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Trapping effects are playing an essential role in semiconductor devices. The localization of trapping effects with a high spatial resolution can provide valuable information on the interface and oxide quality in state of the art semiconductor devices. On the example of a Si diode with suspected oxide traps, a method based on Scanning Microwave Microscopy (SMM) is shown to resolve charge carriers, which accumulate within the silicon due to trapping effects at the Si/Si02 interface.

From the beginning, the Switched Reluctance Motors (SRM) have been used for aeronautical and automotive industry given its enormous benefits. However, it has some disadvantages, among which are the acoustic noise they generate, the high torque ripple and strong mechanical vibrations that invite to lose enthusiasm by them. This article demonstrates that a suitable control system it is possible even under adverse conditions, operating a switched reluctance motor within tolerable levels of acoustic noise while maintaining acceptable efficiency.

Intense pulsed active detection (IPAD) has been proposed as a means of detecting contraband fissile material using an intense bremsstrahlung pulse to induce photofission. (S.B. Swanekamp, et al., IEEE Trans. Nucl. Sci. 58, 2011, pp. 2047-2056; also see presentations at this conference by B.V. Weber, et al., S.B. Swanekamp, et al., and J.C. Zier, et al.) A number of pulsed power technologies were evaluated for this application including the linear induction accelerator (LIA) and the linear transformer driver (LTD) before selecting the induction voltage adder (IVA) for further study, as described by I.D. Smith et al., also at this conference. An important factor for the I VA choice in this particular exercise is that research and development be minimized if there were to be a design and construction effort.

Intense pulsed active detection (IPAD, [1]; also see presentations at this conference by B.V. Weber, et al., D.P Murphy et al., S.B. Swanekamp et al. and J.C. Zier, et al.) has been proposed as a means of detecting contraband fissile material from a distance. In this approach, an intense bremsstrahlung pulse is used to induce photo fission, the products of which are detected. In this work, we report on an initial effort to evaluate the applicability of various pulsed-power architectures to this approach. The electron energy is 12 MeV with an effective electron charge at 12 MeV of 3 mC to 5 mC delivered in

The recent emergence of plug-in electric vehicles in a global market can offer big challenges and opportunities for both basic and applied research. Although the electrical architecture of a Electric Vehicle (EV) or an Hybrid Electric Vehicle (HEV) can be considered standardized, the development of its different building blocks is an open problem whose solution could contribute to improve significantly the global performance of the vehicle. This paper details the design and control of a bidirectional DC/DC converter for an electric vehicle. The particularity of the chosen topology is the DC/DC converter control by means of a sliding mode control, using only one surface. The designed converter has been modelled and simulated together with an inverter, a motor and a load, which form the electric vehicle traction system.

Helium-3 tagged magnetic resonance imaging has demonstrated potential for calculating pulmonary deformation from medical imagery. Such measurements are useful for determining the biomechanical properties of the lung. Unfortunately, the relative facility of visually tracking deformation via the high contrast tag lines has not transferred readily to the algorithmic domain of automatically establishing tag-line correspondences. We proffer a solution to this dilemma by translating the problem into a unique point-set registration scenario. Not only does this permit capitalizing on certain spectral aspects of tagged MRI but registration can be performed within a deterministic annealing framework for decreased susceptibility to local minima.

Recent innovations in hyperpolarized helium-3 magnetic resonance imaging (MRI) include the employment of MR tagging techniques for assessment of pulmonary deformation. Historically, such tagging methods have been successfully applied to cardiac research inspiring the development of computational techniques for the quantitative analysis of myocardial deformation. We present related research which concerns the calculation of kinematic quantities, such as displacement and strain, in the lung. Utilizing the high contrast tag lines as landmarks in the images and a recently developed fast n-D B-spline approximation algorithm, we fit a parametric object to the sparse tag line data to smoothly interpolate the underlying deformation field and, subsequently, extract lung kinematic information. We present results from a single human volunteer

