Showing papers on "Power density published in 1993"
Patent•
20 Jan 1993
TL;DR: A separable inductive coupler for transferring electrical power across a dielectric medium using magnetic induction was proposed in this article, where the primary and secondary coils are mated, and an extremely low leakage inductance transformer is formed.
Abstract: A separable inductive coupler for transferring electrical power across a dielectric medium using magnetic induction. Its coil geometry allows for easy disassembly of primary and secondary circuits. When primary and secondary coils are mated, an extremely low leakage inductance transformer is formed. This provides for good high frequency operation at high power density. The coupler allows electrical power transfer without metal-to-metal contact. The design allows easy removal of the primary or secondary coil from the transformer. The coil geometry has very low leakage inductance and very low high-frequency resistance which allows high frequency operation. The power transfer density is much higher than previously achieved with separable inductive couplers. Approximately 6000 watts has been transferred through a version of the present separable inductive coupler having a volume of 25.8 cubic inches, yielding a power density of 230 Watts/cubic inch. The coupler is adapted to provide a safe, convenient and weatherproof device for coupling power to a load, such as an electric vehicle to recharge its propulsion battery.
208 citations
TL;DR: In this paper, a novel heat spreading technique was used to regulate internal device currents to avoid the formation of hot spots, and stable high power-density operation can be maintained at multiwatt output power levels.
Abstract: Thermal instability of multi-emitter high-power microwave heterojunction bipolar transistors (HBTs) was eliminated using a novel heat spreading technique that regulates internal device currents to avoid the formation of hot spots. Devices with 2- and 3- mu m minimum emitter sizes and no intentional ballast resistors showed unconditionally stable CW operation up to the device electronic limitations. A record 10-mW/ mu m/sup 2/ power density was obtained at 10 GHz with 7-dB gain and 60% power-added efficiency. The highest efficiency was 67.2% at 9.3-mW/ mu m/sup 2/ power density. It was shown that stable high-power-density operation can be maintained at multiwatt output power levels. >
87 citations
Patent•
03 Jun 1993
TL;DR: A high power lamp which utilizes a lamp fill containing sulfur or selenium, or compounds of these substances, is an electrodeless lamp with a power density in excess of 50 watts/cc.
Abstract: A high power lamp which utilzes a lamp fill containing sulfur or selenium, or compounds of these substances. An electrodeless lamp utilizing such a fill at a pressure at least as high as 1 atmosphere is excited at a power density in excess of 50 watts/cc. An arc lamp utilizing the fill at a pressure at least as high as 1 atmosphere is excited at a power density of at least 60 watts/cm.
72 citations
TL;DR: In this paper, several essential conditions for the long-term stable deposition of highly insulating layers by reactive magnetron sputtering from metal targets are studied, and the defect level of the deposited layers could be reduced by several orders of magnitude compared with layers with a normal magnetron arrangement as a consequence of arc suppression on a microsecond time scale.
Abstract: Several essential conditions for the long-term stable deposition of highly insulating layers by reactive magnetron sputtering from metal targets are studied The following aspects are considered: design of the magnetron and of the deposition arrangement, electric potential of the electrodes surrounding the plasma, position of the gas inlet, appropriate control of the gas inlet, power supply and process stabilization method The defect level of the deposited layers could be reduced by several orders of magnitude compared with layers deposited with a normal magnetron arrangement as a consequence of arc suppression on a microsecond time scale When the magnetron discharge is pulsed at medium frequency (10–200 kHz), the deposition process stabilizes and the arcing tendency is decreased The deposited Al 2 O 3 layers had a maximum thickness of 50 μm The dependences of the deposition rate up to a maximum of 240 nm min -1 and several other film properties ( eg optical and mechanical) on process parameters such as the power density at the target, the reactive gas flow and the discharge voltage were investigated
59 citations
TL;DR: In this paper, single crystals of 3-nitroaniline-2-chloro-4-nitroniline (m.NA-CNA) alloy were grown from the melt and the observed efficiency was 7.7% indicating that a crystal of 1 cm length will produce very high efficiency.
