead clouds passing among PV systems and the random change in the size and/or shape of clouds. The first one is formulated as a low-pass filter, assuming that output fluctuation is transmitted to the same direction as the wind direction at the constant speed. The second one is taken into account by using a Fourier transform surrogate data. The parameters in the proposed method were selected, so that the estimated fluctuation can be similar with that of ensemble average fluctuation of data observed at 5 points used as a training data set. Then, by using the selected parameters, the fluctuation property was estimated for other data set. The results show that the proposed method is useful for estimating the total power output fluctuation of clustered PV systems.

  13. Computing High Accuracy Power Spectra with Pico

    CERN Document Server

    Fendt, William A


    This paper presents the second release of Pico (Parameters for the Impatient COsmologist). Pico is a general purpose machine learning code which we have applied to computing the CMB power spectra and the WMAP likelihood. For this release, we have made improvements to the algorithm as well as the data sets used to train Pico, leading to a significant improvement in accuracy. For the 9 parameter nonflat case presented here Pico can on average compute the TT, TE and EE spectra to better than 1% of cosmic standard deviation for nearly all $\\ell$ values over a large region of parameter space. Performing a cosmological parameter analysis of current CMB and large scale structure data, we show that these power spectra give very accurate 1 and 2 dimensional parameter posteriors. We have extended Pico to allow computation of the tensor power spectrum and the matter transfer function. Pico runs about 1500 times faster than CAMB at the default accuracy and about 250,000 times faster at high accuracy. Training Pico can be...

  14. Review of Power System Stability with High Wind Power Penetration

    DEFF Research Database (Denmark)

    Hu, Rui; Hu, Weihao; Chen, Zhe


    analyzing methods and stability improvement approaches. With increasing wind power penetration, system balancing and the reduced inertia may cause a big threaten for stable operation of power systems. To mitigate or eliminate the wind impacts for high wind penetration systems, although the practical......This paper presents an overview of researches on power system stability with high wind power penetration including analyzing methods and improvement approaches. Power system stability issues can be classified diversely according to different considerations. Each classified issue has special...... and reliable choices currently are the strong outside connections or sufficient reserve capacity constructions, many novel theories and approaches are invented to investigate the stability issues, looking forward to an extra-high penetration or totally renewable resource based power systems. These analyzing...

  15. Wavelength and average power density dependency of the recrystallization of tooth dentin using a MIR-FEL (United States)

    Heya, Manabu; Awazu, Kunio


    Recrystallization of tooth dentin by the application of mid- infrared (MIR) pulsed-laser irradiation is one candidate for a novel, non-invasive treatment for the prevention of tooth decay. Recrystallized dentin functions in a similar way to dental enamel. To recrystallize the dentin effectively and non-invasively it is essential to estimate quantitatively and qualitatively the laser parameters, such as the wavelength and the average power density, required for recrystallization. The laser-tissue interaction is initiated effectively by selective excitation of phosphate acid ions (PO4) in the dentin. Using a tunable, MIR Free Electron Laser (FEL) in the wavelength region of 8.8- 10.6micrometers , corresponding to intense absorption bands due to PO4 vibration modes, we have investigated macroscopically extent of surface modification of dentin, and we have obtained experimental results related to the ablation depth, the MIR absorption spectrum, and the elemental chemical composition. From these results, it was found that (1) the laser parameters at which efficient surface modification, without enhanced ablation effects, occurred were estimated to be approximately in the wavelength and average power density regions of ~9.4- 10.3micrometers and ~10-20 W/cm2, and that (2) in this region PO4 vibration modes with lower binding energy were preferentially excluded from the dentin.

  16. Development of a high average current polarized electron source with long cathode operational lifetime

    Directory of Open Access Journals (Sweden)

    C. K. Sinclair


    Full Text Available Substantially more than half of the electromagnetic nuclear physics experiments conducted at the Continuous Electron Beam Accelerator Facility of the Thomas Jefferson National Accelerator Facility (Jefferson Laboratory require highly polarized electron beams, often at high average current. Spin-polarized electrons are produced by photoemission from various GaAs-based semiconductor photocathodes, using circularly polarized laser light with photon energy slightly larger than the semiconductor band gap. The photocathodes are prepared by activation of the clean semiconductor surface to negative electron affinity using cesium and oxidation. Historically, in many laboratories worldwide, these photocathodes have had short operational lifetimes at high average current, and have often deteriorated fairly quickly in ultrahigh vacuum even without electron beam delivery. At Jefferson Lab, we have developed a polarized electron source in which the photocathodes degrade exceptionally slowly without electron emission, and in which ion back bombardment is the predominant mechanism limiting the operational lifetime of the cathodes during electron emission. We have reproducibly obtained cathode 1/e dark lifetimes over two years, and 1/e charge density and charge lifetimes during electron beam delivery of over 2×10^{5}   C/cm^{2} and 200 C, respectively. This source is able to support uninterrupted high average current polarized beam delivery to three experimental halls simultaneously for many months at a time. Many of the techniques we report here are directly applicable to the development of GaAs photoemission electron guns to deliver high average current, high brightness unpolarized beams.

  17. High power parallel ultrashort pulse laser processing (United States)

    Gillner, Arnold; Gretzki, Patrick; Büsing, Lasse


    The class of ultra-short-pulse (USP) laser sources are used, whenever high precession and high quality material processing is demanded. These laser sources deliver pulse duration in the range of ps to fs and are characterized with high peak intensities leading to a direct vaporization of the material with a minimum thermal damage. With the availability of industrial laser source with an average power of up to 1000W, the main challenge consist of the effective energy distribution and disposition. Using lasers with high repetition rates in the MHz region can cause thermal issues like overheating, melt production and low ablation quality. In this paper, we will discuss different approaches for multibeam processing for utilization of high pulse energies. The combination of diffractive optics and conventional galvometer scanner can be used for high throughput laser ablation, but are limited in the optical qualities. We will show which applications can benefit from this hybrid optic and which improvements in productivity are expected. In addition, the optical limitations of the system will be compiled, in order to evaluate the suitability of this approach for any given application.

  18. High-power FEL design issues - a critical review

    Energy Technology Data Exchange (ETDEWEB)

    Litvinenko, V.N.; Madey, J.M.J.; O`Shea, P.G. [Duke Univ., Durham, NC (United States)


    The high-average power capability of FELs has been much advertised but little realized. In this paper we provide a critical analysis of the technological and economic issues associated with high-average power FEL operation from the UV to near IR. The project of IR FEL for the Siberian Center of photochemical researches is described. The distinguished features of this project are the use of the race-track microtron-recuperator and the {open_quotes}electron output of radiation{close_quotes}. The building for the machine is under reconstruction now. About half of hardware has been manufactured. The assembly of installation began.

  19. Air-clad chirally-coupled-core Yb-fiber femtosecond oscillator with >10W average power

    Directory of Open Access Journals (Sweden)

    Ma Xiuquan


    Full Text Available We demonstrate high-power (> 10 W, 300-fs mode-locked oscillators at 83-MHz repetition rate using air-clad Chirally-Coupled-Core Yb-fiber with 37-µm central-core diameter, corresponding to a 30-µm mode-field-diameter.

  20. Low-power CMOS fully-folding ADC with a mixed-averaging distributed T/H circuit

    Institute of Scientific and Technical Information of China (English)

    Liu Zhen; Jia Song; Wang Yuan; Ji Lijiu; Zhang Xing


    This paper describes an 8-bit 125 Mhzlow-powerCMOS fully-foldinganalog-to-digital converter(ADC).A novel mixed-averaging distributed T/H circuit is proposed to improve the accuracy. Folding circuits are not only used in the fine converter but also in the coarse one and in the bit synchronization block to reduce the number of comparators for low power. This ADC is implemented in 0.5μm CMOS technology and occupies a die area of 2 × 1.5 mm~2. The measured differential nonlinearity and integral nonlinearity are 0.6 LSB/-0.8 LSB and 0.9 LSB/-1.2 LSB, respectively. The ADC exhibits 44.3 dB of signal-to-noise plus distortion ratio and 53.5 dB of spurious-free dynamic range for 1 MHz input sine-wave. The power dissipation is 138 mW at a sampling rate of 125 MHz at a 5 V supply.

  1. Electronic DC transformer with high power density

    NARCIS (Netherlands)

    Pavlovský, M.


    This thesis is concerned with the possibilities of increasing the power density of high-power dc-dc converters with galvanic isolation. Three cornerstones for reaching high power densities are identified as: size reduction of passive components, reduction of losses particularly in active components

  2. High Power Fiber Laser Test Bed (United States)

    Federal Laboratory Consortium — This facility, unique within DoD, power-combines numerous cutting-edge fiber-coupled laser diode modules (FCLDM) to integrate pumping of high power rare earth-doped...

  3. High power RF solid state power amplifier system (United States)

    Sims, III, William Herbert (Inventor); Chavers, Donald Gregory (Inventor); Richeson, James J. (Inventor)


    A high power, high frequency, solid state power amplifier system includes a plurality of input multiple port splitters for receiving a high-frequency input and for dividing the input into a plurality of outputs and a plurality of solid state amplifier units. Each amplifier unit includes a plurality of amplifiers, and each amplifier is individually connected to one of the outputs of multiport splitters and produces a corresponding amplified output. A plurality of multiport combiners combine the amplified outputs of the amplifiers of each of the amplifier units to a combined output. Automatic level control protection circuitry protects the amplifiers and maintains a substantial constant amplifier power output.

  4. High Power Performance of Rod Fiber Amplifiers

    DEFF Research Database (Denmark)

    Johansen, Mette Marie; Michieletto, Mattia; Kristensen, Torben


    An improved version of the DMF rod fiber is tested in a high power setup delivering 360W of stable signal power. Multiple testing degrades the fiber and transverse modal instability threshold from >360W to ~290W.......An improved version of the DMF rod fiber is tested in a high power setup delivering 360W of stable signal power. Multiple testing degrades the fiber and transverse modal instability threshold from >360W to ~290W....

  5. Cutting-Edge High-Power Ultrafast Thin Disk Oscillators

    Directory of Open Access Journals (Sweden)

    Thomas Südmeyer


    Full Text Available A growing number of applications in science and industry are currently pushing the development of ultrafast laser technologies that enable high average powers. SESAM modelocked thin disk lasers (TDLs currently achieve higher pulse energies and average powers than any other ultrafast oscillator technology, making them excellent candidates in this goal. Recently, 275 W of average power with a pulse duration of 583 fs were demonstrated, which represents the highest average power so far demonstrated from an ultrafast oscillator. In terms of pulse energy, TDLs reach more than 40 μJ pulses directly from the oscillator. In addition, another major milestone was recently achieved, with the demonstration of a TDL with nearly bandwidth-limited 96-fs long pulses. The progress achieved in terms of pulse duration of such sources enabled the first measurement of the carrier-envelope offset frequency of a modelocked TDL, which is the first key step towards full stabilization of such a source. We will present the key elements that enabled these latest results, as well as an outlook towards the next scaling steps in average power, pulse energy and pulse duration of such sources. These cutting-edge sources will enable exciting new applications, and open the door to further extending the current performance milestones.

  6. High-speed Power Line Communications

    Directory of Open Access Journals (Sweden)

    Matthew N. O. Sadiku,


    Full Text Available This is the idea of using existing power lines for communication purposes. Power line communications (PLC enables network communication of voice, data, and video over direct power lines. High-speed PLC involves data rates in excess of 10 Mbps. PLC has attracted a lot of attention and has become an interesting subject of research lately.

  7. Incidence Rates of Clinical Mastitis among Canadian Holsteins Classified as High, Average, or Low Immune Responders (United States)

    Miglior, Filippo; Mallard, Bonnie A.


    The objective of this study was to compare the incidence rate of clinical mastitis (IRCM) between cows classified as high, average, or low for antibody-mediated immune responses (AMIR) and cell-mediated immune responses (CMIR). In collaboration with the Canadian Bovine Mastitis Research Network, 458 lactating Holsteins from 41 herds were immunized with a type 1 and a type 2 test antigen to stimulate adaptive immune responses. A delayed-type hypersensitivity test to the type 1 test antigen was used as an indicator of CMIR, and serum antibody of the IgG1 isotype to the type 2 test antigen was used for AMIR determination. By using estimated breeding values for these traits, cows were classified as high, average, or low responders. The IRCM was calculated as the number of cases of mastitis experienced over the total time at risk throughout the 2-year study period. High-AMIR cows had an IRCM of 17.1 cases per 100 cow-years, which was significantly lower than average and low responders, with 27.9 and 30.7 cases per 100 cow-years, respectively. Low-AMIR cows tended to have the most severe mastitis. No differences in the IRCM were noted when cows were classified based on CMIR, likely due to the extracellular nature of mastitis-causing pathogens. The results of this study demonstrate the desirability of breeding dairy cattle for enhanced immune responses to decrease the incidence and severity of mastitis in the Canadian dairy industry. PMID:23175290

  8. Design concept and performance considerations for fast high power semiconductor switching for high repetition rate and high power excimer laser (United States)

    Goto, Tatsumi; Kakizaki, Kouji; Takagi, Shigeyuki; Satoh, Saburoh; Shinohe, Takashi; Ohashi, Hiromichi; Endo, Fumihiko; Okamura, Katsuya; Ishii, Akira; Teranishi, Tsuneharu; Yasuoka, Koichi


    A semiconductor switching power supply has been developed, in which a novel structure semiconductor device, metal-oxide-semiconductor assisted gate-triggered thyristor (MAGT) was incorporated with a single stage magnetic pulse compression circuit (MPC). The MAGT was specially designed to directly replace thyratrons in a power supply for a high repetition rate laser. Compared with conventional high power semiconductor switching devices, it was designed to enable a fast switching, retaining a high blocking voltage and to extremely reduce the transient turn-on power losses, enduring a higher peak current. A maximum peak current density of 32 kA/cm2 and a current density risetime rate di/dt of 142 kA/(cm2×μs) were obtained at the chip area with an applied anode voltage of 1.5 kV. A MAGT switching unit connecting 32 MAGTs in series was capable of switching on more than 25 kV-300 A at a repetition rate of 5 kHz, which, coupled with the MPC, was equivalent to the capability of a high power thyratron. A high repetition rate and high power XeCl excimer laser was excited by the power supply. The results confirmed the stable laser operation of a repetition rate of up to 5 kHz, the world record to our knowledge. An average output power of 0.56 kW was obtained at 5 kHz where the shortage of the total discharge current was subjoined by a conventional power supply with seven parallel switching thyratrons, simultaneously working, for the MAGT power supply could not switch a greater current than that switched by one thyratron. It was confirmed by those excitations that the MAGT unit with the MPC could replace a high power commercial thyratron directly for excimer lasers. The switching stability was significantly superior to that of the thyratron in a high repetition rate region, judging from the discharge current wave forms. It should be possible for the MAGT unit, in the future, to directly switch the discharge current within a rise time of 0.1 μs with a magnetic assist.

  9. Highly Efficient Transmitter for High Peak to Average Power Ratio (PAPR) Waveforms (United States)


    oscillator ( VCO ). Based on the frequency specified by the user, the PLL is set for the appropriate RF frequency and locks the VCO to it defining the...buffered output reference frequency from the internal PLL/ VCO frequency synthesizer which is used in the on-chip mixers. For applications between 30MHz...Inc., Rcv.A, 2010 [6]: TRF372017 Product Datasheet, "Integrated IQ Modulator PLL/ VCO ", Texas Instruments Inc., SLWS224A, 2010 [7]: ADS5474 Product

  10. Development and significance of a fetal electrocardiogram recorded by signal-averaged high-amplification electrocardiography. (United States)

    Hayashi, Risa; Nakai, Kenji; Fukushima, Akimune; Itoh, Manabu; Sugiyama, Toru


    Although ultrasonic diagnostic imaging and fetal heart monitors have undergone great technological improvements, the development and use of fetal electrocardiograms to evaluate fetal arrhythmias and autonomic nervous activity have not been fully established. We verified the clinical significance of the novel signal-averaged vector-projected high amplification ECG (SAVP-ECG) method in fetuses from 48 gravidas at 32-41 weeks of gestation and in 34 neonates. SAVP-ECGs from fetuses and newborns were recorded using a modified XYZ-leads system. Once noise and maternal QRS waves were removed, the P, QRS, and T wave intervals were measured from the signal-averaged fetal ECGs. We also compared fetal and neonatal heart rates (HRs), coefficients of variation of heart rate variability (CV) as a parasympathetic nervous activity, and the ratio of low to high frequency (LF/HF ratio) as a sympathetic nervous activity. The rate of detection of a fetal ECG by SAVP-ECG was 72.9%, and the fetal and neonatal QRS and QTc intervals were not significantly different. The neonatal CVs and LF/HF ratios were significantly increased compared with those in the fetus. In conclusion, we have developed a fetal ECG recording method using the SAVP-ECG system, which we used to evaluate autonomic nervous system development.

  11. High Power/High Temperature Battery Development (United States)


    dcruit stand The bipolar conliguration permits cello be closely packed, share cell walls, and combine the functions of wall and intercell connector. The...LUthco Symp. on Lithium Chem., Ed. R. Bach , John Wiley and Sons, N.Y. M. Wliams, st. al., Proc. 32nd Power Sources Conf., p 658 If (1986). C.D...on Electron Devices ATTN: Documents 2011 Crystal Drive, Suite 307 002 Adington, VA 22202 Page 43 Plop 2 O nlPage Elstronlo Technooyand DvcsLaomtory

  12. Packaging of high power semiconductor lasers

    CERN Document Server

    Liu, Xingsheng; Xiong, Lingling; Liu, Hui


    This book introduces high power semiconductor laser packaging design. The characteristics and challenges of the design and various packaging, processing, and testing techniques are detailed by the authors. New technologies, in particular thermal technologies, current applications, and trends in high power semiconductor laser packaging are described at length and assessed.

  13. High power laser perforating tools and systems (United States)

    Zediker, Mark S; Rinzler, Charles C; Faircloth, Brian O; Koblick, Yeshaya; Moxley, Joel F


    ystems devices and methods for the transmission of 1 kW or more of laser energy deep into the earth and for the suppression of associated nonlinear phenomena. Systems, devices and methods for the laser perforation of a borehole in the earth. These systems can deliver high power laser energy down a deep borehole, while maintaining the high power to perforate such boreholes.

  14. Evolution of Very High Frequency Power Supplies

    DEFF Research Database (Denmark)

    Knott, Arnold; Andersen, Toke Meyer; Kamby, Peter


    in radio frequency transmission equipment helps to overcome those. However those circuits were not designed to meet the same requirements as power converters. This paper summarizes the contributions in recent years in application of very high frequency (VHF) technologies in power electronics, shows results......The ongoing demand for smaller and lighter power supplies is driving the motivation to increase the switching frequencies of power converters. Drastic increases however come along with new challenges, namely the increase of switching losses in all components. The application of power circuits used...

  15. High-power optics lasers and applications

    CERN Document Server

    Apollonov, Victor V


    This book covers the basics, realization and materials for high power laser systems and high power radiation interaction with  matter. The physical and technical fundamentals of high intensity laser optics and adaptive optics and the related physical processes in high intensity laser systems are explained. A main question discussed is: What is power optics? In what way is it different from ordinary optics widely used in cameras, motion-picture projectors, i.e., for everyday use? An undesirable consequence of the thermal deformation of optical elements and surfaces was discovered during studies of the interaction with powerful incident laser radiation. The requirements to the fabrication, performance and quality of optical elements employed within systems for most practical applications are also covered. The high-power laser performance is generally governed by the following: (i) the absorption of incident optical radiation (governed primarily by various absorption mechanisms), (ii) followed by a temperature ...

  16. Average Anisotropy Characteristics of High Energy Cosmic Ray Particles and Geomagnetic Disturbance Index Ap

    Indian Academy of Sciences (India)

    C. M. Tiwari; D. P. Tiwari; Ajay K. Pandey; Pankaj K. Shrivastava


    The average characteristics of the diurnal and semi-diurnal anisotropy of cosmic ray intensity at relativistic energies have been obtained by using data from the worldwide grid of neutron monitor for the period 1989 to 1996. The complex behaviour of the diurnal amplitudes and time of maxima (phase) and its association with the Ap index on a long-term and day-to-day basis have been studied. Even though the general characteristics, on a yearly average basis, have not changed significantly during this period, both the diurnal and semi-diurnal amplitudes and phases vary significantly, besides significant changes being observed for different interplanetary conditions on a short-term basis. It is found that the relationship between the Ap index and the diurnal vector is out of phase during the period 1991 to 1995. On a long-term basis, the correlation of diurnal variation with Ap index has been found to vary during the solar cycle. On a short-term basis, it has been observed that the high Ap days are usually associated with higher amplitudes with phase shifted to earlier hours.

  17. A high-sensitivity 2x2 multi-aperture color camera based on selective averaging (United States)

    Zhang, Bo; Kagawa, Keiichiro; Takasawa, Taishi; Seo, Min-Woong; Yasutomi, Keita; Kawahito, Shoji


    To demonstrate the low-noise performance of the multi-aperture imaging system using a selective averaging method, an ultra-high-sensitivity multi-aperture color camera with 2×2 apertures is being developed. In low-light conditions, random telegraph signal (RTS) noise and dark current white defects become visible, which greatly degrades the quality of the image. To reduce these kinds of noise as well as to increase the number of incident photons, the multi-aperture imaging system composed of an array of lens and CMOS image sensor (CIS), and the selective averaging for minimizing the synthetic sensor noise at every pixel is utilized. It is verified by simulation that the effective noise at the peak of noise histogram is reduced from 1.44 e- to 0.73 e- in a 2×2-aperture system, where RTS noise and dark current white defects have been successfully removed. In this work, a prototype based on low-noise color sensors with 1280×1024 pixels fabricated in 0.18um CIS technology is considered. The pixel pitch is 7.1μm×7.1μm. The noise of the sensor is around 1e- based on the folding-integration and cyclic column ADCs, and the low voltage differential signaling (LVDS) is used to improve the noise immunity. The synthetic F-number of the prototype is 0.6.

  18. High temperature power electronics for space (United States)

    Hammoud, Ahmad N.; Baumann, Eric D.; Myers, Ira T.; Overton, Eric


    A high temperature electronics program at NASA Lewis Research Center focuses on dielectric and insulating materials research, development and testing of high temperature power components, and integration of the developed components and devices into a demonstrable 200 C power system, such as inverter. An overview of the program and a description of the in-house high temperature facilities along with experimental data obtained on high temperature materials are presented.

  19. Description and interpretation of the bracts epidermis of Gramineae (Poaceae) with rotated image with maximum average power spectrum (RIMAPS) technique. (United States)

    Favret, Eduardo A; Fuentes, Néstor O; Molina, Ana M; Setten, Lorena M


    During the last few years, RIMAPS technique has been used to characterize the micro-relief of metallic surfaces and recently also applied to biological surfaces. RIMAPS is an image analysis technique which uses the rotation of an image and calculates its average power spectrum. Here, it is presented as a tool for describing the morphology of the trichodium net found in some grasses, which is developed on the epidermal cells of the lemma. Three different species of grasses (herbarium samples) are analyzed: Podagrostis aequivalvis (Trin.) Scribn. & Merr., Bromidium hygrometricum (Nees) Nees & Meyen and Bromidium ramboi (Parodi) Rúgolo. Simple schemes representing the real microstructure of the lemma are proposed and studied. RIMAPS spectra of both the schemes and the real microstructures are compared. These results allow inferring how similar the proposed geometrical schemes are to the real microstructures. Each geometrical pattern could be used as a reference for classifying other species. Finally, this kind of analysis is used to determine the morphology of the trichodium net of Agrostis breviculmis Hitchc. As the dried sample had shrunk and the microstructure was not clear, two kinds of morphology are proposed for the trichodium net of Agrostis L., one elliptical and the other rectilinear, the former being the most suitable.

  20. On the XFEL Schrödinger Equation: Highly Oscillatory Magnetic Potentials and Time Averaging

    KAUST Repository

    Antonelli, Paolo


    We analyse a nonlinear Schrödinger equation for the time-evolution of the wave function of an electron beam, interacting selfconsistently through a Hartree-Fock nonlinearity and through the repulsive Coulomb interaction of an atomic nucleus. The electrons are supposed to move under the action of a time dependent, rapidly periodically oscillating electromagnetic potential. This can be considered a simplified effective single particle model for an X-ray free electron laser. We prove the existence and uniqueness for the Cauchy problem and the convergence of wave-functions to corresponding solutions of a Schrödinger equation with a time-averaged Coulomb potential in the high frequency limit for the oscillations of the electromagnetic potential. © 2014 Springer-Verlag Berlin Heidelberg.

  1. Average Neutron Total Cross Sections in the Unresolved Energy Range From ORELA High Resolutio Transmission Measurements

    Energy Technology Data Exchange (ETDEWEB)

    Derrien, H


    Average values of the neutron total cross sections of {sup 233}U, {sup 235}U, {sup 238}U, and {sup 239}Pu have been obtained in the unresolved resonance energy range from high-resolution transmission measurements performed at ORELA in the past two decades. The cross sections were generated by correcting the effective total cross sections for the self-shielding effects due to the resonance structure of the data. The self-shielding factors were found by calculating the effective and true cross sections with the computer code SAMMY for the same Doppler and resolution conditions as for the transmission measurements, using an appropriate set of resonance parameters. Our results are compared to results of previous measurements and to the current ENDF/B-VI data.

  2. Comparative Study of Reynolds Averaged and Embedded Large Eddy Simulations of a High Pressure Turbine Stage (United States)

    Jones, Sam; Jemcov, Aleksandar; Corke, Thomas


    An Embedded Large Eddy Simulation (ELES) approach is used to simulate the flow path through a high pressure turbine stage that includes the entry duct, stationary inlet and exit guide vanes, and a rotor. The flowfield around the rotor is simulated using LES. A Reynolds Averaged Simulation (RAS) is used for the rest of the flow domain. The interface between RAS and LES domains uses the RAS turbulence quantities as a means of obtaining length scales that are used in computing the vorticity required to trigger a proper energy cascade within the LES part of the flow field. The objective is to resolve the unsteady vortical motions that eminate from the gap between the rotor tip and duct walls that are presumably under-resolved in a RAS approach. A comparative analysis between RAS and ELES approaches for this turbomachinery problem is then presented. APS Fellow.

  3. Selling students short: Racial differences in teachers' evaluations of high, average, and low performing students. (United States)

    Irizarry, Yasmiyn


    Education scholars document notable racial differences in teachers' perceptions of students' academic skills. Using data from the Early Childhood Longitudinal Study-Kindergarten Cohort, this study advances research on teacher perceptions by investigating whether racial differences in teachers' evaluations of first grade students' overall literacy skills vary for high, average, and low performing students. Results highlight both the overall accuracy of teachers' perceptions, and the extent and nature of possible inaccuracies, as demonstrated by remaining racial gaps net literacy test performance. Racial differences in teachers' perceptions of Black, non-White Latino, and Asian students (compared to White students) exist net teacher and school characteristics and vary considerably across literacy skill levels. Skill specific literacy assessments appear to explain the remaining racial gap for Asian students, but not for Black and non-White Latino students. Implications of these findings for education scholarship, gifted education, and the achievement gap are discussed.

  4. Powering the High-Luminosity Triplets

    CERN Document Server

    Ballarino, A


    The powering of the magnets in the LHC High-Luminosity Triplets requires production and transfer of more than 150 kA of DC current. High precision power converters will be adopted, and novel High Temperature Superconducting (HTS) current leads and MgB2 based transfer lines will provide the electrical link between the power converters and the magnets. This chapter gives an overview of the systems conceived in the framework of the LHC High-Luminosity upgrade for feeding the superconducting magnet circuits. The focus is on requirements, challenges and novel developments.

  5. High power solid state switches (United States)

    Gundersen, Martin


    We have successfully produced an optically triggered thyristor based in Gallium Arsenide, developed a model for breakdown, and are developing two related devices, including a Gallium Arsenide based static inductor thyristor. We are getting at the basic limitations of Gallium Arsenide for these applications, and are developing models for the physical processes that will determine device limitations. The previously supported gas phase work - resulting in the back-lighted thyratron (BLT) - has actually resulted in a very changed view of how switching can be accomplished, and this is impacting the design of important machines. The BLT is being studied internationally: in Japan for laser fusion and laser isotope separation. ITT has built a BLT that has switched 30 kA at 60 kV in testing at NSWC Dahlgren and the device is being commercialized by another American company. Versions of the switch are now being tested for excimer laser and other applications. Basically, the switch, which arose from pulse power physics studies at USC, can switch more current faster (higher di/dt), with less housekeeping, and with other advantageous properties. There are a large number of other new applications, include kinetic energy weapons, pulsed microwave sources and R.F. accelerators.

  6. High-Temperature Passive Power Electronics (United States)


    In many future NASA missions - such as deep-space exploration, the National AeroSpace Plane, minisatellites, integrated engine electronics, and ion or arcjet thrusters - high-power electrical components and systems must operate reliably and efficiently in high-temperature environments. The high-temperature power electronics program at the NASA Lewis Research Center focuses on dielectric and insulating material research, the development and characterization of high-temperature components, and the integration of the developed components into a demonstrable 200 C power system - such as an inverter. NASA Lewis has developed high-temperature power components through collaborative efforts with the Air Force Wright Laboratory, Northrop Grumman, and the University of Wisconsin. Ceramic and film capacitors, molypermalloy powder inductors, and a coaxially wound transformer were designed, developed, and evaluated for high-temperature operation.

  7. Efficient Pumping Schemes for High Average Brightness Collisional X-ray Lasers

    Energy Technology Data Exchange (ETDEWEB)

    Keenan, R; Dunn, J; Shlyaptsev, V N; Smith, R F; Patel, P K; Price, D F


    Advances in transient collisional x-ray lasers have been demonstrated over the last 5 years as a technique for achieving tabletop soft x-ray lasers using 2-10 J of laser pump energy. The high peak brightness of these sources operating in the high output saturation regime, in the range of 10{sup 24}-10{sup 25} ph. mm{sup -2} mrad{sup -2} s-1 (0.1% BW){sup -1}, is ideal for many applications requiring high photon fluence in a single short burst. However, the pump energy required for these x-ray lasers is still relatively high and limits the x-ray laser repetition rate to 1 shot every few minutes. Higher repetition rate collisional schemes have been reported and show some promise for high output in the future. We report a novel technique for enhancing the coupling efficiency of the laser pump into the gain medium that could lead to enhanced x-ray inversion with a factor of ten reduction in the drive energy. This has been applied to the collisional excitation scheme for Ni-like Mo at 18.9 nm and x-ray laser output has been demonstrated. Preliminary results show lasing on a single shot of the optical laser operating at 10 Hz and with 70 mJ in the short pulse. Such a proposed source would have higher average brightness, {approx}10{sup 14} ph. mm{sup -2} mrad{sup -2} s{sup -1} (0.1% BW){sup -1}, than present bending magnet 3rd generation synchrotron sources operating at the same spectral range.

  8. Low Power Design with High-Level Power Estimation and Power-Aware Synthesis

    CERN Document Server

    Ahuja, Sumit; Shukla, Sandeep Kumar


    Low-power ASIC/FPGA based designs are important due to the need for extended battery life, reduced form factor, and lower packaging and cooling costs for electronic devices. These products require fast turnaround time because of the increasing demand for handheld electronic devices such as cell-phones, PDAs and high performance machines for data centers. To achieve short time to market, design flows must facilitate a much shortened time-to-product requirement. High-level modeling, architectural exploration and direct synthesis of design from high level description enable this design process. This book presents novel research techniques, algorithms,methodologies and experimental results for high level power estimation and power aware high-level synthesis. Readers will learn to apply such techniques to enable design flows resulting in shorter time to market and successful low power ASIC/FPGA design. Integrates power estimation and reduction for high level synthesis, with low-power, high-level design; Shows spec...