Studies the feasibility of a magnetic induction (MI) based system to measure the concentration of paramagnetic material in biological tissues. Our final objective is the measurement of hepatic iron overload with a non-invasive method. We have used an analytical expression, for a disc of conducting paramagnetic or diamagnetic material, to estimate the response of the system. Experimental data were acquired with a custom measurement system using an excitation coil and a planar gradiometer as receiver. The output of the system for different concentrations of FeCl/sub 3/ solutions has been used to calibrate the system. Ten in-vitro measurements of liver samples, with a volume around 50 cm/sup 3/, have been made. Measurements were compared against a biochemical iron estimation procedure and histological studies with hematoxilin-eosin and Perls Prussian blue staining. A significant agreement is observed (R=0.92, P

Starting in 1984, studies have been made of 15-65 MV, 4 MJ, 9-16 ns ion drivers for the LIBRA ICF reactor. The Helia approach was adopted. Design options and general design considerations are discussed. A recent 30 MV design is described that consists of 16 modules, each of 28 1.3 MV Metglas induction cells, powered by thyratron-switched capacitor banks through magnetic pulse compressors.

An identical pair of pulsed power systems has been designed to drive the 60 cm aperture amplifier as part of the Naval Research Laboratory's NIKE KrF laser system. The KrF gas volume is pumped from two opposite sides by 60 cm x 200 cm electron beams which are produced by two totally independent systems. Each pulse power system includes a /spl sim/240 kJ Marx, four (parallel) 5 ohm water filled coaxial pulseforming lines (PFLs), four laser triggered output switches and a monolithic, magnetic field immersed diode. Prominent design features include the large area of the water lines, 90/spl deg/ bcnds in the PFLs, radial-plastic output switch diaphragms (as in SUPER-SPRITE at RAL), and inside/out vacuum bushings (as in AURORA at LANL). Triggered diverters and various passive elements were designed to reduce damage in the event of a fault. A 4 ohm peaking section directly precedes the output switches to increase the flat top duration and an anode field shaper has been designed to reduce e-beam halo in the diode. Detailed circuit simulations show each system will produce a 700 keV, 100 kJ, 250 ns electron beam when driving a matched 1.25 ohm diode. Electrical stress and breakdown fractions were calculated throughout. The diode was modelled analytically and with an electron transport code. In the circuit code, the diode was represented by a Child-Langmuir model whose gap closes at 2.5 cm/ps. The transient response of the 900 bends in the PFLs was determined by a fully 3-D transmission line simulation as well as by a scaled analog model. Hardware fabrication is scheduled to begin in August 1991 with the goal of having one pulse power system (one-half the amplifier) operational by April 1992. The full 60 cm amplifier system is scheduled to be on-line by April 1993.

A Wollaston resistive probe based scanning thermal microscope (SThM) is used to investigate the thermal distribution within the gate channel of an nMOSFET with width to length ratio (W/L) of 2.0 /spl mu/m/3.0 /spl mu/m. The dynamic mode of SThM is used to detect and characterize thermal wave propagation in an nMOSFET biased at different operation modes, i.e. linear, near saturation, far saturation, and near breakdown. An ultra compliant polyimide thermal probe is later employed and the resulting 2D thermal distribution is compared with the results obtained using the Wollaston resistive probe. Measurements using the two probes reveal that the highest thermal wave amplitude region in the gate is closest to the drain at pinch-off, and slowly spreads out and extends towards the source as the MOSFET approaches the near breakdown operation mode.

The use of the dual voltage system 14 V/42 V in the electric systems of cars brings many advantages, but it also poses new challenges like a bigger short circuits (SC) casuistic. The fussing management system (FMS) is responsible for managing the 14 V-gnd, 42 V-gnd and 14 V-42 V short circuits, with the objective of eliminating them as soon as possible, reducing in this way the harmful effects for the wires, batteries and electrical loads. In this paper we show an implementation of the FMS with the communication protocol RDbus. We discuss the basic ideas used in the FMS, its main benefits and the experimental results obtained with 14 V-42 V short circuits.