55 citations
Patent•
27 Oct 1993
TL;DR: In this article, the authors applied ultrasonic waves in a frequency range between 15 kilohertz and 10 megahertz to water in a tank with a power density between 15 and 7,000 watts per square centimeter.
Abstract: To provide ultrasonic cleaning of inanimate objects, ultrasonic waves in a frequency range of between 15 kilohertz and 10 megahertz are applied to water (18) in a tank (16) with a power density between 15 and 7,000 watts per square centimeter. Asymmetric power waves are applied to avoid instability leading to transient cavitation. To provide ultrasonic treatment of animals, ultrasonic waves in a frequency range of between 15 kilohertz and 500 kilohertz are applied to water (18) in a tub (16) with a power density between 0.1 and 5 watts per square centimeter. The equipment is able to apply ultrasonic waves with at least two power densities in the vicinity of the portion of the animal with one of said power densities being more than 15 watts per square meter for sterilizing the water before the patient enters the tub and the other being less than 15 watts per square meter.
52 citations
TL;DR: In this paper, the effect of adding Y-stabilized Bi 2 O 3 (YSB) and Y-doped CeO 2 (YDC) layers at the ytria-stable-zirconia (YSZ) electrolyte surfaces was investigated.
48 citations
TL;DR: In this paper, a model was developed to calculate threshold power densities for thermal instability in AlGaAs/GaAs HBT power transistors and the authors provided a dynamic solution for temperature distribution using a three-dimensional model which is very general in its ability to model composite chip cross sections.
Abstract: Simulations of the thermal behavior of AlGaAs/GaAs HBT power transistors have been carried out to establish the quantitative tradeoff between power density, chip layout and junction temperatures. Numerical programs were used to model different aspects of HBT thermal behavior. These programs provide a dynamic solution for temperature distribution using a three-dimensional model which is very general in its ability to model composite chip cross sections. A model was developed to calculate threshold power densities for thermal instability. Standard and novel methods of controlling maximum temperatures in the devices are explored and evaluated. These methods include flip chip bonding and the use of partial vias. The prevention of thermal instability is described. The thermal time constants are found to have a fast component, on order of a few microseconds, and a slower component that depends on substrate thickness. >
48 citations
TL;DR: In this paper, the influence of driving frequency on discharge structure and production efficiency has been investigated over the frequency range from 13.56 MHz to 100 MHz in terms of the relaxation continuum model.
Abstract: The influence of driving frequency on discharge structure and production efficiency has been investigated in Ar over the frequency range from 13.56 MHz to 100 MHz in terms of the relaxation continuum model. Under constant RF voltage, the plasma density increases in proportion to the square of the driving frequency. The net ionization and excitation rates, and the power density, show the same frequency dependence, although the collisional production efficiency per input power density is almost invariant with change of frequency. This has the great advantage for plasma processing and deposition from plasmas that parallel plate discharge in very high frequency (VHF) will lead to the system being rather free from ion damage or effects of confined plasma volume as compared with those in high frequency (HF) and microwave (MW).
42 citations
TL;DR: In this article, a copolymer of 4−2−methacroyloxyethyl methyl methyl amino and methyl methacrylate was tested for optical power handling capability at near-infrared wavelengths.
Abstract: Polymeric nonlinear optical waveguides of a copolymer of 4‐(N’‐2‐methacroyloxyethyl‐N‐ methyl‐amino)‐4’‐nitrostilbene and methyl methacrylate were tested for optical power handling capability at near‐infrared wavelengths. When exposed to about 5×105 W/cm2 optical power density at 1325 nm wavelength laser light, the waveguide showed a rapid decay of optical transmission on the order of about 3 dB/h. Operation of the waveguides in an oxygen‐free environment significantly reduced the decay rate to greater than 0.25 dB/h. The decay was a result of spatially inhomogeneous change of refractive index distributed along the length of the waveguides. Micrographs showing the photoinduced local variations of refractive index and the resulting loss of optical confinement of the waveguides are presented.