  9. Coherent beam combiner for a high power laser (United States)

    Dane, C. Brent; Hackel, Lloyd A.


    A phase conjugate laser mirror employing Brillouin-enhanced four wave mixing allows multiple independent laser apertures to be phase locked producing an array of diffraction-limited beams with no piston phase errors. The beam combiner has application in laser and optical systems requiring high average power, high pulse energy, and low beam divergence. A broad range of applications exist in laser systems for industrial processing, especially in the field of metal surface treatment and laser shot peening.

  10. Optimizing drive parameters of a nanosecond, repetitively pulsed microdischarge high power 121.6 nm source (United States)

    Stephens, J.; Fierro, A.; Trienekens, D.; Dickens, J.; Neuber, A.


    Utilizing nanosecond high voltage pulses to drive microdischarges (MDs) at repetition rates in the vicinity of 1 MHz previously enabled increased time-averaged power deposition, peak vacuum ultraviolet (VUV) power yield, as well as time-averaged VUV power yield. Here, various pulse widths (30-250 ns), and pulse repetition rates (100 kHz-5 MHz) are utilized, and the resulting VUV yield is reported. It was observed that the use of a 50 ns pulse width, at a repetition rate of 100 kHz, provided 62 W peak VUV power and 310 mW time-averaged VUV power, with a time-averaged VUV generation efficiency of ˜1.1%. Optimization of the driving parameters resulted in 1-2 orders of magnitude increase in peak and time-averaged power when compared to low power, dc-driven MDs.

  11. High Power Co-Axial Coupler

    Energy Technology Data Exchange (ETDEWEB)

    Neubauer, M. [Muons, Inc.; Dudas, A. [Muons, Inc.; Rimmer, Robert A. [JLAB; Guo, Jiquan [JLAB; Williams, R. Scott [JLAB


    A very high power Coax RF Coupler (MW-Level) is very desirable for a number of accelerator and commercial applications. For example, the development of such a coupler operating at 1.5 GHz may permit the construction of a higher-luminosity version of the Electron-Ion Collider (EIC) being planned at JLab. Muons, Inc. is currently funded by a DOE STTR grant to develop a 1.5-GHz high-power doublewindowcoax coupler with JLab (about 150 kW). Excellent progress has been made on this R&D project, so we propose an extension of this development to build a very high power coax coupler (MW level peak power and a max duty factor of about 4%). The dimensions of the current coax coupler will be scaled up to provide higher power capability.

  12. High-power atomic xenon laser

    NARCIS (Netherlands)

    Witteman, W.J.; Peters, P.J.M.; Botma, H.; Botma, H.; Tskhai, S.N.; Udalov, Yu.B.; Mei, Q.C.; Mei, Qi-Chu; Ochkin, V.N.


    The high pressure atomic xenon laser is becoming the most promising light source in the wavelength region of a few microns. The merits are high efficiency (so far up to 8 percent), high output energies (15 J/liter at 9 bar), high continuous output power (more than 200 W/liter), no gas dissociation a

  13. Intraindividual neuropsychological test variability in healthy individuals with high average intelligence and educational attainment. (United States)

    Heyanka, Daniel J; Holster, Jessica L; Golden, Charles J


    Knowledge of patterns of neuropsychological performance among normal, healthy individuals is integral to the practice of clinical neuropsychology, because clinicians may not always account for intraindividual variability (IIV) before coming to diagnostic conclusions. The IIV was assessed among a sample of 46 healthy individuals with high average intelligence and educational attainment, utilizing a battery of neuropsychological tests, including the Wechsler Adult Intelligence Scale, Fourth Edition (WAIS-IV) and Wechsler Memory Scale, Fourth Edition (WMS-IV). The data indicated substantial variability in neurocognitive abilities. All participants were found to demonstrate scores considered impaired by at least 2 standard deviations (SDs). Despite adjusting for outliers, no participant produced a "normal" testing profile with an intraindividual maximum discrepancy (MD) of less than 1 SD in either direction. When WAIS-IV Full Scale IQ (FSIQ) was considered, participants generally demonstrated cognitive test scores ranging from 2 SDs less than to 1.5 SDs greater than their FSIQ. Furthermore, after demographic corrections, the majority (59%) of participants demonstrated at least 1 impaired cognitive test score, as defined by being 1 to 1.5 SDs below the mean. Overall, results substantiate the need for clinicians to consider FSIQ and educational attainment in interpretation of neuropsychological testing results, given the relevant commonality of "abnormal" test scores within this population. This may ultimately reduce the likelihood of making false-positive conclusions of impairment when educational attainment and intelligence are high, thus improving diagnostic accuracy.

  14. Advances in Very High Frequency Power Conversion

    DEFF Research Database (Denmark)

    Kovacevic, Milovan

    . Excellent performance and small size of magnetic components and capacitors at very high frequencies, along with constant advances in performance of power semiconductor devices, suggests a sizable shift in consumer power supplies market into this area in the near future. To operate dc-dc converter power...... to be applied, especially at low power levels where gating loss becomes a significant percentage of the total loss budget. Various resonant gate drive methods have been proposed to address this design challenge, with varying size, cost, and complexity. This dissertation presents a self-oscillating resonant gate...

  15. Highly-efficient high-power pumps for fiber lasers (United States)

    Gapontsev, V.; Moshegov, N.; Berezin, I.; Komissarov, A.; Trubenko, P.; Miftakhutdinov, D.; Berishev, I.; Chuyanov, V.; Raisky, O.; Ovtchinnikov, A.


    We report on high efficiency multimode pumps that enable ultra-high efficiency high power ECO Fiber Lasers. We discuss chip and packaged pump design and performance. Peak out-of-fiber power efficiency of ECO Fiber Laser pumps was reported to be as high as 68% and was achieved with passive cooling. For applications that do not require Fiber Lasers with ultimate power efficiency, we have developed passively cooled pumps with out-of-fiber power efficiency greater than 50%, maintained at operating current up to 22A. We report on approaches to diode chip and packaged pump design that possess such performance.

  16. High power density carbonate fuel cell

    Energy Technology Data Exchange (ETDEWEB)

    Yuh, C.; Johnsen, R.; Doyon, J.; Allen, J. [Energy Research Corp., Danbury, CT (United States)


    Carbonate fuel cell is a highly efficient and environmentally clean source of power generation. Many organizations worldwide are actively pursuing the development of the technology. Field demonstration of multi-MW size power plant has been initiated in 1996, a step toward commercialization before the turn of the century, Energy Research Corporation (ERC) is planning to introduce a 2.85MW commercial fuel cell power plant with an efficiency of 58%, which is quite attractive for distributed power generation. However, to further expand competitive edge over alternative systems and to achieve wider market penetration, ERC is exploring advanced carbonate fuel cells having significantly higher power densities. A more compact power plant would also stimulate interest in new markets such as ships and submarines where space limitations exist. The activities focused on reducing cell polarization and internal resistance as well as on advanced thin cell components.

  17. High Power Density Power Electronic Converters for Large Wind Turbines

    DEFF Research Database (Denmark)

    Senturk, Osman Selcuk

    In large wind turbines (in MW and multi-MW ranges), which are extensively utilized in wind power plants, full-scale medium voltage (MV) multi-level (ML) voltage source converters (VSCs) are being more preferably employed nowadays for interfacing these wind turbines with electricity grids...... assessments of these specific VSCs so that their power densities and reliabilities are quantitatively determined, which requires extensive utilization of the electro-thermal models of the VSCs under investigation. In this thesis, the three-level neutral-point-clamped VSCs (3L-NPC-VSCs), which are classified......-HB-VSCs). As the switch technology for realizing these 3L-VSCs, press-pack IGBTs are chosen to ensure high power density and reliability. Based on the selected 3L-VSCs and switch technology, the converter electro-thermal models are developed comprehensively, implemented practically, and validated via a full-scale 3L...

  18. A Comparison of Strategic Development for Multiplication Problem Solving in Low-, Average-, and High-Achieving Students (United States)

    Zhang, Dake; Ding, Yi; Barrett, Dave E.; Xin, Yan Ping; Liu, Ru-de


    The present study investigated the differences of strategy use between low-, average-, and high-achieving students when solving different multiplication problems. Nineteen high-, 48 average-, and 17 low-achieving students participated in this study. All participants were asked to complete three different multiplication tests and to explain how…

  19. High Power Helicon Plasma Propulsion Project (United States)

    National Aeronautics and Space Administration — The proposed work seeks to develop and optimize an electrode-less plasma propulsion system that is based on a high power helicon (HPH) that is being developed...

  20. High Power Helicon Plasma Propulsion Project (United States)

    National Aeronautics and Space Administration — A new thruster has been conceived and tested that is based on a high power helicon (HPH) plasma wave. In this new method of propulsion, an antenna generates and...

  1. Drivers for High Power Laser Diodes

    Institute of Scientific and Technical Information of China (English)

    Yankov P; Todorov D; Saramov E


    During the last year the high power laser diodes jumped over the 1 kW level of CW power for a stack,and the commercial 1 cm bars reached 100 W output optical power at the standard wavelengths around 800 nm and 980 nm. The prices are reaching the industry acceptable levels. All Nd:YAG and fiber industrial lasers manufacturers have developed kW prototypes. Those achievements have set new requirements for the power supplies manufactuers-high and stable output current, and possibilities for fast control of the driving current, keeping safe the expensive laser diode. The fast switching frequencies also allow long range free space communications and optical range finding. The high frequencies allow the design of a 3D laser radar with high resolution and other military applications. The prospects for direct laser diode micro machining are also attractive.

  2. Coupling output of multichannel high power microwaves (United States)

    Li, Guolin; Shu, Ting; Yuan, Chengwei; Zhang, Jun; Yang, Jianhua; Jin, Zhenxing; Yin, Yi; Wu, Dapeng; Zhu, Jun; Ren, Heming; Yang, Jie


    The coupling output of multichannel high power microwaves is a promising technique for the development of high power microwave technologies, as it can enhance the output capacities of presently studied devices. According to the investigations on the spatial filtering method and waveguide filtering method, the hybrid filtering method is proposed for the coupling output of multichannel high power microwaves. As an example, a specific structure is designed for the coupling output of S/X/X band three-channel high power microwaves and investigated with the hybrid filtering method. In the experiments, a pulse of 4 GW X band beat waves and a pulse of 1.8 GW S band microwave are obtained.

  3. High power regenerative laser amplifier (United States)

    Miller, J.L.; Hackel, L.A.; Dane, C.B.; Zapata, L.E.


    A regenerative amplifier design capable of operating at high energy per pulse, for instance, from 20-100 Joules, at moderate repetition rates, for instance from 5-20 Hertz is provided. The laser amplifier comprises a gain medium and source of pump energy coupled with the gain medium; a Pockels cell, which rotates an incident beam in response to application of a control signal; an optical relay system defining a first relay plane near the gain medium and a second relay plane near the rotator; and a plurality of reflectors configured to define an optical path through the gain medium, optical relay and Pockels cell, such that each transit of the optical path includes at least one pass through the gain medium and only one pass through the Pockels cell. An input coupler, and an output coupler are provided, implemented by a single polarizer. A control circuit coupled to the Pockels cell generates the control signal in timed relationship with the input pulse so that the input pulse is captured by the input coupler and proceeds through at least one transit of the optical path, and then the control signal is applied to cause rotation of the pulse to a polarization reflected by the polarizer, after which the captured pulse passes through the gain medium at least once more and is reflected out of the optical path by the polarizer before passing through the rotator again to provide an amplified pulse. 7 figures.

  4. High Voltage Power Transmission for Wind Energy (United States)

    Kim, Young il

    The high wind speeds and wide available area at sea have recently increased the interests on offshore wind farms in the U.S.A. As offshore wind farms become larger and are placed further from the shore, the power transmission to the onshore grid becomes a key feature. Power transmission of the offshore wind farm, in which good wind conditions and a larger installation area than an onshore site are available, requires the use of submarine cable systems. Therefore, an underground power cable system requires unique design and installation challenges not found in the overhead power cable environment. This paper presents analysis about the benefit and drawbacks of three different transmission solutions: HVAC, LCC/VSC HVDC in the grid connecting offshore wind farms and also analyzed the electrical characteristics of underground cables. In particular, loss of HV (High Voltage) subsea power of the transmission cables was evaluated by the Brakelmann's theory, taking into account the distributions of current and temperature.

  5. High power, high repetition rate, few picosecond Nd:LuVO₄ oscillator with cavity dumping. (United States)

    Gao, Peng; Guo, Jie; Li, Jinfeng; Lin, Hua; Yu, Haohai; Zhang, Huaijin; Liang, Xiaoyan


    We investigate the potential use of Nd:LuVO4 in high average power, high repetition rate ultrafast lasers. Maximum mode-locked average power of 28 W is obtained at the repetition rate of 58 MHz. The shortest pulse duration is achieved at 4 ps without dispersion compensation. With a cavity dumping technique, the pulse energy is scaling up to 40.7 μJ at 300 kHz and 14.3 μJ at 1.5 MHz.

  6. High Power Short Wavelength Laser Development (United States)


    Unlimited güä^äsjäsiiiüüü X NRTC-77-43R P I High Power Short Wavelength Laser Development November 1977 D. B. Cohn and W. B. Lacina...NO NRTC-77-43R, «. TITLE fana »uetjjitj BEFORE COMPLETING FORM CIPIENT’S CATALOO NUMBER KIGH.POWER SHORT WAVELENGTH LASER DEVELOPMENT , 7...fWhtn Data Enterte NRTC-77-43R HIGH POWER SHORT WAVELENGTH LASER DEVELOPMENT ARPA Order Number: Program Code Number: Contract Number: Principal

  7. Uppsala High Power Test Stand for ESS Spoke Cavities

    CERN Document Server

    Yogi, RA; Dancila, D; Gajewski, K; Hermansson, L; Noor, M; Wedberg, R; Santiago-Kern, R; Ekelöf, T; Lofnes, T; Ziemann, V; Goryashko, V; Ruber, R


    The European Spallation Source (ESS) is one of the world’s most powerful neutron source. The ESS linac will accelerate 50mA pulse current of protons to 2.5GeV in 2.86 ms long pulses at a repetition rate of 14 Hz. It produces a beam with 5MW average power and 125MW peak power. ESS Spoke Linac consist of 28 superconducting spoke cavities, which will be developed by IPN Orsay, France. These Spoke Cavities will be tested at low power at IPN Orsay and high power testing will be performed in a high power test stand at Uppsala University. The test stand consists of tetrode based RF amplifier chain (352MHz, 350 kW) power and related RF distribution. Outputs of two tetrodes shall be combined with the hybrid coupler to produce 350 kW power. Preamplifier for a tetrode shall be solid state amplifier. As the spoke cavities are superconducting, the test stand also includes horizontal cryostat, Helium liquefier, test bunker etc. The paper describes features of the test stand in details.

  8. Small high cooling power space cooler

    Energy Technology Data Exchange (ETDEWEB)

    Nguyen, T. V.; Raab, J.; Durand, D.; Tward, E. [Northrop Grumman Aerospace Systems Redondo Beach, Ca, 90278 (United States)


    The small High Efficiency pulse tube Cooler (HEC) cooler, that has been produced and flown on a number of space infrared instruments, was originally designed to provide cooling of 10 W @ 95 K. It achieved its goal with >50% margin when limited by the 180 W output ac power of its flight electronics. It has also been produced in 2 stage configurations, typically for simultaneously cooling of focal planes to temperatures as low as 35 K and optics at higher temperatures. The need for even higher cooling power in such a low mass cryocooler is motivated by the advent of large focal plane arrays. With the current availability at NGAS of much larger power cryocooler flight electronics, reliable long term operation in space with much larger cooling powers is now possible with the flight proven 4 kg HEC mechanical cooler. Even though the single stage cooler design can be re-qualified for those larger input powers without design change, we redesigned both the linear and coaxial version passive pulse tube cold heads to re-optimize them for high power cooling at temperatures above 130 K while rejecting heat to 300 K. Small changes to the regenerator packing, the re-optimization of the tuned inertance and no change to the compressor resulted in the increased performance at 150 K. The cooler operating at 290 W input power achieves 35 W@ 150 K corresponding to a specific cooling power at 150 K of 8.25 W/W and a very high specific power of 72.5 W/Kg. At these powers the cooler still maintains large stroke, thermal and current margins. In this paper we will present the measured data and the changes to this flight proven cooler that were made to achieve this increased performance.

  9. Advances in high power semiconductor diode lasers (United States)

    Ma, Xiaoyu; Zhong, Li


    High power semiconductor lasers have broad applications in the fields of military and industry. Recent advances in high power semiconductor lasers are reviewed mainly in two aspects: improvements of diode lasers performance and optimization of packaging architectures of diode laser bars. Factors which determine the performance of diode lasers, such as power conversion efficiency, temperature of operation, reliability, wavelength stabilization etc., result from a combination of new semiconductor materials, new diode structures, careful material processing of bars. The latest progress of today's high-power diode lasers at home and abroad is briefly discussed and typical data are presented. The packaging process is of decisive importance for the applicability of high-power diode laser bars, not only technically but also economically. The packaging techniques include the material choosing and the structure optimizing of heat-sinks, the bonding between the array and the heat-sink, the cooling and the fiber coupling, etc. The status of packaging techniques is stressed. There are basically three different diode package architectural options according to the integration grade. Since the package design is dominated by the cooling aspect, different effective cooling techniques are promoted by different package architectures and specific demands. The benefit and utility of each package are strongly dependent upon the fundamental optoelectronic properties of the individual diode laser bars. Factors which influence these properties are outlined and comparisons of packaging approaches for these materials are made. Modularity of package for special application requirements is an important developing tendency for high power diode lasers.

  10. Silver based batteries for high power applications (United States)

    Karpinski, A. P.; Russell, S. J.; Serenyi, J. R.; Murphy, J. P.

    The present status of silver oxide-zinc technology and applications has been described by Karpinski et al. [A.P. Karpinski, B. Makovetski, S.J. Russell, J.R. Serenyi, D.C. Williams, Silver-Zinc: status of technology and applications, Journal of Power Sources, 80 (1999) 53-60], where the silver-zinc couple is still the preferred choice where high specific energy/energy density, coupled with high specific power/power density are important for high-rate, weight or size/configuration sensitive applications. Perhaps the silver oxide cathode can be considered one of the most versatile electrode materials. When coupled with other anodes and corresponding electrolyte management system, the silver electrode provides for a wide array of electrochemical systems that can be tailored to meet the most demanding, high power requirements. Besides zinc, the most notable include cadmium, iron, metal hydride, and hydrogen electrode for secondary systems, while primary systems include lithium and aluminum. Alloys including silver are also available, such as silver chloride, which when coupled with magnesium or aluminum are primarily used in many seawater applications. The selection and use of these couples is normally the result of a trade-off of many factors. These include performance, safety, risk, reliability, and cost. When high power is required, silver oxide-zinc, silver oxide-aluminum, and silver oxide-lithium are the most energetic. For moderate performance (i.e., lower power), silver oxide-zinc or silver-cadmium would be the system of choice. This paper summarizes the suitability of the silver-based couples, with an emphasis on the silver-zinc system, as primary or rechargeable power sources for high energy/power applications.

  11. Protection Related to High-power Targets

    CERN Document Server

    Plum, M.A.


    Target protection is an important part of machine protection. The beam power in high-intensity accelerators is high enough that a single wayward pulse can cause serious damage. Today's high-power targets operate at the limit of available technology, and are designed for a very narrow range of beam parameters. If the beam pulse is too far off centre, or if the beam size is not correct, or if the beam density is too high, the target can be seriously damaged. We will start with a brief introduction to high-power targets and then move to a discussion of what can go wrong, and what are the risks. Next we will discuss how to control the beam-related risk, followed by examples from a few different accelerator facilities. We will finish with a detailed example of the Oak Ridge Spallation Neutron Source target tune up and target protection.

  12. A compact broadband high efficient X-band 9-watt PHEMT MMIC high-power amplifier for phased array radar applications

    NARCIS (Netherlands)

    Hek, A.P. de; Hunneman, P.A.H.; Demmler, M.; Hulsmann, A.


    ln this paper the development and measurement results of a compact broadband 9-Watt high efficient X-band high-power amplifier are discussed. The described amplifier has the following state-of-the art performance: an average ouput power of 9 Watt, a gain of 20 dB and an average Power Added

  13. A compact broadband high efficient X-band 9-watt PHEMT MMIC high-power amplifier for phased array radar applications

    NARCIS (Netherlands)

    Hek, A.P. de; Hunneman, P.A.H.; Demmler, M.; Hulsmann, A.


    ln this paper the development and measurement results of a compact broadband 9-Watt high efficient X-band high-power amplifier are discussed. The described amplifier has the following state-of-the art performance: an average ouput power of 9 Watt, a gain of 20 dB and an average Power Added Efficienc

  14. High-power picosecond fiber source for coherent Raman microscopy. (United States)

    Kieu, Khanh; Saar, Brian G; Holtom, Gary R; Xie, X Sunney; Wise, Frank W


    We report a high-power picosecond fiber pump laser system for coherent Raman microscopy (CRM). The fiber laser system generates 3.5 ps pulses with 6 W average power at 1030 nm. Frequency doubling yields more than 2 W of green light, which can be used to pump an optical parametric oscillator to produce the pump and the Stokes beams for CRM. Detailed performance data on the laser and the various wavelength conversion steps are discussed, together with representative CRM images of fresh animal tissue obtained with the new source.

  15. High-power picosecond fiber source for coherent Raman microscopy


    Kieu, Khanh; Saar, Brian G.; Holtom, Gary R.; Xie, Xiaoliang Sunney; Wise, Frank W


    We report a high-power picosecond fiber pump laser system for coherent Raman microscopy (CRM). The fiber laser system generates 3.5 ps pulses with 6 W average power at 1030 nm. Frequency doubling yields more than 2 W of green light, which can be used to pump an optical parametric oscillator to produce the pump and the Stokes beams for CRM. Detailed performance data on the laser and the various wavelength conversion steps are discussed, together with representative CRM images of fresh animal t...

  16. 25 W of average power at 172 nm in the vacuum ultraviolet from flat, efficient lamps driven by interlaced arrays of microcavity plasmas (United States)

    Park, S.-J.; Herring, C. M.; Mironov, A. E.; Cho, J. H.; Eden, J. G.


    More than 25 W of average power and >800 W of peak power have been generated at λ =172 nm (h ν =7.2 eV) in the vacuum ultraviolet (VUV) from the Xe2 molecule in flat, 10 × 10 cm2 lamps having an active area and volume of 80 cm2 and 20 % . For a bipolar voltage waveform driving frequency of 137 kHz and a 54% Xe/Ne gas fill mixture at a 300 K pressure of 550 Torr, the lamp generates as much as 31.5 W of average power and intensities >350 mW cm-2 in 40-60 μJ, 70±10 ns FWHM pulses produced in a burst mode-four pulses of 600-850 W peak power in every cycle of the driving waveform. The lamp intensity is uniform to within ±2.5% at ≥10 mm from its surface and average power varies linearly with pulse repetition frequency throughout the 18-135 kHz interval. The spectral breadth of the Xe dimer emission is ˜9 nm FWHM and time-resolved, spatial intensity maps show improved utilization of the power pulse (VṡI) with two or more microcavity arrays that are interleaved. This photonic source technology is capable of generating unprecedented power levels in the VUV spectral region (e.g., ˜2.5 kW m-2) with tiled lamps.

  17. 25 W of average power at 172 nm in the vacuum ultraviolet from flat, efficient lamps driven by interlaced arrays of microcavity plasmas

    Directory of Open Access Journals (Sweden)

    S.-J. Park


    Full Text Available More than 25 W of average power and >800 W of peak power have been generated at λ=172 nm (hν=7.2 eV in the vacuum ultraviolet (VUV from the Xe2 molecule in flat, 10 × 10 cm2 lamps having an active area and volume of 80 cm2 and 20%. For a bipolar voltage waveform driving frequency of 137 kHz and a 54% Xe/Ne gas fill mixture at a 300 K pressure of 550 Torr, the lamp generates as much as 31.5 W of average power and intensities >350 mW cm−2 in 40–60 μJ, 70±10 ns FWHM pulses produced in a burst mode−four pulses of 600–850 W peak power in every cycle of the driving waveform. The lamp intensity is uniform to within ±2.5% at ≥10 mm from its surface and average power varies linearly with pulse repetition frequency throughout the 18−135 kHz interval. The spectral breadth of the Xe dimer emission is ∼9 nm FWHM and time-resolved, spatial intensity maps show improved utilization of the power pulse (V⋅I with two or more microcavity arrays that are interleaved. This photonic source technology is capable of generating unprecedented power levels in the VUV spectral region (e.g., ∼2.5 kW m−2 with tiled lamps.

  18. High Power Test for Klystron Stability

    Energy Technology Data Exchange (ETDEWEB)

    Seol, Kyung-Tae; Kim, Seong-Gu; Kwon, Hyeok-Jung; Kim, Han-Sung; Cho, Yong-Sub [Korea Atomic Energy Research Institute, Gyeongju (Korea, Republic of)


    The 100-MeV linac consists of a 50-keV proton injector based on a microwave ion source, a 3-MeV RFQ with a four-vane structure, and a 100-MeV DTL. Nine sets of 1MW klystrons have been operated for the 100-MeV proton linac. The klystron filament heating time was approximately 5700 hours in 2014. During the high power operation of the klystron, unstable RF waveforms appeared at the klystron output, and we have checked and performed cavity frequency adjustments, magnet and heater current, reflection from a circulator, klystron test without a circulator, and the frequency spectrum measurement. The problems may be from harmonic power stay between the klystron and the circulator. A harmonic filter of waveguide type is designed to eliminate the harmonic power. Nine sets of the klystrons have been operated for the KOMAC 100-MeV proton linac. Some klystrons have unstable RF waveforms at specific power level. We have checked and tested the cavity frequency adjustment, reflection from a circulator, high power test without a circulator, and frequency spectrum at the unstable RF. The unstable RF may be from harmonic power stay between the klystron and the circulator. To eliminate the harmonic power, a harmonic filter of waveguide type is designed.

  19. Diagnostics for High Power Targets and Dumps

    CERN Document Server

    Gschwendtner, E


    High power targets are generally used for neutrino, antiproton, neutron and secondary beam production whereas dumps are needed in beam waste management. In order to guarantee an optimized and safe use of these targets and dumps, reliable instrumentation is needed; the diagnostics in high power beams around targets and dumps is reviewed. The suite of beam diagnostics devices used in such extreme environments is discussed, including their role in commissioning and operation. The handling and maintenance of the instrumentation components in high radiation areas is also addressed.

  20. Information Entropy- and Average-Based High-Resolution Digital Storage Oscilloscope

    Directory of Open Access Journals (Sweden)

    Jun Jiang


    Full Text Available Vertical resolution is an essential indicator of digital storage oscilloscope (DSO and the key to improving resolution is to increase digitalizing bits and lower noise. Averaging is a typical method to improve signal to noise ratio (SNR and the effective number of bits (ENOB. The existing averaging algorithm is apt to be restricted by the repetitiveness of signal and be influenced by gross error in quantization, and therefore its effect on restricting noise and improving resolution is limited. An information entropy-based data fusion and average-based decimation filtering algorithm, proceeding from improving average algorithm and in combination with relevant theories of information entropy, are proposed in this paper to improve the resolution of oscilloscope. For single acquiring signal, resolution is improved through eliminating gross error in quantization by utilizing the maximum entropy of sample data with further noise filtering via average-based decimation after data fusion of efficient sample data under the premise of oversampling. No subjective assumptions and constraints are added to the signal under test in the whole process without any impact on the analog bandwidth of oscilloscope under actual sampling rate.

  1. Average gene length is highly conserved in prokaryotes and eukaryotes and diverges only between the two kingdoms. (United States)

    Xu, Lin; Chen, Hong; Hu, Xiaohua; Zhang, Rongmei; Zhang, Ze; Luo, Z W


    The average length of genes in a eukaryote is larger than in a prokaryote, implying that evolution of complexity is related to change of gene lengths. Here, we show that although the average lengths of genes in prokaryotes and eukaryotes are much different, the average lengths of genes are highly conserved within either of the two kingdoms. This suggests that natural selection has clearly set a strong limitation on gene elongation within the kingdom. Furthermore, the average gene size adds another distinct characteristic for the discrimination between the two kingdoms of organisms.

  2. Advanced High Voltage Power Device Concepts

    CERN Document Server

    Baliga, B Jayant


    Advanced High Voltage Power Device Concepts describes devices utilized in power transmission and distribution equipment, and for very high power motor control in electric trains and steel-mills. Since these devices must be capable of supporting more than 5000-volts in the blocking mode, this books covers operation of devices rated at 5,000-V, 10,000-V and 20,000-V. Advanced concepts (the MCT, the BRT, and the EST) that enable MOS-gated control of power thyristor structures are described and analyzed in detail. In addition, detailed analyses of the silicon IGBT, as well as the silicon carbide MOSFET and IGBT, are provided for comparison purposes. Throughout the book, analytical models are generated to give a better understanding of the physics of operation for all the structures. This book provides readers with: The first comprehensive treatment of high voltage (over 5000-volts) power devices suitable for the power distribution, traction, and motor-control markets;  Analytical formulations for all the device ...

  3. Advances in industrial high-power lasers (United States)

    Schlueter, Holger


    Four major types of laser sources are used for material processing. Excluding Excimer lasers, this paper focuses on advances in High Power CO2 lasers, Solid State Lasers and Diode Lasers. Because of their unrivaled cost to brightness relationship the fast axial flow CO2 laser remains unrivaled for flat-sheet laser cutting. Adding approximately a kW of output power ever four years, this laser type has been propelling the entire sheet metal fabrication industry for the last two decades. Very robust, diffusion cooled annular discharge CO2 lasers with 2kW output power have enabled robot mounted lasers for 3D applications. Solid State Lasers are chosen mainly because of the option of fiber delivery. Industrial applications still rely on lamp-pumped Nd:YAG lasers with guaranteed output powers of 4.5 kW at the workpiece. The introduction of the diode pumped Thin Disc Laser 4.5 kW laser enables new applications such as the Programmable Focus Optics. Pumping the Thin Disc Laser requires highly reliable High Power Diode Lasers. The necessary reliability can only be achieved in a modern, automated semiconductor manufacturing facility. For Diode Lasers, electro-optical efficiencies above 65% are as important as the passivation of the facets to avoid Burn-In power degradation.

  4. Recent advances in phosphate laser glasses for high power applications

    Energy Technology Data Exchange (ETDEWEB)

    Campbell, J.H.


    Recent advances in Nd-doped phosphate laser glasses for high-peak-power and high-average-power applications are reviewed. Compositional studies have progressed to the point that glasses can be tailored to have specific properties for specific applications. Non-radiative relaxation effects can be accurately modeled and empirical expressions have been developed to evaluate both intrinsic (structural) and extrinsic (contamination induced) relaxation effects. Losses due to surface scattering and bulk glass absorption have been carefully measured and can be accurately predicted. Improvements in processing have lead to high damage threshold (e.g. Pt inclusion free) and high thermal shock resistant glasses with improved edge claddings. High optical quality pieces up to 79 x 45 x 4cm{sup 3} have been made and methods for continuous melting laser glass are under development.

  5. High power couplers for Project X

    Energy Technology Data Exchange (ETDEWEB)

    Kazakov, S.; Champion, M.S.; Yakovlev, V.P.; Kramp, M.; Pronitchev, O.; Orlov, Y.; /Fermilab


    Project X, a multi-megawatt proton source under development at Fermi National Accelerator Laboratory. The key element of the project is a superconducting (SC) 3GV continuous wave (CW) proton linac. The linac includes 5 types of SC accelerating cavities of two frequencies.(325 and 650MHz) The cavities consume up to 30 kW average RF power and need proper main couplers. Requirements and approach to the coupler design are discussed in the report. New cost effective schemes are described. Results of electrodynamics and thermal simulations are presented.

