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  • Journal article
    Lebedev SV, Chittenden JP, Bland SN, Beg FN, Dangor AE, Haines MG, Pikuz SA, Shelkovenko TAet al., 2000,

    Plasma formation and seeding of Rayleigh-Taylor instabilities in wire array z-pinches

    , IEEE International Conference on Plasma Science, ISSN: 0730-9244

    X-ray radiography with high temporal (approximately lns) and spatial (approximately 20 μm) resolution was used to study implosion dynamics of wire array Z-pinch in experiments on the 1.4 MA, 240 ns MAGPIE facility. Comparison of laser probing and x-ray radiography data shows that the plasma formed from the wires has a heterogeneous structure, with a low density corona surrounding the dense wire cores. Non-uniform sweeping of the coronal plasma by the global J×B force from the wires towards the array axis produces both mass perturbations in the wire cores and a precursor column on the axis. The spatial scale of these perturbations, which act as seeding for the global m = 0 mode of the Rayleigh-Taylor instability, is determined by the size of wire cores (0.25 mm for Al and 0.1 mm for W). A qualitative change in the implosion dynamics (transition to 0-D-like implosion trajectory) was observed in Al arrays when the ratio of inter-wire gap to the wire core size decreased to approximately 3. This probably explains the existence of `critical' inter-wire gap, below which a significant rise in x-ray power was observed in experiments at Sandia National Lab. Experimental data on `nested' wire array implosions will be presented, which show significant sharpening of the X-ray pulse in different dynamic modes of the interaction between the two arrays.
  • Journal article
    Chittenden JP, Lebedev SV, Bland SN, Ciardi A, Haines MGet al., 2000,

    Modelling the interaction of nested wire arrays in imploding Z-pinches

    , IEEE International Conference on Plasma Science, ISSN: 0730-9244

    Results of two dimensional magnetohydrodynamic simulations of nested array collisions are presented. The fraction of the circumference occupied by the exploded inner array wires determines the fraction of momentum transferred between arrays at collision. For large numbers of wires in the inner array, the momentum transfer is large and a hydrodynamic collision mode results. For much lower numbers of wires in the inner, the outer array material is free to pass through the gaps and a transparent inner mode results. In all cases, flux compression is found to enhance the level of momentum transfer.
  • Conference paper
    Grantham SG, Proud WG, Goldrein HT, Field JEet al., 2000,

    The study of internal deformation fields in granular materials using 3-D digital speckle X-ray flash photography

    , Conference on Laser Interferometry X, Publisher: SPIE-INT SOC OPTICAL ENGINEERING, Pages: 321-328, ISSN: 0277-786X
  • Report
    Lee R W, Baldis H A, Cauble R C, Landen O L, Wark J S, Ng A, Rose S J, Lewis C, Riley D, Gauthier J-C, Audebert Pet al., 2000,

    Plasma-based studies on 4th generation light sources

    , UCRL-JC-141561
  • Conference paper
    Goldrein HT, Synnergren P, Proud WG, 2000,

    Three-dimensional displacement measurements ahead of a projectile

    , 11th Conference of the American-Physical-Society-Topical-Group on Shock Compression of Condensed Matter, Publisher: AMER INST PHYSICS, Pages: 1095-1098, ISSN: 0094-243X
  • Conference paper
    Tsembelis K, Millett JCF, Proud WG, Field JEet al., 2000,

    The shock Hugoniot properties of cement paste up to 5 GPa

    , 11th Conference of the American-Physical-Society-Topical-Group on Shock Compression of Condensed Matter, Publisher: AMER INST PHYSICS, Pages: 1267-1270, ISSN: 0094-243X
  • Conference paper
    Murray NH, Millett JCF, Proud WG, Rosenberg Zet al., 2000,

    Issues surrounding lateral stress measurements in alumina ceramics

    , 11th Conference of the American-Physical-Society-Topical-Group on Shock Compression of Condensed Matter, Publisher: AMER INST PHYSICS, Pages: 581-584, ISSN: 0094-243X
  • Conference paper
    Proud WG, Field JE, 2000,

