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Dielectrics and Electrical Insulation, IEEE Transactions on

Issue 4 • Date August 2009

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Displaying Results 1 - 25 of 48
  • IEEE Transactions on Dielectrics and Electrical Insulation [Front cover]

    Publication Year: 2009 , Page(s): c1
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    Freely Available from IEEE
  • IEEE Transactions on Dielectrics and Electrical Insulation [Staff]

    Publication Year: 2009 , Page(s): c2
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    Freely Available from IEEE
  • Power modulators and repetitive pulsed power - [editorial]

    Publication Year: 2009 , Page(s): 917
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (109 KB) |  | HTML iconHTML  

    Some of the 31 papers in this special issue are the extended, expanded, and revised versions of the presentations of the 2008 International Power Modulator Conference (IPMC) which was held in Las Vegas, USA during May 27-31, 2008 while the other papers are not, but within the general interest of the special issue topics submitted as a result of "Call-for-Papers" announcements placed in several publications and on the web. View full abstract»

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  • An efficient, repetitive nanosecond pulsed power generator with ten synchronized spark gap switches

    Publication Year: 2009 , Page(s): 918 - 925
    Cited by:  Papers (4)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1876 KB) |  | HTML iconHTML  

    This paper describes an efficient, repetitive nanosecond pulsed power generator using a transmission-line-transformer (TLT) based multiple-switch technology. Within this setup, a 10-stage TLT and ten high-pressure spark-gap switches are adopted. At the input side, ten spark-gap switches are interconnected in series via the TLT, so that all the spark-gap switches can be synchronized automatically. At the output side, all the stages of the TLT are connected in parallel, thus a low output impedance (5 ¿) is obtained, and a large output current is realized by adding the currents through all the switches. Experimental results show that 10 spark-gap switches can be synchronized within about 10 ns. The system has been successfully demonstrated at repetition rates up to 300 pps (Pulses Per Second). Pulses with a rise-time of about 11 ns, a pulse width of about 55 ns, an energy of 9-24 J per pulse, a peak power of 300-810 MW, a peak voltage of 40-77 kV, and a peak current of 6-11 kA have been achieved with an energy conversion efficiency of 93-98%. View full abstract»

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  • Dielectric heating in insulating materials subjected to voltage waveforms with high harmonic content

    Publication Year: 2009 , Page(s): 926 - 933
    Cited by:  Papers (9)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (2455 KB) |  | HTML iconHTML  

    Dielectric heating is one potential aging mechanism active below partial discharge inception voltage in materials used as high voltage insulation. When exposed to voltage waveforms containing high amount of harmonics, the heat generation will be larger due to increased power losses as compared with power frequency excitation. This may result in a decreased life or even failure of insulation due to the increased operating temperature or to thermal runaway. An analysis of the power developed due to dielectric heating in two different materials subjected to voltage waveforms with high harmonic content is presented in this paper. By expressing the non-sinusoidal loss as an enhancement factor to the sinusoidal one, a geometry-independent formalism is derived. From dielectric response measurements at low voltage and at several temperatures the dielectric power loss in the material can be calculated for different voltage levels and waveforms. Two important material parameters can be extracted from the calculated dielectric power loss: (i) non-sinusoidal loss compared with sinusoidal loss with the same fundamental frequency (pfact) and (ii) change of loss with changing temperature (dpfact/dT). These two parameters could potentially be used to indicate the suitability of materials for use in applications where voltage waveforms contain high harmonic content. View full abstract»

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  • Nano-enabled metal oxide varistors

    Publication Year: 2009 , Page(s): 934 - 939
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    Zinc oxide based metal oxide varistors (MOV) are widely used electrical surge protection components. The design of modern high power, high-density electronic systems necessitate the need for smaller footprint, higher current density and higher nonlinearity MOVs. Such requirements can no longer be satisfied by commercially available MOVs due to their limited voltage capability, high leakage current and mechanical cracking related reliability issues, most of which are associated with the presence of defects and coarse granularity and lack of uniformity in their microstructures. New formulations and processes have been developed to overcome such limitations. This work has developed nano-enabled MOV compositions that can be sintered at relatively lower temperatures than typical commercial MOVs, but with largely improved I-V characteristics due to refined and uniform sub-micron structures. These nano-enabled MOVs show not only high breakdown strength (1.5 kV/mm) with low leakage current, but also a large nonlinear alpha coefficient > 50 at high fields, a measure of the speed of the transition from the insulating to conducting state and the effectiveness of over-voltage protection. A > 10x increase in breakdown strength compared to commercial MOVs, along with much higher nonlinearity, will enable MOV miniaturization, high voltage surge protection, and open up new areas of application. View full abstract»