  6. Long range prospect of the electric power demand in FY 2,000. Total demand: 8. 38 trillion KWh, annual average increase: 2. 3%

    Energy Technology Data Exchange (ETDEWEB)


    The Agency of Natural Resources and Energy, the Ministry of International Trade and Industry held meetings of the Committee on Demand and Supply of the Electric Utility Industrial Council in October, 1987. This article is the Committee's interim report and establishes the prospect of the electric power supply and demand in Japan in FY 1995 and FY 2000. Total power demand in FY 1995 is about 7.38 trillion KWh and in FY 2000, about 8.38 trillion KWh. Average annual growth is about 2.6% during the period of FY 1995 through FY 2000. Among the above, the public demand will increase and occupy 50.2% of the total power demand in the year of 2000. The industrial demand will increase about 1.4% in terms of annual rate during the period of FY 1995 through FY 2000 due to the demand increase by new industries, etc. against continued rationalization of power utilization. The maximum electric power demand is around 163 million KW in FY 2000. The target of electric power supply in FY 2000 is 53 million KW from atomic power generation, 23 million KW from coal burning thermal power generation, 43 million KW from LNG, 21 million KW from hydro power generation and 52 million KW from oil and LPG. Hereafter, electric load leveling, more efficient electric power supply and strengthening of the basis of electric power utilization are necessary. (1 photo, 3 tabs)

  7. Hollow-core fibers for high power pulse delivery

    DEFF Research Database (Denmark)

    Michieletto, Mattia; Lyngsø, Jens K.; Jakobsen, Christian;


    We investigate hollow-core fibers for fiber delivery of high power ultrashort laser pulses. We use numerical techniques to design an anti-resonant hollow-core fiber having one layer of non-touching tubes to determine which structures offer the best optical properties for the delivery of high power...... picosecond pulses. A novel fiber with 7 tubes and a core of 30 mu m was fabricated and it is here described and characterized, showing remarkable low loss, low bend loss, and good mode quality. Its optical properties are compared to both a 10 mu m and a 18 mu m core diameter photonic band gap hollow......-core fiber. The three fibers are characterized experimentally for the delivery of 22 picosecond pulses at 1032nm. We demonstrate flexible, diffraction limited beam delivery with output average powers in excess of 70W. (C) 2016 Optical Society of America...

  8. Wideband high efficiency CMOS envelope amplifiers for 4G LTE handset envelope tracking RF power amplifiers


    Hassan, Muhammad


    Fourth generation cellular networks offer performance similar to cable modems while allowing wide mobility. Although the use of orthogonal frequency division multiplexing in fourth generation increases its spectral efficiency but it also increases the peak-to-average power ratio of the transmitted signal. If a conventional power amplifier is used to transmit a high peak-to-average power ratio signal, then to meet the stringent linearity requirements, it will be operating 6 to 10 dB back-off f...

  9. High Power Diode Lasers Technology and Applications

    CERN Document Server

    Bachmann, Friedrich; Poprawe, Reinhart


    In a very comprehensive way this book covers all aspects of high power diode laser technology for materials processing. Basics as well as new application oriented results obtained in a government funded national German research project are described in detail. Along the technological chain after a short introduction in the second chapter diode laser bar technology is discussed regarding structure, manufacturing technology and metrology. The third chapter illuminates all aspects of mounting and cooling, whereas chapter four gives wide spanning details on beam forming, beam guiding and beam combination, which are essential topics for incoherently coupled multi-emitter based high power diode lasers. Metrology, standards and safety aspects are the theme of chapter five. As an outcome of all the knowledge from chapter two to four various system configurations of high power diode lasers are described in chapter six; not only systems focussed on best available beam quality but especially also so called "modular" set...

  10. The development of early numeracy skills in kindergarten in low-, average- and high-performance groups

    NARCIS (Netherlands)

    Aunio, P.; Heiskari, P.; van Luit, J.E.H.; Vuorio, J.-M.


    In this study, we investigated how early numeracy skills develop in kindergarten-age children. The participants were 235 Finnish children (111 girls and 124 boys). At the time of the first measurement, the average age of the children was 6 years. The measurements were conducted three times during 1

  11. Charge and fluence lifetime measurements of a dc high voltage GaAs photogun at high average current

    Energy Technology Data Exchange (ETDEWEB)

    J. Grames, R. Suleiman, P.A. Adderley, J. Clark, J. Hansknecht, D. Machie, M. Poelker, M.L. Stutzman


    GaAs-based dc high voltage photoguns used at accelerators with extensive user programs must exhibit long photocathode operating lifetime. Achieving this goal represents a significant challenge for proposed high average current facilities that must operate at tens of milliamperes or more. This paper describes techniques to maintain good vacuum while delivering beam, and techniques that minimize the ill effects of ion bombardment, the dominant mechanism that reduces photocathode yield of a GaAs-based dc high voltage photogun. Experimental results presented here demonstrate enhanced lifetime at high beam currents by: (a) operating with the drive laser beam positioned away from the electrostatic center of the photocathode, (b) limiting the photocathode active area to eliminate photoemission from regions of the photocathode that do not support efficient beam delivery, (c) using a large drive laser beam to distribute ion damage over a larger area, and (d) by applying a relatively low bias voltage to the anode to repel ions created within the downstream beam line. A combination of these techniques provided the best total charge extracted lifetimes in excess of 1000 C at dc beam currents up to 9.5 mA, using green light illumination of bulk GaAs inside a 100 kV photogun.

  12. E3000 High Power SADM development (United States)

    Bamford, Steve G.; McMahon, Paul


    Astrium UK has been actively involved in the study, design, development, manufacture and test of Solar Array Drive Mechanisms (SADMs) and Bearing and Power Transfer Assemblies (BAPTAs) since the early 1970s having delivered 105 of these mechanisms to 22 spacecraft programs. As a result Astrium UK has accumulated in excess of 700 years of failure free SADM operation in-orbit. During that period power transfer requirements have grown steadily from below 1kW to 9.9kW and beyond. With this increase in power handling capability comes the associated problem of handling and dissipating the heat being generated within the SADM. The Eurostar 2000 family of SADMs were designed to handle up to 5.6kW for the E2000 family of spacecraft but the High Power SADM was conceived to meet the needs of the much bigger Eurostar 3000 family of spacecraft that could potentially grow to 15kW.

  13. Operation of Power Grids with High Penetration of Wind Power (United States)

    Al-Awami, Ali Taleb

    The integration of wind power into the power grid poses many challenges due to its highly uncertain nature. This dissertation involves two main components related to the operation of power grids with high penetration of wind energy: wind-thermal stochastic dispatch and wind-thermal coordinated bidding in short-term electricity markets. In the first part, a stochastic dispatch (SD) algorithm is proposed that takes into account the stochastic nature of the wind power output. The uncertainty associated with wind power output given the forecast is characterized using conditional probability density functions (CPDF). Several functions are examined to characterize wind uncertainty including Beta, Weibull, Extreme Value, Generalized Extreme Value, and Mixed Gaussian distributions. The unique characteristics of the Mixed Gaussian distribution are then utilized to facilitate the speed of convergence of the SD algorithm. A case study is carried out to evaluate the effectiveness of the proposed algorithm. Then, the SD algorithm is extended to simultaneously optimize the system operating costs and emissions. A modified multi-objective particle swarm optimization algorithm is suggested to identify the Pareto-optimal solutions defined by the two conflicting objectives. A sensitivity analysis is carried out to study the effect of changing load level and imbalance cost factors on the Pareto front. In the second part of this dissertation, coordinated trading of wind and thermal energy is proposed to mitigate risks due to those uncertainties. The problem of wind-thermal coordinated trading is formulated as a mixed-integer stochastic linear program. The objective is to obtain the optimal tradeoff bidding strategy that maximizes the total expected profits while controlling trading risks. For risk control, a weighted term of the conditional value at risk (CVaR) is included in the objective function. The CVaR aims to maximize the expected profits of the least profitable scenarios, thus

  14. Diode-Pumped Passive Q-Switched 946-nm Nd:YAG Laser with 2.1-W Average Output Power

    Institute of Scientific and Technical Information of China (English)

    ZHANG Ling; LI Chun-Yong; FENG Bao-Hua; WEI Zhi-Yi; LI De-Hua; FU Pan-Ming; ZHANG Zhi-Guo


    @@ We demonstrate a diode-pumped passive Q-switched 946nm Nd:YAG laser with a diffusion-bonded composite laser rod and a co-doped Nd, Cr:YAG as saturable absorber. The average output power of 2.1 W is generated at an incident pump power of 14.3 W. The peak power of the Q-switched pulse is 643 W with 80 kHz repetition rate and 40.8ns pulse width. The slope efficiency and optical conversion efficiency are 17.6% and 14.7%, respectively.

  15. High-power microwave development in Russia (United States)

    Gauthier, Sylvain


    This is a survey of Russian research and development in high-power microwave (HPM) sources. It emphasizes those sources of nanoseconds pulse duration time which have potential weapon as well as radar applications. It does not cover the whole range of Russian HPM research and development but concentrates on those aspects which may lead to military applications. Russian investigators have achieved many world firsts in HPM generation; for example, a multiwave Cerenkov generator with a peak output power of 15 gigawatts. Their successes are based on their impressive capability in pulsed power technology which has yielded high-current generators of terawatt peak power. They have transformed the energy of these currents into microwave radiation using tubes of both conventional and novel designs exploiting relativistic electron beams. Recently, the development of high-current mini-accelerators has moved relativistic electron-beam (REB) HPM generation out of the laboratory and enabled the development of deployable military systems with peak powers in the gigawatt range. As a result, they now see development of a REB-based radar systems as one of the most promising directions in radar systems. Details of such a system are described and the implications for HPM weapons are considered.

  16. State Averages (United States)

    U.S. Department of Health & Human Services — A list of a variety of averages for each state or territory as well as the national average, including each quality measure, staffing, fine amount and number of...

  17. High impact data visualization with Power View, Power Map, and Power BI

    CERN Document Server

    Aspin, Adam


    High Impact Data Visualization with Power View, Power Map, and Power BI helps you take business intelligence delivery to a new level that is interactive, engaging, even fun, all while driving commercial success through sound decision-making. Learn to harness the power of Microsoft's flagship, self-service business intelligence suite to deliver compelling and interactive insight with remarkable ease. Learn the essential techniques needed to enhance the look and feel of reports and dashboards so that you can seize your audience's attention and provide them with clear and accurate information. Al

  18. A comment on the average foil-hit number for a high-intensity proton ring

    CERN Document Server

    Yamane, I


    The minimum value of the average foil-hit number is derived for H sup - charge-exchange injection using a stripping foil, in which the H sup - beam is injected at a corner of the stripper foil and the cross-sectional area of the ring beam is increased as a function of time, kt sup 1 sup / sup n , where k and n are constants.

  19. High power collimated diode laser stack

    Institute of Scientific and Technical Information of China (English)

    LIU Yuan-yuan; FANG Gao-zhan; MA Xiao-yu; LIU Su-ping; FENG Xiao-ming


    A high power collimated diode laser stack is carried out based on fast-axis collimation and stack packaging techniques.The module includes ten typical continuous wave (cw) bars and the total output power can be up to 368W at 48.6A.Using a cylindrical lens as the collimation elements,we can make the fast-axis divergence and the slow-axis divergence are 0.926 40 and 8.2060 respectively.The light emitting area is limited in a square area of 18.3 mm×11 mm.The module has the advantage of high power density and offers a wide potential applications in pumping and material processing.

  20. High Power Disk Loaded Guide Load

    Energy Technology Data Exchange (ETDEWEB)

    Farkas, Z.D.; /SLAC


    A method to design a matching section from a smooth guide to a disk-loaded guide, using a variation of broadband matching, [1, 2] is described. Using this method, we show how to design high power loads. The load consists of a disk-loaded coaxial guide operating in the TE{sub 01}-mode. We use this mode because it has no electric field terminating on a conductor, has no axial currents, and has no current at the cylinder-disk interface. A high power load design that has -35 dB reflection and a 200 MHz, -20 dB bandwidth, is presented. It is expected that it will carry the 600 MW output peak power of the pulse compression network. We use coaxial geometry and stainless steel material to increase the attenuation per cell.

  1. High Power RF Test Facility at the SNS

    CERN Document Server

    Kang, Yoon W; Campisi, Isidoro E; Champion, Mark; Crofford, Mark; Davis, Kirk; Drury, Michael A; Fuja, Ray E; Gurd, Pamela; Kasemir, Kay-Uwe; McCarthy, Michael P; Powers, Tom; Shajedul Hasan, S M; Stirbet, Mircea; Stout, Daniel; Tang, Johnny Y; Vassioutchenko, Alexandre V; Wezensky, Mark


    RF Test Facility has been completed in the SNS project at ORNL to support test and conditioning operation of RF subsystems and components. The system consists of two transmitters for two klystrons powered by a common high voltage pulsed converter modulator that can provide power to two independent RF systems. The waveguides are configured with WR2100 and WR1150 sizes for presently used frequencies: 402.5 MHz and 805 MHz. Both 402.5 MHz and 805 MHz systems have circulator protected klystrons that can be powered by the modulator capable of delivering 11 MW peak and 1 MW average power. The facility has been equipped with computer control for various RF processing and complete dual frequency operation. More than forty 805 MHz fundamental power couplers for the SNS superconducting linac (SCL) cavitites have been RF conditioned in this facility. The facility provides more than 1000 ft2 floor area for various test setups. The facility also has a shielded cave area that can support high power tests of normal conducti...

  2. Repetitively pulsed Fe: ZnSe laser with an average output power of 20 W at room temperature of the polycrystalline active element (United States)

    Velikanov, S. D.; Gavrishchuk, E. M.; Zaretsky, N. A.; Zakhryapa, A. V.; Ikonnikov, V. B.; Kazantsev, S. Yu.; Kononov, I. G.; Maneshkin, A. A.; Mashkovskii, D. A.; Saltykov, E. V.; Firsov, K. N.; Chuvatkin, R. S.; Yutkin, I. M.


    The energy and spectral-temporal characteristics of a Fe : ZnSe laser operating in pulsed and repetitively pulsed regimes are studied at room temperature of the polycrystalline active element. The crystal was pumped by a nonchain electric-discharge HF laser. The energy of the Fe : ZnSe laser in a single-pulse regime was 1.67 J at the slope efficiency with respect to the absorbed and incident energy of ∼43% and ∼27%, respectively. In a repetitively pulsed regime with a pulse repetition rate of 20 Hz and an efficiency with respect to the absorbed power of ∼40%, the average laser power was ∼20 W with an individual pulse energy of ∼1 J. The possibility of increasing the average power of the repetitively pulsed Fe : ZnSe laser at room temperature is discussed.

  3. High power Ka band TWT amplifier

    Energy Technology Data Exchange (ETDEWEB)

    Golkowski, C.; Ivers, J.D.; Nation, J.A.; Wang, P.; Schachter, L.


    Two high power 35 GHz TWT amplifiers driven by a relativistic pencil, 850 kV, 200A electron beam have been assembled and tested. The first had a dielectric slow wave structure and was primarily used to develop diagnostics, and to gain experience in working with high power systems in Ka band. The source of the input power for the amplifier was a magnetron producing a 30 kW, 200ns long pulse of which 10 kW as delivered to the experiment. The 30 cm long dielectric (Teflon) amplifier produced output power levels of about 1 MW with a gain of about 23 dB. These results are consistent with expectations from PIC code simulations for this arrangement. The second amplifier, which is a single stage disk loaded slow wave structure, has been designed. It consists of one hundred uniform cells with two sets of ten tapered calls at the ends to lower the reflection coefficient. The phase advance per cell is {pi}/2. The amplifier passband extends from 28 to 40 GHz. It is designed to increase the output power to about 20 MW. The amplifier is in construction and will be tested in the near future. Details of the design of both systems will be provided and initial results from the new amplifier presented.

  4. Multi-session complex averaging for high resolution high SNR 3T MR visualization of ex vivo hippocampus and insula (United States)

    Stamm, Aymeric; Singh, Jolene M.; Scherrer, Benoit; Afacan, Onur; Warfield, Simon K.


    The hippocampus and the insula are responsible for episodic memory formation and retrieval. Hence, visualization of the cytoarchitecture of such structures is of primary importance to understand the underpinnings of conscious experience. Magnetic Resonance Imaging (MRI) offers an opportunity to non-invasively image these crucial structures. However, current clinical MR imaging operates at the millimeter scale while these anatomical landmarks are organized into sub-millimeter structures. For instance, the hippocampus contains several layers, including the CA3-dentate network responsible for encoding events and experiences. To investigate whether memory loss is a result of injury or degradation of CA3/dentate, spatial resolution must exceed one hundred micron, isotropic, voxel size. Going from one millimeter voxels to one hundred micron voxels results in a 1000× signal loss, making the measured signal close to or even way below the precision of the receiving coils. Consequently, the signal magnitude that forms the structural images will be biased and noisy, which results in inaccurate contrast and less than optimal signal-to-noise ratio (SNR). In this paper, we propose a strategy to perform high spatial resolution MR imaging of the hippocampus and insula with 3T scanners that enables accurate contrast (no systematic bias) and arbitrarily high SNR. This requires the collection of additional repeated measurements of the same image and a proper averaging of the k-space data in the complex domain. This comes at the cost of additional scan time, but long single-session scan times are not practical for obvious reasons. Hence, we also develop an approach to combine k-space data from multiple sessions, which enables the total scan time to be split into arbitrarily short sessions, where the patient is allowed to move and rest in-between. For validation, we hereby illustrate our multi-session complex averaging strategy by providing high spatial resolution 3T MR visualization

  5. Prototype of a high-power, high-energy industrial XeCl laser (United States)

    Borisov, V. M.; Demin, A. I.; Khristoforov, O. B.


    We discuss the results of fabrication and experimental study of a high-power excimer XeCl laser for industrial applications. Compactness of the laser is achieved by the employment of a laser chamber based on a ceramic tube made of Al2O3. High laser output energy (1.5 - 2.5 J pulse-1) is obtained using a wide-aperture (up to 55 × 30 mm) volume discharge with pre-ionisation by a creeping discharge. The pre-ionisation is realised through a semitransparent electrode by the UV radiation of a creeping discharge in the form of uniform plasma sheet on a surface of a plane sapphire plate. The operating lifetime of the gas mixture amounts to ~57 × 106 pulses at a stabilised average laser power of 450 W. The results obtained demonstrate real prospects for developing a new class of excimer XeCl lasers with an average power of ~1 kW.

  6. High Efficiency Microwave Power Amplifier (HEMPA) Design (United States)

    Sims, W. Herbert


    This paper will focus on developing an exotic switching technique that enhances the DC-to-RF conversion efficiency of microwave power amplifiers. For years, switching techniques implemented in the 10 kHz to 30 MHz region have resulted in DC-to-RF conversion efficiencies of 90-95-percent. Currently amplifier conversion efficiency, in the 2-3 GHz region approaches, 10-20-percent. Using a combination of analytical modeling and hardware testing, a High Efficiency Microwave Power Amplifier was built that demonstrated conversion efficiencies four to five times higher than current state of the art.

  7. Multi-Repeated Projection Lithography for High-Precision Linear Scale Based on Average Homogenization Effect

    Directory of Open Access Journals (Sweden)

    Dongxu Ren


    Full Text Available A multi-repeated photolithography method for manufacturing an incremental linear scale using projection lithography is presented. The method is based on the average homogenization effect that periodically superposes the light intensity of different locations of pitches in the mask to make a consistent energy distribution at a specific wavelength, from which the accuracy of a linear scale can be improved precisely using the average pitch with different step distances. The method’s theoretical error is within 0.01 µm for a periodic mask with a 2-µm sine-wave error. The intensity error models in the focal plane include the rectangular grating error on the mask, static positioning error, and lithography lens focal plane alignment error, which affect pitch uniformity less than in the common linear scale projection lithography splicing process. It was analyzed and confirmed that increasing the repeat exposure number of a single stripe could improve accuracy, as could adjusting the exposure spacing to achieve a set proportion of black and white stripes. According to the experimental results, the effectiveness of the multi-repeated photolithography method is confirmed to easily realize a pitch accuracy of 43 nm in any 10 locations of 1 m, and the whole length accuracy of the linear scale is less than 1 µm/m.

  8. Multi-Repeated Projection Lithography for High-Precision Linear Scale Based on Average Homogenization Effect. (United States)

    Ren, Dongxu; Zhao, Huiying; Zhang, Chupeng; Yuan, Daocheng; Xi, Jianpu; Zhu, Xueliang; Ban, Xinxing; Dong, Longchao; Gu, Yawen; Jiang, Chunye


    A multi-repeated photolithography method for manufacturing an incremental linear scale using projection lithography is presented. The method is based on the average homogenization effect that periodically superposes the light intensity of different locations of pitches in the mask to make a consistent energy distribution at a specific wavelength, from which the accuracy of a linear scale can be improved precisely using the average pitch with different step distances. The method's theoretical error is within 0.01 µm for a periodic mask with a 2-µm sine-wave error. The intensity error models in the focal plane include the rectangular grating error on the mask, static positioning error, and lithography lens focal plane alignment error, which affect pitch uniformity less than in the common linear scale projection lithography splicing process. It was analyzed and confirmed that increasing the repeat exposure number of a single stripe could improve accuracy, as could adjusting the exposure spacing to achieve a set proportion of black and white stripes. According to the experimental results, the effectiveness of the multi-repeated photolithography method is confirmed to easily realize a pitch accuracy of 43 nm in any 10 locations of 1 m, and the whole length accuracy of the linear scale is less than 1 µm/m.

  9. Highly efficient sparse-matrix inversion techniques and average procedures applied to collisional-radiative codes

    CERN Document Server

    Poirier, M


    The behavior of non-local thermal-equilibrium (NLTE) plasmas plays a central role in many fields of modern-day physics, such as laser-produced plasmas, astrophysics, inertial or magnetic confinement fusion devices, or X-ray sources. The proper description of these media in stationary cases requires to solve linear systems of thousands or more rate equations. A possible simplification for this arduous numerical task may lie in some type of statistical average, such as configuration or superconfiguration average. However to assess the validity of this procedure and to handle cases where isolated lines play an important role, it may be important to deal with detailed levels systems. This involves matrices with sometimes billions of elements, which are rather sparse but still involve thousands of diagonals. We propose here a numerical algorithm based on the LU decomposition for such linear systems. This method turns out to be orders of magnitude faster than the traditional Gauss elimination. And at variance with ...

  10. High Power Experiments in VX-10 (United States)

    Squire, Jared; Chang-Diaz, Franklin; Araya-Chacon, Gonzalo; Jacobson, Verlin; Glover, Tim; McCaskill, Greg; Vera, Jerry; Baity, Wally; Carter, Mark; Goulding, Rick


    In the Advanced Space Propulsion Laboratory VASIMR experiment (VX-10) we have measured a plasma flux to input gas rate ratio near 100power levels up to 10 kW. The plasma source is being developed to supply a dense target with a high degree of ionization for ICRF acceleration of the flow in an expanding magnetic field. An upgrade to 20 kW helicon operations is underway. Recent results at Oak Ridge National Laboratory show enhanced efficiency operation with a high power density, over 5 kW in a 5 cm diameter tube. Our helicon is presently 9 cm in diameter, so comparable power densities will be achieved in VX-10. We have operated with a Boswell double-saddle antenna design with a magnetic cusp just upstream of the antenna. Recently we have converted to a double-helix half-turn antenna. ICRF experiments have been performed as 1.5 kW that show significant plasma flow acceleration, doubling the flow velocity. A 10 kW ICRF upgrade is underway. Results from high total power ( ˜ 30 kW) experiments with this new helicon antenna and ICRF acceleration are presented.

  11. High Temperature Magnetics for Power Conversion (United States)


    complex zig zag cutout shown earlier. On the secondary, 3 layers at a time were folded. Folds alternated in direction to even out overall foil...ingredients were mixed in a high-shear blender, calcined at 900°C in air, and ground in a stirred ball mill for 2 hours to an average particle size of...approximately 1 micron. Various organic binders and dispersants were added at the milling step to enhance particle size reduction and improve pressing

  12. Discharge Physics of High Power Impulse Magnetron Sputtering

    Energy Technology Data Exchange (ETDEWEB)

    Anders, Andre


    High power impulse magnetron sputtering (HIPIMS) is pulsed sputtering where the peak power exceeds the time-averaged power by typically two orders of magnitude. The peak power density, averaged over the target area, can reach or exceed 107 W/m2, leading to plasma conditions that make ionization of the sputtered atoms very likely. A brief review of HIPIMS operation is given in a tutorial manner, illustrated by some original data related to the self-sputtering of niobium in argon and krypton. Emphasis is put on the current-voltage-time relationships near the threshold of self-sputtering runaway. The great variety of current pulse shapes delivers clues on the very strong gas rarefaction, self-sputtering runaway conditions, and the stopping of runaway due to the evolution of atom ionization and ion return probabilities as the gas plasma is replaced by metal plasma. The discussions are completed by considering instabilities and the special case of ?gasless? self-sputtering.

  13. Performance of improved magnetostrictive vibrational power generator, simple and high power output for practical applications

    Energy Technology Data Exchange (ETDEWEB)

    Ueno, Toshiyuki, E-mail: [Kanazawa University, Kakuma-machi, Kanazawa-city, Ishikawa 920-1192 (Japan)


    Vibration based power generation technology is utilized effectively in various fields. Author has invented novel vibrational power generation device using magnetostrictive material. The device is based on parallel beam structure consisting of a rod of iron-gallium alloy wound with coil and yoke accompanied with permanent magnet. When bending force is applied on the tip of the device, the magnetization inside the rod varies with induced stress due to the inverse magnetostrictive effect. In vibration, the time variation of the magnetization generates voltage on the wound coil. The magnetostrictive type is advantageous over conventional such using piezoelectric or moving magnet types in high efficiency and high robustness, and low electrical impedance. Here, author has established device configuration, simple, rigid, and high power output endurable for practical applications. In addition, the improved device is lower cost using less volume of Fe-Ga and permanent magnet compared to our conventional, and its assembly by soldering is easy and fast suitable for mass production. Average power of 3 mW/cm{sup 3} under resonant vibration of 212 Hz and 1.2 G was obtained in miniature prototype using Fe-Ga rod of 2 × 0.5× 7 mm{sup 3}. Furthermore, the damping effect was observed, which demonstrates high energy conversion of the generator.

  14. Peak torque and average power at flexion/extension of the shoulder and knee when using a mouth guard in adults with mild midline discrepancy. (United States)

    Lee, Sang-Yeol; Hong, Min-Ho; Choi, Seung-Jun


    [Purpose] This study was conducted to investigate the changes in torque and power during flexion and extension of the shoulder and the knee joints caused by midline correction using mouth guards made from different materials in adults with mild midline discrepancy. [Subjects] The subjects of this study were males (n=12) in their 20s who showed a 3-5 mm difference between the midlines of the upper and lower teeth but had normal masticatory function. [Methods] The torque and average power of the lower limb and upper limb were measured during flexion and extension according to various types of mouth guard. [Results] There were significant differences in relative torque and average power between three conditions (no mouth guard, soft-type mouth guard, and hard-type mouth guard) at shoulder flexion and extension. There were no significant differences in relative torque and average power between the three conditions at knee flexion and extension. [Conclusions] These results suggest that use of a mouth guard is a method by which people with a mild midline discrepancy can improve the stability of the entire body.

  15. High-Power, High-Thrust Ion Thruster (HPHTion) (United States)

    Peterson, Peter Y.


    Advances in high-power photovoltaic technology have enabled the possibility of reasonably sized, high-specific power solar arrays. At high specific powers, power levels ranging from 50 to several hundred kilowatts are feasible. Ion thrusters offer long life and overall high efficiency (typically greater than 70 percent efficiency). In Phase I, the team at ElectroDynamic Applications, Inc., built a 25-kW, 50-cm ion thruster discharge chamber and fabricated a laboratory model. This was in response to the need for a single, high-powered engine to fill the gulf between the 7-kW NASA's Evolutionary Xenon Thruster (NEXT) system and a notional 25-kW engine. The Phase II project matured the laboratory model into a protoengineering model ion thruster. This involved the evolution of the discharge chamber to a high-performance thruster by performance testing and characterization via simulated and full beam extraction testing. Through such testing, the team optimized the design and built a protoengineering model thruster. Coupled with gridded ion thruster technology, this technology can enable a wide range of missions, including ambitious near-Earth NASA missions, Department of Defense missions, and commercial satellite activities.

  16. The Behavioral Toxicology of High-Peak, Low Average Power, Pulsed Microwave Irradiation (United States)


    chlordiazepoxide and diazepam combined with low-level microwaves. Neurobehavioral Toxicology, 2, 131-135. Thomas, J. R., Schrot, J.. and Banvard, R. A...229-272. Thomas, J. R., Burch, L. S., and Yeandle. S. S. (1979). Microwave radiation and chlordiazepoxide : Synergistic effects on fixed-interval

  17. Optical under-sampling by using a broadband optical comb with a high average power. (United States)

    Sherman, Alexander; Horowitz, Moshe; Zach, Shlomo


    We demonstrate a new method to improve the performance of photonic assisted analog to digital converters (ADCs) that are based on frequency down-conversion obtained by optical under-sampling. The under-sampling is performed by multiplying the radio frequency signal by ultra-low jitter broadband phase-locked optical comb. The comb wave intensity has a smooth periodic function in the time domain rather than a train of short pulses that is currently used in most photonic assisted ADCs. Hence, the signal energy at the photo-detector output can be increased and the signal to noise ratio of the system might be improved without decreasing its bandwidth. We have experimentally demonstrated a system for electro-optical under-sampling with a 6-dB bandwidth of 38.5 GHz and a spur free dynamic range of 99 dB/Hz(2/3) for a signal with a carrier frequency of 35.8 GHz, compared with 94 dB/Hz(2/3) for a signal at 6.2 GHz that was obtained in the same system when a pulsed optical source was used. The optical comb was generated by mixing signals from two dielectric resonator oscillators in a Mach-Zehnder modulator. The comb spacing is equal to 4 GHz and its bandwidth was greater than 48 GHz. The temporal jitter of the comb measured by integrating the phase noise in a frequency region of 10 kHz to 10 MHz around comb frequencies of 16 and 20 GHz was only about 15 and 11 fs, respectively.

  18. High Average Power Mid-infrared Supercontinuum Generation in a Suspended Core Chalcogenide Fiber

    DEFF Research Database (Denmark)

    Møller, Uffe Visbech; Yu, Yi; Petersen, Christian Rosenberg


    Mid-infrared supercontinuum spanning from 2.0 to 6.1 μm is generated in a 9 cm suspended core chalcogenide fiber by pumping close to the fiber zero-dispersion wavelength at 3.5 μm with an OPA system...

  19. Solid-State Raman Converters for High-Average Power Chemical Oxygen Iodine Laser (United States)


    spectral resolution of the system was 0.2-1.0 cmŕ. The argon laser plasma discharge lines were cut by an additional ÖD •TM...Principles of Nonlinear Optics. New York; Wiley, 1984, ch. 10. 15. R. L. Carman , F. Shimizu, C. S. Wang, and N. Bloembergen, "Theory of Stokes pulse shapes

  20. High Average Power Mid-infrared Supercontinuum Generation in a Suspended Core Chalcogenide Fiber

    DEFF Research Database (Denmark)

    Møller, Uffe Visbech; Yu, Yi; Petersen, Christian Rosenberg;


    Mid-infrared supercontinuum spanning from 2.0 to 6.1 μm is generated in a 9 cm suspended core chalcogenide fiber by pumping close to the fiber zero-dispersion wavelength at 3.5 μm with an OPA system...

