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Corrosion of SA1388-1 diodes

Description: After 5 y storage at Allied Signal, a subassembly with SA1388-1 diodes failed testing and the cause was an unacceptable current leak rate in one of the diodes. This was traced to a CuS deposit in a single production lot of diodes; however only about 0.3% failed the specification. A study was performed to determine the cause and potential long-term significance of this problem. Probable cause was determined to be the P-bearing braze material not being compatible with the Ag immersion plating solution (cyanide-based) and to the storage environment containing sulfur.
Date: June 1, 1996
Creator: Krska, C.; Stimetz, C.; Braithwaite, J.; Sorensen, R. & Hlava, P.
Partner: UNT Libraries Government Documents Department

A STUDY OF RAPID CAVITY TUNING.

Description: An FFAG moot likely requires rapid cavity tuning. The cavity must also have a very high gradient. To satisfy both the high power and rapid tuning requirements is a big challenge. Detailed investigation of the possibility is addressed. Included are general thoughts, dual-loop and simple loop analyses, and a study of using ferrite or PIN diodes. Also proposed is a phase control scheme, which may be a better solution if the needed components can be developed. Finally, an energy analysis reveals the difficult of high power tuning.
Date: July 12, 2001
Creator: ZHAO, Y.
Partner: UNT Libraries Government Documents Department

Beam position monitor

Description: An apparatus for determining the position of an x-ray beam relative to a desired beam axis where the apparatus is positioned along the beam path so that a thin metal foil target intersects the x-ray beam generating fluorescent radiation. A PIN diode array is positioned so that a portion of the fluorescent radiation is intercepted by the array resulting in a series of electrical signals from the PIN diodes making up the array. The signals are then analyzed and the position of the x-ray beam is determined relative to the desired beam path.
Date: September 21, 2000
Creator: Alkire, Randy W.; Rosenbaum, Gerold & Evans, Gwyndaf
Partner: UNT Libraries Government Documents Department

High voltage high brightness electron accelerator with MITL voltage adder coupled to foilless diode

Description: The design and analysis of a high brightness electron beam experiment under construction at Sandia National Laboratory is presented. The beam energy is 12 MeV, the current 35-40 kA, the rms radius 0.5 mm, and the pulse duration FWHM 40 ns. The accelerator is SABRE a pulsed inductive voltage adder, and the electron source is a magnetically immersed foilless diode. This experiment has as its goal to stretch the technology to the edge and produce the highest possible electron current in a submillimeter radius beam.
Date: December 31, 1995
Creator: Mazarakis, M.G.; Poulkey, J.W. & Rovang, D.
Partner: UNT Libraries Government Documents Department

Blocking diodes and fuses in low-voltage PV systems

Description: Instructions and labels supplied with listed PV modules and the requirements of the National Electrical Code (NEC) dictate that a series fuse shall be used to protect the module against backfeed currents. Few of the hundreds of thousands of low-voltage (12, 24, and 48-volt) stand-alone photovoltaic (PV) power systems use series fuses on each module or string of modules. Tests and simulations at the Southwest Technology Development Institute (TDI) and at Sandia National Laboratories (SNL) have established that the absence of these fuses can pose significant fire and safety hazards even on 12-volt PV systems. If the system has sufficient backfeed voltage and current, it is possible that a ground fault in the wiring or inside a module can result in the destruction of a PV module.
Date: November 1, 1997
Creator: Wiles, J.C. & King, D.L.
Partner: UNT Libraries Government Documents Department

High voltage feedthrough bushing

Description: A feedthrough bushing for a high voltage diode provides for using compression sealing for all sealing surfaces. A diode assembly includes a central conductor extending through the bushing and a grading ring assembly circumferentially surrounding and coaxial with the central conductor. A flexible conductive plate extends between and compressively seals against the central conductor and the grading ring assembly, wherein the flexibility of the plate allows inner and outer portions of the plate to axially translate for compression sealing against the central conductor and the grading ring assembly, respectively. The inner portion of the plate is bolted to the central conductor for affecting sealing. A compression beam is also bolted to the central conductor and engages the outer portion of the plate to urge the outer portion toward the grading ring assembly to obtain compression sealing therebetween.
Date: December 31, 1991
Creator: Brucker, J.P.
Partner: UNT Libraries Government Documents Department