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  • Design and control of an active reset circuit for pulse transformers

    Publication Year: 2009 , Page(s): 940 - 947
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (962 KB) |  | HTML iconHTML  

    In pulse modulators applying pulse transformers reset circuits are used to achieve optimal utilization of the core material, which results in lower costs, downsized pulse transformer/system volume and therefore in an improved pulse behavior due to the smaller parasitics. Because of its simplicity the most common method to reset the core is a DC reset circuit, where a DC current is used to premagnetize the core. However, the DC reset circuit - even with an optimal design-leads to significant losses in the freewheeling path. By applying an active reset method the losses due to the passive reset circuit can be reduced significantly. So far, only the theoretical behavior of the active reset circuit has been examined. Therefore, the detailed design and measurement results are presented in this paper. Furthermore, a new control method for achieving symmetrical flux swings in the core is presented. View full abstract»

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  • A corona-stabilised plasma closing switch

    Publication Year: 2009 , Page(s): 948 - 955
    Cited by:  Papers (7)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1706 KB) |  | HTML iconHTML  

    Corona-stabilised plasma closing switches, filled with electronegative gases such as SF6 and air, have been used in pulsed-power applications as repetitive switching devices for the last 10 years. Their high repetition-rate capabilities coupled with their relatively simple design and construction have made them suitable alternatives to thyratrons and semi-conductor switches. As well as having repetitive switching capabilities, corona-stabilised plasma closing switches have the potential to operate at elevated voltages through the incorporation of multiple electrode sets. This allows high-voltage operation with inherent voltage grading between the electrodes. A further feature of such switches is that they can have relatively low jitter under triggered condition. This paper reports on some of the operational features of a new design of corona-stabilised, cascade switch that utilises air as the insulating gas. At pressures between 0 and 1 bar gauge the switch has be shown to operate over the voltage range of 40 to 100 kV with a jitter below 2 ns. View full abstract»

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  • Study of laser target triggering for spark gap switches

    Publication Year: 2009 , Page(s): 956 - 960
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (636 KB) |  | HTML iconHTML  

    The use of laser targets as a method to decrease the required laser energy to trigger a laser triggered gas switch has been investigated at the University of Missouri. Target materials were identified based on durability, melting point, reactivity and reflection coefficient. Laser targets were placed into a cathode of a laser triggered gas switch. The switch was pulse charged by the Tiger pulsed power machine to between 185 kV and 330 kV. The switch was triggered by directing a 1064 nm or 266 nm wavelength laser pulse from an Nd:YAG laser onto a laser target to ablate material and create plasma, closing the switch. The goal of the project was to trigger a high voltage gas switch with less than 1 mJ of laser energy while maintaining a switch jitter comparable to present electrically triggered switches for LTD based systems. The study successfully demonstrated that triggering the switch using a 1 mJ infrared pulse and a graphite target resulted in a jitter less than 5 ns. Findings will be used in the design of switches for LTD based systems. View full abstract»

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  • MAGIC3D simulation of an ultra-compact, highly efficient, and high-power reltron tube

    Publication Year: 2009 , Page(s): 961 - 966
    Cited by:  Papers (1)
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    In this paper, we use a three dimensional particle-in-cell (PIC) code, MAGIC3D, to investigate the operating characteristics of an ultra-compact, high power reltron tube with self-modulation beam and post-acceleration of modulated beam. The simulation model is a full 3D model because the reltron is intrinsically a three-dimensional problem due to the asymmetrical geometry of the modulating cavity. In the reltron, the mode of operation is ¿/2-mode, providing the means to modulate an electron beam in short distances. Simulations show that ultra-compact reltron with a beam voltage of 120 kV and an acceleration voltage of 800 kV generates 38.3 MW high power microwave at 2.887 GHz with an electronic efficiency of 52.7%. View full abstract»

