DOWNSTREAM IMPACTS OF SLUDGE MASS REDUCTION VIA ALUMINUM DISSOLUTION ON DWPF PROCESSING OF SAVANNAH RIVER SITE HIGH LEVEL WASTE - 9382 (open access)

DOWNSTREAM IMPACTS OF SLUDGE MASS REDUCTION VIA ALUMINUM DISSOLUTION ON DWPF PROCESSING OF SAVANNAH RIVER SITE HIGH LEVEL WASTE - 9382

The SRS sludge that was to become a major fraction of Sludge Batch 5 (SB5) for the Defense Waste Processing Facility (DWPF) contained a large fraction of H-Modified PUREX (HM) sludge, containing a large fraction of aluminum compounds that could adversely impact the processing and increase the vitrified waste volume. It is beneficial to reduce the non-radioactive fraction of the sludge to minimize the number of glass waste canisters that must be sent to a Federal Repository. Removal of aluminum compounds, such as boehmite and gibbsite, from sludge can be performed with the addition of NaOH solution and heating the sludge for several days. Preparation of SB5 involved adding sodium hydroxide directly to the waste tank and heating the contents to a moderate temperature through slurry pump operation to remove a fraction of this aluminum. The Savannah River National Laboratory (SRNL) was tasked with demonstrating this process on actual tank waste sludge in our Shielded Cells Facility. This paper evaluates some of the impacts of aluminum dissolution on sludge washing and DWPF processing by comparing sludge processing with and without aluminum dissolution. It was necessary to demonstrate these steps to ensure that the aluminum removal process would not adversely impact …
Date: January 14, 2009
Creator: Pareizs, J; Cj Bannochie, C; Michael Hay, M & Daniel McCabe, D
System: The UNT Digital Library
Theoretical Overview on Recent Developments in Transverse Spin Physics (open access)

Theoretical Overview on Recent Developments in Transverse Spin Physics

Transverse-spin physics has been very active and rapidly developing in the last few years. In this talk, I will briefly summarize recent theoretical developments, focusing on the associated QCD dynamics in transverse spin physics.
Date: January 14, 2009
Creator: Yuan, Feng
System: The UNT Digital Library
TTF HOM Data Analysis with Curve Fitting Method (open access)

TTF HOM Data Analysis with Curve Fitting Method

To investigate the possibility of using HOM signals induced in SC cavities as beam and cavity diagnostics, narrow band (20 MHz) data was recorded around the strong TE111-6(6{pi}/9-like) dipole modes (1.7 GHz) in the 40 L-band (1.3 GHz) cavities at the DESY TTF facility. The analyses of these data have so far focused on using a Singular Value Decomposition (SVD) technique to correlate the signals with each other and data from conventional BPMs to show the dipole signals provide an alternate means of measuring the beam trajectory. However, these analyses do not extract the modal information (i.e., frequencies and Q's of the nearly degenerate horizontal and vertical modes). In this paper, we described a method to fit the signal frequency spectrum to obtain this information, and then use the resulting mode amplitudes and phases together with conventional BPM data to determine the mode polarizations and relative centers and tilts. Compared with the SVD analysis, this method is more physical, and can also be used to obtain the beam position and trajectory angle.
Date: July 14, 2009
Creator: Pei, S.; Adolphsen, C.; Li, Z.; Bane, K. & Smith, J.
System: The UNT Digital Library
Sensor Development and Readout Prototyping for the STAR Pixel Detector (open access)

Sensor Development and Readout Prototyping for the STAR Pixel Detector

The STAR experiment at the Relativistic Heavy Ion Collider (RHIC) is designing a new vertex detector. The purpose of this upgrade detector is to provide high resolution pointing to allow for the direct topological reconstruction of heavy flavor decays such as the D{sup 0} by finding vertices displaced from the collision vertex by greater than 60 microns. We are using Monolithic Active Pixel Sensor (MAPS) as the sensor technology and have a coupled sensor development and readout system plan that leads to a final detector with a <200 {micro}s integration time, 400 M pixels and a coverage of -1 < {eta} < 1. We present our coupled sensor and readout development plan and the status of the prototyping work that has been accomplished.
Date: January 14, 2009
Creator: Greiner, L.; Anderssen, E.; Matis, H. S.; Ritter, H. G.; Stezelberger, T.; Szelezniak, M. et al.
System: The UNT Digital Library
Improved Measurement of B^ \to\rho^ \rho^0 and Determination of the Quark-Mixing Phase Angle~\alpha (open access)