Electrostatic Discharge (ESD) Protection for a Laser Diode Ignited Actuator

Description: The use of laser diodes in devices to ignite pyrotechnics provides unique new capabilities including the elimination of electrostatic discharge (ESD) pulses entering the device. The Faraday cage formed by the construction of these devices removes the concern of inadvertent ignition of the energetic material. However, the laser diode itself can be damaged by ESD pulses, therefore, to enhance reliability, some protection of the laser diode is necessary. The development of the MC4612 Optical Actuator has included a circuit to protect the laser diode from ESD pulses including the ''Fisher'' severe human body ESD model. The MC4612 uses a laser diode and is designed to replace existing hot-wire actuators. Optical energy from a laser diode, instead of electrical energy, is used to ignite the pyrotechnic. The protection circuit is described along with a discussion of how the circuit design addresses and circumvents the historic 1Amp/1Watt requirement that has been applicable to hot-wire devices.
Date: June 1, 2003
Creator: SALAS, FREDERICK J.; SANCHEZ, DANIEL H. & WEINLEIN, JOHN HARVEY
Partner: UNT Libraries Government Documents Department

Transverse Mode Structure and Pattern Formation in Oxide Confined Vertical Cavity Semiconductor Lasers

Description: We analyze the transverse profiles of oxide-confined vertical cavity laser diodes as a function of aperture size. For small apertures we demonstrate that thermal lensing can be the dominant effect in determining the transverse resonator properties. We also analyze pattern formation in lasers with large apertures where we observe the appearance of tilted waves.
Date: July 6, 1999
Creator: Choquette, K.D.; Geib, K.M.; Hegarty, S.P.; Hou, H.Q.; Huyet, G.; McInerney, J.G. et al.
Partner: UNT Libraries Government Documents Department

Reduced mass persistent switches for large superconducting magnets in space

Description: Superconducting magnets in space must operate in the persistent mode. This paper describes the characteristics of low mass niobium titanium persistent switches for low mass superconducting magnets which are designed to quench protect themselves through the quench back process. (The whole coil is driven normal shortly after the quench has started and the magnet stored energy is taken up by the coil and the persistent switch.) The concept Of using a resistor and diode in parallel with the persistent switch to reduce the overall mass of the persistent switch system and the helium consumption during magnet charging is discussed in the report. A 1.4 meter diameter free-flyer version of the 11.6 Mi stored energy ASTROMAG magnet and its persistent switch is presented as an example.
Date: August 1, 1992
Creator: Green, M. A.
Partner: UNT Libraries Government Documents Department

Performance improvements in diode laser arrays

Description: The average power performance capability of semiconductor laser diode arrays has improved dramatically over the past several years. Additionally, optical conditioning technologies have been developed that increase the effective radiance of stacked two-dimensional arrays by nearly two orders of magnitude. These performance improvements have been accompanied by cost reductions that now make feasible the replacement of flashlamp pump sources by laser diode arrays in a large variety of military and commercial solid state laser systems.
Date: June 1, 1994
Creator: Beach, R. J.; Emanuel, M. A.; Freitas, B. L.; Benett, W. J.; Skidmore, J. A.; Carlson, N. W. et al.
Partner: UNT Libraries Government Documents Department

Laser hazard analysis for various candidate diode lasers associated with the high resolution pulsed scanner.

Description: A laser hazard analysis and safety assessment was performed for each various laser diode candidates associated with the High Resolution Pulse Scanner based on the ANSI Standard Z136.1-2000, American National Standard for the Safe Use of Lasers. A theoretical laser hazard analysis model for this system was derived and an Excel{reg_sign} spreadsheet model was developed to answer the 'what if questions' associated with the various modes of operations for the various candidate diode lasers.
Date: October 1, 2004
Creator: Augustoni, Arnold L.
Partner: UNT Libraries Government Documents Department

A transient model of a cesium-barium diode

Description: In this work a transient model of a Cs-Ba diode is developed, and a series of experiments is performed using a diode equipped with Langmuir probes. The Langmuir probe data show that the electron energy distribution is non-Maxwellian at low discharge currents, indicating the presence of an electron beam from the emitter. Experimental results also showed that the plasma properties are non-homogeneous across the 1 mm diode gap; the electron temperature and plasma potential were higher near the emitter and the plasma density was higher near the collector. Experimental evidence is presented to show that the discharge contracts to a filament below the maximum thermal emission current.
Date: January 1, 1995
Creator: Luke, J.R. & El-Genk, M.S.
Partner: UNT Libraries Government Documents Department

