Showing papers on "Insulator (electricity) published in 1997"

High voltage pulsed electric field treatment chambers for the preservation of liquid food products

Abstract: A pulsed electric field treatment device for the sterilization and preservation of pumpable food products having at least two electrodes (201, 203) and an insulator (202) and particularly suited for the inactivation of vegetative and bacterial spore micro-organisms. Each electrode includes an electrode flow chamber (207, 208) for making electrical contact with the pumpable food product and for allowing the pumpable food product to flow through the treatment devices. The insulator (202) is situated between the electrodes (201, 203) and includes an insulator flow chamber (206) positioned between the electrode flow chambers (207, 208) and provides for the flow of pumpable food product from one electrode flow chamber to the other. A high voltage pulse generator (107) applies a high voltage signal of variable voltage, frequency and pulse duration to the electrodes. The electrode and insulator flow chambers may employ a variety of sectional and cross-sectional geometries including tubular, cylindrical, rectangular, elliptical and non-uniform design.

Insulated gate semiconductor device

Abstract: In a semiconductor device having a trench type insulated gate structure, in the case where a drift layer (2) of an n- conduction type has a high carrier concentration, when a high voltage is applied between a drain and a source in such a manner that a channel is not formed, the electric field strength of an insulator layer (9) below the trench type insulated gate is increased, thus causing breakdown The withstand voltage of the semiconductor device is limited by the breakdown of the insulator layer (9), and it is difficult to realize high withstand voltage Thus, a field relaxation semiconductor region (1) of a conduction type opposite to the conduction type of the drift layer (2) is formed within the drift layer (2) below the insulator layer (9) in the trench of the trench type insulated gate semiconductor device Also, the thickness of a bottom portion of the insulator layer (9) provided in the trench of the trench type insulated gate semiconductor device is made significantly greater than the thickness of a lateral portion thereof

Method and device for electro microsurgery in a physiological liquid environment

Abstract: A method and device for electrical emulation of pulsed laser is disclosed. The device utilizes high voltage electrical discharges of sub-microsecond duration in a liquid medium to produce cavitation bubbles of sub-millimeter size for use in high speed precision cutting. Such bubbles are produced by a micro-electrode (1.6) having a central wire having a diameter of 1 microns to 100 microns embedded in an insulator. A coaxial electrode (1.9) surrounds the insulator, and may be spaced from the outer surface of the insulator to provide a path for removing tissue.

Modeling of the ac arc discharge on ice surfaces. Discussion. Authors' reply

Abstract: A model for predicting the flashover voltage of ice-covered insulators energized with ac voltage is presented in this paper. The model takes into account the variation of ice surface conductivity as a function of freezing water conductivity. The effects of the length of the arc on its own characteristics, as well as the ac arc reignition condition, were determined in a laboratory investigation using triangular ice samples. The model is applied to a short string of 5 IEEE standard insulator units. There is an excellent concordance between the 50% flashover voltage calculated from the mathematical model and the experimental results.

Modeling of the AC ARC Discharge on Ice Surfaces

Abstract: A model for predicting the flashover voltage of ice-covered insulators energized with AC voltage is presented in this paper. The model takes into account the variation of ice surface conductivity as a function of freezing water conductivity. The effects of the length of the arc on its own characteristics, as well as the AC arc reignition condition, were determined in a laboratory investigation using triangular ice samples. The model is applied to a short string of 5 IEEE standard insulator units. There is an excellent concordance between the 50% flashover voltage calculated from the mathematical model and the experimental results.

Low dielectric constant insulator formed by downstream plasma CVD at room temperature using TMS/O2

Abstract: We present an insulator with a dielectric constant lower than 3.0, thermal stability up to 500° C and good gap-filling characteristics. This insulator was formed by downstream plasma chemical vapor deposition (CVD) at room temperature using tetra-methylsilane (TMS)/O2 gases. It contained a large amount of water in the as-deposited state. Annealing at 350° C resulted in a decrease in the water content of the insulator, and the insulator did not absorb water after the annealing. The film is constructed from Si–O and Si–CH3 bonds, which produce a low dielectric constant and high thermal stability.