Improved Measurement of B^ \to\rho^ \rho^0 and Determination of the Quark-Mixing Phase Angle~\alpha

The authors present improved measurements of the branching fraction {Beta}, the longitudinal polarization fraction f{sub L}, and the direct CP asymmetry A{sub CP} in the B meson decay channel B{sup +} {yields} {rho}{sup +}{rho}{sup 0}. The data sample was collected with the BABAR detector at SLAC. The results are {Beta}(B{sup +} {yields} {rho}{sup +}{rho}{sup 0}) = (23.7 {+-} 1.4 {+-} 1.4) x 10{sup -6}, f{sub L} = 0.950 {+-} 0.015 {+-} 0.006, and A{sub CP} = -0.054 {+-} 0.055 {+-} 0.010, where the uncertainties are statistical and systematic, respectively. Based on these results, they perform an isospin analysis and determine the CKM weak phase angle {alpha} to be (92.4{sub -6.5}{sup +6.0}){sup 0}.
Date: July 14, 2009
Creator: Aubert, B.; Karyotakis, Y.; Lees, J. P.; Poireau, V.; Prencipe, E.; Prudent, X. et al.
System: The UNT Digital Library
Highly 15N-Enriched Chondritic Clasts in the Isheyevo Meteorite (open access)

Highly 15N-Enriched Chondritic Clasts in the Isheyevo Meteorite

The metal-rich carbonaceous chondrites (CB and CH) have the highest whole-rock {sup 15}N enrichment ({delta}{sup 15}N up to +1500{per_thousand}), similar to {delta}{sup 15}N values reported in micron-sized regions (hotspots) of Interplanetary Dust Particles (IDPs) of possibly cometary origin and fine-grained matrices of unmetamorphosed chondrites. These {sup 15}N-rich hotspots are commonly attributed to low-temperature ion-molecule reactions in the protosolar molecular cloud or in the outer part of the protoplanetary disk. The nature of the whole-rock {sup 15}N enrichment of the metal-rich chondrites is not understood. We report a discovery of a unique type of primitive chondritic clasts in the CH/CB-like meteorite Isheyevo, which provides important constraints on the origin of {sup 15}N anomaly in metal-rich chondrites and nitrogen-isotope fractionation in the Solar System. These clasts contain tiny chondrules and refractory inclusions (5-15 {micro}m in size), and abundant ferromagnesian chondrule fragments (1-50 {micro}m in size) embedded in the partly hydrated, fine-grained matrix material composed of olivines, pyroxenes, poorly-organized aromatic organics, phyllosilicates and other hydrous phases. The mineralogy and oxygen isotope compositions of chondrules and refractory inclusions in the clasts are similar to those in the Isheyevo host, suggesting formation at similar heliocentric distances. In contrast to the previously known extraterrestrial samples, the …
Date: January 14, 2009
Creator: Bonal, L; Huss, G R; Krot, A N; Nagashima, K; Ishii, H A; Bradley, J P et al.
System: The UNT Digital Library
Molecular uranates - laser synthesis of uranium oxide anions in the gas phase (open access)

Molecular uranates - laser synthesis of uranium oxide anions in the gas phase

Laser ablation of solid UO{sub 3} or (NH{sub 4}){sub 2}U{sub 2}O{sub 7} yielded in the gas phase molecular uranium oxide anions with compositions ranging from [UO{sub n}]{sup -} (n = 2-4) to [U{sub 14}O{sub n}]{sup -} (n = 32-35), as detected by Fourier transform ion cyclotron resonance mass spectrometry. The cluster series [U{sub x}O{sub 3x}]{sup -} for x {le} 6 and various [U{sub x}O{sub 3x-y}]{sup -}, in which y increased with increasing x, could be identified. A few anions with H atoms were also present, and their abundance increased when hydrated UO{sub 3} was used in place of anhydrous UO{sub 3}. Collision-induced dissociation experiments with some of the lower m/z cluster anions supported extended structures in which neutral UO{sub 3} constitutes the building block. Cationic uranium oxide clusters [U{sub x}O{sub n}]{sup +} (x = 2-9; n = 3-24) could also be produced and are briefly discussed. Common trends in the O/U ratios for both negative and positive clusters could be unveiled.
Date: December 14, 2009
Creator: Marcalo, Joaquim; Santos, Marta; Pires de Matos, Antonio & Gibson, John K
System: The UNT Digital Library
Radioisotope Electric Propulsion for Deep Space Sample Return (open access)