Microtechnology engineering at Lawrence Livermore National Laboratory

Description: The capability of cooling laser diode bars in an architecture that allows the construction of a high-irradiance pump source for solid-state lasers, together with a beam path that exploits the very beneficial average-power thermomechanical properties of crystalline solid-state laser materials, makes high-repetition-rate, diode-pumped slab lasers ideally suited for high-repetition-rate, small-single-pulse-energy, average-power applications. We have built a 1-kW version of this laser design to verify the basic concepts of high-average-power diode packaging and wave-front control in the new zig-zag architecture. With what we have learned in the process, it is quite straightforward to build versions that exceed 2 kW and have very-near-diffraction-limited beam quality. Such lasers will have numerous applications in the military as well as the civil sector.
Date: February 1, 1998
Creator: Langland, B.
Partner: UNT Libraries Government Documents Department

Experimental Comparison of 2-3MV X-Ray Sources for Flash Radiography

Description: High-brightness flash x-ray sources are needed for penetrating dynamic radiography for a variety of applications. Various bremsstrahlung source experiments have been conducted on the TriMeV accelerator (3MV, 60 {Omega}, 20 ns) to determine the best diode and focusing configuration in the 2-3 MV range. Three classes of candidate diodes were examined: gas cell focusing, magnetically immersed, and rod pinch. The best result for the gas cell diode was 6 rad at 1 meter from the source with a 5 mm diameter x-ray spot. Using a 0.5 mm diameter cathode immersed in a 17 T solenoidal magnetic field, the best shot produced 4.1 rad with a 2.9 mm spot. The rod pinch diode demonstrated very reproducible radiographic spots between 0.75 and 0.8 mm in diameter, producing 1.2 rad. This represents a factor of eight improvement in the TriMeV flash radiographic capability above the original gas cell diode to a figure of merit (dose/spot diameter) > 1.8 rad/mm. These results clearly show the rod pinch diode to be the choice x-ray source for flash radiography at 2-3 M V endpoint.
Date: January 1, 2002
Creator: MENGE, PETER RICHARD; JOHNSON, DAVID LEE; MAENCHEN, JOHN E.; OLSON, CRAIG L.; ROVANG, DEAN C.; DROEMER, D. et al.
Partner: UNT Libraries Government Documents Department

Changes in electrical device characteristics during the formation of dislocations in situ in the TEM

Description: By adding electrical connections to a specimen heating holder for a transmission electron microscope, we have measured the characteristics of electronic devices such as diodes while they remain under observation in the microscope. We have made electron-transparent specimens from metastable GeSi/Si p-n junction diodes and introduced dislocations by heating in situ. The combination of electrical measurement and real-time observation of dislocation formation allows us to examine the electrical properties of dislocations in individual devices and the influence of defects on device performance.
Date: March 1, 1993
Creator: Ross, F. M.; Hull, R.; Bahnck, D.; Bean, J. C.; Peticolas, L. J.; King, C. A. et al.
Partner: UNT Libraries Government Documents Department

LLE Review. Quarterly report, January--March 1992: Volume 50

Description: This volume of the LLE Review, covering the period January--March 1992, contains articles on the use of diffraction gratings in laser applications, and the fabrication of gratings for use in these applications. there are two articles on the use of lasers to explore fundamental physics issues and an article on the use of a solid-state diode array for x-ray imaging. Finally, the activities of the National Laser Users Facility and the GDL and OMEGA laser systems are summarized.
Date: September 1, 1992
Creator: Keck, R. L.
Partner: UNT Libraries Government Documents Department

Repetitive, electron-beam diode development

Description: We constructed a stacked-Blumlein pulse generator that can deliver pulses of nearly 200 kV to an electron beam diode load. This pulse generator has an output impedance of 100 {Omega} and a pulse width of 80 ns. It can operate continuously at pulse repetition rates as high as 500 Hz. We discharged the pulse generator into two diodes. One had a 2.9 cm diameter sintered bronze cathode, and the other had a 4.0 cm diameter graphite cathode with points machined into it. The sintered bronze cathode turned on completely with a peak, macroscopic field of 100 kV/cm. The graphite cathode required a peak, macroscopic field of 150 kV/cm in order to operate reproducibly. Nevertheless, only about 10% of the area of the graphite cathode emitted. The bronze cathode operated at 30 Hz, and it exhibited heat damage. Specifically, it melted in places. Conversely, the graphite cathode, operated at 50 Hz, exhibited little damage: principally, minor erosion around the perimeter.
Date: August 1, 1993
Creator: McClenahan, C. R.; Martinez, L. E.; Pena, G. E. & Weber, G. J.
Partner: UNT Libraries Government Documents Department

Data mining for ontology development.

