[en] This report covers the Second International Conference on Dense Z-pinches (that is, Z-pinches in which the density is within 1-2 orders of magnitude of solid density), held 26-28 April, 1989, in Laguna Beach, CA. In the conference, attended by scientists from a wide variety of nations working on various aspects of the linear dense Z-pinch, the multifaceted applications and problems associated with this physical phenomenon were apparent, and the common grounds forming the basis of the scientific work led to fruitful exchanges. These mutual areas of interest related not only to the hardware needed to form such pinch devices, but to magnetic compression, stability, and fusion properties. Diagnostics also provided another common area of interest. A succeeding conference is to be held in 1992 in London

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[en] The first part of this work is a review of results of z-pinch plasma experiments. The main part reports on spectroscopic investigations of dense plasmas. The investigations have been carried out on two pinch experiments in Bochum, supplementary measurements were possible on a new high voltage pinch in Los Alamos. (author)

[en] Short communication

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[en] In numerous experiments, magnetic energy coupled to strongly radiating Z-pinch plasmas exceeds the thermalized kinetic energy, sometimes by a factor of 2-3. An analytical model describing this additional energy deposition based on the concept of macroscopic magnetohydrodynamic (MHD) turbulent pinch heating proposed by Rudakov and Sudan [Phys. Reports 283, 253 (1997)] is presented. The pinch plasma is modeled as a foam-like medium saturated with toroidal ''magnetic bubbles'' produced by the development of surface m=0 Rayleigh-Taylor and MHD instabilities. As the bubbles converge to the pinch axis, their magnetic energy is converted to thermal energy of the plasma through pdV work. Explicit formulas for the average dissipation rate of this process and the corresponding contribution to the resistance of the load, which compare favorably to the experimental data and simulation results, are presented. The possibility of using this enhanced (relative to Ohmic heating) dissipation mechanism to power novel plasma radiation sources and produce high K-shell yields using long current rise time machines is discussed. (c) 2000 American Institute of Physics

[en] Rayleigh endash Taylor (RT) instability of cylindrical, imploding plasma liners in a Z-pinch is analyzed. The reduction in total perturbation growth for multicascade systems (multiple imploding shells) is presented. This reduction is effective if the pressure produced by the impacting shell exceeds the magnetic pressure at the time of impact. Analytical and numerical solutions are also obtained for the RT instability of an imploding plasma liner accelerated into undisturbed plasma. The snowplow model is used in which the mass encountered by the imploding magnetic piston is swept into an infinitely thin sheath. A shock front launched ahead of the liner is shown to reduce the growth rate. It is also shown that accumulating the mass increases the growth rate. However, the total perturbation growth can be reduced if the liner accumulates the mass during the implosion compared to a liner with the same mass imploding into vacuum. Finally, it is shown that the final kinetic energy density for a given shell nonuniformity is largest if the final liner mass is accumulated during the implosion. copyright 1997 American Institute of Physics

[en] Ultrahigh pulsed power with short rise time has been needed in many applications. For single linear transformer driver (LTD) module with sixty cavities connected in series, this paper has explored the effect of the cavity-triggering sequences on the output current parameters of the LTD module and discussed the possibility to optimize the output parameters of single LTD module through adjusting the triggering time of each cavity. The results indicate that the current shapes of single LTD module could be adjusted effectively through adjusting the cavity triggering sequence. And the output current will have shorter risetime and higher peak if the switches in each cavity are closed after the arrival of the electromagnetic pulses from its neighbor immediately upstream. With the insulation level of present switches used in LTD facilities considered, a pulsed current with the risetime of 12.5 ns reduced by a factor of 4 from 56.50 ns and the peak of 1 340 kA increased by 30% from 1 018 kA could be generated by the LTD module when the cavity-triggering sequence is optimized to make the Jantage across the switches before closure increase from DC charging Jantage 200 kV to pulse Jantage of 400 kV. (authors)

No abstract available

[en] Z-pinch experiments using cryogenic deuterium fibre loads have been carried out on the MAGPIE generator at currents up to 1.4MA. M=0 instabilities in the corona caused plasma expansion and disruption before the plasma could enter the collisionless Large ion Larmor radius regime. For the last 12 months we have studied Aluminium wire array implosions using laser probing, optical streaks and gated X-ray images. Plasma from the wires in accelerated to the axis as radial plasma streams with uncorrelated m=0 instabilities superimposed. Later in the discharge a global Rayleigh-Taylor (R-T) instability develops. Single and double aluminium and tungsten wire shots were conducted at 150kA. 2-D and 3-D simulations and a heuristic model of wire arrays will be presented along with theories on the combined MHD/R-T instability and sheared axial flow generation by large ion Larmor radius effects. (author)