Cygnus, a dual-beam x-ray source, supports the Subcritical Experiments Program at the Nevada National Security Site for both Los Alamos and Livermore National laboratories. Since 2004, Cygnus has been successfully fired over 3000 times and refurbishment activities were completed in 2012 and 2016. The major refurbishment in 2016, conducted over a six-month period, will rejuvenate Cygnus...
This paper presents a new type of equivalent circuit of a high-voltage pulse transformer and an accurate method to measure it’s parameters. The new equivalent circuit is obtained from the impedance characteristic curves when the primary and secondary coils are in different states (open circuit or short circuit). In the new equivalent circuit, the distributed capacitance between primary and...
This paper proposes a dual-line closed transition transfer switch (CTTS) and a technique for fault and lifetime self-diagnosis. The proposed system consists of the dual-line CTTS, a closed transition operator, active and inactive channel inspectors that extract the switch characteristics, and a self-diagnosis block for fault and lifetime of the switch using the characteristics. The system...
The dynamical behavior of plasmas is strongly dependent on frequency. At the lowest frequency the plasma is in the regime of magnetohydrodynamics (MHD) and has been the focus of extensive research in fluid plasma modeling in the past few decades. At somewhat higher frequencies, the electrons and ions can move relative to each other, behaving like two charge separated, interpenetrating fluids....
To further the goal of optimized material design for pulsed power components, we aim to achieve a fundamental understanding of the model non linear dielectric material BaTiO3, through concurrent experimental and theoretical study. This effort is intended to lead to improved synthesis and design control, and a validated model to enable material predictions difficult to obtain in controlled...
This paper describes the results of an experimental investigation carried out to compare the contamination performance and surface degradation of outdoor insulators made from different polymeric materials. The tested insulators included silicone rubber (SR), ethylene propylene diene monomer (EPDM) and high-density polyethylene (HPDE), which were used for reference. To replicate typical harsh...
The Dual Beam Radiographic Facility (aka Cygnus) has been operating successfully for over 10 years providing invaluable data for our nation’s stockpile mission. However successful, there have been some failures that may have been predicted, hence eradicated, during an uninterrupted operation phase. This report describes a statistical method to incorporate existing machine diagnostics, such as...
During the last three years, a programme of research into studying the lightning impact on a high peak mountain tower has been undertaken at the SIAME Laboratory. Various diagnostics equipment has been mounted near the tower, such as fast speed cameras to capture the arc propagation and capacitive antennas for electric field measurement.
The present paper presents the design and calibration of...
High current facilities have been used for a wide variety of HEDP experiments, such as fusion energy, radiation-physics, equation-of-state, plasma-physics and astrophysics etc. Linear transformer driver (LTD) is a new technical approach that can deliver fast high current and high voltage pulses with very compact devices. One of the most difficult technical problems encountered in building...
A switch module assembly utilizing a power crowbar circuit and high-pressure plasma closing switch technology has been designed, constructed and tested. The switch module is the central block of a lightning impulse current generator under development, capable of producing a 10/350μs waveform at a peak magnitude in excess of 200kA (W/R = 10MJ/Ω). The circuit consists of two separately charged...
A pulsed power system based on a coaxial switched oscillator was built and tested. The switched oscillator is charged to over 100 kV either by a Marx generator or a PZT-based autonomous power supply. When coupled to a helical antenna, the system generates electromagnetic radiation with a frequency bandwidth centred on 500 MHz.
Pulse power generators have been used in various fields such as environment, biology, agriculture and so on. Therefore, many researchers demand functions such as high power, short pulse, safety, miniaturization, low cost and ease of use. Our research aim to develop a high performance pulse power generator. The generator has ease of use and miniaturization. It is able to output various trigger...
Power cables are exposed to various stresses in their service lifetime due to loading and transient effects that appear in the system. These stresses degrade the insulation in the long term and can even result in premature failure depending on the severity of the deterioration. Electrical treeing is closely related with partial discharge (PD) and in some stages of its growth it can be...
We have developed two advanced designs of a field-distortion air-insulated spark-gap switch that reduce the size of a linear-transformer-driver (LTD) brick. Both designs operate at 200 kV and a peak current of ~50 kA. At these parameters, both achieve a jitter of less than 2 ns and a prefire rate of ~0.1% over 5000 shots. We have reduced the number of switch parts and assembly steps, which has...
Design considerations and initial static charge and transient discharge simulations using COMSOL Multiphysics™ are presented for a stacked set of pulse-forming transmission (T-) line modules charged in parallel and discharged in series. Each module is designed to use a rigid injection-molded dielectric (cast in halves to accommodate the center conductor) with a helical discharge path of...