A new proposal model for flashover of polluted insulators

Abstract: In this paper, the principal pollution flashover models are reviewed and then an impedance criterion for arc propagation is proposed. This criterion differentiates the case in which the arc elongates until total flashover occurs from the case in which the arc stops before it reaches the end of the insulator. It is shown that the Hampton criterion is not a sufficient condition for initiation of the arc. Indeed, the latter can expand, under certain conditions, even if the Hampton criterion is not satisfied. An analytical model allowing one to determine the critical voltage that insulators can withstand is also established. This is based on an energetic balance, an equivalent electrical circuit and the physical characteristics of the arc. The critical voltage, the critical current and the critical arc length for polluted insulators are calculated using the elaborated model. The results so obtained are found to be in accordance with the experimental ones represented by known empirical relations.

Performance and ageing of polymeric insulators

Abstract: Long-term field experiences of ageing and performance of polymeric silicone rubber (SIR) and ethylene-propylene-diene monomer (EPDM) insulators under natural contamination conditions in an outdoor installation are presented. The primary aim of the work is to study the interrelation between surface conditions and the electrical performance of polymeric insulators. In this paper, the leakage current statistics, the hydrophobicity and the surface conditions of six SIR and three EPDM commercially available insulators are studied in detail. The surface conditions were studied using electron spectroscopy for chemical analysis (ESCA), attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy and scanning electron microscopy (SEM). The results show a strong interrelation between the conditions of the insulator surface, especially the hydrophobicity and the performance with respect to leakage currents and voltage withstand.

The influence of surface charge upon flash-over of particle-contaminated insulators in under impulse-voltage conditions

Abstract: This paper presents an experimental investigation of the effect of surface charge upon the impulse flash-over of metallic-particle-contaminated insulators, which were clamped between two parallel planar electrodes, in at 1.0 bar. The results show that the accumulated surface charge greatly affects the impulse flash-over strength of insulators. The influence of the surface charge is closely dependent upon its polarity and density, as well as upon the electrode configuration. For a PTFE cylindrical insulator with a metallic particle in contact with the anode, a 25% reduction in the 50% impulse flash-over voltage occurs when negative charge of peak density about is present. However, with positive charge, the impulse flash-over voltage is not decreased, but increased instead, the enhancement in impulse strength being 21% at . When metal inserts are used to shield the electrode triple junction, charge accumulation on the insulator surface will be predominantly determined by the field normal to the surface. In this case, the accumulated surface charge appears to have little influence upon the impulse flash-over voltage.

Devices for high-frequency electric power applying, plasma generating, and plasma treating; and methods for high-frequency electric power applying, plasma generating, and plasma treating

Abstract: PROBLEM TO BE SOLVED: To generate plasma under the pressure of high-vacuum degree in a plasma treating device, regardless of applied high-frequency electric power, having a high frequency, thereby to accurately perform plasma treating having high uniformity and low damage. SOLUTION: A lower electrode 12, for retaining an object 13 to be treated, is provided via an insulator 11 on the bottom part in a chamber 10a. In a first high-frequency power source 14, high-frequency electric power is applied to a multi-spiral-coil 15A, consisting of four parallely connected spiral coil parts 15a, via an impedance matching apparatus 16A. The length of respective coil portions 15a to one coil is 1/4 of the wavelength of the high-frequency electric power supplied from the first high frequency power source 14. The second high frequency power source 17 applies high-frequency bias voltage to the lower electrode 12. COPYRIGHT: (C)1997,JPO

Printed wiring board and manufacture thereof

Abstract: PROBLEM TO BE SOLVED: To enable manufacturing with cost reduction, without need for long time using a simple manufacturing method, by simultaneously forming a conductor pattern on the surface of an insulator. SOLUTION: An ink-jet unit 7 connected with a personal computer 10 has an ink-jet nozzle 8 which can be slid sideways and longitudinally, and an insulator 9 is placed on a carrier which can carry the insulator 9 in the direction of travel, and both of a conductor pattern and an insulating pattern are formed simultaneously on the surface of the insulator 9 by a jet of ink from a nozzle on the basis of pictorial information data transmitted by the personal computer. When ink to be used is solvent type or heat curing type, the insulator 9 is carried through a heating furnace subsequent to the ink-jet unit 7 for drying solvent or cure binder. This allows manufacturing time to be shorten by simple equipment and method.