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  • Hybrid MOSFET/driver for ultra-fast switching

    Publication Year: 2009 , Page(s): 967 - 970
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (865 KB) |  | HTML iconHTML  

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

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  • Optimization of a low jitter, 50 kV, 100 Hz triggered spark gap with high pressure gas mixtures

    Publication Year: 2009 , Page(s): 971 - 978
    Cited by:  Papers (5)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (2662 KB) |  | HTML iconHTML  

    Recent research efforts at Texas Tech University on impulse antenna phased array has needed to develop a reliable high voltage, high repetition rate switch that will operate with ultra low jitter. An ideal jitter of a small fraction of the risetime is required to accurately synchronize the array to steer and preserve the risetime of the radiated pulse. In, we showed the initial test system with sub-ns results for operations in different gases and gas mixtures. This paper discusses in detail 50 kV, 100 Hz switch operations with different gases. The effects of gases and gas mixtures have on switch performance which includes recovery rate and in particular jitter will be investigated. Gases tested include, dry air, H2, N2, and SF6, as well as H2-N2, and N2-SF6 gas mixtures. Switch jitter as a result of triggering conditions is discussed, also including a comprehensive evaluation of jitter as a function of formative delay in the various gases. The temperature of gas and its effects on switch jitter is also documented in this paper. A 50 ¿, 1 nF pulse forming line is charged to 50 kV and provides the low inductance voltage source to test the different gases. Triggering is provided by a solid state opening switch voltage source that supplies ~150 kV, 10 ns risetime pulses at a rep rate up to 100 Hz in burst mode. A hermetically sealed spark gap with a Kel-F-PCTFE (polychlorotrifluoroethylene) lining is used to house the switch and high pressure gas. View full abstract»

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  • Research on applications of TVS and thyristor in a pulsed power supply system used for EMG

    Publication Year: 2009 , Page(s): 979 - 984
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1246 KB) |  | HTML iconHTML  

    A compact pulsed power supply (PPS) system is important for the electromagnetic gun (EMG) system, which should supply high energy and large current. The paper presents the setup of compact PPS system based on high energy density capacitors. The PPS system includes ten 50 kJ modules, which can be triggered in sequence. Each module is composed of a capacitor (1000 ¿F/10 kV), a pulse shaping inductor (20 ¿H), a crowbar diodes with a crowbar resistor(30 m¿), as well as a main switch which can be a triggered vacuum switch (TVS) or thyristors. The peak value of the output current of each module is 70 kA. Characteristics of the TVS and thyristors are comparatively studied to determine their influence on the output current and energy. The requirements for the diode-stacks of the crowbar are fast-recovery, high voltage withstanding. A proper protection measure is used in order to protect the crowbar diodes from the damage of over-voltage when switch is fired. In the end, the overall discharge currents of the PPS triggered in sequence are presented. View full abstract»

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  • Characterization of polymeric insulators using thermal and UV imaging under laboratory conditions

    Publication Year: 2009 , Page(s): 985 - 992
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1848 KB) |  | HTML iconHTML  

    This paper presents an efficient monitoring methodology for polymeric insulators. The experiments allow that the correlation of internal and external temperatures of the insulators be implemented. Clean and polluted insulators were also inspected with infrared and ultraviolet cameras, and the influence of well dimensioned corona rings under polluted conditions was evaluated. The electrical behavior of the insulators and corona rings was estimated in simulations using the Finite Element Method. View full abstract»

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  • Quantum efficiency measurements of photocathode candidates for back-lighted thyratrons

    Publication Year: 2009 , Page(s): 993 - 998
    Cited by:  Papers (4)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (385 KB) |  | HTML iconHTML  

