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NREL Invention Speeds Solar Cell Quality Testing for Industry (Fact Sheet)

Description: A solid-state optical system, invented by the National Renewable Energy Laboratory (NREL), measures solar cell quantum efficiency (QE) in less than a second, enabling a suite of new capabilities for solar cell manufacturers. QE is a measurement of how cells respond to light across the solar spectrum, but traditional methods for measuring QE had been too slow, limiting its application to small samples pulled from the production line and analyzed in laboratories. NREL's technique, commercialized … more
Date: August 1, 2013
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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ICFA Beam Dynamics Newsletter

Description: The Collider-Accelerator Department at Brookhaven National Laboratory is building a high-brightness 500 mA capable Energy Recovery Linac (ERL) as one of its main R&D thrusts towards eRHIC, the polarized electron - hadron collider as an upgrade of the operating RHIC facility. The ERL is in final assembly stages, with injection commisioning starting in October 2012. The objective of this ERL is to serve as a platform for R&D into high current ERL, in particular issues of halo generation a… more
Date: July 1, 2012
Creator: Ben-Zvi, Ilan; A., Kuczewski; Altinbas, Z.; Beavis, D.; Belomestnykh, & Dai, J. et al
Item Type: Refine your search to only Journal/Magazine/Newsletter
Partner: UNT Libraries Government Documents Department
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Raising Photoemission Efficiency with Surface Acoustic Waves

Description: We are developing a novel technique that may help increase the efficiency and reduce costs of photoelectron sources used at electron accelerators. The technique is based on the use of Surface Acoustic Waves (SAW) in piezoelectric materials, such as GaAs, that are commonly used as photocathodes. Piezoelectric fields produced by the traveling SAW spatially separate electrons and holes, reducing their probability of recombination, thereby enhancing the photoemission quantum efficiency of the photo… more
Date: July 1, 2012
Creator: A. Afanasev, F. Hassani, C.E. Korman, V.G. Dudnikov, R.P. Johnson, M. Poelker, K.E.L. Surles-Law
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Surface Characterization of the LCLS RF Gun Cathode

Description: The first copper cathode installed in the LCLS RF gun was used during LCLS commissioning for more than a year. However, after high charge operation (> 500 pC), the cathode showed a decline of quantum efficiency within the area of drive laser illumination. They report results of SEM, XPS and XAS studies that were carried out on this cathode after it was removed from the gun. X-ray absorption and X-ray photoelectron spectroscopy reveal surface contamination by various hydrocarbon compounds. In… more
Date: June 25, 2012
Creator: Brachmann, Axel; /SLAC; Decker, Franz-Josef; /SLAC; Ding, Yuantao; /SLAC et al.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Analysis of Solar Cell Quality Using Voltage Metrics: Preprint

Description: The highest efficiency solar cells provide both excellent voltage and current. Of these, the open-circuit voltage (Voc) is more frequently viewed as an indicator of the material quality. However, since the Voc also depends on the band gap of the material, the difference between the band gap and the Voc is a better metric for comparing material quality of unlike materials. To take this one step further, since Voc also depends on the shape of the absorption edge, we propose to use the ultimate me… more
Date: June 1, 2012
Creator: Toberer, E. S.; Tamboli, A. C.; Steiner, M. & Kurtz, S.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Hydrogenation of Dislocation-Limited Heteroepitaxial Silicon Solar Cells: Preprint

Description: Post-deposition hydrogenation by remote plasma significantly improves performance of heteroepitaxial silicon solar cells. Heteroepitaxial deposition of thin crystal silicon on sapphire for photovoltaics (PV) is an excellent model system for the study and improvement of deposition on inexpensive Al2O3-coated (100) biaxially-textured metal foils. Without hydrogenation, PV conversion efficiencies are less than 1% on our model system. Performance is limited by carrier recombination at electrically … more
Date: June 1, 2012
Creator: Bolen, M. L.; Grover, S.; Teplin, C. W.; Bobela, D.; Branz, H. M. & Stradins, P.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Surface science analysis of GaAs photocathodes following sustained electron beam delivery

Description: Degradation of the photocathode materials employed in photoinjectors represents a challenge for sustained operation of nuclear physics accelerators and high power Free Electron Lasers (FEL). Photocathode quantum efficiency (QE) degradation is due to residual gasses in the electron source vacuum system being ionized and accelerated back to the photocathode. These investigations are a first attempt to characterize the nature of the photocathode degradation, and employ multiple surface and bulk an… more
Date: June 1, 2012
Creator: Carlos Hernandez-Garcia, Fay Hannon, Marcy Stutzman, V. Shutthanandan, Z. Zhu, M. Nandasri, S. V. Kuchibhatla, S. Thevuthasan, W. P. Hess
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Analysis of Full Charge Reconstruction Algorithms for X-Ray Pixelated Detectors