  1. Reduced filamentation in high power semiconductor lasers

    DEFF Research Database (Denmark)

    Skovgaard, Peter M. W.; McInerney, John; O'Brien, Peter


    High brightness semiconductor lasers have applications in fields ranging from material processing to medicine. The main difficulty associated with high brightness is that high optical power densities cause damage to the laser facet and thus require large apertures. This, in turn, results in spatio...... in the optical field causes spatial hole-burning and thus filamentation. To reduce filamentation we propose a new, relatively simple design based on inhomogeneous pumping in which the injected current has a gradual transverse profile. We confirm the improved laser performance theoretically and experimentally...

  2. High power all-solid-state quasi-continuous-wave tunable Ti: sapphire laser system

    Institute of Scientific and Technical Information of China (English)

    Lei Zou; Xin Ding; Yue Zou; Hongmei Ma; Wuqi Wen; Peng Wang; Jianquan Yao


    This paper reports a high power, all-solid-state, quasi-continuous-wave tunable Ti:sapphire laser system pumped by laser diode (LD) pumped frequency-doubled Nd:YAG laser. The maximum tuned output power of 4.2 W (797 nm) and tuned average power of 3.7 W were achieved when fixing the Ti:sapphire broadband output power at 5.0 W and applying 750-850 nm broadband coated mirror.

  3. Estimation of the hydraulic conductivity of a two-dimensional fracture network using effective medium theory and power-law averaging (United States)

    Zimmerman, R. W.; Leung, C. T.


    Most oil and gas reservoirs, as well as most potential sites for nuclear waste disposal, are naturally fractured. In these sites, the network of fractures will provide the main path for fluid to flow through the rock mass. In many cases, the fracture density is so high as to make it impractical to model it with a discrete fracture network (DFN) approach. For such rock masses, it would be useful to have recourse to analytical, or semi-analytical, methods to estimate the macroscopic hydraulic conductivity of the fracture network. We have investigated single-phase fluid flow through generated stochastically two-dimensional fracture networks. The centers and orientations of the fractures are uniformly distributed, whereas their lengths follow a lognormal distribution. The aperture of each fracture is correlated with its length, either through direct proportionality, or through a nonlinear relationship. The discrete fracture network flow and transport simulator NAPSAC, developed by Serco (Didcot, UK), is used to establish the “true” macroscopic hydraulic conductivity of the network. We then attempt to match this value by starting with the individual fracture conductances, and using various upscaling methods. Kirkpatrick’s effective medium approximation, which works well for pore networks on a core scale, generally underestimates the conductivity of the fracture networks. We attribute this to the fact that the conductances of individual fracture segments (between adjacent intersections with other fractures) are correlated with each other, whereas Kirkpatrick’s approximation assumes no correlation. The power-law averaging approach proposed by Desbarats for porous media is able to match the numerical value, using power-law exponents that generally lie between 0 (geometric mean) and 1 (harmonic mean). The appropriate exponent can be correlated with statistical parameters that characterize the fracture density.

  4. High Power UV LED Industrial Curing Systems

    Energy Technology Data Exchange (ETDEWEB)

    Karlicek, Robert, F., Jr; Sargent, Robert


    UV curing is a green technology that is largely underutilized because UV radiation sources like Hg Lamps are unreliable and difficult to use. High Power UV LEDs are now efficient enough to replace Hg Lamps, and offer significantly improved performance relative to Hg Lamps. In this study, a modular, scalable high power UV LED curing system was designed and tested, performing well in industrial coating evaluations. In order to achieve mechanical form factors similar to commercial Hg Lamp systems, a new patent pending design was employed enabling high irradiance at long working distances. While high power UV LEDs are currently only available at longer UVA wavelengths, rapid progress on UVC LEDs and the development of new formulations designed specifically for use with UV LED sources will converge to drive more rapid adoption of UV curing technology. An assessment of the environmental impact of replacing Hg Lamp systems with UV LED systems was performed. Since UV curing is used in only a small portion of the industrial printing, painting and coating markets, the ease of use of UV LED systems should increase the use of UV curing technology. Even a small penetration of the significant number of industrial applications still using oven curing and drying will lead to significant reductions in energy consumption and reductions in the emission of green house gases and solvent emissions.

  5. Website Design Guidelines: High Power Distance and High Context Culture

    Directory of Open Access Journals (Sweden)

    Tanveer Ahmed


    Full Text Available This paper aims to address the question of offering a culturally adapted website for a local audience. So far, in the website design arena the vast majority of studies examined mainly Western and the American (low power distance and low context culture disregarding possible cultural discrepancies. This study fills this gap and explores the key cultural parameters that are likely to have an impact on local website design for Asian-Eastern culture high power distance and high context correlating with both Hofstede’s and Hall’s cultural dimensions. It also reviews how website localisation may be accomplished more effectively by extracting the guidelines from two different yet compatible cultural dimensions: high power distance and high context.

  6. Power Supplies for High Energy Particle Accelerators (United States)

    Dey, Pranab Kumar


    The on-going research and the development projects with Large Hadron Collider at CERN, Geneva, Switzerland has generated enormous enthusiasm and interest amongst all to know about the ultimate findings on `God's Particle'. This paper has made an attempt to unfold the power supply requirements and the methodology adopted to provide the stringent demand of such high energy particle accelerators during the initial stages of the search for the ultimate particles. An attempt has also been made to highlight the present status on the requirement of power supplies in some high energy accelerators with a view that, precautionary measures can be drawn during design and development from earlier experience which will be of help for the proposed third generation synchrotron to be installed in India at a huge cost.

  7. High-Power Wind Turbine: Performance Calculation

    Directory of Open Access Journals (Sweden)

    Goldaev Sergey V.


    Full Text Available The paper is devoted to high-power wind turbine performance calculation using Pearson’s chi-squared test the statistical hypothesis on distribution of general totality of air velocities by Weibull-Gnedenko. The distribution parameters are found by numerical solution of transcendental equation with the definition of the gamma function interpolation formula. Values of the operating characteristic of the incomplete gamma function are defined by numerical integration using Weddle’s rule. The comparison of the calculated results using the proposed methodology with those obtained by other authors found significant differences in the values of the sample variance and empirical Pearson. The analysis of the initial and maximum wind speed influence on performance of the high-power wind turbine is done

  8. Microbial Carbon Substrate Utilization Differences among High- and Average-Yield Soybean Areas

    National Research Council Canada - National Science Library

    Taylor C. Adams; Kristofor R. Brye; Mary C. Savin; Jung Ae Lee; Edward E. Gbur


    Since soybean (Glycine max L. (Merr.)) yields greater than 6719 kg ha−1 have only recently and infrequently been achieved, little is known about the soil microbiological environment related to high-yield soybean production...

  9. High power/large area PV systems (United States)

    Wise, Joseph; Baraona, Cosmo


    The major photovoltaic power system technology drivers for a wide variety of mission types were ranked. Each technology driver was ranked on a scale of high, medium, or low in terms of importance to each particular mission type. The rankings were then compiled to determine the overall importance of each driver over the entire range of space missions. In each case cost was ranked the highest.

  10. Power management systems for sediment microbial fuel cells in high power and continuous power applications (United States)

    Donovan, Conrad Koble

    The objective of this dissertation was to develop power management systems (PMS) for sediment microbial fuel cells (SFMCs) for high power and continuous applications. The first part of this dissertation covers a new method for testing the performance of SMFCs. This device called the microbial fuel cell tester was developed to automatically test power generation of PMS. The second part focuses on a PMS capable of delivering high power in burst mode. This means that for a small amount of time a large amount of power up to 2.5 Watts can be delivered from a SMFC only generating mW level power. The third part is aimed at developing a multi-potentiostat laboratory tool that measures the performance at fixed cell potentials of microbial fuel cells so that I can optimize them for use with the PMS. This tool is capable of controlling the anode potential or cathode potential and measuring current of six separate SMFCs simultaneously. By operating multiple potentiostats, I was able to run experiments that find ideal operating conditions for the sediment microbial fuel cells, and also I can optimize the power management system for these conditions. The fourth part of the dissertation is targeting a PMS that was able to operate a sensor continuously which was powered by an SMFC. In pervious applications involving SMFCs, the PMS operated in batch mode. In this PMS, the firmware on the submersible ultrasonic receiver (SUR) was modified for use with my PMS. This integration of PMS and SUR allowed for the continuous operation of the SUR without using a battery. Finally, the last part of the dissertation recommends a scale-up power management system to overcome the linearity scale up issue of SMFCs as future work. Concluding remarks are also added to summarize the goal and focus of this dissertation.

  11. Overview of High Power Vacuum Dry RF Load Designs

    Energy Technology Data Exchange (ETDEWEB)

    Krasnykh, Anatoly [SLAC National Accelerator Lab., Menlo Park, CA (United States)


    A specific feature of RF linacs based on the pulsed traveling wave (TW) mode of operation is that only a portion of the RF energy is used for the beam acceleration. The residual RF energy has to be terminated into an RF load. Higher accelerating gradients require higher RF sources and RF loads, which can stably terminate the residual RF power. RF feeders (from the RF source though the accelerating section to the load) are vacuumed to transmit multi-megawatt high power RF. This overview will outline vacuumed RF loads only. A common method to terminate multi-MW RF power is to use circulated water (or other liquid) as an absorbing medium. A solid dielectric interface (a high quality ceramic) is required to separate vacuum and liquid RF absorber mediums. Using such RF load approaches in TW linacs is troubling because there is a fragile ceramic window barrier and a failure could become catastrophic for linac vacuum and RF systems. Traditional loads comprising of a ceramic disk have limited peak and average power handling capability and are therefore not suitable for high gradient TW linacs. This overview will focus on ''vacuum dry'' or ''all-metal'' loads that do not employ any dielectric interface between vacuum and absorber. The first prototype is an original design of RF loads for the Stanford Two-Mile Accelerator.

  12. The future of high power laser techniques (United States)

    Poprawe, Reinhart; Loosen, Peter; Hoffmann, Hans-Dieter


    High Power Lasers have been used for years in corresponding applications. Constantly new areas and new processes have been demonstrated, developed and transferred to fruitful use in industry. With the advent of diode pumped solid state lasers in the multi-kW-power regime at beam qualities not far away from the diffraction limit, a new area of applicability has opened. In welding applications speeds could be increased and systems could be developed with higher efficiently leading also to new perspectives for increased productivity, e.g. in combined processing. Quality control is increasingly demanded by the applying industries, however applications still are rare. Higher resolution of coaxial process control systems in time and space combined with new strategies in signal processing could give rise to new applications. The general approach described in this paper emphasizes the fact, that laser applications can be developed more efficiently, more precisely and with higher quality, if the laser radiation is tailored properly to the corresponding application. In applying laser sources, the parameter ranges applicable are by far wider and more flexible compared to heat, mechanical or even electrical energy. The time frame ranges from several fs to continuous wave and this spans approximately 15 orders of magnitude. Spacewise, the foci range from several µm to cm and the resulting intensities suitable for materials processing span eight orders of magnitude from 10 3 to 10 11 W/cm2. In addition to space (power, intensity) and time (pulse) the wavelength can be chosen as a further parameter of optimization. As a consequence, the resulting new applications are vast and can be utilized in almost every market segment of our global economy (Fig. 1). In the past and only partly today, however, this flexibility of laser technology is not exploited in full in materials processing, basically because in the high power regime the lasers with tailored beam properties are not

  13. Direct generation of 2  W average-power and 232  nJ picosecond pulses from an ultra-simple Yb-doped double-clad fiber laser. (United States)

    Huang, Yizhong; Luo, Zhengqian; Xiong, Fengfu; Li, Yingyue; Zhong, Min; Cai, Zhiping; Xu, Huiying; Fu, Hongyan


    We report the generation of 2.06 W average-power and 232 nJ picosecond mode-locked pulses directly from an ultra-simple Yb-doped fiber laser. A section of Yb-doped double-clad fiber pumped by a 976 nm laser diode provides the large gain, and the linear cavity is simply formed by a 1064 nm highly reflective fiber Bragg grating and a fiber loop mirror (FLM) using a 5/95 optical coupler. The asymmetric FLM not only acts as the output mirror for providing ∼20% optical feedback, but also equivalently behaves as a nonlinear optical loop mirror (NOLM) to initiate the mode-locking operation in this cavity. Stable mode-locking is therefore achieved over a pump power of 3.76 W. The mode-locked pulses show the dissipative soliton resonance (DSR), which has the pulse duration of 695 ps to ∼1  ns, and the almost unchanged peak power of ∼200  W as increasing the pump power. In particular, this laser can emit 232 nJ high-energy DSR pulses with an average output power of >2  W. This is, to the best of our knowledge, the first demonstration of such an ultra-simple, mode-locked fiber laser that enables watt-level, high energy, picosecond DSR pulses.

  14. Highly efficient high power single-mode fiber amplifier utilizing the distributed mode filtering bandgap rod fiber

    DEFF Research Database (Denmark)

    Laurila, Marko; Alkeskjold, Thomas T.; Jørgensen, Mette Marie


    We report on an ytterbium doped single mode distributed mode filtering rod fiber in an amplifier configuration delivering high average output power, up to 292 watts, using a mode-locked 30ps source at 1032nm with good power conversion efficiency. We study the modal stability of the output beam...

  15. The final power calibration of the IPEN/MB-01 nuclear reactor for various configurations obtained from the measurements of the absolute average neutron flux

    Energy Technology Data Exchange (ETDEWEB)

    Silva, Alexandre Fonseca Povoa da, E-mail: [Centro Tecnologico da Marinha em Sao Paulo (CTMSP), Sao Paulo, SP (Brazil); Bitelli, Ulysses d' Utra; Mura, Luiz Ernesto Credidio; Lima, Ana Cecilia de Souza; Betti, Flavio; Santos, Diogo Feliciano dos, E-mail: [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)


    The use of neutron activation foils is a widely spread technique applied to obtain nuclear parameters then comparing the results with those calculated using specific methodologies and available nuclear data. By irradiation of activation foils and subsequent measurement of its induced activity, it is possible to determine the neutron flux at the position of irradiation. The power level during operation of the reactor is a parameter which is directly proportional to the average neutron flux throughout the core. The objective of this work is to gather data from irradiation of gold foils symmetrically placed along a cylindrically configured core which presents only a small excess reactivity in order to derive the power generated throughout the spatial thermal and epithermal neutron flux distribution over the core of the IPEN/MB-01 Nuclear Reactor, eventually lending to a proper calibration of its nuclear channels. The foils are fixed in a Lucite plate then irradiated with and without cadmium sheaths so as to obtain the absolute thermal and epithermal neutron flux. The correlation between the average power neutron flux resulting from the gold foils irradiation, and the average power digitally indicated by the nuclear channel number 6, allows for the calibration of the nuclear channels of the reactor. The reactor power level obtained by thermal neutron flux mapping was (74.65 ± 2.45) watts to a mean counting per seconds of 37881 cps to nuclear channel number 10 a pulse detector, and 0.719.10{sup -5} ampere to nuclear linear channel number 6 (a non-compensated ionization chamber). (author)

  16. High-power LEDs for plant cultivation (United States)

    Tamulaitis, Gintautas; Duchovskis, Pavelas; Bliznikas, Zenius; Breive, Kestutis; Ulinskaite, Raimonda; Brazaityte, Ausra; Novickovas, Algirdas; Zukauskas, Arturas; Shur, Michael S.


    We report on high-power solid-state lighting facility for cultivation of greenhouse vegetables and on the results of the study of control of photosynthetic activity and growth morphology of radish and lettuce imposed by variation of the spectral composition of illumination. Experimental lighting modules (useful area of 0.22 m2) were designed based on 4 types of high-power light-emitting diodes (LEDs) with emission peaked in red at the wavelengths of 660 nm and 640 nm (predominantly absorbed by chlorophyll a and b for photosynthesis, respectively), in blue at 455 nm (phototropic function), and in far-red at 735 nm (important for photomorphology). Morphological characteristics, chlorophyll and phytohormone concentrations in radish and lettuce grown in phytotron chambers under lighting with different spectral composition of the LED-based illuminator and under illumination by high pressure sodium lamps with an equivalent photosynthetic photon flux density were compared. A well-balanced solid-state lighting was found to enhance production of green mass and to ensure healthy morphogenesis of plants compared to those grown using conventional lighting. We observed that the plant morphology and concentrations of morphologically active phytohormones is strongly affected by the spectral composition of light in the red region. Commercial application of the LED-based illumination for large-scale plant cultivation is discussed. This technology is favorable from the point of view of energy consumption, controllable growth, and food safety but is hindered by high cost of the LEDs. Large scale manufacturing of high-power red AlInGaP-based LEDs emitting at 650 nm and a further decrease of the photon price for the LEDs emitting in the vicinity of the absorption peak of chlorophylls have to be achieved to promote horticulture applications.

  17. Is it better to be average? High and low performance as predictors of employee victimization. (United States)

    Jensen, Jaclyn M; Patel, Pankaj C; Raver, Jana L


    Given increased interest in whether targets' behaviors at work are related to their victimization, we investigated employees' job performance level as a precipitating factor for being victimized by peers in one's work group. Drawing on rational choice theory and the victim precipitation model, we argue that perpetrators take into consideration the risks of aggressing against particular targets, such that high performers tend to experience covert forms of victimization from peers, whereas low performers tend to experience overt forms of victimization. We further contend that the motivation to punish performance deviants will be higher when performance differentials are salient, such that the effects of job performance on covert and overt victimization will be exacerbated by group performance polarization, yet mitigated when the target has high equity sensitivity (benevolence). Finally, we investigate whether victimization is associated with future performance impairments. Results from data collected at 3 time points from 576 individuals in 62 work groups largely support the proposed model. The findings suggest that job performance is a precipitating factor to covert victimization for high performers and overt victimization for low performers in the workplace with implications for subsequent performance.

  18. High-power LED package requirements (United States)

    Wall, Frank; Martin, Paul S.; Harbers, Gerard


    Power LEDs have evolved from simple indicators into illumination devices. For general lighting applications, where the objective is to light up an area, white LED arrays have been utilized to serve that function. Cost constraints will soon drive the industry to provide a discrete lighting solution. Early on, that will mean increasing the power densities while quantum efficiencies are addressed. For applications such as automotive headlamps & projection, where light needs to be tightly collimated, or controlled, arrays of die or LEDs will not be able to satisfy the requirements & limitations defined by etendue. Ultimately, whether a luminaire requires a small source with high luminance, or light spread over a general area, economics will force the evolution of the illumination LED into a compact discrete high power package. How the customer interfaces with this new package should be an important element considered early on in the design cycle. If an LED footprint of adequate size is not provided, it may prove impossible for the customer, or end user, to get rid of the heat in a manner sufficient to prevent premature LED light output degradation. Therefore it is critical, for maintaining expected LED lifetime & light output, that thermal performance parameters be defined, by design, at the system level, which includes heat sinking methods & interface materials or methdology.


    Directory of Open Access Journals (Sweden)

    M. I. Baranov


    Full Text Available Purpose. Calculation and experimental determination of average geometrical features of distributing of macroscopic electron wave packages (EWP in round cylindrical metallic conductors with the pulsed axial current of high density. Methodology. Theoretical bases of the electrical engineering, bases of atomic and quantum physics, electrophysics bases of technique of high voltage and high pulsed currents. Results. The results of the conducted calculation and experimental researches are resulted on close determination of average geometrical features of distribution of longitudinal and radial EWP of macroscopic sizes in the indicated conductors. These descriptions are included by the average widths of «hot» and «cold» longitudinal and radial areas of conductor, and also average steps of division into the periods of similar areas. Results of the executed calculations and high temperature experiments for average geometrical features of longitudinal EWP in the zincked steel wire of diameter of 1.6 mm and length of 320 mm with the aperiodic impulse of current of temporal form 9 ms/160 ms and by amplitude 745 A coincide within the limits of 19 %. Originality. First with the use of methods of atomic and quantum physics the features of the stochastic distributing and mean values of basic geometrical sizes are analysed macroscopic longitudinal and radial EWP in round cylindrical metallic conductors with the pulsed axial current of high density. Practical value. Drawing on the got results in practice will allow more reliably to forecast geometrical sizes and places of localization of arising up in the probed metallic conductors with pulsed axial current of high density longitudinal and radial EWP.

  20. The Effect of Computer Based Instructional Technique for the Learning of Elementary Level Mathematics among High, Average and Low Achievers (United States)

    Afzal, Muhammad Tanveer; Gondal, Bashir; Fatima, Nuzhat


    The major objective of the study was to elicit the effect of three instructional methods for teaching of mathematics on low, average and high achiever elementary school students. Three methods: traditional instructional method, computer assisted instruction (CAI) and teacher facilitated mathematics learning software were employed for the teaching…

  1. Are Confidence Ratings Test- or Trait-Driven? Individual Differences among High, Average, and Low Comprehenders in Fourth Grade (United States)

    Kasperski, Ronen; Katzir, Tami


    The aim of this study was to examine whether low, average, and high comprehenders (LC, AC, and HC, respectively) differed in their reading self-confidence and bias ratings, and whether confidence ratings were driven by reading ability or distributed evenly among diverse readers. Seventy fourth-graders with good decoding abilities were administered…

  2. Are Confidence Ratings Test- or Trait-Driven? Individual Differences among High, Average, and Low Comprehenders in Fourth Grade (United States)

    Kasperski, Ronen; Katzir, Tami


    The aim of this study was to examine whether low, average, and high comprehenders (LC, AC, and HC, respectively) differed in their reading self-confidence and bias ratings, and whether confidence ratings were driven by reading ability or distributed evenly among diverse readers. Seventy fourth-graders with good decoding abilities were administered…

  3. A Study on Collaborative Operation Methods between New Energy Type Dispersed Power Supply System and SMES by Modified Euler Type Moving Average Prediction Model (United States)

    Monai, Toshiharu; Takano, Ichiro; Nishikawa, Hisao; Sawada, Yoshio

    In this paper, the modified Euler type Moving Average Prediction (EMAP) model is proposed in order to operate a dispersed power supply system using new energy in autonomous mode. Furthermore, EMAP model is applied to operate a new type dispersed power supply system consisting of a large scale photovoltaic system (PV), a fuel cell (FC) as well as a small scale superconducting magnetic energy storage system (SMES). This distributed power supply system can meet the multi-quality electric power requirements of customers, and ensures voltage stability and UPS (Uninterruptible Power Supply) function as well. Each sub-system of this distributed power supply contributes to the above-mentioned system performance with its own excellent characteristics. Moreover, response characteristics of this system are confirmed with simulation by software PSIM, and, under collaborative operation methods by EMAP model, the required capacity of SMES to compensate the fluctuation of both PV output and load demand is examined by the simulation using software MATLAB/Simulink.

  4. On the possibility of the determining the average mass composition near 10 to the 14th power eV through the solar magnetic field (United States)

    Lloyd-Evans, J.


    The discovery of primary ultrahigh energy (UHE) gamma-rays has spawned plans for a new generation of air shower experiments with unprecedented directional resolution. Such accuracy permits observation of a cosmic ray shadow due to the solar disc. Particle trajectory simulations through models of the large scale solar magnetic field were performed. The shadow is apparent above 10 to the 15th power eV for all cosmic ray charges /Z/ 26; at lower energies, trajectories close to the Sun are bent sufficiently for this shadow to be lost. The onset of the shadow is rigidity dependent, and occurs at an energy per nucleus of approx. Z x 10 to the 13th power eV. The possibility of determining the average mass composition near 10 to the 14th power eV from 1 year's observation at a mountain altitude array is investigated.

  5. Microstructured fibers for high power applications (United States)

    Baggett, J. C.; Petrovich, M. N.; Hayes, J. R.; Finazzi, V.; Poletti, F.; Amezcua, R.; Broderick, N. G. R.; Richardson, D. J.; Monro, T. M.; Salter, P. L.; Proudley, G.; O'Driscoll, E. J.


    Fiber delivery of intense laser radiation is important for a broad range of application sectors, from medicine through to industrial laser processing of materials, and offers many practical system design and usage benefits relative to free space solutions. Optical fibers for high power transmission applications need to offer low optical nonlinearity and high damage thresholds. Single-mode guidance is also often a fundamental requirement for the many applications in which good beam quality is critical. In recent years, microstructured fiber technology has revolutionized the dynamic field of optical fibers, bringing with them a wide range of novel optical properties. These fibers, in which the cladding region is peppered with many small air holes, are separated into two distinct categories, defined by the way in which they guide light: (1) index-guiding holey fibers (HFs), in which the core is solid and light is guided by a modified form of total internal reflection, and (2) photonic band-gap fibers (PBGFs) in which guidance in a hollow core can be achieved via photonic band-gap effects. Both of these microstructured fiber types offer attractive qualities for beam delivery applications. For example, using HF technology, large-mode-area, pure silica fibers with robust single-mode guidance over broad wavelength ranges can be routinely fabricated. In addition, the ability to guide light in an air-core within PBGFs presents obvious power handling advantages. In this paper we review the fundamentals and current status of high power, high brightness, beam delivery in HFs and PBGFs, and speculate as to future prospects.

  6. Transportable high-energy high-power generator. (United States)

    Novac, B M; Smith, I R; Senior, P; Parker, M; Louverdis, G


    High-power applications sometimes require a transportable, simple, and robust gigawatt pulsed power generator, and an analysis of various possible approaches shows that one based on a twin exploding wire array is extremely advantageous. A generator based on this technology and used with a high-energy capacitor bank has recently been developed at Loughborough University. An H-configuration circuit is used, with one pair of diagonally opposite arms each comprising a high-voltage ballast inductor and the other pair exploding wire arrays capable of generating voltages up to 300 kV. The two center points of the H configuration provide the output to the load, which is coupled through a high-voltage self-breakdown spark gap, with the entire autonomous source being housed in a metallic container. Experimentally, a load resistance of a few tens of Ohms is provided with an impulse of more than 300 kV, having a rise time of about 140 ns and a peak power of over 1.7 GW. Details of the experimental arrangement and typical results are presented and diagnostic measurements of the current and voltage output are shown to compare well with theoretical predictions based on detailed numerical modeling. Finally, the next stage toward developing a more powerful and energetic transportable source is outlined.


    Energy Technology Data Exchange (ETDEWEB)

    Robert Rimmer


    Steady development in SRF accelerator technology combined with the success of large scale installations such as CEBAF at Jefferson Laboratory and the SNS Linac at ORNL gives credibility to the concept of very high average power CW machines for light sources or Proton drivers. Such machines would be powerful tools for discovery science in themselves but could also pave the way to reliable cost effective drivers for such applications as neutrino factories, an energy-frontier muon collider, nuclear waste transmutation or accelerator driven subcritical reactors for energy production. In contrast to machines such as ILC that need maximum accelerating gradient, the challenges in these machines are mainly in efficiency, reliability, beam stability, beam loss and of course cost. In this paper the present state of the art is briefly reviewed and options for a multi-GeV, multi-MW CW linac are discussed.

  8. High Efficiency Reversible Fuel Cell Power Converter

    DEFF Research Database (Denmark)

    Pittini, Riccardo

    The large scale integration of renewable energy sources requires suitable energy storage systems to balance energy production and demand in the electrical grid. Bidirectional fuel cells are an attractive technology for energy storage systems due to the high energy density of fuel. Compared...... entitled "High Efficiency Reversible Fuel Cell Power Converter" and it presents the design of a high efficiency dc-dc converter developed and optimized for bidirectional fuel cell applications. First, a brief overview of fuel cell and energy storage technologies is presented. Different system topologies...... to traditional unidirectional fuel cell, bidirectional fuel cells have increased operating voltage and current ranges. These characteristics increase the stresses on dc-dc and dc-ac converters in the electrical system, which require proper design and advanced optimization. This work is part of the PhD project...

  9. Hybrid high power femtosecond laser system (United States)

    Trunov, V. I.; Petrov, V. V.; Pestryakov, E. V.; Kirpichnikov, A. V.


    Design of a high-power femtosecond laser system based on hybrid chirped pulse amplification (CPA) technique developed by us is presented. The goal of the hybrid principle is the use of the parametric and laser amplification methods in chirped pulse amplifiers. It makes it possible to amplify the low-cycle pulses with a duration of <= fs to terawatt power with a high contrast and high conversion efficiency of the pump radiation. In a created system the Ti:Sapphire laser with 10 fs pulses at 810 nm and output energy about 1-3 nJ will be used like seed source. The oscillator pulses were stretched to duration of about 500 ps by an all-reflective grating stretcher. Then the stretched pulses are injected into a nondegenerate noncollinear optical parametric amplifier (NOPA) on the two BBO crystals. After amplification in NOPA the residual pump was used in a bow-tie four pass amplifier with hybrid active medium (based on Al II0 3:Ti 3+ and BeAl IIO 4:Ti 3+ crystals). The final stage of the amplification system consists of two channels, namely NIR (820 nm) and short-VIS (410 nm). Numerical simulation has shown that the terawatt level of output power can be achieved also in a short-VIS channel at the pumping of the double-crystal BBO NOPA by the radiation of the fourth harmonic of the Nd:YAG laser at 266 nm. Experimentally parametric amplification in BBO crystals of 30-50 fs pulses were investigated and optimized using SPIDER technique and single-shot autocomelator for the realization of shortest duration 40 fs.

  10. Photovoltaics for high capacity space power systems (United States)

    Flood, Dennis J.


    The anticipated energy requirements of future space missions will grow by factors approaching 100 or more, particularly as a permanent manned presence is established in space. The advances that can be expected in solar array performance and lifetime, when coupled with advanced, high energy density storage batteries and/or fuel cells, will continue to make photovoltaic energy conversion a viable power generating option for the large systems of the future. The specific technologies required to satisfy any particular set of power requirements will vary from mission to mission. Nonetheless, in almost all cases the technology push will be toward lighter weight and higher efficiency, whether of solar arrays of storage devices. This paper will describe the content and direction of the current NASA program in space photovoltaic technology. The paper will also discuss projected system level capabilities of photovoltaic power systems in the context of some of the new mission opportunities under study by NASA, such as a manned lunar base, and a manned visit to Mars.

  11. High-power converters and AC drives

    CERN Document Server

    Wu, Bin


    This new edition reflects the recent technological advancements in the MV drive industry, such as advanced multilevel converters and drive configurations. It includes three new chapters, Control of Synchronous Motor Drives, Transformerless MV Drives, and Matrix Converter Fed Drives. In addition, there are extensively revised chapters on Multilevel Voltage Source Inverters and Voltage Source Inverter-Fed Drives. This book includes a systematic analysis on a variety of high-power multilevel converters, illustrates important concepts with simulations and experiments, introduces various megawatt drives produced by world leading drive manufacturers, and addresses practical problems and their mitigations methods.

  12. High performance power-configurable preamplifier in a high-density paralleloptical receiver

    Institute of Scientific and Technical Information of China (English)

    Wang Xiaoxia; Wang Zhigong


    A power-configurable high performance preamplifier was implemented in standard 180-nm CMOS technology for 12 × 10 Gb/s high-density ultra-high speed parallel optical communication system.With critical limitations on power consumption,area and fabrication cost,the preamplifier achieves high performance,e.g.high bandwidth,high trans-impedance gain,low noise and high stability.A novel feed-forward common gate (FCG)stage is adopted to alleviate contradictions on trans-impedance gain and bandwidth by using a low headroom consuming approach to isolate a large input capacitance and using complex pole peaking techniques to substitute inductors to achieve bandwidth extension.A multi-supply power-configurable scheme was employed to avoid wasteful power caused by a pessimistic estimation of process-voltage-temperature (PVT) variation.Two representative samples provide a trans-impedance gain of 53.9 dBΩ,a 3-dB bandwidth of 6.8 GHz,a power dissipation of 6.26 mW without power-configuration and a trans-impedance gain of 52.1 dBΩ,a 3-dB bandwidth of 8.1 GHz,a power dissipation of 6.35 mW with power-configuration,respectively.The measured average input-referred noise-current spectral density is no more than 28 pA/√Hz.The chip area is only 0.08 × 0.08 mm2.