    Shock-induced reaction in hydrogen peroxide

    , 11th Conference of the American-Physical-Society-Topical-Group on Shock Compression of Condensed Matter, Publisher: AMER INST PHYSICS, Pages: 937-940, ISSN: 0094-243X
  • Conference paper
    Lebedev SV, Aliaga-Rossel R, Bland SN, Chittenden JP, Dangor AE, Haines MG, Willi Oet al., 1999,

    Study of Rayleigh-Taylor instability growth in wire array z-pinch experiments

    , ISSN: 0730-9244

    Wire array z-pinches are extremely efficient sources of high power soft x-ray pulses (up to 280 TW) for energizing hohlraums for inertial confinement fusion and other high energy density physics applications. The main processe affecting quality of the implosion and x-ray power at stagnation is development of the Rayleigh-Taylor instability in a plasma accelerated by the magnetic pressure. In this paper we present experimental results on Rayleigh-Taylor instability growth in wire array z-pinches driven by a 1.4 MA, 240 ns current pulse. Al, W and Ti wire arrays of 16 mm diameter with between 8 and 64 wires were studied. Comparison of the instability development for different wire material and wire number will be presented. The radial structure of the instability was observed by laser probing and soft x-ray imaging in implosions of arrays consisting of four groups of four closely spaced wires (4×4 wire array). Experiments to study the instability development in nested-wire arrays and effect of the Bz magnetic field induced by wires twisting will be presented.
  • Journal article
    Lebedev SV, Aliaga-Rossel R, Bland SN, Chittenden JP, Dangor AE, Haines MGet al., 1999,

    Physics of wire array Z-pinch implosions: Experiments on magpie generator

    , IEE Colloquium (Digest), ISSN: 0963-3308
  • Conference paper
    Chittenden JP, Lebedev SV, Aliaga-Rossel R, Bell AR, Bland SN, Lucek SG, Haines MGet al., 1999,

    Two dimensional and three dimensional MHD simulations of wire array Z-pinch experiments

    , ISSN: 0730-9244

    Recent experiments on the MAGPIE generator at Imperial College have demonstrated the complex three dimensional nature of wire array Z-pinch implosions. We have developed a 3D resistive MHD code, in order to model these experiments. Running the code in 2D(x,y) geometry with high spatial resolution, reproduces the collapse dynamics, radial plasma streaming and precursor formation observed experimentally. The persistence of cold, unionized, wire cores dominates the collapse dynamics. Lower resolution 3D runs illustrate the differences in the behavior of the Rayleigh-Taylor instability in wire arrays compared to uniform shell implosions. Results of simulations of single and nested wire array experiments at Sandia National Laboratories will also be presented.
  • Conference paper
    Lebedev SV, Aliaga-Rossel R, Bland SN, Chittenden JP, Dangor AE, Haines MGet al., 1999,

    Effect of wire material on plasma formation in wire array z-pinches

    , ISSN: 0730-9244

    Plasma formation in wire array z-pinches was studied in experiments with 16-mm diameter arrays of between 8 and 64 aluminum, tungsten or titanium wires, imploded in 200 to 260 ns by a 1.4 MA current pulse. Side-on (r-z plane) diagnostics included laser probing with interferometer, schlieren and shadow channels, gated 4-frame soft x-ray imaging and radial and axial optical streak photography. End-on (r-θ plane) laser probing gave information about the azimuthal structure of the implosion. The x-ray radiation at stagnation and during the implosion phase was measured with filtered PCD and XRD detectors. A comparison of plasma formation for different wire material will be presented, including measurements of the expansion velocities of the coronal plasma in the radial and azimutal directions, the wavelength of instabilities and the parameters of the precursor pinch.
  • Journal article
    Aggarwal KM, Norrington PH, Bell KL, Keenan FP, Pert GJ, Rose SJet al., 1999,

    Electron impact excitation of Ni-like gadolinium

    , JOURNAL OF PHYSICS B-ATOMIC MOLECULAR AND OPTICAL PHYSICS, Vol: 32, Pages: 5067-5082, ISSN: 0953-4075
  • Journal article
    Chittenden JP, Lebedev SV, Bell AR, Aliaga-Rossel R, Bland SN, Haines MGet al., 1999,

    Plasma formation and implosion structure in wire array <i>Z</i> pinches

    , PHYSICAL REVIEW LETTERS, Vol: 83, Pages: 100-103, ISSN: 0031-9007
  • Journal article
    Synnergren P, Goldrein HT, Proud WG, 1999,

    Application of digital speckle photography to flash x-ray studies of internal deformation fields in impact experiments

    , APPLIED OPTICS, Vol: 38, Pages: 4030-4036, ISSN: 1559-128X
  • Conference paper
    Lebedev SV, Aliaga-Rossel R, Bland SN, Chittenden JP, Dangor AE, Haines MG, Mitchell IHet al., 1999,

    The dynamics of wire array Z-pinch implosions

    , 40th Annual Meeting of the Division of Plasma Physics of the American-Physical-Society, Publisher: AIP Publishing, Pages: 2016-2022, ISSN: 1070-664X
  • Conference paper
    Lebedev SV, Aliaga-Rossel R, Bland SN, Chittenden JP, Dangor AE, MGHaineset al., 1999,

    Physics of wire array Z-pinch implosions: Experiments on magpie generator

    , Pages: 49-52, ISSN: 0963-3308

    The study of the plasma behaviour during different stages of the wire array z-pinch implosions was investigated. Experiments were performed on the MAGPIE generator with a current rising to 1.4MA in 240ns. Time-resolved soft X-ray images were obtained with a gated 4-frame camera. Comparison of the instabilities in different wires shows that they are not correlated during the initial stages of the discharge. The scaling of the time of appearance of the global instability with the number of wires was found to be consistent with a heuristic model for the magnetic rayleigh-taylor instability whose initial perturbation amplitude was determined by statistically averaging the initial uncorrelated instabilities of the individual wires.
  • Conference paper
    Norreys PA, Bakarezos M, Barringer L, Borghesi M, Beg FN, Castro-Colins M, Chambers D, Dangor AE, Danson CN, Djaoui A, Fews AP, Galliard R, Gibbon P, Gizzi L, Glinsky ME, Hammel BA, Key MH, Lee P, Loukakos P, MacKinnon AJ, Meyer C, Meyer-ter-Vehn J, Moustaizis S, Preston SG, Pukhov A, Rose SJ, Tatarakis M, Wark JS, Willi O, Zepf M, Zhang Jet al., 1999,

    Studies of the fast ignition route to inertial confinement fusion at the Rutherford Appleton Laboratory

    , IAEA Technical Committee Meeting on Drivers and Ignition Facilities for Inertial Fusion, Publisher: ELSEVIER SCIENCE SA, Pages: 239-243, ISSN: 0920-3796
  • Conference paper
    Rae PJ, Goldrein HT, Bourne NK, Proud WG, Forde LC, Liljekvist Met al., 1999,

    Measurement of dynamic large-strain deformation maps using an automated fine grid technique

    , Fringe-Analysis-Special-Interest-Group Meeting, at the Institute-of-Physics Congress, Publisher: ELSEVIER SCI LTD, Pages: 113-122, ISSN: 0143-8166
  • Journal article
    Lebedev SV, Aliaga-Rossel R, Bland SN, Chittenden JP, Dangor AE, Haines MG, Mitchell IHet al., 1999,

    The dynamics of wire array Z-pinch implosions

    , Physics of Plasmas, Vol: 6, Pages: 2016-2022, ISSN: 1070-664X

    Wire array Z-pinch dynamics are studied in experiments with 16-mm diameter arrays of between 8 and 64, 15-μm diameter aluminum wires, imploded in 200-260 ns by a 1.4-MA current pulse. Side-on laser probing shows early development of noncorrelated m = 0-like instabilities with an axial wavelength ∼0.5 mm in individual wires. End-on interferometry (r-θ plane) shows azimuthal merging of the plasma with a density of 1017cm-3 in 90-65 ns for 8-64 wires, respectively. At the same time low-density plasma reaches the array axis and forms a precursor pinch by 120-140 ns. At 0.7-0.85 of the implosion time a global m=0 instability with a wavelength of 1.7-2.3 mm was detected in soft x-ray gated images, laser probing, and optical streaks. The time when the instability reaches the observable level corresponds to the number of e-foldings for the growth of the classical Rayleigh-Taylor instability of (Latin small letter esh) γ dt∼5.6-7. The scaling of this number with the number of wires is consistent with the instability growth from the seed level determined by the averaging of uncorrelated density perturbations in individual wires. Preliminary results from a 4×4 array permit the simultaneous observation by laser probing of the characteristic bubble and spike structure of the magneto Rayleigh-Taylor instability. © 1999 American Institute of Physics.
  • Conference paper
    Wolfrum E, Wark JS, Zhang J, O'Rourke N, Keenan R, Lewis CLS, MacPhee AG, Kalantar D, Key MH, Remington BA, Neely D, Djaoui A, Rose SJ, Eker G, Lin J, Smith R, Tallents GJet al., 1999,