Radioisotope Electric Propulsion for Deep Space Sample Return

The need to answer basic questions regarding the origin of the Solar System will motivate robotic sample return missions to destinations like Pluto, its satellite Charon, and objects in the Kuiper belt. To keep the mission duration short enough to be of interest, sample return from objects farther out in the Solar System requires increasingly higher return velocities. A sample return mission involves several complicated steps to reach an object and obtain a sample, but only the interplanetary return phase of the mission is addressed in this paper. Radioisotope electric propulsion is explored in this parametric study as a means to propel small, dedicated return vehicles for transferring kilogram-size samples from deep space to Earth. Return times for both Earth orbital rendezvous and faster, direct atmospheric re-entry trajectories are calculated for objects as far away as 100 AU. Chemical retro-rocket braking at Earth is compared to radioisotope electric propulsion but the limited deceleration capability of chemical rockets forces the return trajectories to be much slower.
Date: July 14, 2009
Creator: Noble, Robert J.
System: The UNT Digital Library
Simulation Studies of the X-Ray Free-Electron Laser Oscillator (open access)

Simulation Studies of the X-Ray Free-Electron Laser Oscillator

Simulations of the x-ray free-electron laser (FEL) oscillator are presented that include transverse effects and realistic Bragg crystal properties with the two-dimensional code GINGER. In the present cases considered the radiation divergence is much narrower than the crystal acceptance, and the numerical algorithm can be simplified by ignoring the finite angular bandwidth of the crystal. In this regime GINGER shows that the saturated x-ray pulses have 109 photons and are nearly Fourier-limited with peak powers in excess of 1 MW. Wealso include preliminary results for a four-mirror cavity that can be tuned in wavelength over a few percent, with future plans to incorporate the full transverse response of the Bragg crystals into GINGER to more accurately model this tunable source.
Date: August 14, 2009
Creator: Lindberg, R. R.; Shyd'ko, Y.; Kim, K. J. & Fawley, W. M.
System: The UNT Digital Library
LESSONS FROM THE RED BEADS (open access)

LESSONS FROM THE RED BEADS

None
Date: April 14, 2009
Creator: SS, PREVETTE
System: The UNT Digital Library
Chemical pressure and hidden one-dimensional behavior in rare earth tri-telluride (open access)

Chemical pressure and hidden one-dimensional behavior in rare earth tri-telluride

We report on the first optical measurements of the rare-earth tri-telluride charge-density-wave systems. Our data, collected over an extremely broad spectral range, allow us to observe both the Drude component and the single-particle peak, ascribed to the contributions due to the free charge carriers and to the charge-density-wave gap excitation, respectively. The data analysis displays a diminishing impact of the charge-density-wave condensate on the electronic properties with decreasing lattice constant across the rare-earth series. We propose a possible mechanism describing this behavior and we suggest the presence of a one-dimensional character in these two-dimensional compounds. We also envisage that interactions and umklapp processes might play a relevant role in the formation of the charge-density-wave state in these compounds.
Date: December 14, 2009
Creator: Sacchetti, A.; Degiorgi, L.; Giamarchi, T.; Ru, N. & Fisher, I. R.
System: The UNT Digital Library
Pressure Dependence of the Charge-Density-Wave Gap in Rare-Earth Tri-Tellurides (open access)

Pressure Dependence of the Charge-Density-Wave Gap in Rare-Earth Tri-Tellurides

We investigate the pressure dependence of the optical properties of CeTe{sub 3}, which exhibits an incommensurate charge-density-wave (CDW) state already at 300 K. Our data are collected in the mid-infrared spectral range at room temperature and at pressures between 0 and 9 GPa. The energy for the single particle excitation across the CDW gap decreases upon increasing the applied pressure, similarly to the chemical pressure by rare-earth substitution. The broadening of the bands upon lattice compression removes the perfect nesting condition of the Fermi surface and therefore diminishes the impact of the CDW transition on the electronic properties of RTe{sub 3}.
Date: December 14, 2009
Creator: Sacchetti, A.; /Zurich, ETH; Arcangeletti, E.; Perucchi, A.; Baldassarre, L.; Postorino, P. et al.
System: The UNT Digital Library
The Open Source Stochastic Building Simulation Tool SLBM and Its Capabilities to Capture Uncertainty of Policymaking in the U.S. Building Sector (open access)