  13. Analysis of Highly Wind Power Integrated Power System model performance during Critical Weather conditions

    DEFF Research Database (Denmark)

    Basit, Abdul; Hansen, Anca Daniela; Sørensen, Poul Ejnar


    . For this purpose, the power system model has been developed that represents the relevant dynamic features of power plants and compensates for power imbalances caused by the forecasting error during critical weather conditions. The regulating power plan, as an input time series for the developed power system model......Secure power system operation of a highly wind power integrated power system is always at risk during critical weather conditions, e.g. in extreme high winds. The risk is even higher when 50% of the total electricity consumption has to be supplied by wind power, as the case for the future Danish...... power system in 2020. This paper analyses and compares the performance of the future Danish power system during extreme wind speeds, where wind power plants are either controlled through a traditional High Wind Shut Down storm controller or a new High Wind Extended Production storm controller...

  14. The Effect of High School Socioeconomic Status on the Predictive Validity of SAT Scores and High School Grade-Point Average (United States)

    Zwick, Rebecca; Himelfarb, Igor


    Research has often found that, when high school grades and SAT scores are used to predict first-year college grade-point average (FGPA) via regression analysis, African-American and Latino students, are, on average, predicted to earn higher FGPAs than they actually do. Under various plausible models, this phenomenon can be explained in terms of…

  15. Optimal Operation of Plug-In Electric Vehicles in Power Systems with High Wind Power Penetrations

    DEFF Research Database (Denmark)

    Hu, Weihao; Su, Chi; Chen, Zhe


    The Danish power system has a large penetration of wind power. The wind fluctuation causes a high variation in the power generation, which must be balanced by other sources. The battery storage based Plug-In Electric Vehicles (PEV) may be a possible solution to balance the wind power variations...... in the power systems with high wind power penetrations. In this paper, the integration of plug-in electric vehicles in the power systems with high wind power penetrations is proposed and discussed. Optimal operation strategies of PEV in the spot market are proposed in order to decrease the energy cost for PEV...

  16. Scale Law of the High Power Free Electron Laser

    Institute of Scientific and Technical Information of China (English)


    The scale law and design procedure of the high power FEL are discussed. It is pointed out that theextraction efficiency, which is the critical factor of the output power besides the power of the electron

  17. Improved cooling design for high power waveguide system (United States)

    Chen, W. C. J.; Hartop, R.


    Testing of X band high power components in a traveling wave resonator indicates that this improved cooling design reduces temperature in the waveguide and flange. The waveguide power handling capability and power transmission reliability is increased substantially.

  18. Fibrous zinc anodes for high power batteries (United States)

    Zhang, X. Gregory

    This paper introduces newly developed solid zinc anodes using fibrous material for high power applications in alkaline and large size zinc-air battery systems. The improved performance of the anodes in these two battery systems is demonstrated. The possibilities for control of electrode porosity and for anode/battery design using fibrous materials are discussed in light of experimental data. Because of its mechanical integrity and connectivity, the fibrous solid anode has good electrical conductivity, mechanical stability, and design flexibility for controlling mass distribution, porosity and effective surface area. Experimental data indicated that alkaline cells made of such anodes can have a larger capacity at high discharging currents than commercially available cells. It showed even greater improvement over commercial cells with a non-conventional cell design. Large capacity anodes for a zinc-air battery have also been made and have shown excellent material utilization at various discharge rates. The zinc-air battery was used to power an electric bicycle and demonstrated good results.

  19. Digitally Controlled High Availability Power Supply

    Energy Technology Data Exchange (ETDEWEB)

    MacNair, David; /SLAC


    This paper will report on the test results of a prototype 1320 watt power module for a high availability power supply. The module will allow parallel operation for N+1 redundancy with hot swap capability. The two quadrant output of each module allows pairs of modules to provide a 4 quadrant (bipolar) operation. Each module employs a novel 4 FET buck regulator arranged in a bridge configuration. Each side of the bridge alternately conducts through a small saturable ferrite that limits the reverse current in the FET body diode during turn off. This allows hard switching of the FETs with low switching losses. The module is designed with over-rated components to provide high reliability and better then 97% efficiency at full load. The modules use a Microchip DSP for control, monitoring, and fault detection. The switching FETS are driven by PWM modules in the DSP at 60 KHz. A Dual CAN bus interface provides for low cost redundant control paths. The DSP will also provide current sharing between modules, synchronized switching, and soft start up for hot swapping. The input and output of each module have low resistance FETs to allow hot swapping and isolation of faulted units.

  20. Design and characterization of a novel power over fiber system integrating a high power diode laser (United States)

    Perales, Mico; Yang, Mei-huan; Wu, Cheng-liang; Hsu, Chin-wei; Chao, Wei-sheng; Chen, Kun-hsein; Zahuranec, Terry


    High power 9xx nm diode lasers along with MH GoPower's (MHGP's) flexible line of Photovoltaic Power Converters (PPCs) are spurring high power applications for power over fiber (PoF), including applications for powering remote sensors and sensors monitoring high voltage equipment, powering high voltage IGBT gate drivers, converters used in RF over Fiber (RFoF) systems, and system power applications, including powering UAVs. In PoF, laser power is transmitted over fiber, and is converted to electricity by photovoltaic cells (packaged into Photovoltaic Power Converters, or PPCs) which efficiently convert the laser light. In this research, we design a high power multi-channel PoF system, incorporating a high power 976 nm diode laser, a cabling system with fiber break detection, and a multichannel PPC-module. We then characterizes system features such as its response time to system commands, the PPC module's electrical output stability, the PPC-module's thermal response, the fiber break detection system response, and the diode laser optical output stability. The high power PoF system and this research will serve as a scalable model for those interested in researching, developing, or deploying a high power, voltage isolated, and optically driven power source for high reliability utility, communications, defense, and scientific applications.

  1. Low-timing-jitter high-power mode-locked 1063 nm Nd:GdVO₄ master oscillator power amplifier. (United States)

    Wang, Zhi-min; Zhang, Feng-feng; Zuo, Jun-wei; Yang, Jing; Yuan, Lei; Peng, Qin-jun; Cui, Da-fu; Xu, Zu-yan


    A low-timing-jitter high-power semiconductor saturable absorber mirror mode-locked picosecond (ps) 1063 nm Nd:GdVO4 master oscillator power amplifier is presented. Using a single-pass Nd:GdVO4 amplifier, an amplified laser with 21.5 W output power and 8.3 ps pulsewidth was achieved at 250 MHz repetition rate. Employing a servo control, an average RMS timing jitter of ∼222  fs was realized. This laser can be used as a drive laser for photocathode injectors in free-electron lasers.

  2. Inter-antenna and subblock shifting and inversion for peak-to-average power ratio reduction in MIMO-OFDM systems

    Institute of Scientific and Technical Information of China (English)

    WANG Yi; TAO Xiao-feng


    In this article, an inter-antenna inter-subblock shifting and inversion (IASSI) scheme is proposed to reduce the peak-to-average power ratio (PAPR) in multi-input multi- output orthogonal frequency division multiplexing (MIMO- OFDM) systems. It exploits multiple antennas and subblocks to provide additional degrees of freedom to benefit the system. To reduce the implementation complexity of the proposed scheme, two simple suboptimal schemes are further presented based on the minimum current maximum criterion; one adopts sequential search and the other employs random binary grouping. The simulation results exhibit the effectiveness of these proposed schemes.

  3. High photon flux XUV and soft x-ray sources enabled by high harmonic generation of high power fiber lasers (United States)

    Rothhardt, Jan; Hädrich, Steffen; Krebs, Manuel; Limpert, Jens; Tünnermann, Andreas


    This contribution reports on the recent advances in high harmonic generation (HHG) with high power femtosecond fiber lasers at high repetition rates. The capabilities of high power fiber lasers, the challenges of phase matching in the tight-focusing regime and recent experimental results will be discussed. In particular, post compressed pules as short as 30 fs, with ~150 μJ pulse energy at 0.6 MHz repetition rate have been used for efficient HHG into the XUV. Despite the tight focusing phase matching is ensured by providing the target gas with adequately high density. A conversion efficiency in excess of 10-6 at ~30 eV has been achieved in xenon gas. This resulted in more than 100μW of average power (>1013 photons per second), which represents the highest photon flux achieved by any HHG source in this spectral region so far. In addition, further pulse compression yielded few-cycle pulses at high average power that have enabled efficient soft Xray generation in neon and helium. HHG in neon provided more than 3·109 photons/s within a 1% bandwidth at 120 eV and helium allowed for HHG up to the water window spectral region beyond 283 eV. These compact sources provide highest photon flux on a table-top and will enable exciting applications such as nanometer-resolution imaging or coincidence spectroscopy in the near future.

  4. Effects of Visible and Invisible Hyperlinks on Vocabulary Acquisition and Reading Comprehension for High- and Average-Foreign Language Achievers

    Directory of Open Access Journals (Sweden)

    Ofelia R. Nikolova


    Full Text Available This study investigated the effects of visible and invisible links for annotated words in a computer module for learning French on the vocabulary acquisition and reading comprehension of two types of students – high – and average-achievers. Two hundred and sixty four second-semester students of French were identified as high- or average-achievers. Each type of students was then randomly assigned to two groups – with visible or invisible hyperlinks. All students were instructed to read a short passage in French (181 words for general comprehension and allowed to consult the annotated words (made visible by bold face for the visible links group as much as they needed. The students took a vocabulary pretest and an immediate and delayed (two weeks vocabulary and reading comprehension posttest. The results of the study showed that average- achievers benefited more from the visible links for vocabulary acquisition and reading comprehension than high-achievers. The results are discussed in light of second language acquisition and gifted-student theories and suggestions for future research are made.

  5. The Mercury Laser System: An Average power, gas-cooled, Yb:S-FAP based system with frequency conversion and wavefront correction

    Energy Technology Data Exchange (ETDEWEB)

    Bibeau, C; Bayramian, A; Armstrong, P; Ault, E; Beach, R; Benapfl, M; Campbell, R; Dawson, J; Ebbers, C; Freitas, B; Kent, R; Liao, Z; Ladran, T; Menapace, J; Molander, B; Moses, E; Oberhelman, S; Payne, S; Peterson, N; Schaffers, K; Stolz, C; Sutton, S; Tassano, J; Telford, S; Utterback, E; Randles, M


    We report on the operation of the Mercury laser with fourteen 4 x 6 cm{sup 2} Yb:S-FAP amplifier slabs pumped by eight 100 kW peak power diode arrays. The system was continuously run at 55 J and 10 Hz for several hours, (2 x 10{sup 5} cumulative shots) with over 80% of the energy in a 6 times diffraction limited spot at 1.047 um. Improved optical quality was achieved in Yb:S-FAP amplifiers with magneto-rheological finishing, a deterministic polishing method. In addition, average power frequency conversion employing YCOB was demonstrated at 50% conversion efficiency or 22.6 J at 10 Hz.

  6. Evaluation of the peak torque, total work, average power of flexor-estensor and prono-supinator muscles of the elbow in baseball players. (United States)

    Costantino, Cosimo; Vaienti, Enrico; Pogliacomi, Francesco


    The Authors, after a short analysis on biomechanics of the elbow during throwing in baseball, show the movements of the elbow during the different phases of the throw and the stabilizing action of the ulnar collateral ligament, flexor-pronator muscles of the wrist, anconeus and brachial triceps muscles. Aim of this study is the evaluation of the peak torque, total work and average power of the flexor-extensor and pronator-supinator muscles of the elbows in professional baseball players. Isokinetic test data show that a mayor peak torque in flexo-extension at power and resistance test in the pitchers compared to the strikers. Whereas the strikers show a higher peak torque in pronation at the resistance test. This may happen because during a baseball match the ball is hit many times by the bat and the pronator muscle of the wrist are notably stimulated and reinforced.

  7. Series-Tuned High Efficiency RF-Power Amplifiers

    DEFF Research Database (Denmark)

    Vidkjær, Jens


    An approach to high efficiency RF-power amplifier design is presented. It addresses simultaneously efficiency optimization and peak voltage limitations when transistors are pushed towards their power limits.......An approach to high efficiency RF-power amplifier design is presented. It addresses simultaneously efficiency optimization and peak voltage limitations when transistors are pushed towards their power limits....

  8. K-band high power latching switch (United States)

    Mlinar, M. J.; Piotrowski, W. S.; Raue, J. E.


    A 19 GHz waveguide latching switch with a bandwidth of 1400 MHz and an exceptionally low insertion loss of 0.25 dB was demonstrated. The RF and driver ferrites are separate structures and can be optimized individually. This analysis for each structure is separately detailed. Basically, the RF section features a dual turnstile junction. The circulator consists of a dielectric tube which contains two ferrite rods, and a dielectric spacer separating the ferrite parts along the center of symmetry of the waveguide to form two turnstiles. This subassembly is indexed and locked in the center of symmetry of a uniform junction of three waveguides by the metallic transformers installed in the top and bottom walls of the housing. The switching junction and its actuating circuitry met all RF performance objectives and all shock and vibration requirements with no physical damage or performance degradation. It exceeds thermal requirements by operating over a 100 C temperature range (-44 C to +56 C) and has a high power handling capability allowing up to 100 W of CW input power.

  9. High Energy High Power Battery Exceeding PHEV40 Requirements

    Energy Technology Data Exchange (ETDEWEB)

    Rempel, Jane [TIAX LLC, Lexington, MA (United States)


    TIAX has developed long-life lithium-ion cells that can meet and exceed the energy and power targets (200Wh/kg and 800W/kg pulse power) set out by DOE for PHEV40 batteries. To achieve these targets, we selected and scaled-up a high capacity version of our proprietary high energy and high power CAM-7® cathode material. We paired the cathode with a blended anode containing Si-based anode material capable of delivering high capacity and long life. Furthermore, we optimized the anode blend composition, cathode and anode electrode design, and selected binder and electrolyte compositions to achieve not only the best performance, but also long life. By implementing CAM-7 with a Si-based blended anode, we built and tested prototype 18650 cells that delivered measured specific energy of 198Wh/kg total energy and 845W/kg at 10% SOC (projected to 220Wh/kg in state-of-the-art 18650 cell hardware and 250Wh/kg in 15Ah pouch cells). These program demonstration cells achieved 90% capacity retention after 500 cycles in on-going cycle life testing. Moreover, we also tested the baseline CAM-7/graphite system in 18650 cells showing that 70% capacity retention can be achieved after ~4000 cycles (20 months of on-going testing). Ultimately, by simultaneously meeting the PHEV40 power and energy targets and providing long life, we have developed a Li-ion battery system that is smaller, lighter, and less expensive than current state-of-the-art Li-ion batteries.

  10. Peak power tunable mid-infrared oscillator pumped by a high power picosecond pulsed fiber amplifier with bunch output (United States)

    Wei, Kaihua; Guo, Yan; Lai, Xiaomin; Fan, Shanhui


    A high power mid-infrared optical parametric oscillator (OPO) with picosecond pulse bunch output is experimentally demonstrated. The pump source was a high power master oscillation power amplifier (MOPA) picosecond pulsed fiber amplifier. The seed of the MOPA was a gain-switched distributed Bragg reflector (DBR) laser diode (LD) with picosecond pulse operation at a high repetition rate. The seed laser was amplified to 50 W by two-stage pre-amplifiers and a large mode area (LMA) Yb fiber based power-amplifier. A fiber-pigtailed acousto-optic modulator with the first order diffraction transmission was inserted into the second pre-amplifier to form a picosecond pulse bunch train and to change the peak power simultaneously. The power-amplified pulse bunches were focused to pump a wavelength-tunable OPO for emitting high power mid-infrared laser. By adjusting the OPO cavity length, the maximum average idler powers obtained at 3.1, 3.3 and 3.5 μm were 7, 6.6 and 6.4 W respectively.

  11. High-peak-power, high-repetition-rate intracavity optical parametric oscillator at 1.57μm

    Institute of Scientific and Technical Information of China (English)

    Yuye Wang; Degang Xu; Yizhong Yu; Wuqi Wen; Jingping Xiong; Peng Wang; Jianquan Yao


    We report a high-peak-power, high-repetition-rate diode-side-pumped Nd:YAG Q-switched intracavity optical parametric oscillator (IOPO) at 1.57μm with a type-Ⅱ non-critically phase-matched x-cut KTP crystal. The average power of 1.15 W at 1.57μm is obtained at 4.3-kHz repetition rate. The peak power of the pulses amounts to 33.4 kW with 8-ns duration. The average conversion efficiency from Q-switched 1.064-μm-wavelength input power to OPO signal output power is up to 10.5%.

  12. Innovations in high power fiber laser applications (United States)

    Beyer, Eckhard; Mahrle, Achim; Lütke, Matthias; Standfuss, Jens; Brückner, Frank


    Diffraction-limited high power lasers represent a new generation of lasers for materials processing, characteristic traits of which are: smaller, cost-effective and processing "on the fly". Of utmost importance is the high beam quality of fiber lasers which enables us to reduce the size of the focusing head incl. scanning mirrors. The excellent beam quality of the fiber laser offers a lot of new applications. In the field of remote cutting and welding the beam quality is the key parameter. By reducing the size of the focusing head including the scanning mirrors we can reach scanning frequencies up to 1.5 kHz and in special configurations up to 4 kHz. By using these frequencies very thin and deep welding seams can be generated experienced so far with electron beam welding only. The excellent beam quality of the fiber laser offers a high potential for developing new applications from deep penetration welding to high speed cutting. Highly dynamic cutting systems with maximum speeds up to 300 m/min and accelerations up to 4 g reduce the cutting time for cutting complex 2D parts. However, due to the inertia of such systems the effective cutting speed is reduced in real applications. This is especially true if complex shapes or contours are cut. With the introduction of scanner-based remote cutting systems in the kilowatt range, the effective cutting speed on the contour can be dramatically increased. The presentation explains remote cutting of metal foils and sheets using high brightness single mode fiber lasers. The presentation will also show the effect of optical feedback during cutting and welding with the fiber laser, how those feedbacks could be reduced and how they have to be used to optimize the cutting or welding process.

  13. High power solid state laser modulator (United States)

    Birx, Daniel L.; Ball, Don G.; Cook, Edward G.


    A multi-stage magnetic modulator provides a pulse train of .+-.40 kV electrical pulses at a 5-7 kHz repetition rate to a metal vapor laser. A fractional turn transformer steps up the voltage by a factor of 80 to 1 and magnetic pulse compression is used to reduce the pulse width of the pulse train. The transformer is fabricated utilizing a rod and plate stack type of construction to achieve a high packing factor. The pulses are controlled by an SCR stack where a plurality of SCRs are electrically connected in parallel, each SCR electrically connected to a saturable inductor, all saturable inductors being wound on the same core of magnetic material for enhanced power handling characteristics.

  14. High power coherent polarization locked laser diode. (United States)

    Purnawirman; Phua, P B


    We have coherently combined a broad area laser diode array to obtain high power single-lobed output by using coherent polarization locking. The single-lobed coherent beam is achieved by spatially combining four diode emitters using walk-off crystals and waveplates while their phases are passively locked via polarization discrimination. While our previous work focused on coherent polarization locking of diode in Gaussian beams, we demonstrate in this paper, the feasibility of the same polarization discrimination for locking multimode beams from broad area diode lasers. The resonator is designed to mitigate the loss from smile effect by using retro-reflection feedback in the cavity. In a 980 nm diode array, we produced 7.2 W coherent output with M2 of 1.5x11.5. The brightness of the diode is improved by more than an order of magnitude.

  15. Splitting of high power, cw proton beams

    CERN Document Server

    Facco, Alberto; Berkovits, Dan; Yamane, Isao


    A simple method for splitting a high power, continuous wave (cw) proton beam in two or more branches with low losses has been developed in the framework of the EURISOL (European Isotope Separation On-Line adioactive Ion Beam Facility) design study. The aim of the system is to deliver up to 4 MW of H beam to the main radioactive ion beam production target, and up to 100 kWof proton beams to three more targets, simultaneously. A three-step method is used, which includes magnetic neutralization of a fractionof the main H- beam, magnetic splitting of H- and H0, and stripping of H0 to H+. The method allowsslow raising and individual fine adjustment of the beam intensity in each branch.

  16. High-temperature alloys for high-power thermionic systems

    Energy Technology Data Exchange (ETDEWEB)

    Shin, Kwang S.; Jacobson, D.L.; D' cruz, L.; Luo, Anhua; Chen, Bor-Ling.


    The need for structural materials with useful strength above 1600 k has stimulated interest in refractory-metal alloys. Tungsten possesses an extreme high modulus of elasticity as well as the highest melting temperature among metals, and hence is being considered as one of the most promising candidate materials for high temperature structural applications such as space nuclear power systems. This report is divided into three chapters covering the following: (1) the processing of tungsten base alloys; (2) the tensile properties of tungsten base alloys; and (3) creep behavior of tungsten base alloys. Separate abstracts were prepared for each chapter. (SC)

  17. Photoinjector RF cavity design for high power CW FEL

    Energy Technology Data Exchange (ETDEWEB)

    Kurennoy, S. (Sergey); Schrage, D. L. (Dale L.); Wood R. L. (Richard L.); Young, L. M. (Lloyd M.); Schultheiss, T. (Thomas); Christina, V.; Rathke, J.


    The project is under way to develop a key enabling technology for highpower CW FEL: an RF photoinjector capable of producing continuous average current greater than 100 mA. The specific aim is a n-mode, normalconducting IW photoinjector, 3 nC of bunch charge, 100 mA of current (at 33.3-MHz bunch repetition rate) and emittance less than 10 mm-mad. This level of performance will enable robust 100-kW-class FEL operation with electron beam energy <100 MeV, thereby reducing the size and cost of the FEL. This design is scalable to the MW power level by increasing the electron bunch repetition rate to a higher value. The major challenges are emittance control and high heat flux within the CW 700-MHz RF cavities. Results of RF cavity design and cooling schemes are presented, including both high-velocity water and liquid-nitrogen cooling options.

  18. Active beam integrator for high power coherent lasers

    Energy Technology Data Exchange (ETDEWEB)

    Laguarta, F.; Armengol, J.; Vega, F.; Lupon, N. [Univ. Politecnica de Catalunya, Terrassa (Spain). Dept. d`Optica i Optometria


    In laser materials processing applications it is often necessary to work with uniform intensity distributions. This goal is quite difficult to achieve when dealing with high power laser beams, and becomes critical for a successful application involving surface heat treatment of non-metallic materials. The authors have designed and tested a very simple beam shaper for transforming the initial intensity distribution of a CO{sub 2} laser beam mode into a more uniform intensity profile. The beam shaper is a two-faceted mirror for active integration of high power coherent laser beams. After reflection in the faceted mirror, a TEM00 or TEM01 CO{sub 2} laser beam is divided into two beamlets that overlap to give a more uniform intensity distribution. A sharp interference pattern due to the high spatial coherence of the incident beam appears. This interference pattern is actively integrated by a high-frequency longitudinal displacement of one of the facets. This provides a change in the relative phase of the two beamlets, and consequently the interference pattern vibrates and its contribution to the intensity distribution averages out. When sweeping this distribution over a sample, a uniform amount of energy is deposited at every point of its surface. It must be emphasized that unlike multifaceted mirrors, the two-facet integrator may provide uniform intensity profiles over any working distance. Finally, as in other integration devices an imaging system may be used to obtain a spot of the shape and the size desired for a particular application.

  19. High Power High Efficiency Ka-Band Power Combiners for Solid-State Devices (United States)

    Freeman, Jon C.; Wintucky, Edwin G.; Chevalier, Christine T.


    Wide-band power combining units for Ka-band are simulated for use as MMIC amplifier applications. Short-slot couplers as well as magic-tees are the basic elements for the combiners. Wide bandwidth (5 GHz) and low insertion (approx.0.2 dB) and high combining efficiencies (approx.90 percent) are obtained.

  20. High-power Čerenkov microwave oscillators utilizing High-Current nanosecond Electron beams (United States)

    Korovin, S. D.; Polevin, S. D.; Rostov, V. V.


    A short review is given of results obtained at the Institute of High-Current Electronics of the Siberian Branch of the Russian Academy of Sciences on generating high-power microwave radiation. Most of the research was devoted to a study of stimulated Čerenkov radiation from relativistic electron beams. It is shown that the efficiency of a relativistic 3-cm backward wave tube with a nonuniform coupling resistance can reach 35%. High-frequency radiation was discovered in the emission spectrum of the Čerenkov oscillators and it was shown that the nature of the radiation was associated with the stimulated scattering of low-frequency radiation by the relativistic electrons. Radiation with a power of 500 MW was obtained in the 8-mm wavelength range using a two-beam Čerenkov oscillator. High-current pulse-periodic nanosecond accelerators with a charging device utilizing a Tesla transformer were used in the experiments. The possibility was demonstrated of generating high-power microwave radiation with a pulse-repetition frequency of up to 100 Hz. An average power of ˜500 W was achieved from the relativistic oscillators. A relativistic backward wave tube with a high-current electron beam was used to make a prototype nanosecond radar device. Some of the results presented were obtained jointly with the Russian Academy of Sciences Institute of Applied Physics. Questions concerning multiwave Čerenkov interaction are not considered in this paper.

  1. Method and apparatus for improved high power impulse magnetron sputtering (United States)

    Anders, Andre


    A high power impulse magnetron sputtering apparatus and method using a vacuum chamber with a magnetron target and a substrate positioned in the vacuum chamber. A field coil being positioned between the magnetron target and substrate, and a pulsed power supply and/or a coil bias power supply connected to the field coil. The pulsed power supply connected to the field coil, and the pulsed power supply outputting power pulse widths of greater that 100 .mu.s.

  2. High Power Combiner/Divider Design for Dual Band RF Power Amplifiers


    Flattery, Kyle; Amin, Shoaib; Rönnow, Daniel; Mahamat, Yaya; Eroglu, Abdullah


    Design of low loss with an enhanced thermal profile power divider/combiner for high power dual-band Radio Frequency (RF) power amplifier applications is given. The practical implementation, low loss and substrate characteristics make this type of combiner ideal for high power microwave applications.  The combiner operational frequencies are chosen to operate at 900 MHz and 2.14 GHz, which are common frequencies for concurrent dual band RF power amplifiers. The analytical results are verified ...

  3. Measurement and modeling of mirror distortion in a high power FEL

    Energy Technology Data Exchange (ETDEWEB)

    Benson, S.; Neil, G.; Michelle D. Shinn


    Mirror heating in a high power FEL can alter the optical mode and affect the gain of the laser. This can lead to a large reduction of the laser power from ideal values. Measurements of the power and mode size in the Jefferson Lab IR Demo laser have shown clear evidence of mirror distortion at high average power leading (up to 17 kW incident on the mirrors and over 40 W absorbed per mirror). The measurements and comparisons with modeling will be presented. Both steady state and transient analyses and measurements are considered.

  4. Screening for hepatitis C in average and high-risk populations of Qatar using rapid point-of-care testing (United States)

    Al Kaabi, Saad; John, Anil K; Al Dweik, Nazeeh; Ullah Wani, Hameed; Babu Thandassary, Ragesh; Derbala, Moutaz F; Al Ejji, Khalid; Sultan, Khaleel; Pasic, Fuad; Al Mohannadi, Munnera; Yacoub, Rafae; Butt, Mohd Tariq; Singh, Rajvir


    Background Screening for hepatitis C has been found to be beneficial in high-risk individuals and ‘baby boomers’. Objective Our aim was to screen for hepatitis C in average and high-risk individuals and compare the disease characteristics and response to treatment among the screened group (SG) and non-screened group (NSG). Method Community-based screening for hepatitis C was done in the average and high-risk populations of Qatar. Screening was done using rapid point-of-care testing. All patients with stage 1 fibrosis on liver biopsy were treated with pegylated interferon and ribavirin. Results In total, 13,704 people were screened and 272 (2%, 95% CI (1.8–2.2%) had positive antibodies to hepatitis C. During the same period, 237 non-screened patients (NSG) with hepatitis C were referred for treatment. Alanine and aspartate aminotransferases (ALT, AST) and overall fibrosis were significantly lower in the SG as compared with the NSG (p = 0.04, 0.04 and 0.01, respectively). The response to treatment was similar in the SG as compared with the NSG (sustained viral response 61.7 % versus 69.1%, p = 0.55). Average-risk patients had significantly lower ALT levels (p = 0.04) but had similar response to treatment as the high-risk individuals (sustained viral response 63.2 % versus 61%, p = 0.87). Conclusion Screening detects hepatitis C with lesser fibrosis but does not result in better response to pegylated interferon and ribavirin as compared with non-screened patients. PMID:26279845

  5. A satellite snow depth multi-year average derived from SSM/I for the high latitude regions (United States)

    Biancamaria, S.; Mognard, N.M.; Boone, A.; Grippa, M.; Josberger, E.G.


    The hydrological cycle for high latitude regions is inherently linked with the seasonal snowpack. Thus, accurately monitoring the snow depth and the associated aerial coverage are critical issues for monitoring the global climate system. Passive microwave satellite measurements provide an optimal means to monitor the snowpack over the arctic region. While the temporal evolution of snow extent can be observed globally from microwave radiometers, the determination of the corresponding snow depth is more difficult. A dynamic algorithm that accounts for the dependence of the microwave scattering on the snow grain size has been developed to estimate snow depth from Special Sensor Microwave/Imager (SSM/I) brightness temperatures and was validated over the U.S. Great Plains and Western Siberia. The purpose of this study is to assess the dynamic algorithm performance over the entire high latitude (land) region by computing a snow depth multi-year field for the time period 1987-1995. This multi-year average is compared to the Global Soil Wetness Project-Phase2 (GSWP2) snow depth computed from several state-of-the-art land surface schemes and averaged over the same time period. The multi-year average obtained by the dynamic algorithm is in good agreement with the GSWP2 snow depth field (the correlation coefficient for January is 0.55). The static algorithm, which assumes a constant snow grain size in space and time does not correlate with the GSWP2 snow depth field (the correlation coefficient with GSWP2 data for January is - 0.03), but exhibits a very high anti-correlation with the NCEP average January air temperature field (correlation coefficient - 0.77), the deepest satellite snow pack being located in the coldest regions, where the snow grain size may be significantly larger than the average value used in the static algorithm. The dynamic algorithm performs better over Eurasia (with a correlation coefficient with GSWP2 snow depth equal to 0.65) than over North America

  6. A High Power and High Repetition Rate Modelocked Ti-Sapphire Laser for Photoinjectors

    Energy Technology Data Exchange (ETDEWEB)

    J. Hansknecht; M. Poelker


    A high power cw mode-locked Ti-sapphire laser has been constructed to drive the Jefferson Lab polarized photoinjector and provide > 500 mW average power with 50 ps pulsewidths at 499 MHz or 1497 MHz pulse repetition rates. This laser allows efficient, high current synchronous photoinjection for extended periods of time before intrusive steps must be taken to restore the quantum efficiency of the strained layer GaAs photocathode. The use of this laser has greatly enhanced the maximum high polarization beam current capability and operating lifetime of the Jefferson Lab photoinjector compared with previous performance using diode laser systems. A novel modelocking technique provides a simple means to phase-lock the optical pulse train of the laser to the accelerator and allows for operation at higher pulse repetition rates to {approx} 3 GHz without modification of the laser cavity. The laser design and characteristics are described below.

