Abstract: An energy efficient data center incorporating superconducting power transmission cables coupled with cryogenically cooled semiconductor inverters and converters, used to supply power to cryogenically operated or room-temperature computers and servers. Other options and features include a lighting system whose performance is enhanced by the cold temperatures, fiber optic connections operated at cryogenic temperatures, integrated renewable energy power sources, advanced energy storage technologies, cryogenically operated computers, and a number of other cryogenic hardware. The operating temperature of the cryogenic components can be anywhere in the range between 0 K and 200 K, with other components operating above 200 K.

Abstract: An energy efficient data center incorporating superconducting power transmission cables coupled with cryogenically cooled semiconductor inverters and converters, used to supply power to cryogenically operated or room-temperature computers and servers. Other options and features include a lighting system whose performance is enhanced by the cold temperatures, fiber optic connections operated at cryogenic temperatures, integrated renewable energy power sources, advanced energy storage technologies, cryogenically operated computers, and a number of other cryogenic hardware. The operating temperature of the cryogenic components can be anywhere in the range between 0 K and 200 K, with other components operating above 200 K.

Abstract: Described is a novel aircraft lighting system with the potential for achieving increased efficiency, improved thermal management, higher reliability, and longer lifetimes. The proposed approach involves combining solar cells and light-emitting diodes (LEDs), and utilizing the cold temperatures of about ?50 degrees centigrade encountered in high-altitude (12,000 m) flight to improve thermal management and efficiency in both components.

Abstract: An ultra compact ring topology puts the output terminals of solid state switches physically at the center of a circuit with the switches surrounded by voltage busses. The switches are symmetrically arranged around the output bus, the voltage busses are filtered (decoupled) to ground using symmetrically positioned filter components, and lead lengths to and from the switches are minimized. Switch driver circuits are closely integrated with each switch and positioned as close as possible, each to its associated switch, and arranged symmetrically. Switches may be at cryogenic temperatures and busses and lead connectors may be superconductive.

Abstract: This invention describes a means by which performance characteristics of capacitors can be improved. This is achieved by reducing the temperature, preferably but not exclusively to cryogenic temperatures below 100 K. The dielectric strength, dielectric losses, equivalent series resistance, and plate losses in many capacitors, such as film capacitors, improve as the temperature is decreased. Current carrying capacity is improved. A capacitor bank exhibits energy densities up to four times those of conventional, room-temperature capacitor banks. Cryogenic capacitors can be combined with cryogenically operated semiconductors or with superconductors to reduce the size, weight, and losses of a complete system.

Abstract: Switching losses and conduction losses are isolated by networks which are partially cryogenic and partially at room temperature. Switching losses are independent of temperature. Advantageously the switching losses are taken in a snubber network at room temperature and conduction losses are incurred at cryogenic temperatures, where majority carrier devices like MOSFETs operate with ultra low on-state resistance and corresponding low conduction losses. Low loss leads carry current efficiently from the cryogenic environment to room temperature without adversely affecting refrigeration. Switch and snubber network may both operate cryogenically.

Abstract: A method and apparatus for reducing conductive thermal losses in high-current cryogenic power electronics systems needing large cables to interface between warm and cold environments. Thermal losses increase with increasing cross-sectional area. The total current at the warm/cold interface is split into many smaller currents by splitting the power buss into a plurality of parallel leads. Respective physical switches in each smaller lead at the interface interrupt current flow, and at the same time open the path for thermal conduction along the lead. When little or no current is flowing through the system, selected smaller leads of the power buss are physically opened by the associated switches to stop the thermal and electrical flow along these leads. Current diverts to another parallel lead in the buss but the cross section for heat flow is reduced at the interface.

Abstract: This invention describes a means by which performance characteristics of capacitors can be improved. This is achieved by reducing the temperature, preferably but not exclusively to cryogenic temperatures below 100 K. This is based on the observation that the dielectric strength, dielectric losses and plate losses in many capacitors, such as film capacitors, improve as the temperature is decreased. A cryogenic capacitor bank is also described, which exhibits energy densities up to four times those of conventional, room-temperature capacitor banks. Cryogenic capacitors can be combined with cryogenically operated semiconductors or with superconductors in such a way as to reduce the size, weight, and losses of a complete system.

Abstract: Sub-systems and components of a MRI system have enhanced electrical efficiency, faster operation, reduced physical metrics, by operating at cryogenic temperatures and/or incorporating superconducting elements. A plurality of sub-systems and a super-conducting magnet are enclosed in a common Temperature-controlled chamber. Resistive or permanent magnets may be used in place of the superconductive magnet.

Abstract: A cryogenic power conditioning system for fuel cells is proposed which is cooled by liquid hydrogen or liquid natural gas (methane) used to power these fuel cells, or by liquid nitrogen supplied by high-temperature superconducting cables. The main applications are in large vehicles such as transit buses. The result is a combined motor and motor-drive system exhibiting higher efficiency, lower weight, smaller size and lower cost.

Abstract: A cryogenic power conditioning system for fuel cells is proposed which is cooled by liquid hydrogen or liquid natural gas (methane) feeding these fuel cells or by liquid nitrogen supplied by high-temperature superconducting cables. The main application are vehicles such as transit buses, etc. The result is higher efficiency, lower weight, smaller size and lower cost.

