A5062610455- Pulsed Power Technology Applications
- High voltage insulation and dielectric phenomena
- Power Transformer Diagnostics and Insulation
- Laser-Plasma Interactions and Diagnostics
- Electrostatic Discharge in Electronics
- Electromagnetic Launch and Propulsion Technology
- Gyrotron and Vacuum Electronics Research
- Lightning and Electromagnetic Phenomena
- Plasma Diagnostics and Applications
- Particle accelerators and beam dynamics
- Particle Accelerators and Free-Electron Lasers
- Silicon Carbide Semiconductor Technologies
- High-pressure geophysics and materials
- Laser-induced spectroscopy and plasma
- Electrohydrodynamics and Fluid Dynamics
- Integrated Circuits and Semiconductor Failure Analysis
- Magnetic confinement fusion research
- Laser Design and Applications
- Non-Destructive Testing Techniques
- Plasma Applications and Diagnostics
- Superconducting Materials and Applications
- Petroleum Processing and Analysis
- Power Quality and Harmonics
- Advanced X-ray and CT Imaging
- Energetic Materials and Combustion
Atomic Weapons Establishment
2011-2022
University of Strathclyde
2020
UK Power Networks
2001-2009
Applied Pulsed Power (United States)
2008
Age UK
2004
Sandia National Laboratories
2003
Imperial College London
2002
The application of high intensity laser-produced gamma rays is discussed with regard to picosecond resolution deep-penetration radiography. spectrum and angular distribution these measured using an array thermoluminescent detectors for both underdense (gas) target overdense (solid) target. It found that the use in a laser plasma accelerator configuration produces much more intense directional source. peak dose also increased significantly. Radiography demonstrated experiments source size estimated.
Measurements of energetic electron beams generated from ultrahigh intensity laser interactions ($I>{10}^{19}\text{ }\text{ }\mathrm{W}/{\mathrm{c}\mathrm{m}}^{2}$) with dense plasmas are discussed. These have been shown to produce very directional beams, although a broad energy spectrum. In the regime where beam density approaches background plasma, we show that these unstable filamentation and ``hosing'' instabilities. Particle-in-cell simulations also indicate development such This is...
The Atomic Weapons Establishment, Aldermaston, U.K., has a number of pulsed-power-driven flash X-ray machines for diagnosing the hydrodynamics explosively-driven high-atomic-number materials. most powerful these is Mogul-E, which operates at about 10 MV and 30 kA, delivering 400 R 1 m in 5-mm spot. Longer-term plans envisage upgrading existing facilities through construction hydrodynamic research facility (HRF) with multiaxis radiography. It proposed that HRF will be furnished initially...
The generation of MeV electron and ion beams using lasers with intensities up to 1020 W cm−2 is reported. Intense high energies (up 40 3×1012 protons >5 MeV) are observed. properties these particle were measured in considerable detail the results compared current theoretical explanations for their generation.
Surface breakdown of oil-immersed solids chosen to insulate high-voltage, pulsed-power systems is a problem that can lead catastrophic failure. Statistical analysis the voltages, or times, associated with such liquid-solid interfaces reveal useful information aid system designers in selection solid materials. Described this paper are results Weibull statistical analysis, applied both breakdown-voltage data and time-to-breakdown generated gaps consisting five different polymers immersed...
In sub-systems of high-voltage, pulsed-power machines, the introduction a solid into bulk liquid insulation located between two conductors is often necessary to provide mechanical support. Breakdown events on or around surface can result in permanent damage system. Described present paper are experimental results pertaining breakdown five different dielectrics held plane-parallel electrodes immersed mineral oil. The effect varying level peak applied field from 200 kV/cm (dV/dt 70 kV/μs) 1...
The plasma-filled rod-pinch diode (PFRP) is a new X-ray source appropriate for pulsed hydrodynamic radiography with endpoint voltage in the 1-2 MV range. use of plasma prefill rod-pinch-electrode configuration results intense concentration 150-300 kA, ~2 MeV, ~100 ns electron beam at tip tapered tungsten rod, producing an submillimeter diameter and dose 25 rad (CaF <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> ) distance 1 m. These...
The applied electrical fields required to initiate surface flashover of different types dielectric material immersed in insulating oil have been investigated, by applying impulses increasing peak voltage until occurred. behavior the materials repeatedly over-volted gaps was also analyzed terms breakdown mode (some bulk sample behaviour witnessed this regime), time breakdown, and voltage. Cylindrical samples polypropylene, low-density polyethylene, ultra-high molecular weight Rexolite, were...
A method of measuring the temperature fast electrons produced in ultraintense laser–plasma interactions is described by inducing photonuclear reactions, particular (γ,n) and (γ,3n) reactions tantalum. Analysis γ rays emitted daughter nuclei these using a germanium counter enables relatively straightforward near real-time measurement to be made. This especially important for high plasmas where alternative diagnostic techniques are usually difficult time consuming. technique can used while...
Surface discharges along oil-immersed solids used as insulators and supports in high-voltage pulsed-power equipment can lead to catastrophic system failures. To achieve reliable compact systems, it is important quantify the electrical fields at which surface flashover, or other types of breakdown event, will occur for different dielectric materials. This paper reports observed behavior samples polypropylene, lowdensity polyethylene, ultrahigh-molecular-weight Rexolite, Torlon, were subjected...
This paper describes a novel MOSFET gate driver circuit design for pulsed power application. It is shown that switching speed can be enhanced by using an energised inductor as high current source in series with the terminal of MOSFET. topology demonstrates speeds less than 10ns MOSFETs input capacitance. also increasing drive and optimised layout, single used to multiple parallel connected synchronously without compromising their performance. The analysed experimental results presented when...