42 citations
TL;DR: In this article, the vibrational and rotational-translational (RT) heating and cooling mechanisms in SiH4-H2 radio-frequency (RF) glow discharges are analyzed.
Abstract: The electrical power dissipation and the vibrational (v) and rotational-translational (RT) heating and cooling mechanisms in SiH4-H2 radio-frequency (RF) glow discharges are analysed. Detailed balance of the various contributions leads to determination of the steady state v and RT temperatures TV and TR depending on the discharge geometry, total and partial pressures, wall temperature and power density. In low-power SiH4-dominated discharges (0.1-0.2 Torr range), v excitation is mostly due to low-energy electron-SiH4 collisions, but in high-power discharges, dominated by H2 (0.1-1 Torr), v excitation proceeds via collisional relaxation of hot H atoms and exothermic chemical reactions. v cooling is mostly controlled by v-RT transfer and thermal diffusion to the walls and by electron impact dissociation of v excited molecules. In any case the contribution of spontaneous decomposition highly v excited SiH4 molecules (pyrolysis) remains negligible. The model is tested on various experimental situations and the computed values of TV and TR are in fair agreement with available measurements by IR emission spectroscopy and CARS. It is also shown that the spatial temperature profiles may induce thermophoresis on particulates generated within the discharge.
TL;DR: In this paper, a GaAs/AlGaAs multiple quantum well (MQW) structure was investigated as a coherent detector using a CO2-laser local oscillator (LO).
Abstract: A GaAs/AlGaAs multiple quantum well (MQW) structure has been investigated as a coherent detector using a CO2‐laser local oscillator (LO). At an operating temperature of 77 K, an LO power of 10 mW, an LO wavelength of 10.2 μm, and a bias voltage of 2.0 V, a 150‐μm‐diam detector displayed an external quantum efficiency η0 of 11% and a 3‐dB electrical bandwidth BIF of 1.5 GHz. Under the same conditions the noise‐equivalent power density (NEPHET/Δf) at an intermediate frequency of 1.5 GHz was 5.5×10−19 W/Hz, which is within 50% of the photon‐noise limit for this detector. A 75‐μm‐diam detector with a lower‐capacitance bond wire was found to have a BIF of 8 GHz and an NEPHET/Δf of 4.1×10−19 W/Hz with only 2.5 mW of LO power. The photoelectron lifetime in the MQW structure at 77 K was estimated to be 2.5 ps corresponding to an intrinsic detector bandwidth of 64 GHz.
TL;DR: In this paper, the authors demonstrate low-threshold lasing at 4 K in optically pumped hemispherical In0.2Ga0.8As singlequantum-well microcavities.
Abstract: We demonstrate low‐threshold lasing at 4 K in optically pumped hemispherical In0.2Ga0.8As single‐quantum‐well microcavities. The incident threshold pump power density is 11 kW/cm2 corresponding to an absorbed power density of about 320 W/cm2, and the measured spontaneous emission factor β is about 0.01.
01 Jun 1993-Nuclear Instruments & Methods in Physics Research Section A-accelerators Spectrometers Detectors and Associated Equipment
TL;DR: In this paper, a man-made perfect single crystal isotopically-enriched diamond is demonstrated to be an excellent X-ray monochromator even when subjected to the highest incident power density expected at third-generation synchrotron source undulator beam lines.
Abstract: Man-made perfect single crystal isotopically-enriched diamond is demonstrated to be an excellent X-ray monochromator even when subjected to the highest incident power density expected at third-generation synchrotron source undulator beam lines. Double-crystal rocking curve tests of a diamond (400) wafer exposed to an X-ray power density of 207 W/mm2 (75 W total power) revealed just 1 arc sec of induced thermal distortion integrated across the beam footprint.