Abstract: Energy distribution and conversion system suitable for high-rise structures, large building complexes, factories, ships, airplanes, city blocks, etc., based on: High-Temperature Superconductors (HTS) and Cryogenic Power and Energy Conversion (CPEC) using Low-Temperature Operated Semiconductor Devices (LOTOS). Energy from an AC source is converted to DC by LOTOS, distributed as DC, and reconverted at low temperatures to AC at levels and fequencies to satisfy individual end-users of energy. The DC energy is distributed via a plurality of super-conductive leads that are submerged in cryogenic liquid. Substantial savings in energy, cost, size, weight are produced. Additionally, load shedding, power quality, and fire protection are provided. The new system supports air conditioning/cooling systems. Expensive floor space is saved; electrical energy savings of 5-10% are achieved.

Abstract: An electronic power conversion circuit includes cryogenically cooled MOSFET power switching devices arranged in a switch-mode configuration and responsive to control signals for reducing capacitive discharge and commutation losses in the circuit by controlling the period between switch-on and switch-off time (i.e., “deadtime”) of the MOSFET devices. When one of the MOSFET devices of the circuit is switched off, the opposing MOSFET, after the short deadtime period, is switched on to serve as a commutating device rather, than the opposing MOSFET's intrinsic drain-source diode. The power conversion circuit may include a half-bridge circuit or combinations thereof.

Abstract: A staggered-frequency AC inverter includes at least first and second pulse width modulated bridge circuits connected in series. The first bridge circuit receives a DC voltage and operates at a first pulse width modulated switch frequency to generate a first output corresponding to a first region of the AC signal. The second bridge circuit receives a DC voltage and operates at a second pulse width modulated switch frequency substantially lower than the first frequency. The second bridge circuit generates a second output corresponding to a second region of the AC signal in which the AC signal changes less rapidly than in the first region, minus a maximum voltage magnitude of the first region. Another aspect of the invention features a staggered-voltage multiple-phase circuit having at least a first-phase portion for generating a voltage signal in a first phase, and a second-phase portion for generating the voltage signal in a second phase.

Abstract: A power device component package includes a substrate supporting a drain lead, a source lead, and a gate lead. Each of the leads comprises an electrically conductive material having a thickness sufficient to form a high current contact. A power device component with component pads has an electrically conductive backside supported by and electrically coupled to the drain lead. A dielectric layer overlies at least portions of the component, the source lead, and the gate lead and has a plurality of vias therein aligned with predetermined ones of the component pads and predetermined portions of the source and gate leads. A pattern of electrical conductors extends through selected ones of the vias, with a first portion of the pattern coupling selected ones of the component pads to the source lead and a second portion of the pattern coupling at least one other of the component pads to the gate lead.

Abstract: A circuit for amplifying signals received by the receive coil of a magnetic resonance (MR) system includes a preamplifier employing an active circuit device, such as a GaAs-MESFET or HEMT. The preamplifier is located proximate to the receive coil in order to maintain as high a signal-to-noise ratio as possible for the preamplifier output signals. A capacitance is coupled to the receive coil to form an input impedance matching network for the input of the preamplifier. The preamplifier output is coupled through a fiber optic cable to remotely located MR signal processing electronics, which further processes signals received by the MR receive coil and amplified by the preamplifier.

Abstract: An in-situ method of extracting contaminants from a soil volume comprises applying a radiofrequency (RF) excitation signal to heat the soil with an array of electrodes. The electrodes are inserted into the contaminated volume or inserted into a matrix of holes drilled into the volume. A first row of electrodes is electrically coupled to a shield of a coaxial cable, with a second row electrically coupled to the central conductor of the coaxial cable. RF energy is applied to pairs of electrode rows through the coaxial cable and a matching network is installed in front of the electrode-row pair to maximize power flow into the electrode-row pair. This results in very evenly distributed voltages which results in even heating. A balanced-to-unbalanced transformer (balun) is installed at the input to the matching network to prevent the deposition of RF energy outside the target volume and creation of voltages that could be hazardous to personnel.

Abstract: This invention relates to refrigerated superconducting MR magnets having integrated cryogenic gradient coils. In particular, the amount of eddy currents produced by the magnet are substantially reduced while reducing the size and weight, and, therefore, the cost of the superconducting magnet required to produce an acceptable MR image.

Abstract: A gradient amplifier for use in magnetic resonance imaging equipment employs a low voltage DC power supply connected in series between a pair of higher voltage DC power supplies, the latter supplies serving to provide increased power for rapid gradient switching and the former supply providing correction current to produce the desired voltage output. The high voltage DC power supplies preferably comprise multiple DC units which can be combined to provide finer steps of control prior to correction by the lower voltage supply. The low voltage DC power supply preferably comprise one or more linear amplifiers connected in series, or one or more switchmode amplifiers connected in series. The DC power supplies are controlled in an open loop manner from a gradient signal that designates the desired current for the gradient coil and the amplifiers are operated in a closed loop responding to to a feedback signal from the gradient coil.

Abstract: An in-situ method of extracting oil from a hydrocarbon bearing layer such as oil-shale or tar sands lying beneath a surface layer comprises applying a radiofrequency excitation signal to the hydrocarbon bearing layer through a system of electrodes. The electrodes are inserted into a matrix of holes drilled through the surface layer and into the hydrocarbon bearing layer. A coaxial line extending through the surface layer is connected to the electrodes extending into the hydrocarbon bearing layer. The electrodes have a length that is an integral number of quarter wavelengths of the radiofrequency energy. A matching network connected between the coaxial cable and a respective one of the electrodes maximizes the power flow into each electrode. The electrodes are excited uniformly in rows and as a "balanced-line" RF array where adjacent rows of electrodes are 180.degree. out of phase.