For many years AWE has used self magnetic (SM) pinch diodes on its lower voltage flash X-ray machines (MEVEX @ 0.8 MV and Mini-B 2 MV). With the recent emphasis reduction of spot size, one part diode research project been to field SM at higher voltages. A series experiments conducted Mogul D Eros pulsed power drivers in an attempt meet HRF source term requirements. The charging was increased operational maximum 62R with a 2.1 mm (AWE definition) produced 4.2 MV. Further shots EROS driver...
Experimental data on the propagation of streamers in mineral oil is important for design high-voltage systems power and pulsed-power industries. In present study, breakdown voltages pre-breakdown delay times were measured plane-parallel electrodes, two non-uniform electrode arrangements. For each geometry, characteristics determined impulses rise-time 100 ns, also 1 μs. The maximum rate voltage rise (dV/dt) was 4 MV/μs. geometries with inter-electrode gap length 8.5 mm, time to 2.5-3 longer...
The Pulsed Power Group at the Atomic Weapons Establishment (AWE) is interested in generation of small, intense, multimegavolt X-ray sources for radiographic applications. For this paper, research has been carried out into electron beam transport and focusing studies on one our single pulse forming line flash machines. Experiments were undertaken E Minor to improve spot size generated by "paraxial diode". This a novel anode/cathode assembly designed produce small-diameter focused onto high-Z...
The Hydrodynamics Department at AWE has built up an impressive suite of X-ray machines over the last four decades. cover a voltage range from 800 kV to 9.5 MV which caters for broad experiments. service radiographic are fielded in pairs gives added bonus that two images can be gained each experiment. All on same principles. A Marx generator charges Blumlein is discharged by self closing switch. output pulse passes through insulator stack (X-ray tube) into magnetically insulated transmission...
A joint program involving the study and practical performance of a foil-flyer electromagnetic accelerator has recently been initiated by Atomic Weapons Establishment, Aldermaston, Loughborough University. As an initial phase work, both 0-D 2-D numerical models for have developed. The model, although very crude, is capable providing insight into phenomena currently used parametric design studies. model based on well-proven filamentary modeling technique accurately calculating distribution...
This article reports and discusses the results of impulse breakdown study different insulating liquids under highly divergent electric field conditions. Samples a natural ester (Envirotemp FR3), synthetic (MIDEL 7131), naphthenic mineral oil (Shell Diala S4 ZX) at levels relative humidity were exposed to HV impulses with nominal 7-μs rise time 150-kV peak voltage both positive negative polarity. A strong dependence investigated dielectric was observed respect polarity applied impulses. It...
An experimental programme, leading to the development of a foil-flyer electromagnetic accelerator (FFEMA), is being conducted at AWE. A high current pulsed power generator driving used provide tailored impulse profiles into targets for testing material properties strain rates. This work has required design and construction both an platform conduct experiments, named AMPERE, as well number computer models predict electrical mechanical performance its interaction with target.
Experimental data on the propagation of streamers in mineral oil is important for design high-voltage systems power and pulsed-power industries. In present study, pre-breakdown delay times were measured plane-parallel electrodes, two types non-uniform electrode arrangement. For each geometry, breakdown characteristics determined impulses rise-time 100 ns, also 1 μs. The maximum applied voltage magnitude was 400 kV, giving a dV/dt 4 kV/ns. geometries with inter-electrode gap length 8.5 mm,...
A statistical analysis has been undertaken to determine the and formative times associated with breakdowns along a polymer-oil interface under impulse conditions. Early was based on an assumption that breakdown data followed von Laue Distribution. However, it found in plots there were deviations from expected straight line behavior at short breakdown, which may be due normal distribution values of times. In addition, showed multiple sections, suggested changes occurring processes during...
Summary form only given. The plasma-filled rod-pinch diode (PFRP) is a new technique for making an intense, small, pulsed X-ray source radiographic applications. PFRP utilizes injected plasma in rod-pinch-diode configuration to concentrate 1-2 MeV, 0.1-0.8 MA electron beam at the tip of 1-mm diameter, tapered tungsten rod, producing extremely intense pulse with parameters thought be impossible conventional vacuum-diode techniques. small diameter [0.4-mm full-width-at-half-maximum (FWHM)...
A replacement Marx generator for one of AWE's flash radiographic machines is required to mitigate component obsolescence. The design uses twelve 250 nF capacitors charge a 14 Blumlein 700 kV. For ease maintenance the removable from oil tank by use rail system. Electrostatic codes have been used new earthing system with access hidden capacitor terminals. paper describes and results construction high voltage commissioning into resistive load.
The average statistical time and formative associated with breakdown across a polymer-oil interface have been extracted from experimental time-to-breakdown data, gathered using non-uniform electrode geometry designed to promote surface discharges. Five polymer materials of relevance the designers pulsed-power systems considered: polypropylene; LDPE; UHMWPE; Rexolite; Torlon. It has assumed that temporal distribution breakdowns can be described approach developed by von Laue, validity this is...
This paper describes the design of a MOSFET gate driver using an inductor based current source topology, which enables repetitive ultra-fast switching and reproducible pulses. Optimal layout grounding methods have been employed to minimise parasitic inductances can significantly limit performance. The oxide is protected from overvoltage TVS diodes without affecting slew rate signal. circuit was tested with up three devices in parallel. experimental results demonstrate rise times ~4 ns fall...