Description: A multi-laboratory ontology construction effort during the summer and fall of 2009 prototyped an ontology for counterfeit semiconductor manufacturing. This effort included an ontology development team and an ontology validation methods team. Here the third team of the Ontology Project, the Data Analysis (DA) team reports on their approaches, the tools they used, and results for mining literature for terminology pertinent to counterfeit semiconductor manufacturing. A discussion of the value of ontology-based analysis is presented, with insights drawn from other ontology-based methods regularly used in the analysis of genomic experiments. Finally, suggestions for future work are offered.
Date: June 1, 2010
Creator: Davidson, George S.; Strasburg, Jana (Pacific Northwest National Laboratory, Richland, WA); Stampf, David (Brookhaven National Laboratory, Upton, NY); Neymotin,Lev (Brookhaven National Laboratory, Upton, NY); Czajkowski, Carl (Brookhaven National Laboratory, Upton, NY); Shine, Eugene (Savannah River National Laboratory, Aiken, SC) et al.
Partner: UNT Libraries Government Documents Department

Progress in the development of scintillating optical fibers

Description: Starting with 1 inch diameter PVT scintillator as a preform, the authors have drawn fibers of several diameters ranging from 1 to 4 mm. These fibers have been coated in line with the draw to form optical fibers. Several cladding materials whose index of refraction ranges from 1.35 to 1.55 have been used. The most successful fiber has been obtained with an extra thick (200 micron) cladding of silicone in combination with a linear draw, as opposed to a spool draw. This fiber is acceptable, but it is extremely fragile and its quality is difficult to control. The authors are currently constructing a 12 channel hodoscope with 1 mm spatial resolution using 4 mm diameter fibers. An account is also given of the progress made in using the Avalanche Photo Diode (APD) operated in the Geiger mode as the photo detector.
Date: January 1, 1983
Creator: Borenstein, S.R. & Strand, R.C.
Partner: UNT Libraries Government Documents Department

High power 2 {micro}m wing-pumped Tm{sup 3+}:YAG laser

Description: Using a scalable diode end-pumping technology developed at Lawrence Livermore National Laboratory the authors have demonstrated a compact Tm{sup 3+}:YAG laser capable of generating greater than 50 W of cw 2 {micro}m laser output power. The design and operational characteristics of this laser will be discussed.
Date: January 1, 1996
Creator: Beach, R.J.; Sutton, S.B.; Honea, E.C.; Skidmore, J.A. & Emanuel, M.A.
Partner: UNT Libraries Government Documents Department

Microstructural evaluation of Sb-adjusted Al{sub 0.5}Ga{sub 0.5}As{sub 1{minus}y}Sb{sub y} buffer layer systems for IR applications

Description: The authors report on a transmission electron microscopy (TEM) study of Sb-adjusted quaternary Al{sub 0.5}Ga{sub 0.5}As{sub 1{minus}y}Sb{sub y} buffer-layers grown on <001> GaAs substrates. A series of structures were grown by MBE at 470 C that utilize a multilayer grading scheme in which the Sb content of Al{sub 0.5}Ga{sub 0.5}As{sub 1{minus}y}Sb{sub y} buffer-layers grown on <001> GaAs substrates. A series of structures were grown by MBe at 470 C that utilize a multilayer grading scheme in which the Sb content of Al{sub 0.5}Ga{sub 0.5}As{sub 1{minus}y}Sb{sub y} is successively increased in a series of 125 nm thick layers. Post growth analysis using conventional bright field and weak beam dark field imaging of these buffer layers in cross-section reveals that the interface misfit dislocations are primarily of the 60{degree} type and are distributed through out the interfaces of the buffer layer. When optimized, the authors have shown, using plan view and cross-sectional TEM, that this approach can reduce the threading defect density to below the detectability limit of TEM (< 10{sup 5}/cm{sup 2}) and preserve growth surface planarity. The Sb-graded approach was used to fabricate two 2.2 {micro}m power converter structures fabricated using InGaAs grown on Sb-based buffer layers on GaAs substrates. A microstructural and electrical characterization was performed on these device structures and the results are contrasted with a sample in which InP was selected as the substrate. Microstructure, defect density and device performance in these not-yet-optimized Sb-based buffer layers compares favorably to equivalent devices fabricated using InP substrates.
Date: June 1, 1998
Creator: Chen, E.; Paine, D.C.; Uppal, P.; Ahearn, J.S.; Nichols, K. & Charache, G.W.
Partner: UNT Libraries Government Documents Department

