Change search
Refine search result
1 - 15 of 15
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Rows per page
  • 5
  • 10
  • 20
  • 50
  • 100
  • 250
Sort
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
Select
The maximal number of hits you can export is 250. When you want to export more records please use the Create feeds function.
  • 1.
    Appelgren, Patrik
    KTH, School of Electrical Engineering (EES), Space and Plasma Physics.
    Experiments with and modelling of explosively driven mangetic flux compression generators2008Licentiate thesis, comprehensive summary (Other scientific)
    Abstract [en]

    This thesis presents work performed on explosively driven magnetic flux compression generators. This kind of devices converts the chemically stored energy in a high explosive into electromagnetic energy in the form of a powerful current pulse. The high energy density of the high explosives makes flux compression generators attractive as compact power sources. In order to study these devices a generator was designed at FOI in the mid-90ies. Two generators remained unused and became available for this licentiate work.

    The thesis reports experiments with, and simulations of, the operation of the two remaining generators. The aim was to fully understand the performance of the generator design and be able to accurately simulate its behaviour. The generators were improved and fitted with various types of diagnostics to monitor the generator operation.

    Two experiments were performed of which the first generator was operated well below its current capability limits while the second was stressed far above its limits. Since the generator generates a rapidly increasing current, a current measurement is the most important diagnostic revealing the current amplification of the generator and its overall performance. Further it is important to measure the timing of various events in the generator. With a common time reference it is possible to combine data from different probes and extract interesting information which cannot be directly obtained with a single measurement.

    Two types of numerical simulations have been performed: Hydrodynamic simulations of the high explosive interaction with the armature were used to verify the measured armature dynamics. A zero-dimensional code was used to perform circuit simulations of the generator. The model takes into account the inductance reduction due to the compression of the generator as well as the change in conductivity due to heating of the conductors in the generators.

  • 2.
    Appelgren, Patrik
    KTH, School of Electrical Engineering (EES), Space and Plasma Physics.
    Gigawatt pulsed power technologies and applications2011Doctoral thesis, comprehensive summary (Other academic)
  • 3.
    Appelgren, Patrik
    et al.
    KTH, School of Electrical Engineering (EES), Space and Plasma Physics. Swedish Defence Research Agency, Sweden .
    Andreasson, S.
    Hurtig, T.
    Larsson, A.
    Nyholm, S. E.
    Modelling of a small helical magnetic flux compression generator2007In: PPPS-2007 - Pulsed Power Plasma Science 2007, 2007, p. 1155-1158Conference paper (Refereed)
    Abstract [en]

    Helical flux-compression generators convert the chemical energy bond in explosives into electric energy. This paper briefly presents a model of, implemented in Matlab-Simulink, and simulation results for such a device. The simulation results are compared to experimental data from two experiments with identical generators but with different seed currents, influencing the resistive losses and thus the current amplification. The model is used to analyse the performance of the generator.

  • 4.
    Appelgren, Patrik
    et al.
    KTH, School of Electrical Engineering (EES), Space and Plasma Physics. wedish Defence Research Agency, Sweden.
    Bjarnholt, G.
    Elfsberg, M.
    Hurtig, T.
    Larsson, Anders
    Nyholm, S. E.
    Small helical magnetic flux compression generators: Experiments and analysis2007In: PPPS-2007 - Pulsed Power Plasma Science 2007, IEEE , 2007, p. 1151-1154Conference paper (Refereed)
    Abstract [en]

    This paper presents experimental results with helical magnetic flux-compression generators (FCGs). FCGs convert the chemical energy bond in explosives into electric energy. The generator had an initial inductance of 23 μH and was operated into a load of 0.2 μH. 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 fibres, and piezo gauges. The results are analysed and the expansion of the armature compared with hydrodynamic simulations.

  • 5.
    Appelgren, Patrik
    et al.
    KTH, School of Electrical Engineering (EES), Space and Plasma Physics.
    Brenning, Nils
    KTH, School of Electrical Engineering (EES), Space and Plasma Physics.
    Hurtig, Tomas
    Larsson, Anders
    Novac, Bucur
    Nyholm, Sten E.
    Modeling of a small helical magnetic flux compression generator2008In: IEEE Transactions on Plasma Science, ISSN 0093-3813, E-ISSN 1939-9375, Vol. 36, no 5, p. 2662-2672Article in journal (Refereed)
    Abstract [en]

     In order to gain experience in explosive pulsed power and to provide experimental data as the basis for computer modeling, a small high-explosive-driven helical magnetic flux-compression generator (FCG) was designed at the Swedish Defence Research Agency. 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 a simulation model of this helical FCG. The model, which was implemented in Matlab-Simulink, uses analytical expressions for the generator inductance. The model of resistive losses takes into account the heating of the conductors and the diffusion of the magnetic field into the conductors. The simulation results are compared with experimental data from two experiments with identical generators but with different seed currents, influencing the resistive losses. The model is used to analyze the performance of the generator.