Description: Existence of the natural diffusive spread of charge carriers on the course of their drift towards collecting electrodes in planar, segmented detectors results in a division of the original cloud of carriers between neighboring channels. This paper presents the analysis of algorithms, implementable with reasonable circuit resources, whose task is to prevent degradation of the detective quantum efficiency in highly granular, digital pixel detectors. The immediate motivation of the work is a photo… more
Date: May 21, 2012
Creator: Baumbaugh, A.; Carini, G.; Deptuch, G.; Grybos, P.; Hoff, J.; Siddons, P. et al.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Simulations of multipacting in the cathode stalk and FPC of 112 MHz superconducting electron gun

Description: A 112 MHz superconducting quarter-wave resonator electron gun will be used as the injector of the Coherent Electron Cooling (CEC) proof-of-principle experiment at BNL. Furthermore, this electron gun can be used for testing of the performance of various high quantum efficiency photocathodes. In a previous paper, we presented the design of the cathode stalks and a Fundamental Power Coupler (FPC). In this paper we present updated designs of the cathode stalk and FPC. Multipacting in the cathode st… more
Date: May 20, 2012
Creator: Xin, T.; Ben-Zvi, Ilan; Belomestnykh, S.; Chang, X.; Rao, T.; Skaritka, J. et al.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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RF Gun Photo cathode Research at SLAC

Description: LCLS is presently operating with a third copper photocathode in the original rf gun, with a quantum efficiency (QE) of {approx}1 x 10{sup -4} and projected emittance {gamma}{var_epsilon}{sub x,y} = 0.45 {micro}m at 250 pC bunch charge. The spare LCLS gun is installed in the SLAC Accelerator Structure Test Area (ASTA), fully processed to high rf power. As part of a wider photocathode R and D program, a UV laser system and additional gun diagnostics are being installed at ASTA to measure QE, QE l… more
Date: May 16, 2012
Creator: Jongewaard, E.; Akre, R.; Brachmann, A.; Corbett, J.; Gilevich, S.; Grouev, K. et al.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Ultracompact Accelerator Technology for a Next-Generation Gamma-Ray Source

Description: This presentation reported on the technology choices and progress manufacturing and testing the injector and accelerator of the 250 MeV ultra-compact Compton Scattering gamma-ray Source under development at LLNL for homeland security applications. This paper summarizes the status of various facets of current accelerator activities at LLNL. The major components for the X-band test station have been designed, fabricated, and await installation. The XL-4 klystron has been delivered, and will short… more
Date: May 14, 2012
Creator: Marsh, R A; Albert, F; Anderson, S G; Gibson, D J; Wu, S S; Hartemann, F V et al.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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X-ray Streak Camera Cathode Development and Timing Accuracy of the 4w UV Fiducial System at the National Ignition Facility

Description: The convergent ablator experiments at the National Ignition Facility (NIF) are designed to measure the peak velocity and remaining ablator mass of an indirectly driven imploding capsule. Such a measurement can be performed using an x-ray source to backlight the capsule and an x-ray streak camera to record the capsule as it implodes. The ultimate goal of this experiment is to achieve an accuracy of 2% in the velocity measurement, which translates to a {+-}2 ps temporal accuracy over any 300 ps i… more
Date: May 2, 2012
Creator: Opachich, Y P; Palmer, N; Homoelle, D; Hatch, B W; Bell, P; Bradley, D et al.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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CALIBRATION OF X-RAY IMAGING DEVICES FOR ACCURATE INTENSITY MEASUREMENT

Description: National Security Technologies (NSTec) has developed calibration procedures for X-ray imaging systems. The X-ray sources that are used for calibration are both diode type and diode/fluorescer combinations. Calibrating the X-ray detectors is key to accurate calibration of the X-ray sources. Both energy dispersive detectors and photodiodes measuring total flux were used. We have developed calibration techniques for the detectors using radioactive sources that are traceable to the National Institu… more
Date: February 16, 2012
Creator: Haugh, M. J.; Charest, M. R.; Ross, P. W.; Lee, J. J.; Schneider, M. B.; Palmer, N. E. et al.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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NREL Researchers Demonstrate External Quantum Efficiency Surpassing 100% in a Quantum Dot Solar Cell (Fact Sheet)

Description: A new device that produces and collects multiple electrons per photon could yield inexpensive, high-efficiency photovoltaics. A new device developed through research at the National Renewable Energy Laboratory (NREL) reduces conventional losses in photovoltaic (PV) solar cells, potentially increasing the power conversion efficiency-but not the cost-of the solar cells. Solar cells convert optical energy from the sun into usable electricity; however, almost 50% of the incident energy is lost as h… more
Date: December 1, 2011
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