Analysis of filtered silicon diode data from the MAGO II and MAGO III experiments

Description: The magnetic compression (MAGO) experiments were conceived by the All-Russia Scientific Institute for Experimental Physics (VNIIEF) several years ago, and only recently has Los Alamos National Laboratory (LANL) participated in joint US/Russian experiments intended to combine the advanced US diagnostic technology with the unsurpassed explosive pulsed power technology fielded by VNIIEF. On two of the four joint LANL/VNIIEF magnetized plasma generation (MAGO) experiments fielded thus far, filtered silicon diode measurements of the plasma emission were made. Both VNIIEF and Los Alamos have analyzed the data from those two sets of measurements. Here the results of the Los Alamos analysis are given. In these experiments sets of filtered silicon diodes were used to measure the plasma soft X-ray emission integrated by the different band passes of the thin metal and plastic filters. The filtered silicon diode diagnostic on MAGO III represented a considerable advance over the same diagnostic fielded on MAGO II, but experimental details resulted in data that is very difficult to interpret in a quantitative way. An attempt to derive the spectral character from some of the MAGO III data that might be salvageable does not seem worthwhile. The codes and procedures developed for MAGO III have been valuable for interpreting MAGO II data, and should also be valuable for interpreting future filtered silicon diode data. Because of the better understanding of the physics processes associated with this diagnostic, and the reasonable agreement with the VNIIEF analysis for MAGO II the authors have more confidence in their ability to interpret the filtered silicon diode data from future MAGO experiments. They believe that the filtered silicon diode data from MAGO II is consistent with emission from a long-lived hot magnetized plasma, and that the temperature and density deduced from the data are reasonably consistent with the temperature and density computed ...
Date: September 1, 1996
Creator: Kirkpatrick, R.C. & Idzorek, G.
Partner: UNT Libraries Government Documents Department

MOCVD growth of AlGaN UV LEDs

Description: Issues related to the MOCVD growth of AlGaN, specifically the gas-phase parasitic reactions among TMG, TMA, and NH{sub 3}, are studied using an in-situ optical reflectometer. It is observed that the presence of the well-known gas phase adduct (TMA: NH{sub 3}) could seriously hinder the incorporation behavior of TMGa. Relatively low reactor pressures (30--50 Torr) are employed to grow an AlGaN/GaN SCH QW p-n diode structure. The UV emission at 360 nm (FWHM {approximately} 10 nm) represents the first report of LED operation from an indium-free GaN QW diode.
Date: September 1, 1998
Creator: Han, J. & Crawford, M.H.
Partner: UNT Libraries Government Documents Department

Dielectrics for GaN based MIS-diodes

Description: GaN MIS diodes were demonstrated utilizing AlN and Ga{sub 2}O{sub 3}(Gd{sub 2}O{sub 3}) as insulators. A 345 {angstrom} of AlN was grown on the MOCVD grown n-GaN in a MOMBE system using trimethylamine alane as Al precursor and nitrogen generated from a wavemat ECR N2 plasma. For the Ga{sub 2}O{sub 3}(Gd{sub 2}O{sub 3}) growth, a multi MBE chamber was used and a 195 {angstrom} oxide is E-beam evaporated from a single crystal source of Ga{sub 5}Gd{sub 3}O{sub 12}. The forward breakdown voltage of AlN and Ga{sub 2}O{sub 3}(Gd{sub 2}O{sub 3}) diodes are 5V and 6V, respectively, which are significantly improved from {approximately} 1.2 V of schottky contact. From the C-V measurements, both kinds of diodes showed good charge modulation from accumulation to depletion at different frequencies. The insulator GaN interface roughness and the thickness of the insulator were measured with x-ray reflectivity.
Date: February 1998
Creator: Ren, F.; Abernathy, C. R. & MacKenzie, J. D.
Partner: UNT Libraries Government Documents Department