Traditionally, large-amplitude, fast-rising currents and magnetic fields has been measured with electro-magnetic probes such as Rogowski coils or B-dot probes. Such probes are observed to work satisfactorily for many experimental configurations but the probe to digitizer signal is affected by cabling and cabling elements. Measurements must frequently be made in the presence of significant...
This paper presents the n stage dynamic model generalization for bipolar Marx Generators, during the capacitors charging mode, to estimate the generator pulse repetition rate.
Bipolar Marx Generators are based in modular solid-state switching stages. Their operating principle can be reduced to two operating modes; Mode-I - Capacitors charging and Mode-II – Output pulse forming. In mode I, n...
The most prominent advantage of Brooks-type coil is that it can obtain the highest energy storage density and the resistance of per unit inductance coil is smaller. However, the biggest problem of the Brooks-type coil is that there is a very large fringe field around it. For preventing electromagnetic radiation interference, it is necessary to consider the safety distance between the coil and...
Perfluorinated liquids are attractive for use in high-voltage devices because of their chemical stability under electrical discharges. For applications like liquid spark gaps, the breakdown velocity is an important parameter. In this work, we present the results of measurements of the anode-initiated electrical breakdown velocity at 140 kV in perfluorinated liquids of several chemical classes....
A new architecture of high voltage pulse generator has been proposed. It is based on combining two types of switches’ technologies, namely IGBT used as opening switch and spark gap used as closing one, and two types of energy storage, Inductive and capacitive, in order to get a compromise with a better performances dedicated especially for embedded applications.
This new architecture has...
References [1-3] studied contactless skin-effect opening switches (SEOS) in combination with semi-conductor opening switches (SOS) and plasma opening switches (POS). This paper proposes to review in greater detail one of these combinations: a SEOS and an SOS. This combination has several attractive properties: durable functioning of each component and a good ratio of charging time to energy...
Abstract- The evaluation of pulsed power systems and their constituent components requires unconventional loads with exceptional voltage, current, impulse energy, and continuous power dissipation capability. This paper presents the design and construction of a reconfigurable resistive load with active temperature monitoring for the evaluation of ultra-high voltage pulsed power modulators and...
The object of the study is a pulse transformer with a toroidal magnetic core wound by a transformer steel strap operating under short voltage pulses, at which the magnetic field has no time to steady in the core material. The pulse magnetic field diffusion in the steel strap of the core was analyzed using a 1-D model of dynamic losses, covering the effects of hysteretic and excess losses [1]....
The Hermes III accelerator at Sandia National Laboratories is a 20 cavity multi-stage linear induction voltage accelerator typically producing a 20-MV, 20-ns, 600-kA output pulse. Energy is initially stored in Marx banks that are each discharged into two intermediate store capacitors. Each of these capacitors are then switched with an SF6-insulated high voltage rim-fire gas switch into four...
In present theory of vacuum surface flashover, secondary electron emission avalanche (SEEA) plays the dominant role in surface flashover development. But more and more researchers have the opinion that surface trapping can participate in the SEEA development and significantly affect the surface flashover characteristics of insulation materials in vacuum. The trap parameters of several typical...
Two pulsed power arrangements have been designed and tested, both based on a circuit containing an air-core pulsed transformer and a miniature explosively-driven flux-compression generator. The power supply in both cases is provided either by a conventional HV charger or by a PZT autonomous power supply. For both pulsed power arrangements, output voltage oscillations with a peak close to 100...
A triggered vacuum switch (TVS) was designed with a flat electrode at the beginning and developed to a multi-gap electrode which reduces heavy electrode erosion. Recently the demands of the TVS is increased, as the high power system is extended in the various fields. It invokes the improvement of the performance for a TVS, therefore, a fast camera experiment is suggested to research the...
The lifetime of high voltage ceramic capacitors (HVCC) are always shorted because of suffering from circularly electrical, thermal and mechanical stresses, electric field concentrations and high current density. The reasons shall be analyzed and measures should be taken to prolong the lifetime of HVCC.
In this paper, a repetitive frequency testing platform was setup to study the influence of...
A triggered vacuum switch (TVS) is widely used as a closing switch in the field of high pulsed power systems. A designed final sealed-off TVS is aimed to operate at maximum voltage of 20 kV with maximum current of 150 kA, a lifetime more than 1000 shots. Before we reach the final goals, a sealed-off prototype with Cu electrodes is fabricated to recognize a full producing process. This...