The Open Source Stochastic Building Simulation Tool SLBM and Its Capabilities to Capture Uncertainty of Policymaking in the U.S. Building Sector

The increasing concern about climate change as well as the expected direct environmental economic impacts of global warming will put considerable constraints on the US building sector, which consumes roughly 48percent of the total primary energy, making it the biggest single source of CO2 emissions. It is obvious that the battle against climate change can only be won by considering innovative building approaches and consumer behaviors and bringing new, effective low carbon technologies to the building / consumer market. However, the limited time given to mitigate climate change is unforgiving to misled research and / or policy. This is the reason why Lawrence Berkeley National Lab is working on an open source long range Stochastic Lite Building Module (SLBM) to estimate the impact of different policies and consumer behavior on the market penetration of low carbon building technologies. SLBM is designed to be a fast running, user-friendly model that analysts can readily run and modify in its entirety through a visual interface. The tool is fundamentally an engineering-economic model with technology adoption decisions based on cost and energy performance characteristics of competing technologies. It also incorporates consumer preferences and passive building systems as well as interactions between technologies (such as …
Date: May 14, 2009
Creator: Stadler, Michael; Marnay, Chris; Azevedo, Ines Lima; Komiyama, Ryoichi & Lai, Judy
System: The UNT Digital Library
A structure zone diagram including plasma based deposition and ion etching (open access)

A structure zone diagram including plasma based deposition and ion etching

An extended structure zone diagram is proposed that includes energetic deposition, characterized by a large flux of ions typical for deposition by filtered cathodic arcs and high power impulse magnetron sputtering. The axes are comprised of a generalized homologous temperature, the normalized kinetic energy flux, and the net film thickness, which can be negative due to ion etching. It is stressed that the number of primary physical parameters affecting growth by far exceeds the number of available axes in such a diagram and therefore it can only provide an approximate and simplified illustration of the growth condition?structure relationships.
Date: October 14, 2009
Creator: Anders, Andre
System: The UNT Digital Library
Fel Gain Length and Taper Measurements at Lcls (open access)

Fel Gain Length and Taper Measurements at Lcls

We present experimental studies of the gain length and saturation power level from 1.5 nm to 1.5 Angstroms at the Linac Coherent Light Source (LCLS). By disrupting theFEL process with an orbit kick, we are able to measure the X-ray intensity as a function of undulator length. This kick method is cross-checked with the method of removing undulator sections. We also study the FEL-induced electron energy loss after saturation to determine the optimal taper of the undulator K values. The experimental results are compared to theory and simulations.
Date: August 14, 2009
Creator: Ratner, D.; Fawley, W. M.; Brachmann, A.; Decker, F. J.; Ding, Y.; Dowell, D. et al.
System: The UNT Digital Library
Pressure dependence of the optical properties of the charge-density-wave compound LaTe2 (open access)

Pressure dependence of the optical properties of the charge-density-wave compound LaTe2

We report the pressure dependence of the optical response of LaTe{sub 2}, which is deep in the charge-density-wave (CDW) ground state even at 300 K. The reflectivity spectrum is collected in the mid-infrared spectral range at room temperature and at pressures between 0 and 7 GPa. We extract the energy scale due to the single particle excitation across the CDW gap and the Drude weight. We establish that the gap decreases upon compressing the lattice, while the Drude weight increases. This signals a reduction in the quality of nesting upon applying pressure, therefore inducing a lesser impact of the CDW condensate on the electronic properties of LaTe{sub 2}. The consequent suppression of the CDW gap leads to a release of additional charge carriers, manifested by the shift of weight from the gap feature into the metallic component of the optical response. On the contrary, the power-law behavior, seen in the optical conductivity at energies above the gap excitation and indicating a weakly interacting limit within the Tomonaga-Luttinger liquid scenario, seems to be only moderately dependent on pressure.
Date: December 14, 2009
Creator: Lavagnini, M.; Sacchetti, A.; Degiorgi, L.; Arcangeletti, E.; Baldassarre, L.; Postorino, P. et al.
System: The UNT Digital Library
B meson decays to charmless meson pairs containing eta or eta' (open access)

B meson decays to charmless meson pairs containing eta or eta'