The six-cell RITS-6 accelerator is an upgrade of the existing RITS-3 accelerator and is next in the sequence of Sandia IVA accelerators built to investigate/validate critical accelerator and radiographic diode issues for scaling to the Radiographic Integrated Test Stand (RITS) (nominally 16 MV, 156 kA, and 70 ns). In the RITS-6 upgrade to RITS-3 the number of cells/cavities, PFLs, laser triggered gas switches and intermediate stores is being doubled. A rebuilt single 61-nF Marx generator will charge the two intermediate storage capacitors. The RITS-3 experiments have demonstrated a MITL configuration matched to the PFL/induction cell impedance and a higher impedance MITL. RITS-6 is designed to utilize the higher impedance MITL providing a 10.5-MV, 123-kA output. The three years of pulsed power performance data from RITS-3 will be summarized and the design improvements being incorporated into RITS-6 will be outlined. The predicted output voltage and current for RITS-6 as a function of diode impedance will be shown. Particle-in-cell simulations of the vacuum power flow from the cell to the load for a range of diode impedances from matched to ~ 40 Ohms will be shown and compared with the re-trapped parapotential flow predictions. The status of the component fabrication and system integration will be given. Another potential upgrade under consideration is RITS-62. In this case the RITS-6 Marx, intermediate stores, gas switches, and PFLs would be duplicated and a tee would replace the elbow that now connects a single PFL to a cell thereby allowing two PFLs to be connected to one cell. The output of RITS-62 matched to the cell/PFL impedance would then be 8 MV, 312 kA or 25.6 ohms. The predicted operating curves for RITS-62 with other non-matched MITLs will be shown. The power delivered to a radiographic diode can be maximized by the correct choice of MITL impedance given the cell/PFL and radiographic diode impedances. If the radiated output for a given diode has a stronger than linear voltage dependence this dependence can also be included in the correct choice of MITL impedance. The optimizations and trade-offs will be shown for RITS-6 and RITS-62 for diode impedances characteristic of radiographic diodes.

This paper describes an induction voltage adder (IVA) being designed by Titan Pulse Sciences Division (TPSD) for AWE Aldermaston, UK. This IVA will be used to power the radiography sources in AWE's planned three-axis Hydrodynamic Research Facility (HRF). TPSD will provide the IVAs and AWE will provide the radiographic diodes. The full IVA will in its initial configuration deliver a 14 MV, 110 kA, 50-60 ns pulse first to a large area diode and then to a developmental radiographic diode. The HRF IVA has been designed utilizing two-conductor water dielectric pulse forming lines (pfls) with laser triggered gas switches and can be reconfigured to power a range of radiographic diodes with peak powers from 1.5 to 3.9 TW and peak voltages from 8 to 16.8 MV. LSP simulations of the vacuum region aided by parapotential theory have explored and optimized the coupling of the different IVA configurations to various diodes.

We have performed a conceptual design of a 6 MV IVA with cells that are directly driven from individual Marx/peaker circuits. The present design assumes use of the RITS IVA cell parameters, driving a negative polarity vacuum coax, and a load impedance of 40-60 ohms. However, the approach scales to at least 16 MV, and is adaptable to positive polarity systems over a range of cell designs and load impedances. In contrast to the more familiar PFL-driven IVAs, this system topology close-couples a compact Marx, coaxial water peaking capacitor and output switch with a single IVA cell. The peaking circuit effectively isolates the Marx series inductance from the load for the first 50-100 ns of the output pulse, thereby providing the desired pulse characteristics for the application. This is accomplished while utilizing COTS components, easily serviceable configurations and mature technologies throughout.

In this paper we analyze the advantages and disadvantages of the basic electrical architecture of the dual voltage 14/42 V system for vehicles proposed up to date. Certain functions of management of the electrical power and protection of the electrical system are also discussed such as the circuit protection, battery management system and fusing. In our analysis of circuit protection we consider the problem of battery discharge and how to avoid the dump load. To control these functions of the electrical architecture, a data communications bus must be provided. In this paper we analyze 4 buses (CAN, TTP, LIN and RDbus) that comply with the appropriate requirements for this type of control. This new electrical system should perform at least the same as the previous one as far as security, reliability and robustness are concerned. Finally, we discuss the most appropriate electrical and communication architectures according to present day requirements.

