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We developed four types of GaAs PCDs: bremsstrahlung (two types), soft X-ray, and gamma for pulsed reactors. GaAs PCDs are advantageous in applications that require fast response, high dose rate, and/or neutron insensitivity. Desired detector sensitivity and response were obtained through modification of carrier lifetime by neutron irradiation, size of the sensing element, and orientation of the sensing...
Increasing demands of the Nevada Test Site's Stockpile Stewardship initiative require new approaches for designing brighter, highly energetic, efficient pulsed power X-ray sources. Marx generators are common devices often used for such pulsed power and x-ray source applications. One particular design challenge for these devices is to develop accurate circuit models that simulate and predict the Marx's...
The induction cells of the Dual Axis Radiographic Hydrotest (DARHT) second axis facility are scheduled to be refurbished with performance and reliability upgrades. The refurbishment process involves extracting each cell from the accelerator hall, performing a complete teardown of the cell, reassembling with new or modified components, fidulizing the magnetic axis, testing and certifying pulse power...
The ZR upgrade to the Z accelerator at Sandia National Laboratories will replace much of the power flow components. The single most massive of these components is the 1.6 meter diameter, four-feed MITL system. This 14.5 Ton assembly transports electromagnetic energy from the vacuum interface to the load. The MITLs must cany 30 MA total with 99% reliability. Optimum performance requires careful control...
The design and testing of explosive-driven ferroelectric generators (FEGs) with output voltages exceeding 200 kV is presented. The generator design is aimed at achieving high voltages in a compact device by explosively compressing stacks of ferroelectric ceramic discs. The ferroelectric used in this application is EC -64 lead zirconate- titanate (PZT), a hard ferroelectric ceramic with a high dielectric...
For some pulsed transformers, a primary coil should bear severe mechanical stresses caused by high-current (up to MA) pulses, and a secondary coil should be sufficiently insulated so that electrical breakdown would not occur owing to high voltage. To satisfy the above conditions, we applied two techniques in designing a relatively compact air-core foil-wound step-up pulsed transformer. A tapered secondary...
Experiments were performed on a prototype very high power lithium-ion battery cell from Saft Batteries for its pulsed power capacity. The experiments were centered on a series of tests designed to exercise the battery for maximum power transfer and maximum charge/current transfer from battery to a load. The pulsing periods ranged from 0.5 ms to 50 ms. The maximum power obtained was 14.6 kW/kg for...
The Air Force Research Laboratory (AFRL) maintains an extensive capability for the design, analysis, construction and testing of explosive pulsed power (EPP) components. Three flux compression generators (FCGs) were designed as part of an EPP technology development effort sponsored by AFRL and the Defense Advanced Research Projects Agency (DARPA). A secondary-stage, high-current FCG was designed to...
The subcritical experiment (SCE) program was initiated after the 1992 moratorium on underground nuclear testing in support of stockpile stewardship. The dynamic material properties of plutonium are a major topic of exploration for the SCE program. In order to provide for a multilayered containment of plutonium, the SCEs are executed in the Ula underground tunnel complex at the Nevada Test Site (NTS)...
We have performed a conceptual design of a 6 MV IVA with cells that are directly driven from individual Marx/peaker circuits. The present design assumes use of the RITS IVA cell parameters, driving a negative polarity vacuum coax, and a load impedance of 40-60 ohms. However, the approach scales to at least 16 MV, and is adaptable to positive polarity systems over a range of cell designs and load impedances...
By using a 2.5 and 3-D particle-in-cell code, this paper reports on the electron beam propagation behavior, in a drift tube, under different acceleration potentials ranging from 15 kV to 125 kV in a PPM (periodic-permanent magnet) focusing structure. The investigation is carried out under two approaches. First, an electron beam with a constant electric current of Iomicron = 24 A is injected into a...
We have been developed a compact, insulation oil filled modulator for the X-ray free electron laser (X-FEL) project at SPring-8. The modulator supplies 114 MW of peak power at a 60 pps maximum repetition rate. The first prototype was constructed in March 2003, and a second was constructed with minor-improvements in January 2005. We obtained the expected design performance: PFN charging voltage up...
The major limiting factor in the transmission of HPM has been the interface between dielectric-vacuum or even more severely between dielectric-air if HPM is to be radiated into the atmosphere. Extensive studies have identified the physical mechanisms associated with vacuum-dielectric flashover, as opposed to the mechanisms associated with air-dielectric flashover, which are not as well known. Surface...
Mechanisms in vacuum flashover caused by rf (f<10 GHz) or unipolar voltages are virtually identical. Similarities between rf (representing high power microwave window breakdown on the high pressure side) and unipolar flashover are expected in an atmospheric environment as well. Our experimental setups enable studying both unipolar flashover and rf window flashover at atmospheric conditions while...
The experiments with combined launcher joined together the preliminary adiabatic compression of working gas by means of powder charge and its subsequent heating by the electric arc are continuing at the IEE RAS. This operation mode provides the high efficiency of launcher and allows to decrease required temperature and pressure of working gas. The results of combine launcher tests experiments are...
The optimization of the discharge gap electrodes of electrothermal launcher operating in repetitive regime as well as the use of erosion-proof materials resulted in diminishing their erosion wear by more than an order. The analysis based on the developed physical models and performed experiments made it possible to determine the ablating layers dynamics as well as the ablation wear of corundum ceramic...
The U.S. Navy is considering the development of an electromagnetic launcher (EML) for surface-fire support and other missions[1]. The EML system will need to have fire rates of 6-12 rounds per minute and barrel lifetimes approaching 10,000 rounds. The Naval Research Laboratory has initiated a program to develop and test materials to achieve these fire rates and lifetimes[2]. A facility is being assembled...
The "pseudo-liquid (PSL) armature with air-spring" is a novel railgun armature concept developed by Dr. Richard A. Marshall during the end of last century. Advantages of the PSL armature with air-spring include lower mass and more compliance than conventional "C-type" railgun armature. Beijing Institute of Special Electromechanical Technology began to study this armature in 2003...
We summarize the highlights of the pulsed power work of Dr. Leland Schlitt, winner of the 2005 Erwin Marx Award for outstanding contributions to pulsed power technology over an extended period of time.
Like many industrial organizations, the US Navy is moving away from an era of hydraulic, pneumatic and mechanical devices to an era dominated by electromechanical devices and all-electric controls. The Navy is also moving to replace many traditional weapon systems (all of which are chemical and thermodynamic in nature) with directed energy and electric weapons. For these applications there are few,...
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