The authors present updated measurements of the branching fractions for B{sup 0} meson decays to {eta}K{sup 0}, {eta}{eta}, {eta}{phi}, {eta}{omega}, {eta}{prime}K{sup 0}, {eta}{prime}{eta}{prime}, {eta}{prime}, {phi}, and {eta}{prime}{omega} and branching fractions and CP-violating charge asymmetries for B{sup +} decays to {eta}{pi}{sup +}, {eta}K{sup +}, {eta}{prime}{pi}{sup +}, and {eta}{prime} K{sup +}. The data represent the full dataset of 467 x 10{sup 6} B{bar B} pairs collected with the BABAR detector at the PEP-II asymmetric-energy e{sup +}e{sup -} collider at the SLAC National Accelerator Laboratory. Besides large signals for the four charged B decays modes and for B{sup 0} {yields} {eta}{prime}K{sup 0}, they find evidence for three B{sup 0} decays modes at greater than 3.0{sigma} significance. They find {Beta}(B{sup 0} {yields} {eta}K{sup 0}) = (1.15{sub -0.38}{sup +0.43} {+-} 0.09) x 10{sup -6}, {Beta}(B{sup 0} {yields} {eta}{omega}) = (0.94{sub -0.30}{sup +0.35} {+-} 0.09) x 10{sup -6}, and {Beta}(B{sup 0} {yields} {eta}{prime}{omega}) = (1.01{sub -0.38}{sup +0.46} {+-} 0.09) x 10{sup -6}, where the first (second) uncertainty is statistical (systematic). For the B{sup +} {yields} {eta}K{sup +} decay mode, they measure the charge asymmetry {Alpha}{sub ch} (B{sup +} {yields} {eta}K{sup +}) = -0.36 {+-} 0.11 {+-} 0.03.
Date: December 14, 2009
Creator: Aubert, B.
System: The UNT Digital Library
THE SECOND STAGE OF FERMI@ELETTRA: A SEEDED FEL IN THE SOFT X-RAY SPECTRAL RANGE (open access)

THE SECOND STAGE OF FERMI@ELETTRA: A SEEDED FEL IN THE SOFT X-RAY SPECTRAL RANGE

The second stage of the FERMI FEL, named FEL-2, is based on the principle of high-gain harmonic generation and relies on a double-seeded cascade. Recent developments stimulated a revision of the original setup, which was designed to cover the spectral range between 40 and 10 nm. The numerical simulations we present here show that the nominal (expected) electron-beam performance allows extension of the FEL spectral range down to 4 nm. A significant amount of third harmonic power can be also expected. We also show that the proposed setup is flexible enough for exploiting future developments of new seed sources, e.g., high harmonic generation in gases.
Date: August 14, 2009
Creator: Allaria, E.; DeNinno, G. & Fawley, W. M.
System: The UNT Digital Library
Measurements of Black Carbon Particles Chemical, Physical, and Optical Properties (open access)

Measurements of Black Carbon Particles Chemical, Physical, and Optical Properties

Accurate measurements of the chemical, physical, and optical properties of aerosol particles containing black carbon are necessary to improve current estimates of the radiative forcing in the atmosphere. A collaborative research effort between Aerodyne Research, Inc. and Boston College has focused on conducting field and laboratory experiments on carbonaceous particles and the development and characterization of new particulate instrumentation. This presentation will focus on the chemical, physical, and optical properties of black carbon particles measured in the laboratory in order to understand the effects of atmospheric processing on black carbon particles. Results from a three-week study during July 2008 of mass- and optical-based black carbon measurements will be presented. The project utilized the Boston College laboratory flame apparatus and aerosol conditioning and characterization equipment. A pre-mixed flat flame burner operating at controlled fuel-to-air ratios produced stable and reproducible concentrations of soot particles with known sizes, morphologies, and chemical compositions. In addition, other black carbon particle types, including fullerene soot, glassy carbon spheres, oxidized flame soot, Regal black, and Aquadag, were also atomized, size selected, and sampled. The study covered an experimental matrix that systematically selected particle mobility size (30 to 300 nm) and black carbon particle mass, particle number concentration, …
Date: December 14, 2009
Creator: Onasch, T.B.; Sedlacek, A.; Cross, E. S.; Davidovits, P.; Worsnop, D. R.; Ahern, A. et al.
System: The UNT Digital Library
Toward Accurate Reaction Energetics for Molecular Line Growth at Surface: Quantum Monte Carlo and Density Functional Theory Calculations (open access)