A resistive probe based Scanning Thermal Microscope (SThM) was implemented in an analysis chamber of a Scanning Electron Microscope (SEM). By means of this hybrid-system thermal device, specific characteristics are detectable. Variable punctual heat sources can be simulated and the influence of ambient parameters can be investigated.

The electrical and mechanical design of the Decade Quad Plasma Radiation Source (PRS) mode is described. The primary design criteria and assumptions, key component schematics and a discussion of compatibility with future advanced loads are given.

Proliferation of nodes has been suggested as a means to achieve reliable communications even when a significant fraction of a network is destroyed. The authors examine issues associated with the design of proliferated, survivable networks based on a layered architecture. A concept for proliferated network operation is outlined, and measures of network performance are described. Threats to each network layer are examined, and survivable network design issues are discussed. It is concluded that proliferating network nodes, using multimedia and interconnecting networks, can enhance communication network survivability. >

Presents and analyzes the DROP (dependent receiver oriented protocol), a random assignment algorithm, and the SDROP (selective dependent receiver oriented protocol) a state-dependent assignment algorithm. These two distributed multiple-resource multiple-access algorithms are applicable to dynamic networks connected by point-to-point radio links. The authors derive the maximum channel utilization of both algorithms and show that although the SDROP uses more information than the DROP, they both have the same maximum throughput. They also show that no algorithm that uses the additional SDROP information has better performance than the DROP. >

The author addresses the question of how to obtain the high accuracy inherent in Wigner representations while avoiding the artifacts caused by cross products between multiple signal components. One approach involves separation of the components of a multicomponent signal by means of eigenanalysis. Various distortions are deliberately introduced by differentiation, smoothing, and the use of time varying gains so as to increase the rank of the signal autocovariance matrix. Separate Wigner distributions of the principal eigenvectors of this matrix are weighted by the eigenvalues and added. The filtering/synthesis problem is automatically solved, since different eigenvectors approximate individual signal components. Another approach is to form inner products of the signal with time functions that have line-like Wigner distributions, thus constructing projection samples that can be used to obtain the signal distribution by means of Radon transform inversion. The tomographic technique can completely eliminate cross-product effects with little loss of accuracy. >

A necessary condition for acoustic imaging (e.g., synthetic aperture sonar processing) is the capability to sum echo samples from the same point in the environment over different signal-echo pairs. To decide whether a dolphin has this capability, a limited number N of electronically simulated echoes with constant delay were transmitted back to an echolocating dolphin. The experiment was performed in San Diego Bay, which has a large indigenous population of snapping shrimp. The signal-to-noise ratio (SNR) of the simulated echoes was controlled by adding artificial Gaussian noise and by varying echo amplitude. If the dolphin is capable of SAS-like imaging, then the SNR required for detection should decrease as the number of available echoes N is increased. This phenomenon was indeed observed. The best receiver model for describing the dependence of SNR on N uses binary summation (an M-out-of-N detector). Binary summation is robust against the strong impulsive interference produced by snapping shrimp. The effect of binary summation on SAS-like processing is assessed by creating SAS images from binary-quantized data at the output of a broadband, dolphin-like sonar, and comparing these images to those obtained without binary quantization.

Nike is a recently completed multi-kilojoule krypton fluoride (KrF) laser that has been built to study the physics of direct drive inertial confinement fusion. The two final amplifiers of the Nike laser are both electron beam pumped systems. The smaller of the two has a 20 cm/spl times/20 cm aperture and produces an output laser beam energy in excess of 100 Joules. This 20 cm amplifier uses a single 12 kJ Marx generator to produce two 300 kV, 75 kA, 140 nsec flat top electron beams that are injected into opposite sides of the laser cell. The larger amplifier in Nike has a 60 cm/spl times/60 cm aperture, and amplifies the laser beam up to 5 kJ. This 60 cm amplifier has two independent electron beam systems, with each side powered by a 170 kJ Marx generator that produces a 670 kV, 540 kA, 240 nsec flat top electron beam. Both amplifiers are complete, fully integrated into the laser, and meet the Nike system requirements. Laser-target experiments have begun.

