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Phase-locked arrays of vertical-cavity surface-emitting lasers

Description: Vertical-Cavity Surface-Emitting Lasers (VCSELS) are of increasing interest to the photonics community because of their surface-emitting structure, simple fabrication and packaging, wafer-level testability, and potential for low cost manufacture. Scaling VCSELs to higher power outputs requires increasing the device area, which leads to transverse mode control difficulties if devices become larger than about 5 microns. One approach to increasing the device size while maintaining a well controlle… more
Date: April 1, 1994
Creator: Warren, M. E.; Lear, K. L.; Gourley, P. L.; Hadley, G. R.; Vawter, G. A.; Brennan, T. M. et al.
Partner: UNT Libraries Government Documents Department
open access

Design considerations of a power supply system for fast cycling superconducting accelerator magnets of 2 Tesla b-field generated by a conductor of 100 kA current

Description: Recently proposed fast cycling accelerators for proton drivers (SF-SPS, CERN and SF-MR, SF-BOOSTER, FNAL) neutrino sources require development of new magnet technology. In support of this magnet development a power supply system will need to be developed that can support the high current and high rate of power swing required by the fast cycling (1 sec rise and fall in the SF-MR, 5Hz in Booster). This paper will outline a design concept for a +/- 2000 V and 100,000 A fast ramping power supply sy… more
Date: June 1, 2007
Creator: Hays, Steve; Piekarz, Henryk; Pfeffer, Howie; Claypool, Brad & /Fermilab
Partner: UNT Libraries Government Documents Department
open access

SCALE UP OF Si/Si0.8Ge0.2 AND B4C/B9C SUPERLATTICES FOR HARVESTING OF WASTE HEAT IN DIESEL ENGINES

Description: Thermoelectric devices show significant promise for harvesting and recovery of waste heat from diesel engines, exhaust systems and industrial heat sources. While these devices convert a heat flow directly into electrical energy, cooling can be accomplished by the same device with application of a direct current (Peltier effect). Conversion efficiencies of bulk thermoelectric systems, however, are still too low for economical power conversion in diesel powered vehicles and heavy vehicles. Thermo… more
Date: August 24, 2003
Creator: Martin, P & Olsen, L
Partner: UNT Libraries Government Documents Department
open access

Effects of pulsed-power loads upon an electric power grid

Description: Certain proposed particle-accelerator and laser experiments, and other devices related to fusion research, require multi-megawatt, repetitive power pulses, often at low (subsynchronous) frequency. While some power-delivery technologies call for a certain degree of buffering of the utility demand using capacitive, inductive, or inertial energy storage, considerations have also been made for serving such loads directly from the line. In either case, such pulsed loads represent non-traditional app… more
Date: January 1, 1990
Creator: Smolleck, Howard A.; Ranade, Satish J.; Prasad, Nadipuram R. & Velasco, Rudolph O.
Partner: UNT Libraries Government Documents Department
open access

Harmonic resonance analysis for PEP-II power factor correction upgrades

Description: Recent upgrades to the high voltage utility distribution network at the Stanford Linear Accelerator Center have been accompanied by the installation of a large number of power supplies associated with the PEP-II B Factory project. These power supplies include a diverse assortment of single and three phase units, in two, six and twelve pulse configurations with chopped, pulsed and continuous loading. Viewed as harmonic power sources in a range from a hundred to several kilohertz, they have the p… more
Date: May 1, 1997
Creator: Corvin, C.
Partner: UNT Libraries Government Documents Department
open access

Reactive power and harmonic compensation based on the generalized instantaneous reactive power theory for three-phase power systems

Description: A generalized theory of instantaneous reactive power for three-phase power systems is proposed in this paper. This theory gives a generalized definition of instantaneous reactive power, which is valid for sinusoidal or nonsinusoidal, balanced or unbalanced, three- phase power systems with or without zero-sequence currents and/or voltages. The properties and physical meanings of the newly defined instantaneous reactive power are discussed in detail. With this new reactive power theory, it is ver… more
Date: October 1996
Creator: Peng, Fang Zheng & Lai, Jih-Sheng
Partner: UNT Libraries Government Documents Department
open access

