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Power Modulator and High Voltage Conference (IPMHVC), 2010 IEEE International

Date 23-27 May 2010

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Displaying Results 1 - 25 of 190
  • [Title page]

    Publication Year: 2010 , Page(s): 1
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  • [Copyright notice]

    Publication Year: 2010 , Page(s): 1
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  • Preface

    Publication Year: 2010 , Page(s): 1
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  • Table of contents

    Publication Year: 2010 , Page(s): 1
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  • Editorial by the executive committee chair

    Publication Year: 2010 , Page(s): i - ii
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  • High voltage association student excellence Award

    Publication Year: 2010 , Page(s): iii - xxiv
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  • 2010 IEEE IPMHVC proceedings paper index

    Publication Year: 2010 , Page(s): xxv - xliii
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  • The science, technology, and applications of Terawatt-class pulsed power drivers at Sandia National Laboratories

    Publication Year: 2010 , Page(s): 1 - 16
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    There has been significant progress in the past few years in the development and application of Terawatt-class pulsed power generators. Sandia's flagship is the Z facility, which was recently refurbished to improve its energy, power (~100 TWe), reliability, and precision. We are now routinely performing one shot per day, obtaining load currents as high as 26 MA to create high magnetic fields (>; 1000 Tesla) and pressures (10s of Mbar). In a z-pinch configuration, the magnetic pressure (Lorentz Force) supersonically implodes a plasma created from a cylindrical wire array or liner, which at stagnation generates a plasma with energy densities as high as 10 MJ/cm3 and temperatures exceeding 1 keV at 0.1% of solid density. These plasma implosions can produce over 2 MJ of x-ray energy at powers greater than 200 TW for Inertial Confinement Fusion (ICF), radiation hydrodynamics, radiation-material interaction, Inertial Fusion Energy (IFE), and astrophysics experiments. In an alternate configuration, the large magnetic pressure is used to directly drive Isentropic Compression Experiments (ICE) to pressures greater than 6 Mbar or accelerate flyer plates to velocities as high as 45 km/s for equation of state experiments at pressures as high as 20 Mbar. This research and development is performed in collaboration with many other research groups from large laboratories and universities around the world. This paper summarizes research performed with Z and more recently with the refurbished Z facility, advances in high photon-energy radiography, derivative applications of the pulsed power program, and advances in the science of pulsed power that could revolutionize the next generation facilities. View full abstract»

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  • A durable, repetitively pulsed, 200 kV, 4.5 kA, 300 ns solid state pulsed power system

    Publication Year: 2010 , Page(s): 17 - 20
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    A solid state pulser, designed and constructed by PLEX LLC, has been tested at the Naval Research Laboratory. It has achieved more than 11,500,000 continuous shots at 10 pps and generated 200 kV, 4.5 kA, 300 ns pulses, and the standard deviation time jitter of the output voltage was less than ± 1 ns. The pulser consists of a 12 stage Marx, coupled with a 3rd harmonic stage, a main magnetic switch, a compact pulse forming line used as a transit time isolator, and a resistive load. Each Marx stage uses an APP Model S33A compact high voltage switch that is comprised of 12 series connected thyristors. The Marx has an efficiency of 80% based on thermal measurements. View full abstract»

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  • P1-Marx modulator for the ILC

    Publication Year: 2010 , Page(s): 21 - 22
    Cited by:  Papers (4)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (221 KB) |  | HTML iconHTML  

    A first generation prototype, PI, Marx-topology klystron modulator has been developed at the SLAC National Accelerator Laboratory for the International Linear Collider (ILC) project[1]. It is envisioned as a lower cost, smaller footprint, and higher reliability alternative to the present, bouncer-topology, baseline design. The application requires 120 kV (+/-0.5%), 140 A, 1.6 ms pulses at a rate of 5 Hz. The Marx constructs the high voltage pulse by combining, in series, a number of lower voltage cells. The Marx employs solid state elements; IGBTs and diodes, to control the charge, discharge and isolation of the cells. Active compensation of the output is used to achieve the voltage regulation while minimizing the stored energy. The P1-Marx has been integrated into a test stand with a 10 MW L-band klystron, where each is undergoing life testing. A review of the P1-Marx design and its operational history in the L band test stand are presented. View full abstract»