  • 6.
    Appelgren, Patrik
    et al.
    KTH, School of Electrical Engineering (EES), Space and Plasma Physics.
    Brenning, Nils
    KTH, School of Electrical Engineering (EES), Space and Plasma Physics.
    Nyholm, Sten E.
    Small helical magnetic flux compression generators: experiments and analysis2008In: IEEE Transactions on Plasma Science, ISSN 0093-3813, E-ISSN 1939-9375, Vol. 36, no 5, p. 2673-2683Article in journal (Refereed)
    Abstract [en]

     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.

  • 7.
    Appelgren, Patrik
    et al.
    KTH, School of Electrical Engineering (EES), Space and Plasma Physics.
    Carlsson, Torgny E.
    Helte, Andreas
    Hurtig, Tomas
    Larsson, Anders
    Lundberg, Patrik
    Skoglund, Melker
    Westerling, Lars
    Interaction between solid copper jets and powerful electrical current pulses2011In: Journal of applied mechanics, ISSN 0021-8936, E-ISSN 1528-9036, Vol. 78, no 2Article in journal (Refereed)
    Abstract [en]

    The interaction between a solid copper jet and an electric current pulse is studied. Copper jets that were created by a shaped-charge device were passed through an electrode configuration consisting of two aluminum plates with a separation distance of 150 mm. The electrodes were connected to a pulsed-power supply delivering a current pulse with amplitudes up to 250 kA. The current and voltages were measured, providing data on energy deposition in the jet and electrode contact region, and flash X-ray diagnostics were used to depict the jet during and after electrification. The shape of, and the velocity distributions along, the jet has been used to estimate the correlation between the jet mass flow through the electrodes and the electrical energy deposition. On average, 2.8 kJ/g was deposited in the jet and electrode region, which is sufficient to bring the jet up to the boiling point. A model based on the assumption of a homogenous current flow through the jet between the electrodes underestimates the energy deposition and the jet resistance by a factor 5 compared with the experiments, indicating a more complex current flow through the jet. The experimental results indicate the following mechanism for the enhancement of jet breakup. When electrified, the natural-formed necks in the jet are subjected to a higher current density compared with other parts of the jet. The higher current density results in a stronger heating and a stronger magnetic pinch force. Eventually, the jet material in the neck is evaporated and explodes electrically, resulting in a radial ejection of vaporized jet material.

  • 8.
    Appelgren, Patrik
    et al.
    KTH, School of Electrical Engineering (EES), Space and Plasma Physics. Swedish Defence Research Agency (FOI), Sweden.
    Hurtig, T.
    Larsson, A.
    Skoglund, M.
    Parametric studies of an electrohydrodynamic plasma actuator for boundary layer flow control2009In: PPC '09. IEEE Pulsed Power Conference, 2009, IEEE , 2009, p. 1069-1074Conference paper (Refereed)
    Abstract [en]

    An electrohydrodynamic plasma actuator can be used as an aerodynamic flow control device. A plasma actuator is realised as a surface-mounted dielectric barrier discharge (DBD) that transfers directed energy from ions in the discharge to the surrounding air. Parametric studies have been performed in order to investigate the relative efficiency in terms of electrical power into the actuator versus mechanical power in the generated boundary flow. The parametric study includes variations of the applied driving voltage and frequency as well as different electrode and dielectric materials. It is found that, within the range tested, for each value of electrical power into the actuator there exists an optimum driving frequency in terms of boundary layer flow velocity. It is also found that the same trend seems to be true when analyzing electric to mechanical efficiency of the device, i.e. for a given input power there exists an optimum driving frequency that produces the highest efficiency. However, this peak in efficiency of the actuator lies on the edge of the parametric space tested so that further experiments are needed to validate these results.

  • 9. Appelgren, Patrik
    et al.
    Larsson, Anders
    Lundberg, Patrik
    Skoglund, Melker
    Westerling, Lars
    Studies of Electrically-Exploded Conductors for Electric Armour Applications2009In: Acta Physica Polonica. A, ISSN 0587-4246, E-ISSN 1898-794X, Vol. 115, no 6, p. 1072-1074Article in journal (Refereed)
    Abstract [en]

    This paper presents experimental studies of current interaction with static copper rods. The results of the static experiments are used to discuss the effects responsible for the disruption of shaped-charge jets in electric armour. These effects include ohmic heating of, and current diffusion into, the rod as well as radial magnetic forces.