    Light-activated pseudospark switches, also called back-lighted thyratrons (BLTs), are low pressure, high voltage (typ. 10-50 kV), high current (typ. 1-100 kA) glow-mode switches. It is of interest to develop BLTs with reliable and practical optical triggering systems for applications of compact pulsed power. This paper reports the results of research into photocathode materials for BLTs to enhance switching performance and provide optimal cathode conditions for optical triggering. Effective photocathode materials have many specific qualities, the most important being low work function, high quantum yield, and long lifetime at typical BLT operation pressures of 1.3-133 Pa (0.01-1 Torr). Photoemission measurements were conducted with 266 nm, 5 ns laser pulses in a pressure range from 4 × 10-5- 13.3 Pa (3 × 10-7 to 0.1 Torr) using helium as the background gas. Quantum efficiencies up to 1.5 × 10-5, 1.4 × 10-5, and 1.2 × 10-5 were measured for magnesium, copper, and molybdenum samples, respectively. An increase in gas pressure 4 × 10-5- 13.3 Pa (3 × 10-7 to 0.1 Torr) corresponded to an increase in quantum efficiency (QE) of 13% for magnesium and copper; the same increase in pressure corresponded to a quantum efficiency decrease of 10% for molybdenum. Square root of quantum efficiency shows a linear dependence on the square root of the sample surface's electric field due to the Schottky effect. 2D electrostatic simulation of the electric field distribution in a typical compact BLT shows that the field strengths are up to hundreds of kV/cm near the surfaces of the electrodes when a voltage potential of 30 kV is applied between the electrodes. This indicates that higher photoelectron yields can be expected when the tested photocathodes are implemented into BLTs. View full abstract»

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  • Effects of laser triggering parameters on runtime and jitter of a gas switch

    Publication Year: 2009 , Page(s): 999 - 1005
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (2237 KB) |  | HTML iconHTML  

    Parameters affecting the runtime and jitter of a laser triggered gas switch have been studied. Experiments tested a variety of switch parameters including percentage of selfbreak and switch pressure. The effects of laser beam parameters were also considered, including focal length, laser energy, laser spark length, and laser wavelength. Experiments were performed on the Tiger pulsed power machine. Measurements were taken on a spark gap switch built from the trigger section of a Rimfire switch. A Marx bank consisting of 32, 3.1 uF, capacitors that fed into a 7 nF intermediate storage capacitor was used to drive the switch into a 4 ¿ resistive load. The test switch was pressurized to 306 kPa (30 psig) with SF6 and operated near 1 MV. A New Wave Tempest Nd:YAG laser was used to trigger breakdown of the switch. The laser was focused at the mid-gap between the switch electrodes using lenses with focal lengths between 30 cm and 100 cm. Focused laser energy in the switch ranged from <5 mJ to 80 mJ. The effects of switch and laser beam parameters on the runtime and jitter of a laser triggered gas switch are presented. The end goal of the research is to determine optimal conditions for improved switch performance. View full abstract»

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  • Development of solid state pulse power modulator using toroidal amorphous core

    Publication Year: 2009 , Page(s): 1006 - 1010
    Cited by:  Papers (6)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1437 KB) |  | HTML iconHTML  

    This paper discusses the experiments conducted for the development of 50 kV, 10 A, 10 mus duration, and rise time of 2 mus solid state pulse power modulator using toroidal amorphous steel core and low cost IGBT switches. The experiments revealed (i) the need for new design methodologies based on energy transfer between the electrical and magnetic systems and (ii) the success of low-cost switching circuit. View full abstract»

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  • Photoconductive switch design for microwave applications

    Publication Year: 2009 , Page(s): 1011 - 1019
    Cited by:  Papers (6)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (345 KB) |  | HTML iconHTML  

    A procedure for choosing the dimensions of a photoconductive semiconductor switch (PCSS) for operation at microwave switching frequencies, and particularly at 10.0 GHZ, is described. The critical dimension is the switch length (electrode separation), which must be small enough to force photoinduced charge removal during switch turn-off via sweep out rather than recombination. The switch depth in the direction of turn-on optical pulse absorption must be several optical absorption depths long to ensure absorption of all the incident light, which optimizes optical to electrical signal gain. The switch width is determined in conjunction with the peak intensity of the optical pulse because the switch width-optical intensity product, which represents optical power, determines the turn-on time, the on-state switch resistance and the turn-off delay time. Simulations show that a switch with a 0.5 ¿m length, 5.0 ¿m depth, and 20 ¿m width, illuminated with 1.0 W peak power optical pulses at 10 GHz, will have a 4.8 ps turn-on time, a 0.23 ¿ on-state resistance, and a 46 ps turn-off time. View full abstract»

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  • Double-stage gate drive circuit for parallel connected IGBT modules

    Publication Year: 2009 , Page(s): 1020 - 1027
    Cited by:  Papers (4)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1583 KB) |  | HTML iconHTML  

    Solid state modulators are increasingly being used in pulsed power applications. In these applications IGBT modules must often be connected in parallel due to their limited power capacity. In a previous paper, we introduced a control method for balancing the currents in the IGBTs. In this paper, we investigate techniques to minimize the modules' rise and fall times, which can positively impact the modulator's output pulse parameters, which in turn must meet the application's specifications. Further, a reduction in rise and fall times lowers switching losses and thus increases the modulator's efficiency. To reduce the voltage rise time of the pulse without increasing the maximal over-voltage of the parallel IGBTs we have investigated a double-stage gate driver with protection circuits to avoid over-voltages and over-currents. Additionally voltage edge detection has been implemented to improve current balancing. Our measurement results reveal the dependency of the rise-time and turnoff losses on the design parameters of the gate drive. We show that our design achieves a 62% reduction in the turn-off rise time, and a 32% reduction in the turn-off losses. View full abstract»

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  • Surface flashover of oil-immersed dielectric materials in uniform and non-uniform fields

    Publication Year: 2009 , Page(s): 1028 - 1036
    Cited by:  Papers (7)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (751 KB) |  | HTML iconHTML  

    The applied electrical fields required to initiate surface flashover of different types of dielectric material immersed in insulating oil have been investigated, by applying impulses of increasing peak voltage until surface flashover occurred. The behavior of the materials in repeatedly over-volted gaps was also analyzed in terms of breakdown mode (some bulk sample breakdown behaviour was witnessed in this regime), time to breakdown, and breakdown voltage. Cylindrical samples of polypropylene, low-density polyethylene, ultra-high molecular weight polyethylene, and Rexolite, were held between two electrodes immersed in insulating oil, and subjected to average applied electrical fields up to 870 kV/cm. Tests were performed in both uniform- and nonuniform- fields, and with different sample topologies. In applied field measurements, polypropylene required the highest levels of average applied field to initiate flashover in all electrode configurations tested, settling at ~600 kV/cm in uniform fields, and ~325 kV/cm in non-uniform fields. In over-volted point-plane gaps, ultra-high molecular weight polyethylene exhibited the longest pre-breakdown delay times. The results will provide comparative data for system designers for the appropriate choice of dielectric materials to act as insulators for high-voltage, pulsed-power machines. View full abstract»

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  • Generalized solid-state marx modulator topology

    Publication Year: 2009 , Page(s): 1037 - 1042
    Cited by:  Papers (15)  |  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (483 KB) |  | HTML iconHTML  

    A generalized circuit topology for bipolar or unipolar high voltage repetitive pulse power applications is proposed. This circuit merges the negative and positive solid state Marx modulator concepts, which take advantage of the intensive use of semiconductor devices to increase the performance of the original dissipative Marx modulators. The flexibility of the proposed modular circuit enables the operation with negative and/or positive pulses, selectable duty cycles, frequencies and relaxation times between the positive and negative pulse. Additionally, the switching topology enables the discharge of the parasitic capacitances after each pulse, allowing the use of capacitive loads, and the clamping of inductive loads, recovering the reset energy back to the main capacitors. Analysis of efficiency and power loss will be addressed, as well as experimental details for different conditions based on laboratory prototype, with 1200 volt Insulated Gate Bipolar Transistors (IGBT), diodes, and 4.5 muF capacitors. View full abstract»

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  • An ultra compact back-lighted thyratron for nanosecond switching applications

    Publication Year: 2009 , Page(s): 1043 - 1047
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (547 KB) |  | HTML iconHTML  

    An ultra-compact back-lighted thyratron (BLT), which is also named as mini-BLT, with effective volume of 15 cm3 was developed to serve as a high voltage switch in compact transient plasma ignition systems. The mini-BLT can hold off 40 kV and was used to conduct a peak current up to 4.5 kA. A 30 ns switching delay with 2 ns jitter was achieved when triggered by a 70 mJ, 355 nm laser pulse. Delay and jitter increase as the photon energy of the trigger pulse decreases. The plasma density in the switch measured at a peak current of 3.2 kA is 9×1014cm-3. The mini-BLT was successfully used as the switch in a 100 ns, 60 kV pulse generator for generation of streamers in a plasma ignition system. View full abstract»

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  • A linear, single-stage, nanosecond pulse generator for delivering intense electric fields to biological loads

    Publication Year: 2009 , Page(s): 1048 - 1054
    Cited by:  Papers (20)  |  Patents (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (816 KB) |  | HTML iconHTML  

    A compact pulse generator capable of producing high voltage pulses with halfmaximum widths as short as 2.5 ns and amplitudes as high as 5 kV has been developed to enable current and future in vivo and in vitro research into the effects of ultra-short, intense electric fields on biological matter. This pulse generator is small, simple, and free of saturable magnetic cores, which frequently introduce amplitude jitter and an undesirable correlation between amplitude and pulse width. In place of a non-linear pulse-forming network is a single-stage resonant network that drives a bank of junction recovery diodes. The diodes function as an opening switch that commutes current from an inductor to a resistive load. The use of air-core inductors in the resonant network results in a stable output pulse with an amplitude that scales linearly with input voltage and a pulse width that is independent of amplitude. The ability to scale the output amplitude independently of the pulse width simplifies the setup for experiments that require pulses with different electric field strengths but the same rise time and duration. Jurkat T lymphoblast cells exposed to 2.5 ns fields produced by this pulse generator showed an increasing degree of electropermeabilization with increasing pulse dosage and electric field intensity. View full abstract»

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  • Redesign of the SNS modulator H-bridge for utilization of press-pack IGBTs

    Publication Year: 2009 , Page(s): 1055 - 1060
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (2511 KB) |  | HTML iconHTML  

    The Power Systems Development group at SLAC has developed an improved design for the H-bridge switch plates of the High Voltage Converter Modulators at the Spallation Neutron Source. This integral modulator component has been identified as the source of numerous modulator faults. This paper presents the design and implementation of the alternative switch plate, which is based upon press-pack IGBTs. View full abstract»

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  • Large area pulsed corona discharge in water for disinfection and pollution control

    Publication Year: 2009 , Page(s): 1061 - 1065
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1134 KB) |  | HTML iconHTML  

    To investigate the efficiency of submerged pulse corona (SPC) discharges in water we built a laboratory scale, parallel-plate reactor that is part of a closed loop water circulation system. A pulsed voltage is applied across the electrodes. One of the electrodes is coated with a porous ceramic layer to create local field enhancements to initiate corona discharges. For energization of the SPC reactor a pulse generator was developed which is based on a capacitor discharge initiated by a semiconductor switch. A pulse transformer, followed by two magnetic pulse compression stages, produces voltage pulses with amplitudes of up to 30 kV at a pulse width of 0.3 ¿s. Simulation of the circuit behavior leads to good agreement with voltage and current measurements. Details of the pulse generator and first experimental results concerning the efficiency of radical production are presented. Depending on the conductivity of the water to be treated, pulse currents of > 600 A at a voltage of 20 kV to > 30 kV are obtained for electrode sizes of around 50 cm2. The efficiency of the radical production is measured in terms of the hydrogen peroxide (H2O2) concentration, which is formed by recombination of hydroxyl radicals (OH.) at sufficiently high concentrations downstream of the plasma reactor. At pulse repetition rates of 20 to 100 Hz, H2O2 concentrations of several mg/l are produced, at efficiencies in the range of up to ¿1 g/kWh. View full abstract»

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Aims & Scope

IEEE Transactions on Dielectrics and Electrical Insulation contains topics concerned with dielectric phenomena and measurements with development and characterization of gaseous, vacuum, liquid and solid electrical insulating materials and systems.

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Meet Our Editors

Editor-in-Chief
Reuben Hackam