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  • Status update on the second-generation ILC Marx modulator prototype

    Publication Year: 2010 , Page(s): 23 - 26
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (402 KB) |  | HTML iconHTML  

    This paper is a status update of the SLAC P2 Marx. This Marx-topology klystron modulator is a second-generation modulator which builds upon experience gained from the SLAC PI Marx. There are several fundamental differences between these modulators including the correction scheme, bus voltages, and the control system architecture. These differences, along with preliminary experimental results and the schedule for further development, are detailed in this paper. View full abstract»

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  • A Solid State Marx Modulator that can drive a magnetron in a remote location

    Publication Year: 2010 , Page(s): 27 - 29
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1218 KB) |  | HTML iconHTML  

    Most modulators designs can be configured as stand alone or in the hybrid configuration using a pulse transformer to increase its output voltage. The Solid State Marx is no exception. By combining a standard pulse transformer with a Solid State Marx Modulator, the result is a lower cost flexible modulator. The unique features of the Solid State Marx, of variable pulse width, fast adjustable rise times, dynamically controlled amplitude, low output impedance and high reputation rate makes it ideally suitable for most modulator applications. The low output impedance of a Solid State Marx can drive cables that are impedance matched to the load using a pulse transformer. The cables allow the operation of a magnetron or klystron at a considerable distances from the modulator and power source. The unique properties of the Solid State Marx enable the core bias of the pulse transformer and heater supply to be located and controlled at the modulator without additional interconnecting wiring to the pulse transformer and load. The paper will delineate this unique design of the Solid State Hybrid Marx Modulator and its performance for a remotely located magnetron or klystron. View full abstract»

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  • Transient analysis of Silicon Carbide MOSFET switches

    Publication Year: 2010 , Page(s): 30 - 33
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (566 KB) |  | HTML iconHTML  

    This research was conducted to determine the transient performance of Silicon Carbide MOSFET devices. The device under test for these results is a CREE CMF20120D D-MOSFET rated for a blocking voltage of 1200 V and a forward conduction current of 20 A. The first test involves testing the limit of voltage rise time, or the dV/dt of these devices to determine when the device turns itself on. The second test studies the effects of large current pulses, 10x the rated current, on these devices to determine how well these devices are able to handle over current situations. For both of these tests a test bed had to be designed and built. View full abstract»

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  • Carrier lifetime studies of semi-insulating silicon carbide for photoconductive switch applications

    Publication Year: 2010 , Page(s): 34 - 37
    Cited by:  Papers (4)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (431 KB) |  | HTML iconHTML  

    A contactless microwave photoconductivity decay (MPCD) method has been used to measure recombination lifetime and relative conductivity of semi-insulating (SI) silicon carbide (SiC) wafers. A pulsed laser, tunable from 210 nm to 2 μm, has been used to probe above and below band gap photoconductive responses of four SI SiC wafers. The carrier lifetimes were calculated by comparing the reflected microwave signal to the photo response of a fast (<; 300 ps) photodiode. Three vanadium-doped 6H-SiC wafers, with bulk resistivities ranging from 105 Ω-cm to 1011 Ω-cm, and one high purity semi-insulating (HPSI) 4H-SiC wafer (>; 109 Ω-cm) were studied. The photoconductive response of each wafer set is presented. The HPSI wafer demonstrated longer carrier lifetime and improved above band gap photoconductivity compared to the vanadium-doped wafers. The difference in carrier lifetimes are attributed to higher densities of recombination centers (vanadium acceptors) in the 6H-SiC substrates. View full abstract»

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  • Fundamentals for the compounding of nanocomposites to enhance electrical insulation performance

    Publication Year: 2010 , Page(s): 38 - 41
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (381 KB) |  | HTML iconHTML  

    Although it is undeniable that the promise of enhanced dielectric properties through the use of nanotechnology has generated worldwide interest in nanodielectrics in the last decade, study of the experimental literature indicates that there are numerous inconsistencies in the results obtained. In many instances, it is likely that this is due to a lack of quality control during the formulation of this new class of material. By examining several nanocomposite examples, this contribution seeks to shed some light on the likely causes for these inconsistencies. Through the paramount property of dielectric strength, it is confirmed that poor dispersion and/or agglomeration is often the cause of poor material performance. Examples are provided to show how this can be rectified through the use of particle functionalization and compatibilizers, the use of shear in compounding, and the careful control of moisture. However, good dispersion alone is not sufficient since some of the techniques used may also lead to microcavity formation and other undesirable phenomena. The optimization of nanocomposite compounding is intimately connected with the need to quantify the resulting structure. Consequently, the paper includes a brief discussion of the part played by thermogravimetric and thermal analyses as well as the use of the focused ion beam method to supplement scanning electron microscopy as a viable alternative to (the more difficult) transmission electron microscopy for the evaluation of dispersion and percolation. View full abstract»