  • 10.
    Appelgren, Patrik
    et al.
    KTH, School of Electrical Engineering (EES), Space and Plasma Physics.
    Larsson, Anders
    Nyholm, Sten E.
    Numerical simulations of flux compression generator systems2007In: Proceedings of the 20th IET Pulsed Power Symposium, 2007, p. 123-127Conference paper (Other academic)
  • 11.
    Appelgren, Patrik
    et al.
    KTH, School of Electrical Engineering (EES), Space and Plasma Physics.
    Skoglund, Melker
    Lundberg, Patrik
    Westerling, Lars
    Larsson, Anders
    Hurtig, Tomas
    Disruption mechanisms in electrified solid copper jets2011In: Journal of applied mechanics, ISSN 0021-8936, E-ISSN 1528-9036, Vol. 78, no 2Article in journal (Refereed)
    Abstract [en]

    Interaction between a solid copper jet and an electric current pulse is a complex process that has been experimentally studied by letting a jet created by a shaped charge device pass through an electrode configuration consisting of two aluminum plates with a separation distance of 150 mm. When the jet bridged the electrodes, which are connected to a charged pulsed power supply, current pulses with amplitude up to 250 kA were passed through the jet. By using flash X-ray diagnostics, the disruption of the electrified jets could be studied. In this paper, the disruption of the electrified jets is discussed and compared with disruption phenomena observed in electrically exploded metal rods in a static setup. Necks are naturally formed along a stretching jet, and in the experiments with current interaction these necks explode electrically. In the static experiments, the metal rods have small notches distributed along the rod to resemble the necks of the jet. When two neighboring necks or notches explode, the shock of the explosion compresses the intermediate jet or rod segment axially and the material is forced out radially. The disruption phenomena in the jet and rod experiments are similar with rapid expansion of the metal at explosion and at comparable velocities.

  • 12.
    Appelgren, Patrik
    et al.
    KTH, School of Electrical Engineering (EES), Space and Plasma Physics.
    Skoglund, Melker
    Lundberg, Patrik
    Westerling, Lars
    Larsson, Anders
    Hurtig, Tomas
    Experimental Study of Electromagnetic Effects on Solid Copper Jets2010In: Journal of applied mechanics, ISSN 0021-8936, E-ISSN 1528-9036, Vol. 77, no 1, p. 011010-Article in journal (Refereed)
    Abstract [en]

    In this paper we present a study of the interaction between all electric current pulse and a solid copper jet. Experiments were performed using a dedicated pulsed power supply delivering a current pulse of such amplitude, rise little, and duration that the jet is efficiently affected. The copper jet was created by using a shaped charge warhead. All electrode configuration consisting of two aluminum plates with a separation distance of 150 mm was used. The discharge current pulse and the voltages at the capacitors and at the electrodes were measured to obtain data oil energy deposition in and the resistance of the jet and electrode contact region. X-ray diagnostics were used to radiograph the jet, and by analyzing the radiograph, the degree of disruption of the electrified jet could be obtained. It was found that a current pulse with an amplitude of 200-250 kA and a rise time of 16 mu s could strongly enhance the natural fragmentation of the jet. In this case, the initial electric energy was 100 kJ and about 90% of the electric energy was deposited in the jet and electrodes. At the exit of the electrode region, the jet fragments formed rings with a radial velocity of up to 200 m/s, depending oil the initial electric energy in the pulsed power supply. [DOI: 10.1115/1.3172251]

  • 13. Appelgren, Patrik
    et al.
    Westerling, Lars
    Skoglund, Melker
    Lundberg, Patrik
    Hurtig, Tomas
    Larsson, Anders
    Radial Jet Dispersion Due to Current Interaction in an Electric Armour Application2008In: Ballistics 2008: 24th International Symposium on Ballistics, 2008Conference paper (Refereed)
  • 14. Novac, Bucur M.
    et al.
    Istenic, Marko
    Luo, Jing
    Smith, Ivor R.
    Brown, John
    Hubbard, Martin
    Appelgren, Patrik
    KTH, School of Electrical Engineering (EES), Space and Plasma Physics.
    Elfsberg, Mattias
    Hurtig, Tomas
    KTH, School of Electrical Engineering (EES), Space and Plasma Physics.
    Möller, Cecilia
    KTH, School of Electrical Engineering (EES), Space and Plasma Physics.
    Larsson, Anders
    Nyholm, Sten E.
    A 10-GW pulsed power supply for HPM sources2006In: IEEE TRANS PLASMA SCI, 2006, Vol. 34, no 5, p. 1814-1821Conference paper (Refereed)
    Abstract [en]

    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.

  • 15. Senior, P.
    et al.
    Smith, I. R.
    Appelgren, Patrik
    Elfsberg, Mattias
    Lundberg, Patrik
    Skoglund, Melker
    A 400 kj 22 kV Mobile Pulsed Power System with Waliable Pulse Forming2006In: Proceedings of Megagauss XI, 2006, p. 257-261Conference paper (Refereed)
1 - 15 of 15
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf