Publications
313 results found
Chittenden JP, Dunne AM, Zepf M, et al., 2002, The production of hypersonic, radiatively cooled plasma projectiles of extremely high energy density in imploding Z-pinches, Melville, 5th international conference on dense z-pinches, Albuquerque, New Mexico, 23 - 28 June 2002, Publisher: American Institute of Physics, Pages: 291-294
Sherlock M, Chittenden JP, Lebedev SV, et al., 2002, A kinetic description of ions in aluminium wire-array precursor plasma, Melville, 5th international conference on dense z-pinches, Albuquerque, New Mexico, 23 - 28 June 2002, Publisher: American Institute of Physics, Pages: 408-411
Sherlock M, Chittenden JP, Lebedev SV, et al., 2002, A kinetic description of ions in aluminium wire-array precursor plasma, Melville, 5th international conference on dense z-pinches, Albuquerque, New Mexico, 23 - 28 June 2002, Publisher: American Institute of Physics, Pages: 408-411
Lebedev SV, Ampleford DJ, Bland SN, et al., 2002, Ablation rate of wire cores in wire array Z-pinch experiments, Melville, 5th International Conference on Dense Z-Pinches, Albuquerque, New Mexico, 23 - 28 June 2002, Publisher: American Institute of Physics, Pages: 71-74
Palmer JBA, Lebedev SV, Bland SN, et al., 2002, The effect of precursor plasma flow on foam targets in wire array Z-pinch experiments, 5th International Conference on Dense Z-Pinches, Publisher: AMER INST PHYSICS, Pages: 79-82, ISSN: 0094-243X
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- Citations: 2
Bland SN, Lebedev SV, Beg F, et al., 2002, The effect of array configuration on current distribution in a wire array Z-pinch, Melville, 5th international conference on dense z-pinches, Albuquerque, New Mexico, 23 - 28 June 2002, Publisher: American Institute of Physics, Pages: 83-86
Bland SN, Lebedev SV, Chittenden JP, et al., 2002, Implosion dynamics and X-ray characteristics of nested wire array Z- pinches, Melville, 5th International Conference on Dense Z-Pinches, Albuquerque, New Mexico, 23 - 28 June 2002, Publisher: American Institute of Physics, Pages: 75-78
Ampleford DJ, Lebedev SV, Bland SN, et al., 2002, Deflection of supersonic plasma jets by ionised hydrocarbon targets, Melville, 5th international conference on dense z-pinches, Albuquerque, New Mexico, 23 - 28 June 2002, Publisher: American Institute of Physics, Pages: 321-324
Chittenden JP, Lebedev SV, Cuneo ME, et al., 2002, How 3D effects limit X-ray power in wire array Z-pinches, Melville, 5th international conference on dense z-pinches, Albuquerque, New Mexico, 23 - 28 June 2002, Publisher: American Institute of Physics, Pages: 354-357
Lebedev SV, Ampleford DJ, Bland SN, et al., 2002, Ablation rate of wire cores in wire array Z-pinch experiments, Melville, 5th International Conference on Dense Z-Pinches, Albuquerque, New Mexico, 23 - 28 June 2002, Publisher: American Institute of Physics, Pages: 71-74
Haines MG, Lebedev SV, Chittenden JP, et al., 2002, Why do wire-array Z-pinches give such a sharp and efficient X-ray pulse?, Melville, 5th international conference on dense z-pinches, Albuquerque, New Mexico, 23 - 28 June 2002, Publisher: American Institute of Physics, Pages: 345-349
Chittenden JP, Lebedev SV, Cuneo ME, et al., 2002, How 3D effects limit X-ray power in wire array Z-pinches, Melville, 5th international conference on dense z-pinches, Albuquerque, New Mexico, 23 - 28 June 2002, Publisher: American Institute of Physics, Pages: 354-357
Pikuz SA, Shelkovenko TA, Sinars DB, et al., 2001, Spatial, temporal, and spectral characteristics of an X pinch, JOURNAL OF QUANTITATIVE SPECTROSCOPY & RADIATIVE TRANSFER, Vol: 71, Pages: 581-594, ISSN: 0022-4073
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- Citations: 35
Chittenden JP, Lebedev SV, Bland SN, et al., 2001, Two- and three-dimensional modeling of the different phases of wire-array <i>z</i>-pinch evolution, LASER AND PARTICLE BEAMS, Vol: 19, Pages: 323-343, ISSN: 0263-0346
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- Citations: 25
Lebedev SV, Beg FN, Bland SN, et al., 2001, Plasma formation and the implosion phase of wire array <i>z</i>-pinch experiments, LASER AND PARTICLE BEAMS, Vol: 19, Pages: 355-376, ISSN: 0263-0346
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- Citations: 52
Lebedev SV, Beg FN, Bland SN, et al., 2001, Effect of discrete wires on the implosion dynamics of wire array Z pinches, PHYSICS OF PLASMAS, Vol: 8, Pages: 3734-3747, ISSN: 1070-664X
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- Citations: 303
Chittenden JP, Lebedev SV, Bland SN, et al., 2001, One-, two-, and three-dimensional modeling of the different phases of wire array Z-pinch evolution, 42nd Annual Meeting of the Division of Plasma Physics Of the American-Physical-Society/10th International Congress on Plasma Physics, Publisher: AIP Publishing, Pages: 2305-2314, ISSN: 1070-664X
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- Citations: 61
Chittenden JP, Lebedev SV, Bland SN, et al., 2001, The different dynamical modes of nested wire array Z pinches, PHYSICS OF PLASMAS, Vol: 8, Pages: 675-678, ISSN: 1070-664X
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- Citations: 40
Lebedev SV, Chittenden JP, Beg FN, et al., 2001, Radiatively cooled supersonic plasma jets generated in wire array Z-pinches, ISSN: 0730-9244
We will present experiments on the generation of a highly supersonic plasma jet by a convergent precursor plasma flow, produced by electrodynamic acceleration of plasma in a conical array of fine metallic wires (a modification of the wire array Z-pinch). Stagnation of the plasma flow on the axis of symmetry forms a standing conical shock, which effectively collimates the flow in the axial direction. The use of different materials (Al, Fe and W) show that a highly supersonic (M∼20) and a well-collimated jet is generated when the radiative cooling rate of the plasma is significant. The interaction of this jet with different plasma targets is used for studies of hydrodynamic instabilities in decelerated plasma flow and the experimental results will be presented. The study of collisionless interpenetration of colliding plasmas is also possible in this system. Scaling of the jet parameters with the drive current from the present 1MA level will be discussed.
Beg FN, Lebedev SV, Bland SN, et al., 2001, Effect of resistivity on dynamics of the wire arrays, ISSN: 0730-9244
We report on the implosion dynamics of single nickel and copper wire arrays on the MAGPIE generator with a 1.4 MA, 240 ns current pulse. Plasma formed from individual wires has a corecorona structure. In the nickel arrays, a core size of 75 μm is measured by x-ray radiography. The formation of precursor on axis takes place at about 150 ns. Initially the precursor plasma is stable but shows an m=1 instability later in time. The implosion of the array occurs later than that predicted by a 0-D model, indicating that a fraction of the current flows through the precursor plasma. Like aluminum and tungsten, the m=1 instability in the precursor plasma is not observed in the copper arrays, and the implosion time is in accordance with a 0-D model. This implies that the resistivity of the wires play an important role in the dynamics of the wire arrays. Detailed results will be presented.
Chittenden JP, Zepf M, Lebedev SV, et al., 2001, Indirect drive ICF using highly supersonic, radiatively cooled, plasma slugs, ISSN: 0730-9244
Details are presented of a new approach to indirect drive inertial confinement fusion which makes use of highly supersonic, radiatively cooled, slugs of plasma to energise a hohlraum. Such projectiles could be formed by, for example, the implosion of a conical tungsten wire array (in a similar fashion to radiatively cooled jets) or by using a radial wire array accelerated along a coaxial plasma gun. In each case, substantial radiative cooling of the tungsten plasma at the launch point results in very high Mach numbers and low divergence. 2D resistive MHD simulations are presented which suggest that a 'Z' class machine can produce a mm sized slug of a few ns duration containing several hundred kJ of kinetic energy. This object therefore has the potential to deliver - 100TW of kinetic flux (similar to a singly charged heavy ion beam of ∼100MA current) into a hohlraum of small dimension. Simulations of the interaction of such a plasma slug with a convener foil show efficient conversion of kinetic energy into radiation. 3D view-factor calculations of a roughly NIF-scale cylindrical hohlraum with twin converter foils are then used to establish the drive temperature and symmetry for capsule implosion experiments. The potential advantages of the system for the ignition of relatively small capsules on modest sized facilities with the potential for limited stand-off between the driver and the target are discussed.
Chandler GA, Cuneo ME, Lazier SE, et al., 2001, Z-pinch radial behaviour using ID visible and X-ray streak measurements on the Z-accelerator, ISSN: 0730-9244
At Sandia National Laboratories we are using the Z-accelerator, which provides nominally a 20-MA peak current with a 100-ns risetime, to study fast Z-pinch physics. On the Z accelerator we use wire arrays in a cylindrical geometry as the initial pinch configuration. Typical arrays are 1-2 cm tall with radii of 1 2 cm. The array implosions are modeled with 0-D circuit codes and 1 or 2-D radiative-magneto-hydrodynamic simulations which assume a shell-like behaviour for the imploding array. The actual 3D nature of the implosion may be much more complicated. Work at Imperial College, on a much smaller driver, has shown that there can be significant plasma pre-fill due to coronal discharge from individual wires resulting in array radius vs time behaviour which is very different from a simple thin imploding shell. Motivated by this work we have used a fiber array coupled to an optical streak camera viewing visible and (by utilizing a scintillator) x-ray emission from the array as a function of radius. We will present the diagnostic setup and results from a number of wire array configurations showing the radius of the emissions compared with calculations.
Chittenden JP, Zepf M, Lebedev SV, et al., 2001, Indirect drive ICF using highly supersonic, radiatively cooled, plasma slugs, IEEE International Conference on Plasma Science, ISSN: 0730-9244
Details are presented of a new approach to indirect drive inertial confinement fusion which makes use of highly supersonic, radiatively cooled, slugs of plasma to energise a hohlraum. Such projectiles could be formed by, for example, the implosion of a conical tungsten wire array (in a similar fashion to radiatively cooled jets) or by using a radial wire array accelerated along a coaxial plasma gun. In each case, substantial radiative cooling of the tungsten plasma at the launch point results in very high Mach numbers and low divergence. 2D resistive MHD simulations are presented which suggest that a 'Z' class machine can produce a mm sized slug of a few ns duration containing several hundred kJ of kinetic energy. This object therefore has the potential to deliver - 100TW of kinetic flux (similar to a singly charged heavy ion beam of ∼100MA current) into a hohlraum of small dimension. Simulations of the interaction of such a plasma slug with a convener foil show efficient conversion of kinetic energy into radiation. 3D view-factor calculations of a roughly NIF-scale cylindrical hohlraum with twin converter foils are then used to establish the drive temperature and symmetry for capsule implosion experiments. The potential advantages of the system for the ignition of relatively small capsules on modest sized facilities with the potential for limited stand-off between the driver and the target are discussed.
Lebedev SV, Beg FN, Bland SN, et al., 2001, Implosions of wire arrays with mixed materials and wire diameters, ISSN: 0730-9244
The results of experiments on the MAGPIE generator (1.4 MA, 240ns) with single wire arrays composed from wires of two different materials (e.g. W and Al) or from wires of different diameters will be presented. The wires are placed in an array alternately on the same diameter, and this configuration of the array is used to investigate effects of material or wire diameter on the division of current between the wires. It was found that in a 32 Al / W mixed wire array, the Al wires (16 × 155m diameter) implode significantly earlier than W wires (16 × 55m diameter), despite the fact that mass per unit length was the same for both materials. This presumably occurs due to a higher conductivity of plasma formed from Al wires, in which most of the total current flows during the first ∼70% of the implosion time. The difference in the implosion times of the two parts of the mixed wire arrays allows us to separate experimentally the contributions to the X-ray pulse from the kinetic energy and from the compression of the plasma by the magnetic field. This also suggests a possibility to control the shape of the x-ray pulse, in a way similar to the nested wire arrays operating in a current switching mode.
Chittenden JP, Lebedev SV, Jennings C, et al., 2001, Three-dimensional modeling of the implosion phase of array Z pinches, ISSN: 0730-9244
A 3D resistive magneto-hydrodynamic model is used to simulate a single wire in a cylindrical wire array undergoing implosion. As with 2D x-y plane calculations, the persistence of a cold dense wire core results in the injection of radial streams of plasma into the interior of the array prior to implosion. Variations in the mass per unit length along the wire means that some regions of the wire core run out of material and begin imploding towards the array axis earlier than others causing the residual wire core to break up. Rather than attempt to flow across the breaks in the wire plasma, the current flows along the first straight axial path, which is now inside the array. The process of "wire breaking" thus allows the full generator current to bypass the wire cores and be switched directly onto the outside of the radial plasmas streams. The ensuing implosion is then similar to the slug-like or snowplough-like implosion of a uniform fill pinch, in this case having significant axial modulation but little Rayleigh-Taylor instability growth. The origins and structure of the pinch emissions are therefore radically different to those predicted by 2D(r-z) MHD simulations of imploding shells. Simulations of the final stages of implosion may however still be possible using 2D(r-z) models provided appropriate initial conditions are used and examples of this are presented. Comparison of the 3D and 2D results with diagnostic images from the implosion phase of wire arrays on the MAGPIE generator at Imperial College and the SATURN and Z generators at Sandia National Laboratory are presented.
Lebedev SV, Beg FN, Bland SN, et al., 2001, X-ray backlighting of wire array <i>Z</i>-pinch implosions using <i>X</i> pinch, 13th Topical Conference on High-Temperature Plasma diagnostics, Publisher: AMER INST PHYSICS, Pages: 671-673, ISSN: 0034-6748
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- Citations: 94
Pikuz SA, Shelkovenko TA, Romanova VM, et al., 2001, X pinch as a source for X-ray radiography, NUKLEONIKA, Vol: 46, Pages: 21-25, ISSN: 0029-5922
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- Citations: 11
Lebedev SV, Beg FN, Bland SN, et al., 2000, Effect of core-corona plasma structure on seeding of instabilities in wire array <i>Z</i> pinches, PHYSICAL REVIEW LETTERS, Vol: 85, Pages: 98-101, ISSN: 0031-9007
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- Citations: 153
Haines MG, Lebedev SV, Chittenden JP, et al., 2000, The past, present, and future of <i>Z</i> pinches, 41st Annual Meeting of the Division of Plasma Physics of the American-Physical-Society, Publisher: AIP Publishing, Pages: 1672-1680, ISSN: 1070-664X
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- Citations: 75
Chittenden JP, Lebedev SV, Ruiz-Camacho J, et al., 2000, Plasma formation in metallic wire Z pinches, PHYSICAL REVIEW E, Vol: 61, Pages: 4370-4380, ISSN: 1539-3755
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- Citations: 60
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