Nonlinear fillers in electrical insulation

Abstract: The very low conductivities of modern insulating materials do not permit the dissipation of accumulated space charge. Space charge can therefore persist both within the bulk of an insulator and on its surface for long periods of time. This can lead to regions of intense electric field in the surrounding dielectric, producing localised breakdown resulting in the erosion of surfaces and penetration of the bulk by electrical trees. A nonlinear characteristic has been produced in the conductivity of polyester resin by the introduction of an appropriate quantity of particulate ZnO. The critical filler/resin ratio has been determined above which the insulation resistance is high at low fields but decreases as the electric field increases. Alternative fillers, such as Al/sub 2/O/sub 3/ and SiC, have been incorporated into the resin for comparative purposes and to elucidate the conduction mechanisms. The enhanced conductivity at high fields in ZnO-filled polyester permits the dissipation of accumulated space charge at the extremities of electric tree channels as they impinge on barriers of this material, thereby reducing the local electric field. As a of this phenomenon, tree growth and penetration are inhibited, leading to extended lifetimes.

Method and device for manufacturing an insulative material cellular insulator around a conductor and coaxial cable provided with an insulator of this kind

Abstract: A method of manufacturing an insulative material cellular insulator around a conductor, the insulator having a longitudinal passage in which the conductor is housed and closed cells extending longitudinally and separated from each other by radial walls, includes the following operations: the insulative material in the viscous state is extruded to impart the required shape to it to form the cells, the insulative material shaped in this way is applied to the conductor, and the insulative material is cooled to obtain the insulator. The insulative material is applied to the conductor at a distance from the exit of the shaping device such that the material is drawn down sufficiently for the walls of the cells not to be thinned without pressurizing the cells.

Integrated circuit insulator and method

Abstract: A intermetal level dielectrics with fluorinated (co)polymers of parylene (142) between metal lines (112-120), and vapor deposition method for the (co)polymerization followed by fluorination of the (co)polymers.

Structure to reduce the on-resistance of power transistors

Abstract: A power transistor is disclosed that exhibits increased power capacity, reduced on-resistance and prevents current pinch off. The transistor comprises an insulated gate field-effect transistor and including a gate insulator; a protective region having a first conductivity type adjacent the insulator of the transistor for protecting the insulator from the degrading or breakdown effects of a large voltage applied across the device; and a current-enhancing layer having the opposite conductivity type from the protective region and positioned between the protective region and another first conductivity-type region of the transistor.

Effect of anode and insulator materials on plasma focus sheath (pinch) current

Abstract: Plasma sheath (pinch) current in a low energy (2.2 kJ) plasma focus device was measured fur different anode and insulator materials. Among the anode materials, the highest sheath current was observed with tungsten and the lowest with aluminum. Among the ceramic insulators the maximum plasma sheath current was obtained with quartz and the minimum with alumina. The computed high Z (atomic number) impurities in plasma sheath, however, were least in the plasma focus with alumina insulator. None of the nonceramic (plastic) insulators produced neutrons, as the plasma sheath was nonuniform and was highly contaminated with impurities.

Vacuum insulator coating development

Abstract: The authors discuss the electrical and mechanical requirements for vacuum insulators in high peak power generators To increase the lifetime of these insulators, they have developed a coating called Dendresist This coating has extended the insulator lifetime on the PITHON, DM2, CASINO, and Double-EAGLE pulsed power generators They describe its development, and compare its electrical and mechanical strength to that of other candidate coatings and materials used for vacuum insulators They discuss the mechanism for discharges through the bulk of the insulator ("worm-holes"), and how to eliminate these failures using thicker insulating rings

Spark plug for apparatus for detecting ion current without generating spike-like noise on the ion current

Abstract: In a spark plug having a generally cylindrically shaped metallic body, a generally cylindrically shaped insulator held in the metallic body, a center electrode held in the insulator, and a ground electrode facing the center electrode, the insulator has a ramp portion on an outside surface thereof and the metallic body has a supporting portion for supporting the ramp portion of the insulator. Further, a conductive layer (a protection layer) is formed on the surface of the insulator to face the supporting portion of the metallic body. Accordingly, a corona discharge in a clearance between the supporting portion of the metallic body and the insulator is prevented, so that spike-like noise can be prevented.

High voltage insulator

Abstract: An improved high voltage insulator includes a central core and an insulating body fitted tightly around the central core. A flexible coating layer is interposed between a part of the central core and the insulating body. The flexible coating layer fills in shrinkage cavities and compensates for a retraction effect caused by injected material used in forming the insulating body. The insulating body is overmolded to the central core previously coated with the flexible coating layer with an injected insulating resin such as a thermoplastic or thermosetting resin. The insulator could be used as a capactive divider or bushing insulator.