Analysis of full charge reconstruction algorithms for x-ray pixelated detectors

Description: Existence of the natural diffusive spread of charge carriers on the course of their drift towards collecting electrodes in planar, segmented detectors results in a division of the original cloud of carriers between neighboring channels. This paper presents the analysis of algorithms, implementable with reasonable circuit resources, whose task is to prevent degradation of the detective quantum efficiency in highly granular, digital pixel detectors. The immediate motivation of the work is a photo… more
Date: November 1, 2011
Creator: Baumbaugh, A.; Carini, G.; Deptuch, G.; Grybos, P.; Hoff, J.; Siddons, P. et al.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Simulator Developed to Drastically Reduce Time of Multijunction PV Device Efficiency Measurements (Fact Sheet), NREL Highlights, Research & Development

Description: NREL's new simulator helps speed up research in the race to improve photovoltaic efficiency. Scientists at the National Renewable Energy Laboratory (NREL) needed a quick and accurate method to predict energy generated from multijunction photovoltaic (PV) test devices. This method had to take into account the nonlinear behavior of multijunction PV. NREL achieved this by developing the One-Sun Multi-Source Simulator (OSMSS), which reduces the time for this type of reference spectrum efficiency me… more
Date: November 1, 2011
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Better Solar Cells and Manufacturing Processes Using NREL's Ultrafast Quantum Efficiency Method (Fact Sheet)

Description: Fact sheet on the FlashQE system, a 2011 R&D 100 Award winner. A solid-state optical system by NREL and Tau Science measures solar cell quantum efficiency in less than a second, enabling a suite of new capabilities for solar cell manufacturers.
Date: August 1, 2011
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Performance Characterization and Remedy of Experimental CuInGaSe2 Mini-Modules: Preprint

Description: We employed current-voltage (I-V), quantum efficiency (QE), photoluminescence (PL), electroluminescence (EL), lock-in thermography (LIT), and (electrochemical) impedance spectroscopy (ECIS) to complementarily characterize the performance and remedy for two pairs of experimental CuInGaSe2 (CIGS) mini-modules. One pair had the three scribe-lines (P1/P2/P3) done by a single pulse-programmable laser, and the other had the P2/P3 lines by mechanical scribe. Localized QE measurements for each cell str… more
Date: July 1, 2011
Creator: Pern, F. J.; Yan, F.; Mansfield, L.; Glynn, S.; Rekow, M. & Murion, R.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Kesterites and Chalcopyrites: A Comparison of Close Cousins; Preprint

Description: Chalcopyrite solar cells based on CuInSe2 and associated alloys have demonstrated high efficiencies, with current annual shipments in the hundreds of megawatts (MW) range and increasing. Largely due to concern over possible indium (In) scarcity, a related set of materials, the kesterites, which comprise Cu2ZnSnS4 and associated alloys, has received increasing attention. Similarities and differences between kesterites and chalcopyrites are discussed as drawn from theory, depositions, and materia… more
Date: May 1, 2011
Creator: Repins, I.; Vora, N.; Beall, C.; Wei, S. H.; Yan, Y.; Romero, M. et al.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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A mulitple cathode gun design for the eRHIC polarized electron source

Description: The future electron-ion collider eRHIC requires a high average current ({approx}50 mA), short bunch ({approx}3 mm), low emittance ({approx}20 {micro}m) polarized electron source. The maximum average current of a polarized electron source so far is more than 1 mA, but much less than 50 mA, from a GaAs:Cs cathode. One possible approach to overcome the average current limit and to achieve the required 50 mA beam for eRHIC, is to combine beamlets from multiple cathodes to one beam. In this paper, w… more
Date: March 28, 2011
Creator: Chang, X.; Ben-Zvi, Ilan; Kewisch, J.; Litvinenko, V.; Pikin, A.; Ptitsyn, V. et al.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Rotating dipole and quadrupole field for a multiple cathode system

Description: A multiple cathode system has been designed to provide the high average current polarized electron bunches for the future electron-ion collider eRHIC [1]. One of the key research topics in this design is the technique to generate a combined dipole and quadrupole rotating field at high frequency (700 kHz). This type of field is necessary for combining bunches from different cathodes to the same axis with minimum emittance growth. Our simulations and the prototype test results to achieve this wil… more
Date: March 28, 2011
Creator: Chang, X.; Ben-Zvi, Ilan; Kewisch, J.; Litvinenko, V.; Meng, W.; Pikin, A. et al.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Investigation into Spectral Parameters as they Impact CPV Module Performance

Description: The CPV industry is well aware that performance of triple junction cells depends on spectral conditions but there is a lack of data quantifying this spectral dependence at the module level. This paper explores the impact of precipitable water vapor, aerosol optical depth (AOD), and optical air mass on multiple CPV module technologies on-sun in Golden, CO.
Date: March 1, 2011
Creator: Muller, M.; Marion, B.; Kurtz, S. & Rodriguez, J.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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