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  • Novel numerical method for acquiring a geometrical description of nanodielectrics

    Publication Year: 2010 , Page(s): 42 - 44
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (683 KB) |  | HTML iconHTML  

    Nanodielectric electrical insulation has shown promising characteristics in recent years. Potential applications are numerous, ranging from advanced capacitors to optical sensors. To be able to tailor novel materials and determine their full potential, one needs to establish the structure-property-performance relationship in these materials. One such approach is laid out in this study. We have employed a widely used numerical method (the finite element method) to estimate the effective permittivity of an actual binary mixture (a clay-filled nanodielectric) from a two-dimensional transmission electron microscopy image. The obtained effective permittivity was then used to determine the spectral densities for various depolarization factors. We show explicitly that the spectral density resolves the geometrical description in the nanodielectric. As a result, low frequency impedance data can be used as a microscopy technique. We believe that the approach employed here has potential in several fields of science and engineering. View full abstract»

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  • Failure mechanisms of polyimide and perfluoroalkoxy films under high frequency pulses

    Publication Year: 2010 , Page(s): 45 - 50
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (2982 KB) |  | HTML iconHTML  

    Breakdown behaviors of polyimide and perfluoroalkoxy high temperature films under unipolar and bipolar repetitive pulses are investigated. A bipolar 20 kV, 20 kHz pulse generator with fast dV/dt pulse risetime has been designed and built to study the impact of pulse frequency, pulse rise time, and pulse polarity and pulse duty cycles on breakdown strength of these films films. Space charge injection and decay processes are also investigated. Possible failure mechanisms are discussed. View full abstract»

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  • Atmospheric flashover in a symmetric electric field geometry

    Publication Year: 2010 , Page(s): 51 - 54
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (469 KB) |  | HTML iconHTML  

    In an attempt to identify the mechanisms leading to pulsed dielectric surface flashover in atmospheric conditions, surface flashover across a magnesium fluoride (MgF2) window was studied. The electrode configuration and the applied pulsed voltage level were chosen such that the generated electric field was symmetric with respect to the centerline between the electrodes. That is, neither electrode was favored with respect to flashover/breakdown initiation. A semiconductor-switched 32 kV pulse with 140 ns rise time was applied to the 8 mm wide flashover gap in air, nitrogen, and oxygen at atmospheric pressure. Fast voltage and current measurements along with nanosecond imaging revealed four stages of flashover development: (1) Onset of a cathode directed streamer with a charge on the order of 100 pC and traveling with a speed of ~1 mm/ns at a macroscopic field level of ~10 kV/cm associated with a slow current rise (on the order of 10-3 A/ns) temporarily augmented by (2) a 5 ns wide current spike at the moment when the streamer reaches the cathode followed by (3) a cathode directed streamer focused toward the center of the flashover gap with a slow rising current leading to (4) a sharp current rise (on the order of 10 A/ns) reaching roughly a circuit limited 45 A about 20 ns after the return strike meets an anode directed streamer. Although present in all tested gases, the current spike at the end of stage (2) is most different for all three gases and having the greatest impact in air. View full abstract»

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  • Monte Carlo simulation of High Power Microwave surface flashover under UV illumination