  7. Fast Decoupled Power Flow for Power System with High Voltage Direct Current Transmission Line System

    Directory of Open Access Journals (Sweden)

    Prechanon Kumkratug


    Full Text Available Problem statement: High voltage direct current transmission line system has been widely applied for control power flow in power system. The power flow analysis was the one of powerful tools by which the power system equipped was analyzed both for planning and operation strategies. Approach: This study presented the method to analyze power flow of power system consisted of HVDC system. HVDC was modeled as the complex power injections. The presented complex power injected was incorporated into the existing power flow program based on fast decoupled method. The presented method was tested on the multimachine power system. Results: The transmission line loss of the system with and without HVDC was compared. Conclusion: From the simulation results, the HVDC can reduce transmission line loss of power system.

  8. Photoinjector RF cavity design for high power CW FEL

    Energy Technology Data Exchange (ETDEWEB)

    Kurennoy, S. (Sergey); Schrage, D. L. (Dale L.); Wood R. L. (Richard L.); Young, L. M. (Lloyd M.); Schultheiss, T. (Thomas); Christina, V.; Rathke, J. (John)


    The project is under way to develop a key enabling technology for high-power CW FEL: an RF photoinjector capable of producing continuous average current greater than 100 mA. The specific aim is a 700 MHz pi-mode, normal-conducting RF photoinjector, 3 nC of bunch charge, 100 mA of current (at 33.3-MHz bunch repetition rate) and emittance less than 10 mm-mrad. This level of performance will enable robust 100-kW-class FEL operation with electron beam energy 400 MeV, thereby reducing the size and cost of the FEL. This design is scalable to the MW power level by increasing the electron bunch repetition rate from 33.3 MHz to a higher value. The major challenges are emittance control and high heat flux within the CW 700-MHz RF cavities. Results of RF cavity design and cooling schemes are presented, including both high-velocity water and liquid nitrogen cooling options.

  9. High power microwave system based on power combining and pulse compression of conventional klystrons

    CERN Document Server

    Xiong, Zheng-Feng; Cheng, Cheng; Ning, Hui; Tang, Chuan-Xiang


    A high power microwave system based on power combining and pulse compression of conventional klystrons is introduced in this paper. This system mainly consists of pulse modulator, power combiner, driving source of klystrons and pulse compressor. A solid state induction modulator and pulse transformer were used to drive two 50 MW S-band klystrons with pulse widths 4 {\\mu}s in parallel, after power combining and pulse compression, the tested peak power had reached about 210 MW with pulse widths nearly 400 ns at 25 Hz, while the experimental maximum output power was just limited by the power capacity of loads. This type of high power microwave system has widely application prospect in RF system of large scale particle accelerators, high power radar transmitters and high level electromagnetic environment generators.

  10. The design of high power, external antennas for radio frequency multicusp ion sources (United States)

    Welton, R. F.; Stockli, M. P.; Roseberry, R. T.; Kang, Y.; Keller, R.


    The ion source for the Spallation Neutron Source (SNS) is a radio-frequency, multicusp source designed to deliver H- beam pulses of 45 mA to the SNS accelerator, with a pulse length of 1 ms and a repetition rate of 60 Hz. In order to achieve this performance the source must operate with both high peak rf power, ˜45 kW, and high average rf power, ˜3 kW, over an operational run period of 3 weeks. The most critical source component in this respect is the plasma-immersed, porcelain coated rf antenna which can be susceptible to damage during high power operation. The DESY group has developed an external antenna configuration utilizing an Al2O3 plasma chamber which has demonstrated a very long operational period exceeding 25 000 h. Their source operates with peak rf powers comparable to the SNS source but with greatly reduced average rf powers, ˜50 W. In order to explore the applicability of this external antenna concept to high average power ion sources like the SNS source, we have performed thermal, mechanical, and electromagnetic analyses of the Al2O3 plasma chamber. This article discusses the final design which has resulted from these studies as well as estimates of the power limitations of such devices.

  11. Laboratory Astrophysics on High Power Lasers and Pulsed Power Facilities

    Energy Technology Data Exchange (ETDEWEB)

    Remington, B A


    Over the past decade a new genre of laboratory astrophysics has emerged, made possible by the new high energy density (HED) experimental facilities, such as large lasers, z-pinch generators, and high current particle accelerators. (Remington, 1999; 2000; Drake, 1998; Takabe, 2001) On these facilities, macroscopic collections of matter can be created in astrophysically relevant conditions, and its collective properties measured. Examples of processes and issues that can be experimentally addressed include compressible hydrodynamic mixing, strong shock phenomena, radiative shocks, radiation flow, high Mach-number jets, complex opacities, photoionized plasmas, equations of state of highly compressed matter, and relativistic plasmas. These processes are relevant to a wide range of astrophysical phenomena, such as supernovae and supernova remnants, astrophysical jets, radiatively driven molecular clouds, accreting black holes, planetary interiors, and gamma-ray bursts. These phenomena will be discussed in the context of laboratory astrophysics experiments possible on existing and future HED facilities.

  12. The SPES High Power ISOL production target (United States)

    Andrighetto, A.; Corradetti, S.; Ballan, M.; Borgna, F.; Manzolaro, M.; Scarpa, D.; Monetti, A.; Rossignoli, M.; Silingardi, R.; Mozzi, A.; Vivian, G.; Boratto, E.; De Ruvo, L.; Sattin, N.; Meneghetti, G.; Oboe, R.; Guerzoni, M.; Margotti, A.; Ferrari, M.; Zenoni, A.; Prete, G.


    SPES (Selective Production of Exotic Species) is a facility under construction at INFN-LNL (Istituto Nazionale di Fisica Nucleare - Laboratori Nazionali di Legnaro), aimed to produce intense neutron-rich radioactive ion beams (RIBs). These will be obtained using the ISOL (Isotope Separation On-Line) method, bombarding a uranium carbide target with a proton beam of 40MeV energy and currents up to 200μA. The target configuration was designed to obtain a high number of fissions, up to 1013 per second, low power deposition and fast release of the produced isotopes. The exotic isotopes generated in the target are ionized, mass separated and re-accelerated by the ALPI superconducting LINAC at energies of 10AMeV and higher, for masses in the region of A = 130 amu , with an expected rate on the secondary target up to 109 particles per second. In this work, recent results on the R&D activities regarding the SPES RIB production target-ion source system are reported.

  13. Test of a High Power Target Design

    CERN Multimedia


    %IS343 :\\\\ \\\\ A high power tantalum disc-foil target (RIST) has been developed for the proposed radioactive beam facility, SIRIUS, at the Rutherford Appleton Laboratory. The yield and release characteristics of the RIST target design have been measured at ISOLDE. The results indicate that the yields are at least as good as the best ISOLDE roll-foil targets and that the release curves are significantly faster in most cases. Both targets use 20 -25 $\\mu$m thick foils, but in a different internal geometry.\\\\ \\\\Investigations have continued at ISOLDE with targets having different foil thickness and internal geometries in an attempt to understand the release mechanisms and in particular to maximise the yield of short lived isotopes. A theoretical model has been developed which fits the release curves and gives physical values of the diffusion constants.\\\\ \\\\The latest target is constructed from 2 $\\mu$m thick tantalum foils (mass only 10 mg) and shows very short release times. The yield of $^{11}$Li (half-life of ...

  14. High Precision Current Measurement for Power Converters

    CERN Document Server

    Cerqueira Bastos, M


    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.

  15. Ultra-flat supercontinuum generated from high-power, picosecond telecommunication fiber laser source. (United States)

    Liao, Ruoyu; Song, Youjian; Zhou, Xiaokang; Chai, Lu; Wang, Chingyue; Hu, Minglie


    An ultra-flat, high-power supercontinuum generated from a picosecond telecommunication fiber laser was presented. The pulse from a carbon nanotube mode-locked oscillator was amplified using an Er-Yb codoped fiber amplifier. The output of the system achieved an average power of 2.7 W, with the center wavelength at 1564 nm and a FWHM of 6 nm in the spectral domain. By passing this amplified high-power pulse through a 4.6 m highly nonlinear photonic crystal fiber, an ultra-flat supercontinuum spanning 1600-2180 nm is generated. And the average power of the supercontinuum achieves 1 W.

  16. High-power converters for space applications (United States)

    Park, J. N.; Cooper, Randy


    Phase 1 was a concept definition effort to extend space-type dc/dc converter technology to the megawatt level with a weight of less than 0.1 kg/kW (220 lb./MW). Two system designs were evaluated in Phase 1. Each design operates from a 5 kV stacked fuel cell source and provides a voltage step-up to 100 kV at 10 A for charging capacitors (100 pps at a duty cycle of 17 min on, 17 min off). Both designs use an MCT-based, full-bridge inverter, gaseous hydrogen cooling, and crowbar fault protection. The GE-CRD system uses an advanced high-voltage transformer/rectifier filter is series with a resonant tank circuit, driven by an inverter operating at 20 to 50 kHz. Output voltage is controlled through frequency and phase shift control. Fast transient response and stability is ensured via optimal control. Super-resonant operation employing MCTs provides the advantages of lossless snubbing, no turn-on switching loss, use of medium-speed diodes, and intrinsic current limiting under load-fault conditions. Estimated weight of the GE-CRD system is 88 kg (1.5 cu ft.). Efficiency of 94.4 percent and total system loss is 55.711 kW operating at 1 MW load power. The Maxwell system is based on a resonance transformer approach using a cascade of five LC resonant sections at 100 kHz. The 5 kV bus is converted to a square wave, stepped-up to a 100 kV sine wave by the LC sections, rectified, and filtered. Output voltage is controlled with a special series regulator circuit. Estimated weight of the Maxwell system is 83.8 kg (4.0 cu ft.). Efficiency is 87.2 percent and total system loss is 146.411 kW operating at 1 MW load power.

  17. Advanced Gunn diode as high power terahertz source for a millimetre wave high power multiplier (United States)

    Amir, F.; Mitchell, C.; Farrington, N.; Missous, M.


    An advanced step-graded Gunn diode is reported, which has been developed through joint modelling-experimental work. The ~ 200 GHz fundamental frequency devices have been realized to test GaAs based Gunn oscillators at sub-millimetre wave for use as a high power (multi mW) Terahertz source in conjunction with a mm-wave multiplier, with novel Schottky diodes. The epitaxial growth of both the Gunn diode and Schottky diode wafers were performed using an industrial scale Molecular Beam Epitaxy (V100+) reactor. The Gunn diodes were then manufactured and packaged by e2v Technologies (UK) Plc. Physical models of the high power Gunn diode sources, presented here, are developed in SILVACO.

  18. Safety approaches for high power modular laser operation (United States)

    Handren, R. T.


    Approximately 20 years ago, a program was initiated at the Lawrence Livermore National Laboratory (LLNL) to study the feasibility of using lasers to separate isotopes of uranium and other materials. Of particular interest was the development of a uranium enrichment method for the production of commercial nuclear power reactor fuel to replace current more expensive methods. The Uranium Atomic Vapor Laser Isotope Separation (U-AVLIS) Program progressed to the point where a plant-scale facility to demonstrate commercial feasibility was built and is being tested. The U-AVLIS Program uses copper vapor lasers which pump frequency selective dye lasers to photoionize uranium vapor produced by an electron beam. The selectively ionized isotopes are electrostatically collected. The copper lasers are arranged in oscillator/amplifier chains. The current configuration consists of 12 chains, each with a nominal output of 800 W for a system output in excess of 9 kW. The system requirements are for continuous operation (24 h a day, 7 days a week) and high availability. To meet these requirements, the lasers are designed in a modular form allowing for rapid change-out of the lasers requiring maintenance. Since beginning operation in early 1985, the copper lasers have accumulated over 2 million unit hours at a greater than 90% availability. The dye laser system provides approximately 2.5 kW average power in the visible wavelength range. This large-scale laser system has many safety considerations, including high-power laser beams, high voltage, and large quantities (approximately 3000 gal) of ethanol dye solutions. The Laboratory's safety policy requires that safety controls be designed into any process, equipment, or apparatus in the form of engineering controls. Administrative controls further reduce the risk to an acceptable level. Selected examples of engineering and administrative controls currently being used in the U-AVLIS Program are described.

  19. Radiological Environmental Protection for LCLS-II High Power Operation (United States)

    Liu, James; Blaha, Jan; Cimeno, Maranda; Mao, Stan; Nicolas, Ludovic; Rokni, Sayed; Santana, Mario; Tran, Henry


    The LCLS-II superconducting electron accelerator at SLAC plans to operate at up to 4 GeV and 240 kW average power, which would create higher radiological impacts particularly near the beam loss points such as beam dumps and halo collimators. The main hazards to the public and environment include direct or skyshine radiation, effluent of radioactive air such as 13N, 15O and 41Ar, and activation of groundwater creating tritium. These hazards were evaluated using analytic methods and FLUKA Monte Carlo code. The controls (mainly extensive bulk shielding and local shielding around high loss points) and monitoring (neutron/photon detectors with detection capabilities below natural background at site boundary, site-wide radioactive air monitors, and groundwater wells) were designed to meet the U.S. DOE and EPA, as well as SLAC requirements. The radiological design and controls for the LCW systems [including concrete housing shielding for 15O and 11C circulating in LCW, 7Be and erosion/corrosion products (22Na, 54Mn, 60Co, 65Zn, etc.) captured in resin and filters, leak detection and containment of LCW with 3H and its waste water discharge; explosion from H2 build-up in surge tank and release of radionuclides] associated with the high power beam dumps are also presented.

  20. High power electronics package: from modeling to implementation

    NARCIS (Netherlands)

    Yuan, C.A.; Kregting, R.; Ye, H.; Driel, W. van; Gielen, A.W.J.; Zhang, G.Q.


    Power electronics, such as high power RF components and high power LEDs, requires the combination of robust and reliable package structures, materials, and processes to guarantee their functional performance and lifetime. We started with the thermal and thermal-mechanical modeling of such component

  1. Unique Power Dense, Configurable, Robust, High-Voltage Power Supplies Project (United States)

    National Aeronautics and Space Administration — Princeton Power will develop and deliver three small, lightweight 50 W high-voltage power supplies that have a configurable output voltage range from 500 to 50 kVDC....

  2. High Power Photonic Crystal Fibre Raman Laser

    Institute of Scientific and Technical Information of China (English)

    YAN Pei-Guang; RUAN Shuang-Chen; YU Yong-Qin; GUO Chun-Yu; GUO Yuan; LIU Cheng-Xiang


    A cw Raman laser based on a 100-m photonic crystal fibre is demonstrated with up to 3.8 W output power at the incident pump power of 12 W, corresponding to an optical-to-optical efficiency of about 31.6%. The second order Stokes light, which is firstly reported in a cw photonic crystal fibre Raman laser, is obtained at 1183nm with an output power of 1.6 W and a slope efficiency of about 45.7%.

  3. Thermoelectric Powered High Temperature Wireless Sensing (United States)

    Kucukkomurler, Ahmet

    This study describes use of a thermoelectric power converter to transform waste heat into electrical energy to power an RF receiver and transmitter, for use in harsh environment wireless temperature sensing and telemetry. The sensing and transmitting module employs a DS-1820 low power digital temperature sensor to perform temperature to voltage conversion, an ATX-34 RF transmitter, an ARX-34 RF receiver module, and a PIC16f84A microcontroller to synchronize data communication between them. The unit has been tested in a laboratory environment, and promising results have been obtained for an actual automotive wireless under hood temperature sensing and telemetry implementation.

  4. Advanced Capacitors for High-Power Applications Project (United States)

    National Aeronautics and Space Administration — As the consumer and industrial requirements for compact, high-power-density, electrical power systems grow substantially over the next decade; there will be a...

  5. Controlled Compact High Voltage Power Lines

    Directory of Open Access Journals (Sweden)

    Postolati V.


    Full Text Available Nowadays modern overhead transmission lines (OHL constructions having several significant differences from conventional ones are being used in power grids more and more widely. Implementation of compact overhead lines equipped with FACTS devices, including phase angle regulator settings (compact controlled OHL, appears to be one of the most effective ways of power grid development. Compact controlled AC HV OHL represent a new generation of power transmission lines embodying recent advanced achievements in design solutions, including towers and insulation, together with interconnection schemes and control systems. Results of comprehensive research and development in relation to 110–500kV compact controlled power transmission lines together with theoretical basis, substantiation, and methodological approaches to their practical application are presented in the present paper.

  6. High Intensity Tactical Power Sources for the 1990 Army. (United States)

    conceptual or physical study which may become feasible as high intensity power sources . These considerations include present state of the art of...requirements, energy and power output capabilities, and fixed costs. From these tables, it may be seen that a variety of electrical power sources would be...required to satisfy diverse requirements, but an attempt is made to categorize possible high intensity power sources into their areas of optimum

  7. Enhanced flat adenoma detection rate with high definition colonoscopy plus i-scan for average-risk colorectal cancer screening

    Directory of Open Access Journals (Sweden)

    Antonio Rodríguez-D'Jesús

    Full Text Available Background and aim: The usefulness of high definition colonoscopy plus i-scan (HD+i-SCAN for average-risk colorectal cancer screening has not been fully assessed. The detection rate of adenomas and other measurements such as the number of adenomas per colonoscopy and the flat adenoma detection rate have been recognized as markers of colonoscopy quality. The aim of the present study was to compare the diagnostic performance of an HD+i-SCAN with that of standard resolution white-light colonoscope. Methods: This is a retrospective analysis of a prospectively collected screening colonoscopy database. A comparative analysis of the diagnostic yield of an HD+i-SCAN or standard resolution colonoscopy for average-risk colorectal screening was conducted. Results: During the period of study, 155/163 (95.1% patients met the inclusion criteria. The mean age was 56.9 years. Sixty of 155 (39% colonoscopies were performed using a HD+i-SCAN. Adenoma-detection-rates during the withdrawal of the standard resolution versus HD+i-SCAN colonoscopies were 29.5% and 30% (p = n.s.. Adenoma/colonoscopy values for standard resolution versus HD+i-SCAN colonoscopies were 0.46 (SD = 0.9 and 0.72 (SD = 1.3 (p = n.s.. A greater number of flat adenomas were detected in the HD+i-SCAN group (6/60 vs. 2/95 (p < .05. Likewise, serrated adenomas/polyps per colonoscopy were also higher in the HD+i-SCAN group. Conclusions: A HD+i-SCAN colonoscopy increases the flat adenoma detection rate and serrated adenomas/polyps per colonoscopy compared to a standard colonoscopy in average-risk screening population. HD+i-SCAN is a simple, available procedure that can be helpful, even for experienced providers. The performance of HD+i-SCAN and substantial prevalence of flat lesions in our average-risk screening cohort support its usefulness in improving the efficacy of screening colonoscopies.

  8. Iterative Bayesian Model Averaging: a method for the application of survival analysis to high-dimensional microarray data

    Directory of Open Access Journals (Sweden)

    Raftery Adrian E


    Full Text Available Abstract Background Microarray technology is increasingly used to identify potential biomarkers for cancer prognostics and diagnostics. Previously, we have developed the iterative Bayesian Model Averaging (BMA algorithm for use in classification. Here, we extend the iterative BMA algorithm for application to survival analysis on high-dimensional microarray data. The main goal in applying survival analysis to microarray data is to determine a highly predictive model of patients' time to event (such as death, relapse, or metastasis using a small number of selected genes. Our multivariate procedure combines the effectiveness of multiple contending models by calculating the weighted average of their posterior probability distributions. Our results demonstrate that our iterative BMA algorithm for survival analysis achieves high prediction accuracy while consistently selecting a small and cost-effective number of predictor genes. Results We applied the iterative BMA algorithm to two cancer datasets: breast cancer and diffuse large B-cell lymphoma (DLBCL data. On the breast cancer data, the algorithm selected a total of 15 predictor genes across 84 contending models from the training data. The maximum likelihood estimates of the selected genes and the posterior probabilities of the selected models from the training data were used to divide patients in the test (or validation dataset into high- and low-risk categories. Using the genes and models determined from the training data, we assigned patients from the test data into highly distinct risk groups (as indicated by a p-value of 7.26e-05 from the log-rank test. Moreover, we achieved comparable results using only the 5 top selected genes with 100% posterior probabilities. On the DLBCL data, our iterative BMA procedure selected a total of 25 genes across 3 contending models from the training data. Once again, we assigned the patients in the validation set to significantly distinct risk groups (p

  9. Investigation of cognitive abilities related to reading and spelling in Korean: readers with high, average, and low skill levels. (United States)

    Park, Hyun-Rin; Uno, Akira


    In this study, we investigated the characteristics of cognitive abilities as predictors of Korean reading and spelling ability, and the characteristics of the cognition of reading difficulty in Korean. In 103 Korean third-grade children, we tested ability to read and spell, nonverbal intelligence, vocabulary size, phonological cognitive processing, visual cognitive processing, and naming speed. Our results indicated that receptive vocabulary, phoneme awareness, and naming speed served as factors for predicting reading test score; receptive vocabulary served as a factor for predicting spelling test score. We found that low reading-level groups had significantly slower performance on the naming speed task and lower scores on the receptive vocabulary test, as compared with the other groups (average and high reading-level groups). The present results have implications concerning useful tasks for screening for Korean poor readers. Copyright © 2012 John Wiley & Sons, Ltd.

  10. High Efficiency Microwave Power Amplifier: From the Lab to Industry (United States)

    Sims, William Herbert, III; Bell, Joseph L. (Technical Monitor)


    Since the beginnings of space travel, various microwave power amplifier designs have been employed. These included Class-A, -B, and -C bias arrangements. However, shared limitation of these topologies is the inherent high total consumption of input power associated with the generation of radio frequency (RF)/microwave power. The power amplifier has always been the largest drain for the limited available power on the spacecraft. Typically, the conversion efficiency of a microwave power amplifier is 10 to 20%. For a typical microwave power amplifier of 20 watts, input DC power of at least 100 watts is required. Such a large demand for input power suggests that a better method of RF/microwave power generation is required. The price paid for using a linear amplifier where high linearity is unnecessary includes higher initial and operating costs, lower DC-to-RF conversion efficiency, high power consumption, higher power dissipation and the accompanying need for higher capacity heat removal means, and an amplifier that is more prone to parasitic oscillation. The first use of a higher efficiency mode of power generation was described by Baxandall in 1959. This higher efficiency mode, Class-D, is achieved through distinct switching techniques to reduce the power losses associated with switching, conduction, and gate drive losses of a given transistor.

  11. Systematic Approach for Design of Broadband, High Efficiency, High Power RF Amplifiers

    National Research Council Canada - National Science Library

    Mohadeskasaei, Seyed Alireza; An, Jianwei; Chen, Yueyun; Li, Zhi; Abdullahi, Sani Umar; Sun, Tie


    ...‐AB RF amplifiers with high gain flatness. It is usually difficult to simultaneously achieve a high gain flatness and high efficiency in a broadband RF power amplifier, especially in a high power design...

  12. Ab interno sclerostomy with a high-powered argon endolaser. (United States)

    Jaffe, G J; Williams, G A; Mieler, W F; Radius, R L


    We used a high-energy argon blue-green laser (15-W maximum power output) to create full-thickness sclerostomies from the region of the anterior chamber angle to the subconjunctival space in pigmented rabbits using an ab interno approach. One to four laser pulses delivered through a 300-micron noncontact fiberoptic probe produced patent sclerostomies in all 20 eyes treated using 0.1-second pulse duration and 5 to 14 W of power. No intraoperative complications were encountered. Intraocular pressure, measured in 12 animals, decreased an average of 12 mm Hg in the treated eye relative to the fellow eye on the first postoperative day. The drop in intraocular pressure was associated with formation of a functioning filtration bleb. Intraocular pressure returned to preoperative levels in ten of 12 (83%) of the animals by the fourth postoperative day, and there was an associated flattening of the filtration bleb. Histologic and radioautographic analysis indicated that the effect of the laser was focal. Tissue damage and cellular proliferative response were limited to within approximately 200 micron of the wound margin.

  13. High power densities from high-temperature material interactions

    Energy Technology Data Exchange (ETDEWEB)

    Morris, J.F.


    Thermionic energy conversion (TEC) and metallic-fluid heat pipes (MFHPs) offer important and unique advantages in terrestrial and space energy processing. And they are well suited to serve together synergistically. TEC and MFHPs operate through working-fluid vaporization, condensation cycles that accept great thermal power densities at high temperatures. TEC and MFHPs have apparently simple, isolated performance mechanisms that are somewhat similar. And they also have obviously difficult, complected material problems that again are somewhat similar. Intensive investigation reveals that aspects of their operating cycles and material problems tend to merge: high-temperature material effects determine the level and lifetime of performance. Simplified equations verify the preceding statement for TEC and MFHPs. Material properties and interactions exert primary influences on operational effectiveness. And thermophysicochemical stabilities dictate operating temperatures which regulate the thermoemissive currents of TEC and the vaporization flow rates of MFHPs. Major high-temperature material problems of TEC and MFHPs have been solved. These solutions lead to productive, cost-effective applications of current TEC and MFHPs - and point to significant improvements with anticipated technological gains.

  14. Pulsed operation of high power light emitting diodes for flow velocimetry


    Willert, Christian; Mößner, Steffen; Klinner, Joachim


    High powered light emitting diodes (LED) are investigated for possible uses as light sources in flow diagnostics, in particular, as an alternative to laser-based illumination in particle imaging flow velocimetry. Recent developments in solid state illumination resulted in mass-produced LEDs that provide average radiant power in excess of 10 Watt. By operating these LEDs with short duration, pulsed currents that are considerably beyond their continuous current damage th...

  15. Pulsed operation of high-power light emitting diodes for imaging flow velocimetry


    Willert, Christian; Stasicki, Boleslaw; Klinner, Joachim; Moessner, S.


    High-powered light emitting diodes (LED) are investigated for possible uses as light sources in flow diagnostics, in particular, as an alternative to laser-based illumination in particle imaging flow velocimetry in side-scatter imaging arrangements. Recent developments in solid state illumination resulted in mass-produced LEDs that provide average radiant power in excess of 10 W. By operating these LEDs with short duration, pulsed currents that are considerably beyond their continuous c...

  16. High brilliance and high efficiency: optimized high power diode laser bars (United States)

    Hülsewede, R.; Schulze, H.; Sebastian, J.; Schröder, D.; Meusel, J.; Hennig, P.


    The strong increasing laser market has ongoing demands to reduce the costs of diode laser pumped systems. For that reason JENOPTIK Diode Lab GmbH (JDL) optimized the bar brilliance (small vertical far field divergence) and bar efficiency (higher optical power operation) with respect to the pump applications. High efficiency reduces the costs for mounting and cooling and high brilliance increases the coupling efficiency. Both are carefully adjusted in the 9xx nm - high power diode laser bars for pump applications in disc- and fiber lasers. Based on low loss waveguide structures high brilliance bars with 19° fast axis beam divergence (FWHM) with 58 % maximum efficiency and 27° fast axis beam divergence (FWHM) with 62 % maximum efficiency are developed. Mounted on conductive cooled heat sinks high power operation with lifetime > 20.000 hours at 120 W output power level (50 % filling factor bars) and 80W (20 % filling factor bars) is demonstrated. 808nm bars used as pump sources for Nd:YAG solid state lasers are still dominating in the market. With respect to the demands on high reliability at high power operation current results of a 100 W high power life time test are showing more than 9000 hour operation time for passively cooled packaged high efficiency 50 % filling factor bars. Measurement of the COMD-level after this hard pulse life time test demonstrates very high power levels with no significant droop in COMD-power level. This confirms the high facet stability of JDL's facet technology. New high power diode laser bars with wavelength of 825 nm and 885 nm are still under development and first results are presented.

  17. High Recharge Areas in the Choushui River Alluvial Fan (Taiwan Assessed from Recharge Potential Analysis and Average Storage Variation Indexes

    Directory of Open Access Journals (Sweden)

    Jui-Pin Tsai


    Full Text Available High recharge areas significantly influence the groundwater quality and quantity in regional groundwater systems. Many studies have applied recharge potential analysis (RPA to estimate groundwater recharge potential (GRP and have delineated high recharge areas based on the estimated GRP. However, most of these studies define the RPA parameters with supposition, and this represents a major source of uncertainty for applying RPA. To objectively define the RPA parameter values without supposition, this study proposes a systematic method based on the theory of parameter identification. A surrogate variable, namely the average storage variation (ASV index, is developed to calibrate the RPA parameters, because of the lack of direct GRP observations. The study results show that the correlations between the ASV indexes and computed GRP values improved from 0.67 before calibration to 0.85 after calibration, thus indicating that the calibrated RPA parameters represent the recharge characteristics of the study area well; these data also highlight how defining the RPA parameters with ASV indexes can help to improve the accuracy. The calibrated RPA parameters were used to estimate the GRP distribution of the study area, and the GRP values were graded into five levels. High and excellent level areas are defined as high recharge areas, which composed 7.92% of the study area. Overall, this study demonstrates that the developed approach can objectively define the RPA parameters and high recharge areas of the Choushui River alluvial fan, and the results should serve as valuable references for the Taiwanese government in their efforts to conserve the groundwater quality and quantity of the study area.

  18. Simulation of High Power Lasers (Preprint) (United States)


    product of laser power. 5. References 1 Wilcox, D. C, Turbulence Modeling for CFD, DCW Industries, Inc. pp. 185-193, July 1998. 2 Menter, F. L...Modeling for CFD, DCW Industries, Inc. pp. 294-296, July 1998. 4 Perram, G. P, .Int. J. Chem. Kinet. 27, 817-28 (1995). 5 Madden, T. J. and Solomon

  19. Coordinated Frequency Control of Wind Turbines in Power Systems with High Wind Power Penetration

    DEFF Research Database (Denmark)

    Tarnowski, Germán Claudio

    particular views. These models were developed and verified during this work, basedaround a particular manufacturer’s wind turbine and on said isolated power system withwind power. The capability of variable speed wind turbines for providing Inertial Response is analysed. To perform this assessment, a control...... and the dynamic stability of the grid frequency under large disturbances would be compromised. The aim of this study is to investigate the integration of large scale wind power generation in power systems and its active power control.Novel methods and solutions dealing specifically with the electric frequency...... stability and high wind power penetration or in islanding situations are addressed. The review of relevant theoretical concepts is supported by measurements carried out on an isolated power system characterized by high wind power penetration. Different mathematical and simulation models are used in several...

  20. Atmospheric Propagation and Combining of High-Power Lasers (United States)


    Naval Research Laboratory Washington, DC 20375-5320 NRL/MR/6703--15-9646 Atmospheric Propagation and Combining of High-Power Lasers W. NelsoN...ABSTRACT c. THIS PAGE 18. NUMBER OF PAGES 17. LIMITATION OF ABSTRACT Atmospheric Propagation and Combining of High-Power Lasers W. Nelson,* P. Sprangle...Turbulence Beam combining In this paper we analyze the beam combining and atmospheric propagation of high-power lasers for directed-energy (DE

  1. High Temperature Power Converters for Military Hybrid Electric Vehicles (United States)


    M) MINI-SYMPOSIUM AUGUST 9-11 DEARBORN, MICHIGAN HIGH TEMPERATURE POWER CONVERTERS FOR MILITARY HYBRID ELECTRIC VEHICLES ABSTRACT...SUBTITLE High Temperature Power Converters for Military Hybrid Electric Vehicles 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 6...public release High Temperature Power Converters for Military Hybrid Electric Vehicles Page 2 of 8 I. INTRODUCTION Today, wide bandgap devices

  2. High-Speed Low Power Design in CMOS

    DEFF Research Database (Denmark)

    Ghani, Arfan; Usmani, S. H.; Stassen, Flemming


    Static CMOS design displays benefits such as low power consumption, dominated by dynamic power consumption. In contrast, MOS Current Mode Logic (MCML) displays static rather than dynamic power consumption. High-speed low-power design is one of the many application areas in VLSI that require...... the appropriate domains of performance and power requirements in which MCML presents benefits over standard CMOS. An optimized cell library is designed and implemented in both CMOS and MCML in order to make a comparison with reference to speed and power. Much more time is spent in order to nderstand...

  3. Design and Construction of Low Cost High Voltage dc Power Supply for Constant Power Operation (United States)

    Kumar, N. S.; Jayasankar, V.


    Pulsed load applications like laser based systems need high voltage dc power supplies with better regulation characteristics. This paper presents the design, construction and testing of dc power supply with 1 kV output at 300 W power level. The designed converter has half bridge switched mode power supply (SMPS) configuration with 20 kHz switching. The paper covers the design of half bridge inverter, closed loop control, High frequency transformer and other related electronics. The designed power supply incorporates a low cost OPAMP based feedback controller which is designed using small signal modelling of the converter. The designed converter was constructed and found to work satisfactorily as per the specifications.

  4. Modelling aluminium wire bond reliability in high power OMP devices

    NARCIS (Netherlands)

    Kregting, R.; Yuan, C.A.; Xiao, A.; Bruijn, F. de


    In a RF power application such as the OMP, the wires are subjected to high current (because of the high power) and high temperature (because of the heat from IC and joule-heating from the wire itself). Moreover, the wire shape is essential to the RF performance. Hence, the aluminium wire is preferre

  5. Multidisciplinary Modelling Tools for Power Electronic Circuits:with Focus on High Power Modules


    Bahman, Amir Sajjad


    This thesis presents multidisciplinary modelling techniques in a Design For Reliability (DFR) approach for power electronic circuits. With increasing penetration of renewable energy systems, the demand for reliable power conversion systems is becoming critical. Since a large part of electricity is processed through power electronics, highly efficient, sustainable, reliable and cost-effective power electronic devices are needed. Reliability of a product is defined as the ability to perform wit...

  6. Measurement of H!gh Power Current-Stabilized Power Supply with High Stability

    Institute of Scientific and Technical Information of China (English)

    YanHuaihai; FengXiuming; BaiZhen; ZhouZhongzu


    The DC power supply system of HIRFL has been upgraded since 1999, these new power supplies are used mainly as high frequency ZVS soft-switching converters or thyristor phase-controlled rectifiers. Each power supply is strictly tested before being put into operation, especially for long-term current stability, current ripple, efficiency, repeatability, EMI and so on. The tested results indicated that performances of power supplies satisfy requirement of HIRFL.

  7. The Baryon Cycle at High Redshifts: Effects of Galactic Winds on Galaxy Evolution in Overdense and Average Regions (United States)

    Sadoun, Raphael; Shlosman, Isaac; Choi, Jun-Hwan; Romano-Díaz, Emilio


    We employ high-resolution cosmological zoom-in simulations focusing on a high-sigma peak and an average cosmological field at z ˜ 6-12 in order to investigate the influence of environment and baryonic feedback on galaxy evolution in the reionization epoch. Strong feedback, e.g., galactic winds, caused by elevated star formation rates (SFRs) is expected to play an important role in this evolution. We compare different outflow prescriptions: (i) constant wind velocity (CW), (ii) variable wind scaling with galaxy properties (VW), and (iii) no outflows (NW). The overdensity leads to accelerated evolution of dark matter and baryonic structures, absent from the “normal” region, and to shallow galaxy stellar mass functions at the low-mass end. Although CW shows little dependence on the environment, the more physically motivated VW model does exhibit this effect. In addition, VW can reproduce the observed specific SFR (sSFR) and the sSFR-stellar mass relation, which CW and NW fail to satisfy simultaneously. Winds also differ substantially in affecting the state of the intergalactic medium (IGM). The difference lies in the volume-filling factor of hot, high-metallicity gas, which is near unity for CW, while such gas remains confined in massive filaments for VW, and locked up in galaxies for NW. Such gas is nearly absent from the normal region. Although all wind models suffer from deficiencies, the VW model seems to be promising in correlating the outflow properties with those of host galaxies. Further constraints on the state of the IGM at high z are needed to separate different wind models.

  8. High specific power flexible integrated IMM photovoltaic blanket Project (United States)

    National Aeronautics and Space Administration — Originally designed for space applications, multi-junction solar cells have a high overall power conversion efficiency (>30%) which compares favorably to...

  9. High Efficiency Hall Thruster Discharge Power Converter Project (United States)

    National Aeronautics and Space Administration — Busek leveraged previous, internally sponsored, high power, Hall thruster discharge converter development which allowed it to design, build, and test new printed...

  10. Temperature Stabilized Characterization of High Voltage Power Supplies

    CERN Document Server

    Krarup, Ole


    High precision measurements of the masses of nuclear ions in the ISOLTRAP experiment relies on an MR-ToF. A major source of noise and drift is the instability of the high voltage power supplies employed. Electrical noise and temperature changes can broaden peaks in time-of-flight spectra and shift the position of peaks between runs. In this report we investigate how the noise and drift of high-voltage power supplies can be characterized. Results indicate that analog power supplies generally have better relative stability than digitally controlled ones, and that the high temperature coefficients of all power supplies merit efforts to stabilize them.

  11. The Baryon Cycle at High Redshifts: Effects of Galactic Winds on Galaxy Evolution in Overdense and Average Regions

    CERN Document Server

    Sadoun, Raphael; Choi, Jun-Hwan; Romano-Díaz, Emilio


    We use high-resolution cosmological zoom-in simulations in order to analyze galaxy evolution at redshifts z~6-12 in highly-overdense 5 sigma density peaks. Strong stellar feedback, in the form of galactic winds, is expected to play an important role in the evolution of these regions. We investigate the effects of these winds by comparing different galactic outflow prescriptions, including (i) a constant velocity model (CW), (ii) a variable velocity model scaling with galaxy properties (VW), and (iii) a model with no outflows (NW). The CW model is also applied to a simulation of an average density region to study the impact of environment on galaxy evolution. A direct consequence of the overdensity is a shallow galaxy mass function slope at the low-mass end and an accelerated evolution of dark matter and baryonic structures. The overdensity hosts massive haloes, up to ~10^{12} Msun, with embedded galaxies up to ~10^{11} Msun in stellar mass by z~6, which are absent in the "normal" region. The CW model leads to...

  12. Analysis of high-frequency energy in long-term average spectra of singing, speech, and voiceless fricatives. (United States)

    Monson, Brian B; Lotto, Andrew J; Story, Brad H


    The human singing and speech spectrum includes energy above 5 kHz. To begin an in-depth exploration of this high-frequency energy (HFE), a database of anechoic high-fidelity recordings of singers and talkers was created and analyzed. Third-octave band analysis from the long-term average spectra showed that production level (soft vs normal vs loud), production mode (singing vs speech), and phoneme (for voiceless fricatives) all significantly affected HFE characteristics. Specifically, increased production level caused an increase in absolute HFE level, but a decrease in relative HFE level. Singing exhibited higher levels of HFE than speech in the soft and normal conditions, but not in the loud condition. Third-octave band levels distinguished phoneme class of voiceless fricatives. Female HFE levels were significantly greater than male levels only above 11 kHz. This information is pertinent to various areas of acoustics, including vocal tract modeling, voice synthesis, augmentative hearing technology (hearing aids and cochlear implants), and training/therapy for singing and speech.

  13. Output beam analysis of high power COIL

    Institute of Scientific and Technical Information of China (English)

    Deli Yu(于德利); Fengting Sang(桑凤亭); Yuqi Jin(金玉奇); Yizhu Sun(孙以珠)


    As the output power of a chemical oxygen iodine laser (COIL) increases, the output laser beam instabilityappears as the far-field beam spot drift and deformation for the large Fresnel number unstable resonator.In order to interpret this phenomenon, an output beam mode simulation code was developed with the fastFourier transform method. The calculation results show that the presence of the nonuniform gain in COILproduces a skewed output intensity distribution, which causes the mirror tilt and bulge due to the thermalexpansion. With the output power of COIL increases, the mirror surfaces, especially the back surface ofthe scraper mirror, absorb more and more heat, which causes the drift and deformation of far field beamspot seriously. The initial misalignment direction is an important factor for the far field beam spot driftingand deformation.

  14. High-power CSI-fed induction motor drive with optimal power distribution based control (United States)

    Kwak, S.-S.


    In this article, a current source inverter (CSI) fed induction motor drive with an optimal power distribution control is proposed for high-power applications. The CSI-fed drive is configured with a six-step CSI along with a pulsewidth modulated voltage source inverter (PWM-VSI) and capacitors. Due to the PWM-VSI and the capacitor, sinusoidal motor currents and voltages with high quality as well as natural commutation of the six-step CSI can be obtained. Since this CSI-fed drive can deliver required output power through both the six-step CSI and PWM-VSI, this article shows that the kVA ratings of both the inverters can be reduced by proper real power distribution. The optimal power distribution under load requirements, based on power flow modelling of the CSI-fed drive, is proposed to not only minimise the PWM-VSI rating but also reduce the six-step CSI rating. The dc-link current control of the six-step CSI is developed to realise the optimal power distribution. Furthermore, a vector controlled drive for high-power induction motors is proposed based on the optimal power distribution. Experimental results verify the high-power CSI-fed drive with the optimal power distribution control.

  15. Numerical research on flow and thermal transport in cooling pool of electrical power station using three depth-averaged turbulence models

    Directory of Open Access Journals (Sweden)

    Li-ren YU


    Full Text Available This paper describes a numerical simulation of thermal discharge in the cooling pool of an electrical power station, aiming to develop general-purpose computational programs for grid generation and flow/pollutant transport in the complex domains of natural and artificial waterways. Three depth-averaged two-equation closure turbulence models, κ- ε, κ-w , and κ-ω, were used to close the quasi three-dimensional hydrodynamic model. The κ-ω model was recently established by the authors and is still in the testing process. The general-purpose computational programs and turbulence models will be involved in a software that is under development. The SIMPLE (Semi-Implicit Method for Pressure-Linked Equation algorithm and multi-grid iterative method are used to solve the hydrodynamic fundamental governing equations, which are discretized on non-orthogonal boundary-fitted grids with a variable collocated arrangement. The results calculated with the three turbulence models were compared with one another. In addition to the steady flow and thermal transport simulation, the unsteady process of waste heat inpouring and development in the cooling pool was also investigated.

  16. Numerical research on flow and thermal transport in cooling pool of electrical power station using three depth-averaged turbulence models

    Institute of Scientific and Technical Information of China (English)

    Li-ren YU; Jun YU


    This paper describes a numerical simulation of thermal discharge in the cooling pool of an electrical power station,aiming to develop general-purpose computational programs for grid generation and flow/pollutant transport in the complex domains of natural and artificial waterways.Three depth-averaged two-equation closure turbulence models,(k)-(ε),(k)-(w),and (k)-(ω),were used to close the quasi three-dimensional hydrodynamic model.The (k)-(ω) model was recently established by the authors and is still in the testing process.The general-purpose computational programs and turbulence models will be involved in a software that is under development.The SIMPLE (Semi-Implicit Method for Pressure-Linked Equation) algorithm and multi-grid iterative method are used to solve the hydrodynamic fundamental governing equations,which are discretized on non-orthogonal boundary-fitted grids with a variable collocated arrangement.The results calculated with the three turbulence models were compared with one another.In addition to the steady flow and thermal transport simulation,the unsteady process of waste heat inpouring and development in the cooling pool was also investigated.

  17. Peak-to-Average Power Ratio Reduction for Integration of Radar and Communication Systems Based on OFDM Signals with Block Golay Coding

    Directory of Open Access Journals (Sweden)

    Li Zi-qi


    Full Text Available Integration of radar and communication systems based on OFDM signals results in large Peak-to-Average Power Ratio (PAPR. Limited by the code rate, algorithm that use the Golay sequence code to restrain PAPR can only be applied under the condition of a few subcarriers. This study proposes an algorithm to restrain the PAPR of systems with a large number of subcarriers. The algorithm combines the group parallel code with the optimization of weight coefficients. First, bit streams are divided into several groups of parallel bits. Next, every group proceeds with Golay sequence coding, data symbol modulating and inverse Fourier transform. Finally, the parallel result is combined with an OFDM symbol. Before the parallel data are combined, several weight coefficients for every group are introduced; thus, the system has several candidate symbols for transmitting. Then the symbol with minimum PAPR is then selected as the transmitting signal, and the PAPR of the whole system is reduced. PAPR performance, Bit Error Radio (BER and wideband ambiguity function of three block methods with different coding rate are also simulated. The simulations show that the PAPR of the system decreases and the BER performance improves significantly. The signal exhibits a thumbtack ambiguity function, which suggests good resolution and accuracy for distance and velocity measurements.

  18. Combined peak-to-average power ratio reduction and physical layer security enhancement in optical orthogonal frequency division multiplexing visible-light communication systems (United States)

    Wang, Zhongpeng; Chen, Shoufa


    A physical encryption scheme for discrete Hartley transform (DHT) precoded orthogonal frequency division multiplexing (OFDM) visible-light communication (VLC) systems using frequency domain chaos scrambling is proposed. In the scheme, the chaos scrambling, which is generated by a modified logistic mapping, is utilized to enhance the physical layer of security, and the DHT precoding is employed to reduce of OFDM signal for OFDM-based VLC. The influence of chaos scrambling on peak-to-average power ratio (PAPR) and bit error rate (BER) of systems is studied. The experimental simulation results prove the efficiency of the proposed encryption method for DHT-precoded, OFDM-based VLC systems. Furthermore, the influence of the proposed encryption to the PAPR and BER of systems is evaluated. The experimental results show that the proposed security scheme can protect the DHT-precoded, OFDM-based VLC from eavesdroppers, while keeping the good BER performance of DHT-precoded systems. The BER performance of the encrypted and DHT-precoded system is almost the same as that of the conventional DHT-precoded system without encryption.

  19. Peak to Average Power Ratio Reduction using a Hybrid of Bacterial Foraging and Modified Cuckoo Search Algorithm in MIMO-OFDM System

    Directory of Open Access Journals (Sweden)

    R. Manjith


    Full Text Available The Partial Transmit Sequence which reduces the PAPR (Peak-to-Average Power Ratio in Multiple Input Multiple Output Orthogonal Frequency Division Multiplexing (MIMO-OFDM system using a novel optimization algorithm is proposed in this study. This novel optimization algorithm is based on a hybrid of Bacterial Foraging Optimization (BFO and Modified Cuckoo Search algorithm (MCS and is thus called HBFOMCS. In HBFOMCS, reproduction of individuals in a new generation is created, not only by swim and tumble operation as in BFO, but also by MCS. The natural reproduction step of BFO is swapped by the concept of searching best solutions as in MCS which then increases the possibility of generating the elite individuals for next generation. These enhanced reproduction step constitute the ready-to-perform population for the new generation once the initial population is performed by swim and tumble operation. Afterwards, discover probability is applied to abandon the worst solution due to the nature of MCS. HBFOMCS is applied to optimize the best combination from a set of allowed phase factors in Partial Transmit Sequence (PTS technique. The performance of HBFOMCS is compared with BFO, Cuckoo Search (CS and Modified cuckoo search MCS in the PAPR reduction in MIMO-OFDM system, accordingly proving its proficiency.

  20. High Energy Density Capacitors for Pulsed Power Applications (United States)


    high energy density energy storage capacitors. High efficency capacitors are available with energy densities as high as 3 J/cc for 1000 shots or...GENERAL ATOMICS ENERGY PRODUCTS Engineering Bulletin HIGH ENERGY DENSITY CAPACITORS FOR PULSED POWER APPLICATIONS Fred MacDougall, Joel...00-2009 4. TITLE AND SUBTITLE High Energy Density Capacitors for Pulsed Power Applications 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM

  1. Investigation on Satellite-borne High-power Solid-state Power Amplifier Technology and Experiment


    Wu Xiao-po; Zhao Hai-yang; Xi Song-tao


    Based on the research and development efforts of satellite-borne lumped solid-state transmitters, the design of a satellite-borne high-power microwave amplifier module is introduced. Focusing on satellite-borne applications, aspects of the high-power density thermal design, multipactor proof design, EMC design and so on, which are critical technologies for a solid-state power amplifier, are discussed. Subsequently, experiments are used to verify the concept.

  2. Investigation on Satellite-borne High-power Solid-state Power Amplifier Technology and Experiment

    Directory of Open Access Journals (Sweden)

    Wu Xiao-po


    Full Text Available Based on the research and development efforts of satellite-borne lumped solid-state transmitters, the design of a satellite-borne high-power microwave amplifier module is introduced. Focusing on satellite-borne applications, aspects of the high-power density thermal design, multipactor proof design, EMC design and so on, which are critical technologies for a solid-state power amplifier, are discussed. Subsequently, experiments are used to verify the concept.

  3. Self-commutating converters for high power applications

    CERN Document Server

    Arrillaga, Jos; Watson, Neville R; Murray, Nicholas J


    For very high voltage or very high current applications, the power industry still relies on thyristor-based Line Commutated Conversion (LCC), which limits the power controllability to two quadrant operation. However, the ratings of self-commutating switches such as the Insulated-Gate Bipolar Transistor (IGBT) and Integrated Gate-Commutated Thyristor (IGCT), are reaching levels that make the technology possible for very high power applications. This unique book reviews the present state and future prospects of self-commutating static power converters for applications requiring either ultr

  4. Design of High Power Density Amplifiers: Application to Ka Band (United States)

    Passi, Davide; Leggieri, Alberto; Di Paolo, Franco; Bartocci, Marco; Tafuto, Antonio


    Recent developments in the design of high-power-high-frequency amplifiers are assessed in this paper by the analysis and measurements of a high power density amplifier operating in the Ka Band. Design procedure is presented and a technical investigation is reported. The proposed device has shown over 23% of useful frequency bandwidth. It is an ensemble of 16 monolithic solid state power amplifiers that employees mixed technologies as spatial and planar combiners. Test performed have given maximum delivered power of 47.2 dBm.

  5. High-power MUTC photodetectors for RF photonic links (United States)

    Estrella, Steven; Johansson, Leif A.; Mashanovitch, Milan L.; Beling, Andreas


    High power photodiodes are needed for a range of applications. The high available power conversion efficiency makes these ideal for antenna remoting applications, including high power, low duty-cycle RF pulse generation. The compact footprint and fiber optic input allow densely packed RF aperture arrays with low cross-talk for phased high directionality emitters. Other applications include linear RF photonic links and other high dynamic range optical systems. Freedom Photonics has developed packaged modified uni-traveling carrier (MUTC) photodetectors for high-power applications. Both single and balanced photodetector pairs are mounted on a ceramic carrier, and packaged in a compact module optimized for high power operation. Representative results include greater than 100 mA photocurrent, >100m W generated RF power and >20 GHz bandwidth. In this paper, we evaluate the saturation and bandwidth of these single ended and balanced photodetectors for detector diameter in the 16 μm to 34 μm range. Packaged performance is compared to chip performance. Further new development towards the realization of <100GHz packaged photodetector modules with optimized high power performance is described. Finally, incorporation of these photodetector structures in novel photonic integrated circuits (PICs) for high optical power application areas is outlined.

  6. Average exceptional Lie and Coxeter group hierarchies with special reference to the standard model of high energy particle physics

    Energy Technology Data Exchange (ETDEWEB)

    El Naschie, M.S. [King Abdullah Al Saud Institute of Nano and Advanced Technologies, Riyadh (Saudi Arabia)], E-mail:


    The notions of the order of a symmetry group may be extended to that of an average, non-integer order. Building on this extension, it can be shown that the five classical exceptional Lie symmetry groups could be extended to a hierarchy, the total sum of which is four times {alpha}-bar{sub 0}=137+k{sub 0} of the electromagnetic field. Subsequently it can be shown that all known and conjectured physical fields may be derived by E-infinity transfinite scaling transformation. Consequently E{sub 8}E{sub 8} exceptional Lie symmetry groups manifold, the SL(2,7){sub c} holographic modular curve boundary {gamma}(7), Einstein-Kaluza gravity R{sup (n=4)} and R{sup (n=5)} as well as the electromagnetic field are all topological transformations of each other. It is largely a matter of mathematical taste to choose E{sub 8} or the electromagnetic field associated with {alpha}-bar{sub 0} as derived or as fundamental. However since E{sub 8} has been extensively studied by the founding father of group theory and has recently been mapped completely, it seems beneficial to discuss at least high energy physics starting from the largest of the exceptional groups.

  7. Normal-Conducting High Current RF Photoinjector for High Power CW FEL

    CERN Document Server

    Kurennoy, Sergey; Nguyen, Dinh C; Rathke, John; Schrage, Dale L; Schultheiss, Tom; Wood, Richard L; Young, Lloyd M


    An RF photoinjector capable of producing high average current with low emittance and energy spread is a key enabling technology for high power CW FEL. The design of a 2.5-cell, pi-mode, 700-MHz normal-conducting RF photoinjector cavity with magnetic emittance compensation is completed. With average gradients of 7, 7, and 5 MV/m in its three accelerating cells, the photoinjector will produce a 2.5-MeV electron beam with 3-nC charge per bunch and transverse rms emittance below 7 mm-mrad. Electromagnetic modeling has been used extensively to optimize ridge-loaded tapered waveguides and RF couplers, and led to a new, improved coupler iris design. The results, combined with a thermal and stress analysis, show that the challenging problem of cavity cooling can be successfully solved. Fabrication of a demo 100-mA (at 35 MHz bunch repetition rate) photoinjector is underway. The design is scalable to higher average currents by increasing the electron bunch repetition rate, and provides a path to a MW-class FEL. This p...

  8. Regime dependence of photo-darkening-induced modal degradation in high power fiber amplifier (Conference Presentation) (United States)

    Boullet, Johan; Vincont, Cyril; Jolly, Alain; Pierre, Christophe


    Thermally induced transverse modal instabilities (TMI) have attracted these five years an intense research efforts of the entire fiber laser development community, as it represents the current most limiting effect of further power scaling of high power fiber laser. Anyway, since 2014, a few publications point out a new limiting thermal effect: fiber modal degradation (FMD). It is characterized by a power rollover and simultaneous increase of the cladding light at an average power far from the TMI threshold together with a degraded beam which does not exhibit temporal fluctuations, which is one of the main characteristic of TMI. We report here on the first systemic experimental study of FMD in a high power photonic crystal fiber. We put a particular emphasis on the dependence of its average power threshold on the regime of operation. We experimentally demonstrate that this dependence is intrinsically linked to regime-dependent PD-saturated losses, which are nearly three times higher in CW regime than in short pulse picosecond regime. We make the hypothesis that the existence of these different PD equilibrium states between CW regime and picosecond QCW pulsed regime is due to a partial photo-bleaching of color centers in picosecond regime thanks to a higher probability of multi-photon process induced photobleaching (PB) at high peak power. This hypothesis is corroborated by the demonstration of the reversibility of the FMD induced in CW regime by simply switching the seed CW 1064 nm light by a short pulse, picosecond oscillator.

  9. Adequacy of Frequency Reserves for High Wind Power Generation

    DEFF Research Database (Denmark)

    Das, Kaushik; Litong-Palima, Marisciel; Maule, Petr


    In this article, a new methodology is developed to assess the adequacy of frequency reserves to handle power imbalances caused by wind power forecast errors. The goal of this methodology is to estimate the adequate volume and speed of activation of frequency reserves required to handle power...... imbalances caused due to high penetration of wind power. An algorithm is proposed and developed to estimate the power imbalances due to wind power forecast error following activation of different operating reserves. Frequency containment reserve requirements for mitigating these power imbalances...... are developed through this methodology. Furthermore, the probability of reducing this frequency containment reserve requirement is investigated through this methodology with activation of different volumes and speed of frequency restoration reserve. Wind power generation for 2020 and 2030 scenarios...

  10. High power double-scale pulses from a gain-guided double-clad fiber laser (United States)

    Zhang, Haitao; Gao, Gan; Li, Qinghua; Gong, Mali


    Generation of high power double-scale pulses from a gain-guided double-clad fiber laser is experimentally demonstrated. By employing the Yb-doped 10/130 double-clad fiber as the gain medium, the laser realizes an output power of 5.1 W and pulse energy of 0.175 µJ at repetition rate of 29.14 MHz. To the best of our knowledge, this average output power is the highest among the reported double-scale pulse oscillators. The autocorrelation trace of pulses contains the short (98 fs) and long (29.5 ps) components, and the spectral bandwidth of the pulse is 27.3 nm. Such double-scale pulses are well suited for seeding the high power MOPA (master oscillator power amplifier) systems, nonlinear frequency conversion and optical coherence tomography.

  11. High density operation for reactor-relevant power exhaust (United States)

    Wischmeier, M.


    With increasing size of a tokamak device and associated fusion power gain an increasing power flux density towards the divertor needs to be handled. A solution for handling this power flux is crucial for a safe and economic operation. Using purely geometric arguments in an ITER-like divertor this power flux can be reduced by approximately a factor 100. Based on a conservative extrapolation of current technology for an integrated engineering approach to remove power deposited on plasma facing components a further reduction of the power flux density via volumetric processes in the plasma by up to a factor of 50 is required. Our current ability to interpret existing power exhaust scenarios using numerical transport codes is analyzed and an operational scenario as a potential solution for ITER like divertors under high density and highly radiating reactor-relevant conditions is presented. Alternative concepts for risk mitigation as well as strategies for moving forward are outlined.

  12. High performance magnet power supply optimization

    Energy Technology Data Exchange (ETDEWEB)

    Jackson, L.T.


    The power supply system for the joint LBL--SLAC proposed accelerator PEP provides the opportunity to take a fresh look at the current techniques employed for controlling large amounts of dc power and the possibility of using a new one. A basic requirement of +- 100 ppM regulation is placed on the guide field of the bending magnets and quadrupoles placed around the 2200 meter circumference of the accelerator. The optimization questions to be answered by this paper are threefold: Can a firing circuit be designed to reduce the combined effects of the harmonics and line voltage combined effects of the harmonics and line voltage unbalance to less than 100 ppM in the magnet field. Given the ambiguity of the previous statement, is the addition of a transistor bank to a nominal SCR controlled system the way to go or should one opt for an SCR chopper system running at 1 KHz where multiple supplies are fed from one large dc bus and the cost--performance evaluation of the three possible systems.

  13. Low reflectance high power RF load

    Energy Technology Data Exchange (ETDEWEB)

    Ives, R. Lawrence; Mizuhara, Yosuke M.


    A load for traveling microwave energy has an absorptive volume defined by cylindrical body enclosed by a first end cap and a second end cap. The first end cap has an aperture for the passage of an input waveguide with a rotating part that is coupled to a reflective mirror. The inner surfaces of the absorptive volume consist of a resistive material or are coated with a coating which absorbs a fraction of incident RF energy, and the remainder of the RF energy reflects. The angle of the reflector and end caps is selected such that reflected RF energy dissipates an increasing percentage of the remaining RF energy at each reflection, and the reflected RF energy which returns to the rotating mirror is directed to the back surface of the rotating reflector, and is not coupled to the input waveguide. Additionally, the reflector may have a surface which generates a more uniform power distribution function axially and laterally, to increase the power handling capability of the RF load. The input waveguide may be corrugated for HE11 mode input energy.

  14. 3-D Printed High Power Microwave Magnetrons (United States)

    Jordan, Nicholas; Greening, Geoffrey; Exelby, Steven; Gilgenbach, Ronald; Lau, Y. Y.; Hoff, Brad


    The size, weight, and power requirements of HPM systems are critical constraints on their viability, and can potentially be improved through the use of additive manufacturing techniques, which are rapidly increasing in capability and affordability. Recent experiments on the UM Recirculating Planar Magnetron (RPM), have explored the use of 3-D printed components in a HPM system. The system was driven by MELBA-C, a Marx-Abramyan system which delivers a -300 kV voltage pulse for 0.3-1.0 us, with a 0.15-0.3 T axial magnetic field applied by a pair of electromagnets. Anode blocks were printed from Water Shed XC 11122 photopolymer using a stereolithography process, and prepared with either a spray-coated or electroplated finish. Both manufacturing processes were compared against baseline data for a machined aluminum anode, noting any differences in power output, oscillation frequency, and mode stability. Evolution and durability of the 3-D printed structures were noted both visually and by tracking vacuum inventories via a residual gas analyzer. Research supported by AFOSR (grant #FA9550-15-1-0097) and AFRL.

  15. Power Constrained High-Level Synthesis of Battery Powered Digital Systems

    DEFF Research Database (Denmark)

    Nielsen, Sune Fallgaard; Madsen, Jan


    We present a high-level synthesis algorithm solving the combined scheduling, allocation and binding problem minimizing area under both latency and maximum power per clock-cycle constraints. Our approach eliminates the large power spikes, resulting in an increased battery lifetime, a property...... of utmost importance for battery powered embedded systems. Our approach extends the partial-clique partitioning algorithm by introducing power awareness through a heuristic algorithm which bounds the design space to those of power feasible schedules. We have applied our algorithm on a set of dataflow graphs...

  16. Improved cutting performance in high power laser cutting

    DEFF Research Database (Denmark)

    Olsen, Flemming Ove


    Recent results in high power laser cutting especially with focus on cutting of mild grade steel types for shipbuilding are described.......Recent results in high power laser cutting especially with focus on cutting of mild grade steel types for shipbuilding are described....

  17. In-volume heating using high-power laser diodes

    NARCIS (Netherlands)

    Denisenkov, V.S.; Kiyko, V.V.; Vdovin, G.V.


    High-power lasers are useful instruments suitable for applications in various fields; the most common industrial applications include cutting and welding. We propose a new application of high-power laser diodes as in-bulk heating source for food industry. Current heating processes use surface

  18. Linear and nonlinear filters under high power microwave conditions

    Directory of Open Access Journals (Sweden)

    F. Brauer


    Full Text Available The development of protection circuits against a variety of electromagnetic disturbances is important to assure the immunity of an electronic system. In this paper the behavior of linear and nonlinear filters is measured and simulated with high power microwave (HPM signals to achieve a comprehensive protection against different high power electromagnetic (HPEM threats.

  19. Improved cutting performance in high power laser cutting

    DEFF Research Database (Denmark)

    Olsen, Flemming Ove


    Recent results in high power laser cutting especially with focus on cutting of mild grade steel types for shipbuilding are described.......Recent results in high power laser cutting especially with focus on cutting of mild grade steel types for shipbuilding are described....

  20. In-volume heating using high-power laser diodes

    NARCIS (Netherlands)

    Denisenkov, V.S.; Kiyko, V.V.; Vdovin, G.V.


    High-power lasers are useful instruments suitable for applications in various fields; the most common industrial applications include cutting and welding. We propose a new application of high-power laser diodes as in-bulk heating source for food industry. Current heating processes use surface heatin

  1. Atmospheric propagation and combining of high power lasers: comment. (United States)

    Goodno, Gregory D; Rothenberg, Joshua E


    Nelson et al. [Appl. Opt.55, 1757 (2016)APOPAI0003-693510.1364/AO.55.001757] recently concluded that coherent beam combining and remote phase locking of high-power lasers are fundamentally limited by the laser source linewidth. These conclusions are incorrect and not relevant to practical high-power coherently combined laser architectures.

  2. Phase noise measurement of high-power fiber amplifiers

    Institute of Scientific and Technical Information of China (English)

    Hu Xiao; Xiaolin Wang; Yanxing Ma; Bing He; Pu Zhou; Jun Zhou; Xiaojun Xu


    We measure the phase fluctuation in a high-power fiber amplifier using a multi-dithering technique. Its fluctuation property is qualitatively analyzed by the power spectral density and integrated spectral density.Low frequency fluctuations caused by the environment are dominant in the phase fluctuations in an amplifier, whereas the high frequency components related to laser power affect the control bandwidth. The bandwidth requirement of the active phase-locking is calculated to be 300 Hz, 670 Hz, 1.6 kHz, and 3.9 kHz under the output power of 25,55, 125, and 180W, respectively. The approximately linear relationship between the control bandwidth and laser power needs to be further investigated.%@@ We measure the phase fluctuation in a high-power fiber amplifier using a multi-dithering technique.Its fluctuation property is qualitatively analyzed by the power spectral density and integrated spectral density.Low frequency fluctuations caused by the environment are dominant in the phase fluctuations in an am-plifier, whereas the high frequency components related to laser power affect the control bandwidth.The bandwidth requirement of the active phase-locking is calculated to be 300 Hz, 670 Hz, 1.6 kHz, and 3.9kHz under the output power of 25, 55, 125, and 180 W, respectively.The approximately linear relationship between the control bandwidth and laser power needs to be further investigated.

  3. Emissions from cycling of thermal power plants in electricity systems with high penetration of wind power: Life cycle assessment for Ireland

    DEFF Research Database (Denmark)

    Turconi, Roberto; O'Dwyer, C.; Flynn, D.


    The increase of renewable sources in the power sector is an important step towards more sustainable electricity production. However, introducing high shares of variable renewables, such as wind and solar, cause dispatchable power plants to vary their output to fulfill the remaining electrical...... significantly affect the average power plant efficiency, with all units seeing an average yearly efficiency noticeably less than optimal. In particular, load following units, on average, saw an 11% reduction. Given that production technologies are typically modeled assuming steady-state operation at full load......, as part of LCA of electricity generation, the efficiency reduction would result in large underestimation of emissions, e.g. up to 65% for an oil power plant. Overall, cycling emissions accounted for less than 7% of lifecycle CO2, NOx and SO2 emissions in the five scenarios considered: while...

  4. High-power FDML laser for swept source-OCT at 1060 nm

    DEFF Research Database (Denmark)

    Marschall, Sebastian; Klein, Thomas; Wieser, Wolfgang;


    We present a novel frequency-swept light source working at 1060nm that utilizes a tapered amplifier as gain medium. These devices feature significantly higher saturation power than conventional semiconductor optical amplifiers and can thus improve the limited output power of swept sources...... in this wavelength range. We demonstrate that a tapered amplifier can be integrated into a fiber-based swept source and allows for high-speed FDML operation. The developed light source operates at a sweep rate of 116kHz with an effective average output power in excess of 30mW. With a total sweep range of 70 nm...

  5. 1.55 Micron High Peak Power Fiber Amplifier Project (United States)

    National Aeronautics and Space Administration — In this proposal, we propose to demonstrate and build a 1.55 micron single frequency high energy and high peak power fiber amplifier by developing an innovative...

  6. 1.55 Micron High Peak Power Fiber Amplifier Project (United States)

    National Aeronautics and Space Administration — In this proposal, we propose to demonstrate and build a 1.55 micron single frequency high energy and high peak power fiber amplifier by developing an innovative...

  7. On the Ongoing Evolution of Very High Frequency Power Supplies

    DEFF Research Database (Denmark)

    Knott, Arnold; Andersen, Toke Meyer; Kamby, Peter


    in radio frequency transmission equipment helps to overcome those. However those circuits were not designed to meet the same requirements as power converters. This paper summarizes the contributions in recent years in application of very high frequency (VHF) technologies in power electronics, describes......The ongoing demand for smaller and lighter power supplies is driving the motivation to increase the switching frequencies of power converters. Drastic increases however come along with new challenges, namely the increase of switching losses in all components. The application of power circuits used...

  8. High power density alkaline fuel cell technology for MMW space burst power (United States)

    Preston, J. Lawrence, Jr.; Trocciola, John C.; Wertheim, Ronald J.

    The use of advanced alkaline regenerative fuel cell energy storage systems to provide 10's to 100's of MWe of sprint (burst) power for 100's of seconds per orbit of SDI weapons platform was studied. Recharge power is supplied by a multimegawatt space based nuclear power system. Regenerative fuel cell energy storage systems offer the potential for significant platform mass reduction by reducing the size and mass of the nuclear power source required. This is because the reactor can be sized for the smaller average power level for the energy storage system, rather than the sprint power level. The regenerative fuel cell is a particularly attractive energy storage device because the fuel cell is essentially a static power conversion device, which results in excellent platform stability for weapon pointing and tracking. Based upon the detailed point design and conceptual layout, the alkaline regenerative fuel cell energy storage system is an attractive choice for integration with a nuclear thermionic system for providing multimegawatt burst power and multi orbit capability.

  9. High-Power Blue Light Generation by External Frequency Doubling of an Optical Parametric Oscillator

    Institute of Scientific and Technical Information of China (English)

    毕勇; 张鸿博; 孙志培; 包照日格图; 李惠清; 孔宇鹏; 林学春; 王桂玲; 张杰; 侯玮; 李瑞宁; 崔大复; 许祖彦; 宋立维; 章萍; 崔建峰; 樊仲维


    We report on an all-solid-state high-power quasi-continuous blue light source by the frequency doubling of a signal wave from an optical parametric oscillator(OPO).A 50-mm-long LiB3O5(LBO)crystal is used for the OPO,which is pumped by a diode-pumped Nd:YAG green laser(10kHz,50ns).Tunable blue emission in a new nonlinear crystal BiB3O6(BiBO)is obtained with a wavelength range from 450 to 495 nm.The average power of the signal output is as high as 9.3 W from 924 to 970nm.The maximum output of the blue laser with the second harmonic walk-off compensation is 1.3 W average power at 470nm for 6.2 W of OPO signal light at 940nm.

  10. High-Power Linac for the Spallation Neutron Source (United States)

    Rej, D. J.


    The Spallation Neutron Source (SNS) will be the world’s most intense source of neutrons for fundamental science and industrial applications. Design and construction of this facility, located at Oak Ridge, is a joint venture between six DOE laboratories. Construction began in 1999 and is currently ahead of the scheduled 2006 completion date. Injecting a high-power, pulsed proton beam into a mercury target produces neutrons. In this talk, we review the physics requirements, design, and status of the construction of the 1-GeV, 1.4-MW average power RF linac for SNS. The accelerator consists of a drift tube linac (DTL), a coupled-cavity linac (CCL), and a superconducting rf (SRF) linac. The phase and quadrupole settings are set to avoid structure and parametric resonances, with coherent resonances posing minimal risk for emittance growth. The DTL is 37 m long and accelerates the ions to 87 MeV. The CCL is 55 m long and accelerates the ions to 186 MeV. The rf structure design and stability for both the DTL and CCL have been validated with scale models. The SRF linac has a modular design to accelerate ions to 1000 MeV, with a straightforward upgrade to 1.3 GeV at a later date. 3D particle-in-cell simulations of beam dynamics are performed to validate performance. The accelerator utilizes 93 MW of pulsed power operating continuously at 60-Hz with an 8factor. Approximately one hundred 402.5 or 805-MHz klystrons, with outputs between 0.55 and 5 MW, are used. The klystrons are powered by a novel converter-modulator that takes advantage of recent advances in IGBT switch plate assemblies and low-loss material cores for boost transformer. Beam diagnostics include position, phase, profile, and current monitors. They are designed to enable accurate beam steering and matching, and to minimize beam loss that would lead to activation and prevent hands-on maintenance.


    Energy Technology Data Exchange (ETDEWEB)

    Randy C. Gee


    This is the Final Report for two solar cooling projects under this Cooperative Agreement. The first solar cooling project is a roof-integrated solar cooling and heating system, called the Power Roof{trademark}, which began operation in Raleigh, North Carolina in late July 2002. This system provides 176 kW (50 ton) of solar-driven space cooling using a unique nonimaging concentrating solar collector. The measured performance of the system during its first months of operation is reported here, along with a description of the design and operation of this system. The second solar cooling system, with a 20-ton capacity, is being retrofit to a commercial office building in Charleston, South Carolina but has not yet been completed.

  12. High power UV and VUV pulsed excilamps (United States)

    Tarasenko, V.; Erofeev, M.; Lomaev, M.; Rybka, D.


    Emission characteristics of a nanosecond discharge in inert gases and its halogenides without preionization of the gap from an auxiliary source have been investigated. A volume discharge, initiated by an avalanche electron beam (VDIAEB) was realized at pressures up to 12 atm. In xenon at pressure of 1.2 atm, the energy of spontaneous radiation in the full solid angle was sim 45 mJ/cm^3, and the FWHM of a radiation pulse was sim 110 ns. The spontaneous radiation power rise in xenon was observed at pressures up to 12 atm. Pulsed radiant exitance of inert gases halogenides excited by VDIAEB was sim 4.5 kW/cm^2 at efficiency up to 5.5 %.

  13. High-Power-Density Organic Radical Batteries. (United States)

    Friebe, Christian; Schubert, Ulrich S


    Batteries that are based on organic radical compounds possess superior charging times and discharging power capability in comparison to established electrochemical energy-storage technologies. They do not rely on metals and, hence, feature a favorable environmental impact. They furthermore offer the possibility of roll-to-roll processing through the use of different printing techniques, which enables the cost-efficient fabrication of mechanically flexible devices. In this review, organic radical batteries are presented with the focus on the hitherto developed materials and the key properties thereof, e.g., voltage, capacity, and cycle life. Furthermore, basic information, such as significant characteristics, housing approaches, and applied additives, are presented and discussed in the context of organic radical batteries.

  14. Laser Cooled High-Power Fiber Amplifier

    CERN Document Server

    Nemova, Galina


    A theoretical model for laser cooled continuous-wave fiber amplifier is presented. The amplification process takes place in the Tm3+-doped core of the fluoride ZBLAN (ZrF4-BaF2-LaF3-AlF3-NaF) glass fiber. The cooling process takes place in the Yb3+:ZBLAN fiber cladding. It is shown that for each value of the pump power and the amplified signal there is a distribution of the concentration of the Tm3+ along the length of the fiber amplifier, which provides its athermal operation. The influence of a small deviation in the value of the amplified signal on the temperature of the fiber with the fixed distribution of the Tm3+ions in the fiber cladding is investigated.

  15. Designing high efficient solar powered lighting systems

    DEFF Research Database (Denmark)

    Poulsen, Peter Behrensdorff; Thorsteinsson, Sune; Lindén, Johannes;


    Some major challenges in the development of L2L products is the lack of efficient converter electronics, modelling tools for dimensioning and furthermore, characterization facilities to support the successful development of the products. We report the development of 2 Three-Port-Converters respec......Some major challenges in the development of L2L products is the lack of efficient converter electronics, modelling tools for dimensioning and furthermore, characterization facilities to support the successful development of the products. We report the development of 2 Three......-Port-Converters respectively for 1-10Wp and 10-50 Wp with a peak efficiency of 97% at 1.8 W of PV power for the 10 Wp version. Furthermore, a modelling tool for L2L products has been developed and a laboratory for feeding in component data not available in the datasheets to the model is described....

  16. High-frequency high-voltage high-power DC-to-DC converters (United States)

    Wilson, T. G.; Owen, H. A.; Wilson, P. M.


    A simple analysis of the current and voltage waveshapes associated with the power transistor and the power diode in an example current-or-voltage step-up (buck-boost) converter is presented. The purpose of the analysis is to provide an overview of the problems and design trade-offs which must be addressed as high-power high-voltage converters are operated at switching frequencies in the range of 100 kHz and beyond. Although the analysis focuses on the current-or-voltage step-up converter as the vehicle for discussion, the basic principles presented are applicable to other converter topologies as well.

  17. High Input Voltage, Silicon Carbide Power Processing Unit Performance Demonstration (United States)

    Bozak, Karin E.; Pinero, Luis R.; Scheidegger, Robert J.; Aulisio, Michael V.; Gonzalez, Marcelo C.; Birchenough, Arthur G.


    A silicon carbide brassboard power processing unit has been developed by the NASA Glenn Research Center in Cleveland, Ohio. The power processing unit operates from two sources: a nominal 300 Volt high voltage input bus and a nominal 28 Volt low voltage input bus. The design of the power processing unit includes four low voltage, low power auxiliary supplies, and two parallel 7.5 kilowatt (kW) discharge power supplies that are capable of providing up to 15 kilowatts of total power at 300 to 500 Volts (V) to the thruster. Additionally, the unit contains a housekeeping supply, high voltage input filter, low voltage input filter, and master control board, such that the complete brassboard unit is capable of operating a 12.5 kilowatt Hall effect thruster. The performance of the unit was characterized under both ambient and thermal vacuum test conditions, and the results demonstrate exceptional performance with full power efficiencies exceeding 97%. The unit was also tested with a 12.5kW Hall effect thruster to verify compatibility and output filter specifications. With space-qualified silicon carbide or similar high voltage, high efficiency power devices, this would provide a design solution to address the need for high power electric propulsion systems.

  18. Overview on the high power excimer laser technology (United States)

    Liu, Jingru


    High power excimer laser has essential applications in the fields of high energy density physics, inertial fusion energy and industry owing to its advantages such as short wavelength, high gain, wide bandwidth, energy scalable and repetition operating ability. This overview is aimed at an introduction and evaluation of enormous endeavor of the international high power excimer laser community in the last 30 years. The main technologies of high power excimer laser are reviewed, which include the pumping source technology, angular multiplexing and pulse compressing, beam-smoothing and homogenous irradiation, high efficiency and repetitive operation et al. A high power XeCl laser system developed in NINT of China is described in detail.

  19. Experiment Safety Assurance Package for Mixed Oxide Fuel Irradiation in an Average Power Position (I-24) in the Advanced Test Reactor

    Energy Technology Data Exchange (ETDEWEB)

    J. M . Ryskamp; R. C. Howard; R. C. Pedersen; S. T. Khericha


    The Fissile Material Disposition Program Light Water Reactor Mixed Oxide Fuel Irradiation Test Project Plan details a series of test irradiations designed to investigate the use of weapons-grade plutonium in MOX fuel for light water reactors (LWR) (Cowell 1996a, Cowell 1997a, Thoms 1997a). Commercial MOX fuel has been successfully used in overseas reactors for many years; however, weapons-derived test fuel contains small amounts of gallium (about 2 parts per million). A concern exists that the gallium may migrate out of the fuel and into the clad, inducing embrittlement. For preliminary out-of-pile experiments, Wilson (1997) states that intermetallic compound formation is the principal interaction mechanism between zircaloy cladding and gallium. This interaction is very limited by the low mass of gallium, so problems are not expected with the zircaloy cladding, but an in-pile experiment is needed to confirm the out-of-pile experiments. Ryskamp (1998) provides an overview of this experiment and its documentation. The purpose of this Experiment Safety Assurance Package (ESAP) is to demonstrate the safe irradiation and handling of the mixed uranium and plutonium oxide (MOX) Fuel Average Power Test (APT) experiment as required by Advanced Test Reactor (ATR) Technical Safety Requirement (TSR) 3.9.1 (LMITCO 1998). This ESAP addresses the specific operation of the MOX Fuel APT experiment with respect to the operating envelope for irradiation established by the Upgraded Final Safety Analysis Report (UFSAR) Lockheed Martin Idaho Technologies Company (LMITCO 1997a). Experiment handling activities are discussed herein.

  20. Feasibility Study on High Concentrating Photovoltaic Power Towers (United States)

    Frohberger, Dirk; Jaus, Joachim; Wiesenfarth, Maike; Schramek, Philipp; Bett, Andreas W.


    This paper presents an analysis on the concept of high concentrating PV power towers. A feasibility study is conducted in order to evaluate the future potential of this technology. Objective of the analysis is to provide an improved basis for establishing research and development priorities for the PV power tower concept. Performance assessments and cost calculations for a 1 MW prototype PV tower power are derived. Based on the assumption of a highly homogeneously illuminated receiver, levelized costs of electricity of 0.29 €/kWh have been calculated for a prototype PV tower power.

  1. A high-power target experiment

    CERN Document Server

    Kirk, H G; Ludewig, H; Palmer, Robert; Samulyak, V; Simos, N; Tsang, Thomas; Bradshaw, T W; Drumm, Paul V; Edgecock, T R; Ivanyushenkov, Yury; Bennett, Roger; Efthymiopoulos, Ilias; Fabich, Adrian; Haseroth, H; Haug, F; Lettry, Jacques; Hayato, Y; Yoshimura, Koji; Gabriel, Tony A; Graves, Van; Spampinato, P; Haines, John; McDonald, Kirk T


    We describe an experiment designed as a proof-of-principle test for a target system capable of converting a 4 MW proton beam into a high-intensity muon beam suitable for incorporation into either a neutrino factory complex or a muon collider. The target system is based on exposing a free mercury jet to an intense proton beam in the presence of a high strength solenoidal field.

  2. A battery-powered high-current power supply for superconductors

    CERN Document Server

    Wake, M; Suda, K


    Since superconductors do not require voltages, a high-current power supply could run with low power if the voltage is sufficiently reduced. Even a battery-powered power supply could give as much as 2,000A for a superconductor. To demonstrate this hypothesis, a battery-powered 2,000A power supply was constructed. It uses an IGBT chopper and Schottky diode together with a specially arranged transformer to produce a high current with low voltage. Testing of 2,000A operation was performed for about 1.5 hr using 10 car batteries. Charging time for this operation was 8 hr. Ramping control was smooth and caused no trouble. Although the IGBT frequency ripple of 16.6 kHz was easily removed using a passive filter, spike noise remained in the output voltage. This ripple did not cause any trouble in operating a pancake-type inductive superconducting load. (author)

  3. Active Photonic crystal fibers for high power applications

    DEFF Research Database (Denmark)

    Olausson, Christina Bjarnal Thulin

    . This plays an important role in high power lasers and ampliers with respect to efficiency, packaging, and thermal handling. The third part of the work has involved developing tools for characterizing the mode quality and stability of large core bers. Stable, single-mode bers with larger cores are essential......The photonic crystal ber technology provides means to realize bers optimized for high power operation, due to the large single-mode cores and the unique design exibility of the microstructure. The work presented in this thesis focuses on improving the properties of active photonic crystal bers...... for high power ber lasers and ampliers, and on adding new functionality to the fibers - all with the purpose of pushing the technology towards high powers. The first part of the work has been to investigate photo darkening, the mitigation of which is crucial in the quest for higher powers. The work has...

  4. High Efficiency, High Temperature Foam Core Heat Exchanger for Fission Surface Power Systems, Phase II Project (United States)

    National Aeronautics and Space Administration — Fission-based power systems with power levels of 30 to ≥100 kWe will be needed for planetary surface bases. Development of high temperature, high efficiency...

  5. Tunable sub-20 fs pulses from a 500 kHz OPCPA with 15 W average power based on an all-ytterbium laser

    CERN Document Server

    Puppin, Michele; Prochnow, Oliver; Ahrens, Jan; Binhammer, Thomas; Morgner, Uwe; Krenz, Marcel; Wolf, Martin; Ernstorfer, Ralph


    An optical parametric chirped pulse amplifier fully based on Yb lasers at 500 kHz is described. Passive optical-synchronization is achieved between a fiber laser-pumped white-light and a 515 nm pump produced with a 200 W picosecond Yb:YAG InnoSlab amplifier. An output power up to 19.7 W with long-term stability of 0.3% is demonstrated for wavelength tunable pulses between 680 nm and 900 nm and spectral stability of 0.2%; 16.5 W can be achieved with a bandwidth supporting 5.4 fs pulses. We demonstrate compression of 30 microjoule pulses to sub-20 fs duration with a prism compressor, suitable for high harmonic generation.

  6. Real-time power measurement and control for high power diode laser (United States)

    Qin, Wen-bin; Liu, You-qiang; Cao, Yin-hua; Wang, Zhi-yong


    As the continual improvement of technology and beam quality, diode laser, with poor beam quality, no longer just apply to pump solid-state laser. As a kind of implement of laser materials processing, high-power diode laser has been used in manufacture, as a brand new means of laser processing. Due to the influence of inevitable unstable factors, for example, the temperature of water-cooler, the current of power supply, etc, the output power of diode laser will be unstable. And laser output power, as an important parameter, frequently affects the performance of the laser beam and the experimental results of processing, especially in the laser materials processing. Therefore, researching the real-time power measurement and control of high power diode laser has great significance, and for diode laser, it would improve performance of itself. To achieve the purpose of real-time detection, traditional measuring method, placing a power sensor behind the total-reflection mirror of laser resonant cavity, is mainly applied in the system of gas laser and solid-state laser. However, Owing to the high integration level of diode laser, traditional measuring method can't be adopted. A technique for real-time measure output power of high power diode laser is developed to improve quality of the laser in this paper. A lens placed at an angle of 45° in the system was used to sample output light of laser, and a piece of ground glass was used to uniform the beam power density, then the photoelectric detector received an optic signal and converted it into electric signal. This feeble signal was processed by amplification circuit with a filter. Finally, this detected electric signal was applied to accomplish the closed-loop control of power. The performance of power measurement and control system was tested with the 300W diode laser, and the measuring inaccuracy achieved was less than +/-1%.

  7. High-power quantum cascade lasers (QCLs) grown by GasMBE (United States)

    Razeghi, Manijeh; Slivken, Steven


    This paper is a brief summary of the technological development and state-of-the-art performance of quantum cascade lasers produced at the Centre for Quantum Devices. Laser design will be discussed, as well as experimental details of device fabrication. Recent work has focused on the development of high peak and average power QCLs emitting at room temperature and above. Scaling of the output is demonstrated by increasing the number of emitting regions in the waveguide core. At λ = 9 μm, over 7 W of peak power has been demonstrated at room temperature for a single diode, with an average power of 300 mW at 6% duty cycle. At shorter wavelengths, laser development includes the use of highly strain-balanced heterostructures in order to maintain a high conduction band offset and minimize leakage current. At λ = 6 μm, utilizing a high reflective coating and epilayer-down mounting of the laser, we have demonstrated 225 mW of average power from a single facet at room temperature. Lastly, these results are put in perspective of other reported results and possible future directions are discussed.

  8. 67.9  W high-power white supercontinuum all-fiber laser source. (United States)

    Sun, Chang; Ge, Tingwu; Li, Siyuan; An, Na; Wang, Zhiyong


    We present a high-power white supercontinuum (SC) all-fiber laser source with average power of 67.9 W, spectrum ranging from 500 to 1700 nm, and spectral width exceeding 1000 nm for spectrum with flatness below 10 dB (except pump wavelength). Also, the visible waveband power (below 850 nm) occupies about 21% of the total SC power. A 145 W high-power picosecond pulse fiber laser is specially designed with high repetition frequency of 656 MHz to reduce nonlinear effects. Meanwhile, a homemade high-power mode field adaptor that can operate stably at hundreds of watts of pulse power has high coupling efficiency of 82%. To our knowledge, the 67.9 W white SC fiber laser source we achieved is the highest reported with such a wide and flat optical spectrum.

  9. High Power Silicon Carbide (SiC) Power Processing Unit Development (United States)

    Scheidegger, Robert J.; Santiago, Walter; Bozak, Karin E.; Pinero, Luis R.; Birchenough, Arthur G.


    NASA GRC successfully designed, built and tested a technology-push power processing unit for electric propulsion applications that utilizes high voltage silicon carbide (SiC) technology. The development specifically addresses the need for high power electronics to enable electric propulsion systems in the 100s of kilowatts. This unit demonstrated how high voltage combined with superior semiconductor components resulted in exceptional converter performance.

  10. Solid State Clipper Diodes for High Power Modulators. (United States)


    modeled at low powers and later confirmed in actua l P W pulsar operation. 0~ \\ ~~~~~~~~~ . ~~~~~ .. . .— - - I. ~~~~~ 3 J~ItV~ . \\ W \\_ UNC l ASSIFIE... modeled at low powers and later confirmed in actual MW pulser where epy is torward anode voltage , and [Zol magni- ~per~ t ion. tude of PFN impedance. For...damage are the Pulse diodes 1 different average current ratings to u nit Formin,~ Netw, rk (PF~.) capacitors , m d the thyratron if this rating would

  11. Overview of space power electronic's technology under the CSTI High Capacity Power Program (United States)

    Schwarze, Gene E.

    The Civilian Space Technology Initiative (CSTI) is a NASA Program targeted at the development of specific technologies in the areas of transportation, operations and science. Each of these three areas consists of major elements and one of the operation's elements is the High Capacity Power element. The goal of this element is to develop the technology base needed to meet the long duration, high capacity power requirements for future NASA initiatives. The High Capacity Power element is broken down into several subelements that includes energy conversion in the areas of the free piston Stirling power converter and thermoelectrics, thermal management, power management, system diagnostics, and environmental compatibility and system's lifetime. A recent overview of the CSTI High capacity Power element and a description of each of the program's subelements is given by Winter (1989). The goals of the Power Management subelement are twofold. The first is to develop, test, and demonstrate high temperature, radiation-resistant power and control components and circuits that will be needed in the Power Conditioning, Control and Transmission (PCCT) subsystem of a space nuclear power system. The results obtained under this goal will also be applicable to the instrumentation and control subsystem of a space nuclear reactor. These components and circuits must perform reliably for lifetimes of 7-10 years. The second goal is to develop analytical models for use in computer simulations of candidate PCCT subsystems. Circuits which will be required for a specific PCCT subsystem will be designed and built to demonstrate their performance and, also, to validate the analytical models and simulations. The tasks under the Power Management subelement will now be described in terms of objectives, approach and present status of work.

  12. Overview of space power electronic's technology under the CSTI High Capacity Power Program (United States)

    Schwarze, Gene E.


    The Civilian Space Technology Initiative (CSTI) is a NASA Program targeted at the development of specific technologies in the areas of transportation, operations and science. Each of these three areas consists of major elements and one of the operation's elements is the High Capacity Power element. The goal of this element is to develop the technology base needed to meet the long duration, high capacity power requirements for future NASA initiatives. The High Capacity Power element is broken down into several subelements that includes energy conversion in the areas of the free piston Stirling power converter and thermoelectrics, thermal management, power management, system diagnostics, and environmental compatibility and system's lifetime. A recent overview of the CSTI High capacity Power element and a description of each of the program's subelements is given by Winter (1989). The goals of the Power Management subelement are twofold. The first is to develop, test, and demonstrate high temperature, radiation-resistant power and control components and circuits that will be needed in the Power Conditioning, Control and Transmission (PCCT) subsystem of a space nuclear power system. The results obtained under this goal will also be applicable to the instrumentation and control subsystem of a space nuclear reactor. These components and circuits must perform reliably for lifetimes of 7-10 years. The second goal is to develop analytical models for use in computer simulations of candidate PCCT subsystems. Circuits which will be required for a specific PCCT subsystem will be designed and built to demonstrate their performance and, also, to validate the analytical models and simulations. The tasks under the Power Management subelement will now be described in terms of objectives, approach and present status of work.

  13. Social power and recognition of emotional prosody: High power is associated with lower recognition accuracy than low power. (United States)

    Uskul, Ayse K; Paulmann, Silke; Weick, Mario


    Listeners have to pay close attention to a speaker's tone of voice (prosody) during daily conversations. This is particularly important when trying to infer the emotional state of the speaker. Although a growing body of research has explored how emotions are processed from speech in general, little is known about how psychosocial factors such as social power can shape the perception of vocal emotional attributes. Thus, the present studies explored how social power affects emotional prosody recognition. In a correlational study (Study 1) and an experimental study (Study 2), we show that high power is associated with lower accuracy in emotional prosody recognition than low power. These results, for the first time, suggest that individuals experiencing high or low power perceive emotional tone of voice differently.

  14. Primary reserve studies for high wind power penetrated systems

    DEFF Research Database (Denmark)

    Das, Kaushik; Altin, Müfit; Hansen, Anca Daniela;


    With high penetration of non-synchronous wind generations replacing conventional generators, the inertia of power system will reduce. A large disturbance in such a power system can cause faster frequency change in this power system and might invoke emergency defence strategies like underfrequency....... This paper further explores the capabilities of wind turbines to provide support during underfrequency to prevent load shedding. Maximum wind penetration possible without causing load shedding following a large disturbance is also investigated....

  15. High-Power Considerations in Metamaterial Antennas (United States)


    adding the lens. Z. H. Jiang, M. D. Gregory, and D. H. Werner, "Experimental Demonstration of a Broadband Transformation Optics Lens for Highly...Directive Multibeam Emission," Phys. Rev. B, 84, 165111 (2011). 5.50 GHz 0 5 10 15 20 25 30 35 Maximum Field Enhancement Factor 5.00 GHz 4.50 GHz 4.00

  16. Modular high voltage power supply for chemical analysis (United States)

    Stamps, James F.; Yee, Daniel D.


    A high voltage power supply for use in a system such as a microfluidics system, uses a DC-DC converter in parallel with a voltage-controlled resistor. A feedback circuit provides a control signal for the DC-DC converter and voltage-controlled resistor so as to regulate the output voltage of the high voltage power supply, as well as, to sink or source current from the high voltage supply.

  17. High Power VCSEL Device with Periodic Gain Active Region

    Institute of Scientific and Technical Information of China (English)


    High power vertical cavity surface emitting lasers(VCSEKLs) with large aperture have been fabricated through improving passivation, lateral oxidation and heat dissipation techniques. Different from conventional three quantum well structures, a periodic gain active region with nine quantum wells was incorporated into the VCSEL structure, with which high efficiency and high power operation were expected. The nine quantum wells were divided into three groups with each of them located at the antinodes of the ca...

  18. A new high-power klystron for the DSN (United States)

    Goldfinger, A.; Gregg, M. A.; Hartop, R.


    A very high reliability 100 kW klystron for the Deep Space Network (DSN) high power transmitters in support of spacecrafts to the distant planets was studied. The last phases included electron gun fabrication and beam analyzer evaluation and klystron prototype fabrication, mechanical and electrical design improvements resulted in the delivery of a prototype klystron meeting all requirements. It is concluded that the development of a new high power klystron for the DSN was very successful as demonstrated by the prototype results.

  19. Silicon-Carbide Power MOSFET Performance in High Efficiency Boost Power Processing Unit for Extreme Environments (United States)

    Ikpe, Stanley A.; Lauenstein, Jean-Marie; Carr, Gregory A.; Hunter, Don; Ludwig, Lawrence L.; Wood, William; Del Castillo, Linda Y.; Fitzpatrick, Fred; Chen, Yuan


    Silicon-Carbide device technology has generated much interest in recent years. With superior thermal performance, power ratings and potential switching frequencies over its Silicon counterpart, Silicon-Carbide offers a greater possibility for high powered switching applications in extreme environment. In particular, Silicon-Carbide Metal-Oxide- Semiconductor Field-Effect Transistors' (MOSFETs) maturing process technology has produced a plethora of commercially available power dense, low on-state resistance devices capable of switching at high frequencies. A novel hard-switched power processing unit (PPU) is implemented utilizing Silicon-Carbide power devices. Accelerated life data is captured and assessed in conjunction with a damage accumulation model of gate oxide and drain-source junction lifetime to evaluate potential system performance at high temperature environments.

  20. Development of High-Power Hall Thruster Power Processing Units at NASA GRC (United States)

    Pinero, Luis R.; Bozak, Karin E.; Santiago, Walter; Scheidegger, Robert J.; Birchenough, Arthur G.


    NASA GRC successfully designed, built and tested four different power processor concepts for high power Hall thrusters. Each design satisfies unique goals including the evaluation of a novel silicon carbide semiconductor technology, validation of innovative circuits to overcome the problems with high input voltage converter design, development of a direct-drive unit to demonstrate potential benefits, or simply identification of lessonslearned from the development of a PPU using a conventional design approach. Any of these designs could be developed further to satisfy NASA's needs for high power electric propulsion in the near future.