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Träfflista för sökning "WFRF:(Elfsberg Mattias) "

Sökning: WFRF:(Elfsberg Mattias)

  • Resultat 1-8 av 8
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1.
  • Appelgren, Patrik, et al. (författare)
  • Small Helical Magnetic Flux-Compression Generators : Experiments and Analysis
  • 2008
  • Ingår i: IEEE Transactions on Plasma Science. - 0093-3813. ; 36:5, s. 2673-2683
  • Tidskriftsartikel (refereegranskat)abstract
    • In order to gain experience in explosive pulsed power and to provide experimental data for modeling, a small high-explosive-driven helical magnetic flux-compression generator (FCG) was designed at the Swedish Defence Research Agency (FOI). The generator, of which three have been built, has an overall length of 300 mm and a diameter of 70 mm. It could serve as the energy source in a pulse-forming network to generate high power pulses for various loads. This paper presents the design of, and tests with, this helical FCG. The generator had an initial inductance of 23 mu H and was operated into a load of 0.2 mu H. The generator is charged with 0.27 kg of high explosives (PBXN-5). Various types of diagnostics were used to monitor the operation of the generator, including current probes, optical fibers, and piezo gauges. With seed currents of 5.7 and 11.2 kA, final currents of 269 and 436 kA were obtained, corresponding to current amplification factors of 47 and 39. The peak of the current was reached about 30 mu s after the time of crowbar. The two generators showed only small losses in terms of 2 pi-clocking. Using signals from optical fibers, the deflection angle of the armature could be determined to be 10 degrees in good agreement with hydrodynamic simulations of the detonation process and the detonation velocity to be 8.7 km/s in agreement with tabulated value.
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2.
  • Carlsson, Torgny E., et al. (författare)
  • Combination of schlieren and pulsed TV holography in the study of a high-speed flame jet
  • 2006
  • Ingår i: Optics and Lasers in Engineering. - Elsevier Ltd.. - 0143-8166. ; 44:6
  • Tidskriftsartikel (övrigt vetenskapligt)abstract
    • This paper presents studies of the propagation of a high-speed turbulent flame jet of an air/hydrogen gas mixture. The experimental results are recorded with the schlieren and the pulsed TV holography method. These methods are compared and combined to benefit from the advantages of each of them. Abel inversion has been used to achieve three-dimensional information i.e. refractive index distributions. Evaluation, calibration and Abel inversion algorithms are described together with experimental results. The results obtained from the different techniques show remarkable similarities concerning both qualitative and quantitative aspects.
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3.
  • Elfsberg, Mattias, et al. (författare)
  • Experimental Studies of Anode and Cathode Materials in a Repetitive Driven Axial Vircator
  • 2008
  • Ingår i: IEEE Transactions on Plasma Science. - 0093-3813. ; 36, s. 688-693
  • Tidskriftsartikel (refereegranskat)abstract
    •  Repetitive use of a high-power microwave (HPM) radiation source implies strong erosion on cathode and anode materials. Electrode material endurance has been studied in a series of experiments with an axial vircator powered by a compact Marx generator. The Marx generator operated in a 10 Hz repetitive mode with a burst of ten pulses. Velvet and graphite was used as electron-emitting materials, and they showed markedly different pulse characteristics. Three different anode materials were used; stainless steel mesh, stainless steel wires and molybdenum wires, which all had different influence on the pulse characteristics.
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4.
  • Möller, Cecilia, et al. (författare)
  • Experimental Studies of the Influence of a Resonance Cavity in an Axial Vircator
  • 2010
  • Ingår i: IEEE Transactions on Plasma Science. - 0093-3813. ; 38:6, s. 1318-1324
  • Tidskriftsartikel (refereegranskat)abstract
    • Experiments on an axial virtual-cathode oscillator (vircator) with a resonance cavity enclosing the virtual cathode are reported. The vircator is driven by a repetitive Marx generator operating in a single-shot mode. To be able to separate different radiation mechanisms, the design of the vircator allows adjustment of the cavity depth as well as the way microwave radiation is extracted. The microwave radiation is measured with a pair of free-field B-dot sensors. The maximum field strengths were registered when the bandwidth was very narrow.
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5.
  • Möller, Cecilia, et al. (författare)
  • Experimental study of a vircator with premodulated electron beam
  • 2011
  • Ingår i: Proc. of Pulse Power Conference (PPC 2011)”, Chicago,USA, June 2011.. - 978-145770629-5 ; s. 815-818
  • Konferensbidrag (refereegranskat)abstract
    • An initial experimental study of a vircator where a feedback mechanism is used to premodulate the electron beam has been performed. The anode-cathode gap distance and the applied voltage were varied and their influence on the frequency content and field strength of the generated microwave pulse are investigated and compared with particle in cell simulations. The frequency content of the microwave radiation was in good agreement between experiments and simulations. The vircator was very narrow banded at 2 GHz.
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6.
  • Möller, Cecilia, et al. (författare)
  • Magnetic field measurement system for HPM research
  • 2009
  • Ingår i: Proc. of Radiovetenskap och kommunikation (RVK08). ; s. 86-93
  • Konferensbidrag (refereegranskat)abstract
    • One method to characterize the radiated microwave field from a high-power microwave (HPM) source is to measure the radiated high-level electromagnetic field in several locations at a high sampling rate registering the frequency time dependence, thus being able to determine the radiated pattern and mode. A complete free-field measurement system for measuring the magnetic field component in high-level electromagnetic fields has been developed at FOI. The system consists of a B-dot sensor and a balun, both designed and constructed at FOI. The B-dot sensor is designed as two cylindrical loop sensors with differential output. The balun is a microstrip design etched on a dual sided PTFE circuit board. Complete systems have been calibrated at SP Technical Research Institute of Sweden. A method to analyze the data from the free-field systems has been developed.
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7.
  • Novac, Bucur M., et al. (författare)
  • A 10-GW pulsed power supply for HPM sources
  • 2006
  • Ingår i: IEEE TRANS PLASMA SCI. ; s. 1814-1821
  • Konferensbidrag (refereegranskat)abstract
    • A research activity involving the detailed consideration of novel high-voltage transformers for pulsed-power applications has recently begun at Loughborough University. Although the main goal is the demonstration of a compact and lightweight unit employing magnetic insulation under vacuum conditions, the initial stage of the work is directed toward the development of a conventional air-cored transformer as a main component in a compact power supply for high power microwave sources. In cooperation with the Swedish Defence Research Agency (FOI), the power supply has been tested with a microwave source of the vircator type. The power generator for the system uses a 70-kJ/25-kV capacitor bank and an exploding wire array to generate a 150-kV voltage pulse in the primary circuit of a transformer. A pressurized SF6 spark gap in the secondary circuit sharpens the high-voltage output so that pulses approaching 500 kV and with a rise time well below 100 ns are generated on a 20-Omega high-power resistors With the peak power in excess of 10 GW. Experimental results are presented from final testing of the system, where a reflex triode vircator replaces the 20-Omega resistor. Measurements of the microwave emission using free-field sensors are presented, and comments are made with the microwave emission from the same vircator when powered by a Marx generator at FOI.
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8.
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