    Publication Year: 2010 , Page(s): 55 - 58
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    High Power Microwave (HPM) induced surface flashover is currently being investigated in order to gain a better understanding of the underlying processes involved and reduce the limitations it places on transmittable pulse lengths. The present experimental setup is designed to produce a flashover on the high pressure side of a transmission window without the influence of a triple point. A 2.5 MW magnetron produces a 900 ns pulse at 2.85 GHz with a 50 ns rise time. The experimental setup allows for the control of several parameters including gas pressure, gas composition, and external UV illumination of the window. Diagnostic equipment enables the analysis of incident, reflected, and transmitted power levels with sub-nanosecond resolution. A previously developed Monte Carlo simulation is used to model the processes involved in the flashover discharge formation. This Monte Carlo code is upgraded to account for the occurrence of field induced electron detachment from negative ion clusters within the high field region, >; 10 kV/cm, near the window. The code has also been expanded to include the occurrence of photoelectrons, emitted from the window while under UV illumination. Such illumination of the transmission window was experimentally shown to reduce the time to flashover by over 100 ns in air at 155 torr, and thereby the total pulse energy that can be transmitted. In addition, UV illumination also reduces the variation in flashover delay times from shot to shot, up to 67% in air at 155 torr. The simulation will determine if the observed reductions in delay time and variation can be explained by the addition of initiatory electrons via UV illumination of the surface. View full abstract»

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  • Simulation of DC high-voltage breakdown for angled dielectric insulators including space- and surface-charging effects

    Publication Year: 2010 , Page(s): 59 - 62
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (676 KB) |  | HTML iconHTML  

    This work reports on 2D Particle-In-Cell simulations of DC multipactor breakdown initiated near a presumed triple-point current source. Models for space charge and dielectric charging are included. Common simulation parameters are dielectric insulator angle, gap width, and applied voltage. Breakdown voltage as a function of angle is presented for a presumed triple-point current source. Initial considerations for a self-consistent Fowler-Nordheim current source are discussed. Breakdown in initial experiments was not observed and some possible reasons for this are considered. Current status and plans are outlined. View full abstract»

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  • Refined dielectric breakdown model for crystalline organic insulators: Electro-thermal instability coupled to interband impact ionization

    Publication Year: 2010 , Page(s): 63 - 68
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (477 KB) |  | HTML iconHTML  

    A refined, substantially improved dielectric breakdown model is presented and applied to solution grown, single crystalline alkane type polymeric (n-C36H74) insulator, representing the iso-electronic analog to polyethylene. Illumination of attached electrodes allows controlled generation, injection into and transport of free charge carriers through the insulator. At sufficiently high electric fields, carrier transport is mediated by delocalized states in the conduction and valence band, respectively. At low and moderate fields, charge transport is suppressed by carrier trapping effects. Electric field induced inter-band impact ionization and generation of electron-hole pairs has been identified from these experiments as the dominant carrier multiplication and breakdown triggering mechanism. Critical field magnitudes >; 1.26MV/cm have been recorded for injected electrons and >; 0.8MV/cm for defect electrons. Application of the energy conservation principle, in accord with the solid state band model, allows determination of critical fields from the insulators electronic band-gap, effective mass and mobility of minority charge carriers. The related electrical breakdown feature and associated rapid dynamic temperature evolution has been explored on basis of the electro-thermal heat balance equation, following previous concepts applied to phase transitions. The non-linear differential equation has been solved numerically, using appropriate thermo-physical materials parameters, while considering the dielectric breakdown phenomenon as a singularity of the solution. Thermal and current run-away is due to strong positive electro-thermal feedback, in connection with an initial transient resistive behavior. Very small thermo-physical parameters are attributed to and explain filamentary charge transport. The temporal evolution of temperature and current in the conducting section or filament during the breakdown event exhibits a time scale up to the microsecond range. Sh- - ock wave emission is apparent, since the spatial temperature propagation exceeds the velocity of sound. View full abstract»

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  • Linear Transformer Drivers (LTD) for high voltage, high current rep-rated systems

    Publication Year: 2010 , Page(s): 69 - 74
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1500 KB) |  | HTML iconHTML  

    The Linear Transformer Driver (LTD) technology can provide very compact devices that deliver very fast high current and high voltage pulses. The output pulse rise time and width can be easily tailored to the specific application needs. Trains of large number of high current pulses can be produced with variable inter-pulse separation from nanoseconds to microseconds. Most importantly these devices can be rep-rated to frequencies only limited by the capacitor specifications that usually is 10Hz. To date we have completed the experimental evaluation of two (LTD I, LTD II) 500-kA cavities in both single and rep-rated modes. A larger 1-MA cavity was tested in a single shot mode and in a voltage adder configuration. The first built inductively isolated 1-MA LTD Voltage Adder (IVA) was composed of five cavity connected in series with a vacuum insulated transmission line. It was tested with both resistive and electron diode loads. The experimental results are in excellent agreement with numerical simulations. Experiments with a 1 TW Inductive Voltage Adder (IVA), which includes ten, 1-MA LTD cavities connected in series, are in preparation at Mykonos LTD Laboratory in Sandia National Laboratories, Albuquerque, NM. This time around the Mykonos voltage adder will be built with a transmission line insulated with de-ionized water. In this experimental work we aim to test the advantages of water insulation as compared to self Magnetic Insulated Transmission Line transport (MITL). It is hoped that the vacuum sheath electron current losses will be avoided without any new difficulties caused by the de-ionized water. This voltage adder will be rep-rated at 6 shots per minute. In the present paper we briefly present the LTD cavity architecture, describe the two LTD cavity types built and experimentally tested in single and rep-rated modes and present the design of the first two-cavity water insulated voltage adder with a liquid salt solution resistive load. This is the first step tow- - ards the assembly of a ten-cavity voltage adder of which most of the components are already built and/or fully designed. View full abstract»

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  • Solid-state LTD module using MOSFETs

    Publication Year: 2010 , Page(s): 75 - 78
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (502 KB) |  | HTML iconHTML  

    It is proposed that linear transformer driver (LTD) concept can be applied to compact, repetitive pulsed-power generation. For experimental demonstration, a table-top LTD module has been constructed by using power MOSFETs and film capacitors. It consists of 24 basic circuits and a magnetic core, contained in a cavity case having a diameter of 33 cm and a height of 1 cm. All MOSFETs can be turned on and off synchronously, controlled by a single optic fiber. This LTD module has been tested with operation voltage of 900 V for single shot and 800 V for repetitive operation at 5 kHz, respectively. Near-rectangle waveforms were obtained on resistive load of ~3.2 Ω, with pulse width of ~60 ns, rise-time of ~20 ns, and fall time of ~40 ns. The overall system efficiency was obtained to be ~76%. View full abstract»

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  • Experimental results using micro-ferromagnetic generators

    Publication Year: 2010 , Page(s): 79 - 81
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1069 KB) |  | HTML iconHTML  

    Several series of tests using explosively loaded ferromagnetic generators to drive inductive coils have been summarized into lessons learned and an outline of best practices for building small FMGs will be presented. Most of these FMGs were built using 25mm diameter, commercially available N50 magnets. All of these experiments were conducted at Redstone Arsenal, AL. Loads representative of flux compression stators were built and used. The long time, tens of microseconds, effects on the inductors were also examined. This paper will summarize over seventy tests with techniques used to mitigate skin losses as well as eddy current losses. A first cut at scaling by linear combination of generators is also shown. View full abstract»

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  • Performance of a dual-stage helical flux compression generator under varying background gas and pressure

    Publication Year: 2010 , Page(s): 82 - 85
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (2269 KB) |  | HTML iconHTML  

    Recent efforts at the Center for Pulsed Power and Power Electronics at Texas Tech University have been focused on the development of a compact and explosively driven High Power Microwave, HPM, system. The primary energy source (other than the seed energy source) driving the microwave load in this system is a mid-sized, dual-stage helical flux compression generator, HFCG. The HFCG has a constant stator inner diameter of 7.6 cm, a length of 26 cm, with a working volume of 890 cm3. Testing at the Center has revealed energy gains in the 30's and 40's with output energy levels in the kilo-joules regime into loads of several micro-Henries. Over the last few years, close to one hundred shots have been taken with these generators into various loads consisting of dummy inductive loads, power conditioning systems, and HPM sources. Throughout these tests, the working volume of the HFCG, i.e. the volume in between the wire stator and the explosive-filled aluminum armature, was filled with SF6 at atmospheric pressure. This was primarily done do avoid electrical breakdown in the generator volume during operation, resulting in flux loss. Recent design updates enable pressurizing the generator volume to pressures up to 0.5 MPa, which is needed, for instance, to replace the SF6 with other gases such as air or nitrogen. The performance of the dual-stage HFCG with pressurized working volume (SF6 and N2) is presented in this paper along with an analysis of the maximum electric field amplitude held off in the volume during operation. The design technique to seal the HFCG will also be briefly discussed. View full abstract»

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