    X-ray laser radiography of hydrodynamic perturbations due to laser imprint

    , 6th International Conference on X-Ray Lasers, Publisher: IOP PUBLISHING LTD, Pages: 657-663, ISSN: 0951-3248
  • Conference paper
    Smith R, Tallents GJ, Pestehe SJ, Hirst G, Lin J, Rose S, Tagviashvili Met al., 1999,

    A spectroscopic analysis of near solid density plasmas

    , 25th European Conferece on Laser Interaction with Matter (ECLIM 1998), Publisher: CAMBRIDGE UNIV PRESS, Pages: 477-485, ISSN: 0263-0346
  • Conference paper
    Bernardinello A, Batani D, Masella V, Hall TA, Ellwi S, Koenig M, Benuzzi A, Krishnan J, Pisani F, Djaoui A, Norreys P, Neely D, Rose S, Key MH, Fews Pet al., 1999,

    Fast electron propagation and energy deposition in laser shock compressed plasmas

    , 25th European Conferece on Laser Interaction with Matter (ECLIM 1998), Publisher: CAMBRIDGE UNIV PRESS, Pages: 519-528, ISSN: 0263-0346
  • Journal article
    Keenan F P, Phillips M E, Rose S J, Burgess D Det al., 1999,

    The Search for Extraterrestrial Intelligence (SETI)

    , The Irish Astronomical Journal, Vol: 26, Pages: 87-90
  • Conference paper
    Ivanova EP, Grant IP, Rose SJ, 1999,

    Gain evaluation for the Ni-like tantalum X-ray laser

    , 6th International Conference on X-Ray Lasers, Publisher: IOP PUBLISHING LTD, Pages: 383-386, ISSN: 0951-3248
  • Conference paper
    Laboucher-Dalimier E, Sauvan P, Angelo P, Derfoul H, Ceccotti T, Gauthier P, Poquérusse A, Calisti A, Talin B, Rose SJ, Förster E, Devdariani Aet al., 1999,

    Alternative treatment of line broadening in dense and hot plasmas

    , 14th International Conference on Spectral Line Shapes, Publisher: AMER INST PHYSICS, Pages: 64-76, ISSN: 0094-243X
  • Journal article
    Mitchell IH, Aliaga-Rossel R, Lebedev S, Bland S, Chittenden JP, Haines MGet al., 1998,

    Mega-amp wire array experiments on the MAGPIE generator

    , IEE Colloquium (Digest), ISSN: 0963-3308
  • Journal article
    Lebedev SV, Mitchell IH, Aliaga-Rossel R, Bland SN, Chittenden JP, Dangor AE, Haines MGet al., 1998,

    Azimuthal structure and global instability in the implosion phase of wire array Z-pinch experiments

    , PHYSICAL REVIEW LETTERS, Vol: 81, Pages: 4152-4155, ISSN: 0031-9007
  • Journal article
    Gumbrell ET, Smith RA, Ditmire T, Djaoui A, Rose SJ, Hutchinson MHRet al., 1998,

    Picosecond optical probing of ultrafast energy transport in short pulse laser solid target interaction experiments

    , PHYSICS OF PLASMAS, Vol: 5, Pages: 3714-3721, ISSN: 1070-664X
  • Journal article
    Hall TA, Ellwi S, Batani D, Bernardinello A, Masella V, Koenig M, Benuzzi A, Krishnan J, Pisani F, Djaoui A, Norreys P, Neely D, Rose S, Key MH, Fews Pet al., 1998,

    Fast electron deposition in laser shock compressed plastic targets

    , PHYSICAL REVIEW LETTERS, Vol: 81, Pages: 1003-1006, ISSN: 0031-9007

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