Toward Accurate Reaction Energetics for Molecular Line Growth at Surface: Quantum Monte Carlo and Density Functional Theory Calculations

We revisit the molecular line growth mechanism of styrene on the hydrogenated Si(001) 2x1 surface. In particular, we investigate the energetics of the radical chain reaction mechanism by means of diffusion quantum Monte Carlo (QMC) and density functional theory (DFT) calculations. For the exchange correlation (XC) functional we use the non-empirical generalized-gradient approximation (GGA) and meta-GGA. We find that the QMC result also predicts the intra dimer-row growth of the molecular line over the inter dimer-row growth, supporting the conclusion based on DFT results. However, the absolute magnitudes of the adsorption and reaction energies, and the heights of the energy barriers differ considerably between the QMC and DFT with the GGA/meta-GGA XC functionals.
Date: October 14, 2009
Creator: Kanai, Y & Takeuchi, N
System: The UNT Digital Library
Magnetic properties of the charge density wave compounds RTe3, R=Y, La, Ce, Pr, Nd, Sm, Gd, Tb, Dy, Ho, Er & Tm (open access)

Magnetic properties of the charge density wave compounds RTe3, R=Y, La, Ce, Pr, Nd, Sm, Gd, Tb, Dy, Ho, Er & Tm

The antiferromagnetic transition is investigated in the rare-earth (R) tritelluride RTe{sub 3} family of charge density wave (CDW) compounds via specific heat, magnetization and resistivity measurements. Observation of the opening of a superzone gap in the resistivity of DyTe{sub 3} indicates that additional nesting of the reconstructed Fermi surface in the CDW state plays an important role in determining the magnetic structure.
Date: December 14, 2009
Creator: Ru, N.; Chu, J.-H.; Fisher, I.R. & /Stanford U., Geballe Lab.
System: The UNT Digital Library
De Haas-van Alphen oscillations in the charge-density wave compound lanthanum tritelluride (LaTe3) (open access)

De Haas-van Alphen oscillations in the charge-density wave compound lanthanum tritelluride (LaTe3)

De Haas-van Alphen oscillations were measured in lanthanum tritelluride (LaTe{sub 3}) to probe the partially gapped Fermi surface resulting from charge density wave (CDW) formation. Three distinct frequencies were observed, one of which can be correlated with a FS sheet that is unaltered by CDW formation. The other two frequencies arise from FS sheets that have been reconstructed in the CDW state.
Date: December 14, 2009
Creator: Ru, N.; Borzi, R. A.; Rost, A.; Mackenzie, A. P.; Laverock, J.; Dugdale, S. B. et al.
System: The UNT Digital Library
Domain wall dynamics in a spin-reorientation transition system Au/Co/Au (open access)

Domain wall dynamics in a spin-reorientation transition system Au/Co/Au

We report measurements of domain wall dynamics in an ultrathin Au/Co/Au system that exhibits a spin reorientation phase transition as a function of temperature.The domain walls exhibit cooperative motion throughout the temperature range of 150 - 300 K. The decay times were found to exhibit a maximum at the transition temperature. The slowdown has been explained as due to formation of a double well in the energy landscape by the different competing interactions. Our results show that the complex, slow dynamics can provide a more fundamental understanding of magnetic phase transitions.
Date: May 14, 2009
Creator: Roy, Sujoy; Seu, Keoki; Turner, Joshua J.; Park, Sungkyun; Kevan, Steve & Falco, Charles M.
System: The UNT Digital Library
Hybrid MOSFET/Driver for Ultra-Fast Switching (open access)

Hybrid MOSFET/Driver for Ultra-Fast Switching

The ultra-fast switching of power MOSFETs, in about 1ns, is very challenging. This is largely due to the parasitic inductance that is intrinsic to commercial packages used for both MOSFETs and drivers. Parasitic gate and source inductance not only limit the voltage rise time on the MOSFET internal gate structure but can also cause the gate voltage to oscillate. This paper describes a hybrid approach that substantially reduces the parasitic inductance between the driver and MOSFET gate, as well as between the MOSFET source and its external connection. A flip chip assembly is used to directly attach a die-form power MOSFET and driver on a PCB. The parasitic inductances are significantly reduced by eliminating bond wires and minimizing lead length. The experimental results demonstrate ultra-fast switching of the power MOSFET with excellent control of the gate-source voltage.
Date: July 14, 2009
Creator: Tang, T
System: The UNT Digital Library