Integrated circuit insulator and structure using low dielectric insulator material including HSQ and fluorinated oxide

Abstract: An intermetal level dielectric with two different low dielectric constant insulators: one for gap filling (140) within a metal level and the other (150) for between metal levels. Preferred embodiments include HSQ (140) as the gap filling low dielectric constant insulator and fluorinated silicon oxide (150) as the between metal level low dielectric constant insulator.

Thin film transistor suitable for use in an active matrix type display and method of fabricating the same

Abstract: A thin film transistor which can be used in an LCD display panel includes an insulator substrate, a gate electrode located on the insulator substrate, an insulator film provided on the insulator substrate and the gate electrode, and a polycrystalline silicon film located on the insulator film. A channel is defined in a first portion of the polycrystalline silicon film over the gate electrode, and a drain and a source are defined in second and third portions of the polycrystalline silicon film over the insulator substrate. Grain sizes of the drain and source are equal to or greater than a grain size of the channel.

High aspect ratio gated emitter structure, and method of making

Abstract: A high aspect ratio gated emitter structure and a method of making the structure are disclosed. Emitters may be provided in a densely packed array on a support. Two distinct layers of insulator material may surround the emitters. The lower layer of insulator material may be a non-conformally applied spray-on or spin-on insulator. The non-conformal insulator material may pool at the base regions of the emitters so that the tip regions of the emitters extend out of the lower layer of insulator material. The upper layer of insulator material is applied to the lower layer using a conformal process so that the tip regions of the emitters are covered by the upper layer of insulator material. Gate material is applied to the upper layer of insulator material. Holes are provided in the gate material over the tip regions and wells are provided in the upper layer of insulator material surrounding the tip regions. An etch resistant layer may optionally be provided between the upper layer of insulator material and the gate material.

Laser activation and metallisation of insulators

Abstract: An analysis is made of two-stage metallisation of insulator surfaces. Laser ablation of the surfaces of a number of insulators (activation stage) creates, on the irradiated surface, catalytic centres capable of reducing metals (deposition stage) in special solutions. Autocatalytic deposition spreads a metal over the whole ablated surface. A review is given of the experimental data on laser activation of Al2O3, SiC, diamond, ZrO2, and other insulators. Surface activation is observed in a wide range of laser radiation wavelengths and is retained for a long time, which makes it possible to deposit a number of metals (Cu, Ni, Pt, Pd, etc.) with a spatial resolution of the order of several microns. A model of the process is considered: according to this model, laser activation is the result of modification of a band gap of an insulator by ablation and appearance of a nonzero density of the electron states with energies close to the reduction potential of a metal. This in turn may be related to the formation of point defects (for example, F centres in Al2O3 and ZrO2) in an insulator or to band bending in the field of mechanical stresses that remain in the treated material after ablation. Data on the activation of insulators by mechanical indentation are in qualitative agreement with the proposed model.

Semiconductor integrated circuit device

Abstract: PROBLEM TO BE SOLVED: To eliminate insulator capacity formed at a portion exceeding upper and lower ends of each conductor between the conductors and hence reduce capacity between the conductors by providing a cavity exceeding the upper and lower ends of each conductor between the conductors. SOLUTION: A plurality of conductors 12, 13 becoming a second layer are formed on a first interlayer insulating film 11 becoming a first insulating film. A second interlayer insulating film 14 becoming a second insulating film is formed to cover the conductors 12, 13. A cavity 15 having its height exceeding the upper and lower ends of each conductor 12, 13 is provided between the conductors 12, 13. For this, the cavity 15 is formed also on an upper layer part of the first interlayer insulating film 11 and also on a lower layer part of the second interlayer insulating film 14 formed at a location higher than the upper surface of each conductor 12, 13. Thus, a specific inductive capacity between the conductors is reduced and hence capacity between the conductors is reduced.

Polymeric Outdoor Insulators - A Long-term Study

Abstract: The long-term performance and the material state of polymeric insulators were examined from December 1987 to February 1997. To a large extent the study was conducted at Anneberg field station, on the west coast of Sweden. The project comprised a great number of commercially available polymeric insulators from several prominent manufacturers. Each type of insulator was energized with high voltage alternating current (HVAC) as well as high voltage direct current (HVDC). In addition, of each type of insulator two were non-energized: one was exposed to the environment only and one was stored indoors. The silicone rubber (SiR) insulators maintained a high degree of their initial hydrophobicity and with respect to leakage currents performed better than the porcelain insulators. The obtained results show that heavily stressed SiR insulators with specific creepage distances in the order of 8.2 mm/kV to 9.3 mm/kV had leakage currents exceeding 80 mA during a salt-storm in January 1993. However, after that occasion they showed relatively low leakage currents indicating that the SiR has the ability to recover its high surface resistivity and good performance. The measurements indicate that, at light levels of pollution, it is possible to reduce the creepage distance of the SiR insulator compared to that of a ceramic one. Under severe field conditions the ethylene-propylene-diene monomer (EPDM) rubber insulators performed worse with respect to leakage currents and flashovers compared to the porcelain insulators with the same electric stress. Visual observations verified that the surfaces of most of the EPDM rubber insulators had eroded. The surface erosion included cracking and chalking due to environmental exposure and leakage current activity. The material aging of the EPDM rubber resulted in a degraded performance of the insulators under contaminated conditions. In sum, the results suggest that the application of a higher electric stress of the EPDM rubber insulator compared to that prescribed for the ceramic one is not advisable.

High-performance insulator structures for accelerator applications

Abstract: A new, high gradient insulator technology has been developed for accelerator systems. The concept involves the use of alternating layers of conductors and insulators with periods of order 1 mm or less. These structures perform many times better (about 1.5 to 4 times higher breakdown electric field) than conventional insulators in long pulse, short pulse, and alternating polarity applications. We describe our ongoing studies investigating the degradation of the breakdown electric field resulting from alternate fabrication techniques, the effect of gas pressure, the effect of the insulator-to-electrode interface gap spacing, and the performance of the insulator structure under bi-polar stress.

A low-profile high-voltage compact gas switch

Abstract: This paper discusses the development and testing of a low-profile, high-voltage, spark-gap switch designed to be closely coupled with other components into an integrated high-energy pulsed-power source. The switch is designed to operate at 100 kV using SF/sub 6/ gas pressurized to less than 0.7 MPa. The volume of the switch cavity region is less than 1.5 cm/sup 3/, and the field stress along the gas-dielectric interface is as high as 130 kV/cm. The dielectric switch body has a low profile that is only 1-cm tall at its greatest extent and nominally 2-mm thick over most of its area. Field modeling was done to determine the appropriate shape for the highly stressed insulator and electrodes, and special manufacturing techniques were employed to mitigate the usual mechanisms that induce breakdown and failure in solid dielectrics. Static breakdown tests verified that the switch operates satisfactorily at 100 kV levels. The unit has been characterized with different shaped electrodes. Capacitor discharge tests in a low inductance test fixture exhibited peak currents up to 25 kA with characteristic frequencies of the ringdown circuit ranging from 10 to 20 MHz. The ringdown waveforms and scaling of measured parameters agree well with circuit modeling of the switch and test fixture. Repetitive operation has been demonstrated at moderate rep-rates up to 15 Hz, limited by the power supply being used. Preliminary tests to evaluate lifetime of the compact switch assembly have been encouraging.

Switching element and memory element using current and electric field induction phase transition in manganese oxide material

Abstract: PROBLEM TO BE SOLVED: To eliminate the need for operating magnetic field and accordingly, to facilitate the incorporation of a switching element into conventional type electronic circuits, by using the insulator-metal transition induced by the current and electric field of a manganese oxide material basically composed of MnO3 and the antiferromagnetic- ferromagnetic transition accompanying it in forming the switching element. SOLUTION: Voltage is impressed at a specified temp. in a zero magnetic field on the manganese oxide crystalline body, which is basically composed of the MnO3 formed as an antiferromagnetic insulator by charge alignment and is expressed by the general formula R1-x Ax MnO3 indicating rare earth ions as R and alkaline earth ions as A. At this time, the high resistance value of 10 Ω is decreased by voltage impression and is switched to the low resistance state of about 10 Ω by the certain threshold voltage. When the impressed voltage is thereafter decreased, the resistance value restores the initial resistance by exhibiting a hysteresis. Since the charge alignment antiferromagnetic insulator state is easily fused and is transferred to the ferromagnetic metallic phase by the magnetic field, the ease of melting of the charge alignment phase may be controlled if the external magnetic field is used.