TL;DR: In this paper, the maximum possible specific power (specific power availability) that can be obtained from heat engines with a set of high temperature heat source and low temperature sink is analyzed.
TL;DR: In this article, the authors show that the low catastrophic optical damage power density observed for AlGaInP laser diodes (LDs) (1/2 to 1/2.9 that of AlGaAs LDs) is mainly attributable to the high thermal resistivities of the materials.
Abstract: We show that the low catastrophic optical damage power density observed for AlGaInP laser diodes (LDs) (1/2 to 1/2.9 that of AlGaAs LDs) is mainly attributable to the high thermal resistivities of the materials (5.5 times higher than for AlGaAs LDs) by using a thermal runaway model calculation.
TL;DR: In this article, three isomers of diaminocyclohexane (DACH) were deposited on polyethylene, SiO2, and mica at 20°C.
Abstract: Plasma polymers of three isomers of diaminocyclohexane (DACH) were deposited on polyethylene, SiO2, and mica at 20°C. The deposition rate was measured as a function of plasma density and power; a maximum was observed in the latter function. The deposition rate was highest for the monomer with the highest flow rate. The film refractive index was observed to increase with both power density and the degree of fragmentation in the plasma. Film composition was measured by elementary analysis, and was found to be almost identical for each of the three isomers; a mechanism for the polymerization reaction is proposed. The percentage of primary amino groups decreased with increasing power density and with film thickness. Surface force measurements of the thickness and refractive index agreed well with the corresponding ellipsometry values in dry air, and am adhesive force, independent of power density, was measured. When the film was exposed to water vapor, it swelled considerably and the adhesion was determined by capillary forces. Associated with swelling, at high power, was an extremely regular 2-ply rope pattern of protruding material. © 1993 John Wiley & Sons. Inc.
Journal Article•
TL;DR: In this paper, it was shown that the errors in the 2D approximation can be eliminated by modifying the true power density distribution function, which can be viewed as a formal method for decoupling the heat equation from the magneto-fluid dynamic equations.
Abstract: Approximating a 3D heat transfer analysis of a weld with a 2D cross-sectional analysis introduces errors in the computed temperatures. This paper reports a method for evaluating this error. The method consists of computing both the 3D and 2D temperature fields. The error is the difference between these two fields. It is shown that the errors in the 2D approximation can be eliminated by modifying the true power density distribution function. It was this type of modification that enabled previous investigations to obtain accurate results from the 2D analysis in spite of this approximation error. A method for computing the modified power density distribution function is presented. It is shown that modeling the heating effect of the arc by a power density distribution function can be viewed as a formal method for decoupling the heat equation from the magneto-fluid dynamic equations of the arc and weld pool. In particular, it is shown that a unique power density distribution exists for every transient temperature field that can be computed by solving the fully coupled equations of the arc.
TL;DR: In this article, a 400 Hz aircraft power generating system was designed to achieve significant improvements in power density and reliability by using a high-frequency resonant link inverter designed so that all inverter switching occurs under zerovoltage conditions.
Abstract: A 400 Hz aircraft power generating system which has been designed to achieve significant improvements in power density and reliability is introduced. Design targets for this exploratory development program include system (generator-plus-converter) power density of 1 kVA/lb and mean-time-between-failure (MTBF) of 500 h. At the heart of the new variable-speed constant-frequency (VSCF) configuration is a high-frequency resonant link inverter designed so that all inverter switching occurs under zero-voltage conditions. Advantages include minimization of switching losses and significant reductions in power device switching stresses and electromagnetic interference (EMI) generation. Inverter losses are further reduced by using MOS-controlled thyristors (MCTs) as the power switches in order to take advantage of their low forward voltage. A 60 kVA breadboard version of the system has been constructed, and test results which confirm its key performance characteristics are presented. >
TL;DR: In this paper, the authors demonstrate the possibility of tuning the output frequency over a wide spectral region and discuss the frequency-competition processes occurring in the active medium, and demonstrate that a considerable increase in the spectral power density of the line can be achieved by tuning the frequency of a laser working on interband transitions of holes in Ge.