Jupiter is a proposed 15-20 MJ laboratory X-ray source. It would store /spl sim/100 MJ in the Marx generators and deliver /spl sim/500 TW to drive high power z-pinch implosions. The pulsed power requirements for Jupiter were evaluated by a national review panel which concluded that the modular IVA technology as used in HERMES III is capable of meeting these requirements. Modularity of construction permits design verification with less than a full size system and offers the flexibility to meet changing requirements. A program to validate this approach at the required power levels has begun with the construction and testing of components that will comprise a full scale IVA generator module. The IVA module will provide a nominal 10 MV, 1.8 MA, 100 ns FWHM output pulse and will consist of four submodules. Each submodule is composed of a Marx generator, two intermediate energy storage capacitors (ISCs) four pulse forming lines (PFLs), one voltage adder cavity (VAC), plus other associated switches and hardware. A conceptual design for this IVA module has been completed. Initial designs for the ISC, PFL, and their gas switches are also complete and hardware has been procured. Testing of these components is underway at Sandia National Laboratories. Discussions of these designs and results of tests are presented in this paper.

Summary form only given. Cygnus is a prototype of a radiographic X-ray source leveraging existing hardware and designs to drive a rod-pinch diode at 2.2 MV. This high-resolution X-ray source is being developed to support the Sub-Critical Experiments Program at the Nevada Test Site, and as such employs a modular technology that is scaleable to higher voltages and can be readily deployed underground. The diode is driven by three Induction Voltage Adder (IVA) cells from the Sandia SABRE accelerator; threaded by a positive polarity vacuum coax that extends 2 in to the diode and is designed to operate below electron emission on the anodized outer electrode. The /spl sim/40 ohm diode impedance requires a 40/(3*3)/spl sim/4.5 ohm source to drive the three IVA cavities in parallel, a convenient impedance for a single water coax. The water coax is further designed to serve as a long, passive water cable accommodating several bends to allow independent positioning of the pulse generator that drives the coax, the IVA, and diode X-ray source at the far end. This long water coax is driven by a water pulse-forming line originally developed for Sandia's Radiographic Integrated Test Stand (RITS). A low inductance commercial Marx charges the single PFL in times similar to the charge-times of parallel sets of PFLs driven by intermediate stores in larger IVA systems such as RITS, Hermes-III. The paper describes the Cygnus accelerator design and presents test results for some components.

At the 1999 IEEE Pulsed Power Conference, we reported on the preliminary design of a water coupler system that would combine the current from four individual Decade modules to drive a single plasma radiation source. The design has been finalized; the hardware has been fabricated and fielded on the Decade Quad at the Arnold Engineering Development Center. The final design issues associated with fabrication of the hardware and initial results into a short circuit load and imploding aluminum wire arrays are presented. We also present initial test results with the Decade Quad in the large area bremsstrahlung mode.

Summary form only given. At the 1999 Pulse Power Conference, we reported on a preliminary design of a water coupler system combining the current from four individual Decade Modules to drive a Plasma Radiation Source (PRS). That design has been finalized and fielded on the Decade-Quad located at Arnold Engineering Development Center. The final design and issues associated with the actual fabrication are be presented. Results of attempts to demonstrate 10 MA into a short-circuit load and 8 MA into an imploding aluminum wire load are discussed.

A novel technique that combines MR imaging of hyperpolarized helium gas and conventional MR imaging facilitates, high resolution imaging of lung functionality for the first time. We put forth a segmentation method for measuring the total lung air space and a classification approach to computing the functional air space. For segmentation, we introduce a parametric active contour that allows automated merging of multiple contours. The active contour technique uses gradient vector flow modified and strengthened by a boundary condition that inhibits contour crossover. The active contour approach is computationally inexpensive and is independent of initial contour placement. For classification of the functional lung air space in the helium images, a fuzzy c-means technique is applied. The classification results, in conjunction with the segmentation, allow the analysis of ventilation. The resultant biomedical image analysis tool can used in determining the efficacy of certain respiratory treatments.