Two-Element Phased Array of Anti-Guided Vertical-Cavity Lasers

Description: We demonstrate for the first time anti-guided coupling of two adjacent vertical-cavity surface-emitting lasers (VCSEL's), obtaining a 1-by-2 phase-locked array at 869 nm. The lateral index modification required for anti-guiding is achieved by a patterned 3-rim etch performed between two epitaxial growths. In contrast with prior evanescently coupled VCSEL's, adjacent anti-guided VCSEL's can emit in-phase and produce a single on-axis lobe in the far field. Greater than 2 mW of in-phase output pow… more
Date: September 27, 1999
Creator: Allerman, Andrew A.; Choquette, Kent D.; Geib, Kent M.; Hadley, G. Ronald & Serkland, Darwin K.
Partner: UNT Libraries Government Documents Department
open access

Instantaneous power factor determined by instantaneous phasors

Description: The instantaneous power factor can be clearly understood from the instantaneous phasors. The unique property of instantaneous phasors is that at any instant the instantaneous three-phase currents and voltages can be represented by a set of balanced phasors. The instantaneous power factor resembles the familiar format of power factor derived from the conventional phasors. This new concept can be used for power quality monitoring, diagnostics, and compensations.
Date: March 1998
Creator: Hsu, J. S.
Partner: UNT Libraries Government Documents Department
open access

Form factors and QCD in spacelike and timelike region

Description: The authors analyze the basic hard exclusive processes: {pi}{gamma}{sup *}{gamma}-transition, pion and nucleon electromagnetic form factors, and discuss the analytic continuation of QCD formulas from the spacelike q{sup 2} < 0 to the timelike region q{sup 2} > 0 of the relevant momentum transfers. They describe the construction of the timelike version of the coupling constant {alpha}{sub s}. They show that due to the analytic continuation of the collinear logarithms each eigenfunction of … more
Date: May 1, 2000
Creator: Bakulev, A.P.; Radyushkin, A.V. & Stefanis, N.G.
Partner: UNT Libraries Government Documents Department
open access

Design and operating experience of a 40 MW, highly-stabilized power supply

Description: Four 10 MW, highly-stabilized power supply modules have been installed at the National High Magnetic Field Laboratory in Tallahassee, FL, to energize water-cooled, resistive, high-field research magnets. The power supply modules achieve a long term current stability if 10 ppM over a 12 h period with a short term ripple and noise variation of <10 ppM over a time period of one cycle. The power supply modules can operate independently, feeding four separate magnets, or two, three or four modules c… more
Date: July 1, 1995
Creator: Boenig, H. J.; Ferner, J. A.; Bogdan, F.; Morris, G. C. & Rumrill, R. S.
Partner: UNT Libraries Government Documents Department
open access

Multilevel converters for power system applications

Description: Multilevel converters are emerging as a new breed of power converter options for power system applications. These converters are most suitable for high voltage high power applications because they connect devices in series without the need for component matching. One of the major limitations of the multilevel converters is the voltage unbalance between different levels. To avoid voltage unbalance between different levels, several techniques have been proposed for different applications. Excludi… more
Date: September 1, 1995
Creator: Lai, J.S.; Stovall, J.P. & Peng, F.Z.
Partner: UNT Libraries Government Documents Department
open access

SLAC synchronous condenser

Description: A synchronous condenser is a synchronous machine that generates reactive power that leads real power by 90{degrees} in phase. The leading reactive power generated by the condenser offsets or cancels the normal lagging reactive power consumed by inductive and nonlinear loads at the accelerator complex. The quality of SLAC`s utility power is improved with the addition of the condenser. The inertia of the condenser`s 35,000 pound rotor damps and smoothes voltage excursions on two 12 kilovolt maste… more
Date: June 1, 1995
Creator: Corvin, C.
Partner: UNT Libraries Government Documents Department
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