Abstract: Intraresonator frequency selection has made it possible to compress to 0.02 cm−1 the output spectral line of a laser working on interband transitions of holes in Ge. This laser operates in the long-wavelength IR region (50–140 cm−1). There is a considerable increase in the spectral power density of the line. We demonstrate the possibility of tuning the output frequency over a wide spectral region. We discuss the frequency-competition processes occurring in the active medium.
TL;DR: In this article, the photoluminescence (PL) behavior of porous Si was investigated and it was found that the PL intensity rises with time under exposure to continuous laser light at high power densities (≳50 W/cm2).
Abstract: We have investigated the photoluminescence (PL) behavior of porous Si and have found that the PL intensity rises with time under exposure to continuous laser light at high power densities (≳50 W/cm2). Samples exposed to lower power density laser light exhibit the well‐known degradation of its PL intensity. As the power density is raised, the PL intensity increases with time and shows a ‘‘window’’ effect in which the PL intensities will again degrade at higher power density. Micro‐Raman studies were performed on the sample and no apparent change in crystalline structure could be found for differing power densities. We correlate this anomalous PL effect with porous Si samples etched with different HF acid concentrations and show that this effect occurs only for porous Si samples etched with a relatively high acid concentration (≳30%).
Patent•
18 Aug 1993
TL;DR: In this paper, a plasma source, preferably a hollow cathode are source, is arranged in the immediate vicinity of the substrate, and between the source and the substrate there is a device for generating a magnetic field so that the region of high plasma density is separated from the evaporator and the electron beam by the magnetic field.
Abstract: It is known that improved coating properties can be obtained by plasma action in vacuum deposition, especially by vaporization. Substantially higher coating rates can be attained in vapor deposition, but, with high plasma densities, they result in excessive scattering of the electron beam and reduce the power density. According to the invention, a plasma source, preferably a hollow cathode are source, is arranged in the immediate vicinity of the substrate. Between the evaporator and the substrate there is a device for generating a magnetic field so that the region of high plasma density is separated from the evaporator and the electron beam by the magnetic field. The boundary field lines of this magnetic field run along an arc curving with respect to the substrate.
TL;DR: In this paper, the ion-induced secondary electron emission coefficient γ from the SiH4 glow discharge was measured in situ using an electrostatic grid analyzer, and the overall electrical power dissipation does not vary with the gas and wall temperature between 25 and 250°C.
Abstract: The ion‐induced secondary electron emission coefficient γ from the a‐Si:H film deposited from a SiH4 glow discharge is measured in situ using an electrostatic grid analyzer. At low SiH4 pressure and discharge power density, γ≊0.033±0.004 and the overall electrical power dissipation does not vary with the gas and wall temperature between 25 and 250 °C, when the SiH4 molecular density is kept constant. However, the a‐Si:H film deposition rate does depend on the temperature, which reveals the effects of thermally activated gas phase of H and SiH2 radicals arising from SiH4 dissociation.
TL;DR: In this paper, an accurate and comprehensive self-consistent kinetic model is applied to a helium radio frequency discharge which in experiments exhibits an ‘α to γ' transition, and there is good agreement (factor of 2) between the experiment and simulation in plasma density, power density, and current density across two orders of magnitude of the applied voltage.
Abstract: An accurate and comprehensive self‐consistent kinetic model is applied to a helium radio frequency (rf) discharge which in experiments exhibits an ‘‘α to γ’’ transition. The main conclusions are (i) there is good agreement (factor of 2) between the experiment and simulation in plasma density, power density, and current density across two orders of magnitude of the applied voltage. (ii) The bulk electron temperature exhibits a transition from high at low driving voltages to low at high voltages. The low‐voltage regime exhibits a larger bulk electric field in the simulation. (iii) Multistep ionization is important under all conditions studied.
02 Aug 1993
TL;DR: In this paper, the authors used thermal shunt and thermal lens techniques to transfer excess heat out of a multi-emitter power device to reduce the thermal resistance of the device by a factor of 2.5-3.
Abstract: Record power density performance of AlGaAs/GaAs microwave power heterojunction bipolar transistors (HBTs) was accomplished through the use of novel design and fabrication techniques. Thermally-stable operation of HBTs up to their electronic limitation (10 mWspl mu/m/sup 2/ output power density at 10 GHz with 0.6 W CW output power, 7.1 dB gain and 60% PAE) was attained. The design of the HBT was based on a detailed electro-thermal device analysis which revealed the necessity to provide an effective heat transfer path between heat sources in a multi-emitter power device. Excess heat was transferred out of the device using thermal shunt and thermal lens techniques. The thermal resistance of the device was lowered by a factor of 2.5-3 compared to conventional devices. >
TL;DR: In this article, a capacitively coupled transverse radio frequency discharge has been successfully applied to excite a gas-dynamically cooled supersonic CO laser operating at 105 K in a semiclosed gas cycle.
Abstract: A capacitively coupled transverse radio frequency discharge has been successfully applied to excite a gasdynamically cooled supersonic CO laser operating at 105 K in a semiclosed gas cycle. The laser head is characterized by a very compact design and a high discharge power density (160 W/cm3). At a discharge pressure of 390 mbar a maximum laser output of 6 kW is obtained with an efficiency of 12.4%.
10 Oct 1993
TL;DR: In this paper, a pseudomorphic high electron mobility transistor (PHEMT) was demonstrated to achieve 10 W output power, 13.5 dB gain and 63% power-added efficiency on a single 16.8 mm PHEMT device at 2.45 GHz.
Abstract: The authors have simultaneously demonstrated 10 W output power, 13.5 dB gain and 63% power-added efficiency on a single 16.8 mm pseudomorphic high electron mobility transistor (PHEMT) device at 2.45 GHz. This result represents the highest output power from a single transistor at S-band frequencies. The power density exhibited by the PHEMT device was 625 mW/mm which is significantly higher than a typical MESFET power density of 400 mW/mm. >
TL;DR: In this article, the experimental and numerical results of dissipated microwave power distribution in a microwave heating applicator with a water locul were presented, where power density profiles predicted using a finite element model developed previously by the author, were shown to agree well with experimental measurements.
Abstract: This paper presents the experimental and numerical results of dissipated microwave power distribution in a microwave heating applicator with a water locul Power density profiles predicted using a finite element model developed previously by the author, was shown to agree well with experimental measurements. Because of the well defined boundary conditions of the experimental applicator, the experimental results can be used for verifying a wide range of numerical models.
TL;DR: In this paper, a single-stage 20 GHz power amplifier was developed using a double-doped AlInAs-GaInAson-InP HEMT, achieving a saturated output power of more than 560 mW (0.7 W/mm).
Abstract: A single-stage 20-GHz power amplifier was developed using a double-doped AlInAs-GaInAs-on-InP HEMT. Output power of 516 mW (0.645 W/mm) with power-added efficiency of 47.1% and 7.1-dB gain were obtained from an 800- mu m-wide device. The device had a saturated output power of more than 560 mW (0.7 W/mm). This is believed to be the highest combination of output power, power density, gain, and power-added efficiency reported for an InP-based FET at this frequency. >
TL;DR: In this paper, the authors measured the signal gain of a molecular fluorine F2 * laser pumped by a coaxial electron beam in gas mixtures of He/F2 and He/Ne/F 2.
Abstract: The net‐small‐signal gain of a molecular fluorine F2 * laser pumped by a coaxial electron beam has been measured in gas mixtures of He/F2 and He/Ne/F2. A peak net‐small‐signal gain of 0.63 cm−1 has been measured in a mixture of He/Ne/F2 at a pressure of 8 bar and a pumping power density of 13 MW/cm3.