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A technique to determine the time of burst for exploding aluminum metallized films has been studied. An experimental approach has been taken to determine the burst time relative to the discharge current, voltage, resistance, and power waveforms. A microphone transducer was employed to detect the time of burst from the sound produced by the bursting of the film and was compared to the calculated burst...
Summary form only given. Foils may soon become necessary to achieve the required mass for higher current-driven x-ray sources. They may also offer useful options for x-ray pulse shaping and as imploding liners for magnetized target fusion. This paper reports our latest design and experimental progress on the dominant instability, the magneto-Rayleigh-Taylor instability (MRT). Planar Al foils as thin...
Star wire arrays with two closely located wires (“gates”) on the inner cylinder of star wire arrays were studied. The gate wires were used to study plasma interpenetration and reproduce transparent and non-transparent regimes of propagation of the imploding plasma through the gates. The non-transparent mode of collision is typical for regular star wire arrays and it was also observed in Al stars with...
Summary form only given. Recent aluminum rod experiments driven by 1-MA Zebra generator at University of Nevada, Reno (UNR) have provided a benchmark for magnetohydrodynamic (MHD) modeling. The innovative 'hourglass' and 'barbell' load geometries used in the experiments made it possible to distinguish between plasma formation due to Ohmic heating, which can be studied numerically utilizing MHD codes,...
Thin wires have been added on the axis of cylindrical and conical wire arrays to investigate the effect of sheared plasma flows on the z-pinch stability. This addition significantly affected the x-ray emission of the conical wire arrays, while having little effect on that of the cylindrical ones. In addition, the material of the axial target had a strong influence on the radiation output. The experiments...
We consider the Hall effect in pulsed power generated plasma flows and its role in the creation of radial electric fields and plasma instability. We have developed a code based on the generalized Ohm's law plasma description that has allowed us to explore physics neglected by the resistive magnetohydrodynamic (MHD) model. We present simulation results of imploding Aluminum cylindrical wire arrays...
Summary form only given. A 0D circuit code is introduced to study the wire array switch concept introduced in. It has been implemented and researched at Imperial College. An exploding wire array, the switch, is in parallel with the load, an imploding wire array. Most of the current flows in the exploding array until it expands and becomes highly resistive. The 0D code contains simple models of Joule...
Magnetic field measurements inside wire-array Z-pinches have shown significant field penetration during the ablation phase, as wire material streams toward the axis producing the mass distribution that ultimately determines the implosion characteristics. End-on imaging is especially useful for observing the dynamical effects of the magnetic field on the ablation streams. Quantitative end-on imaging...
Summary form only given. Distribution of matter in the discharge channel formed upon a nanosecond electrical explosion of Al wire in vacuum was studied experimentally and theoretically. Simultaneous use of optical and UV diagnostics and numerical results made it possible to distinguish qualitatively different regions of the discharge channel, such as the current-carrying plasma layers and the region...
Summary form only given. The ablation phase of exploding multi-wire experiments driven by fast-rising currents in which both global and local magnetic fields are dynamically significant is poorly understood at present. In particular, a quasi-periodic modulation in the plasma flow accelerated from the wire cores following initiation appears at all current levels, and is not fully explained. The lack...
Summary form only given. The magneto-Rayleigh-Taylor (MRT) instability is ubiquitous to pinch plasmas compressed by magnetic pressure, and is an important factor in determining whether a cylindrical liner can reach the axis in a relatively intact form. While there are many RT characterization experiments, there are few well-characterized MRT experiments and none for fast (~100 ns) z-pinch implosions...
A series of Al/Mg nested wire array Z-pinch load experiments has been recently performed on the refurbished Z accelerator. The earlier comparison study of the results from ID and 2D radiation MHD simulations of the Sandia Z1907/1908 experiments [Y. K. Chong, et. al, APS09] has shown that, in addition to the substantial difference in the prediction capability of the ID and 2D models, the radiation...
Summary form only given. Triple Planar Wire Arrays (TPWA) consisted from three planes made of Mo (uniform) or from Mo and Al wire planes (combined). Each plane from Mo or Al wires was almost the same mass and therefore the total linear mass of both uniform and combined TPWAs was about 115 μg/cm. The previous results with 3 mm between planes are revisited. New experiments with the same TPWAs but with...
Summary form only given. Experiments with different Z-pinch loads were performed on 1.4 MA, 100 ns Zebra generator at UNR. The program emphasized investigation of plasma formation, implosion and radiation features as a function of the load configuration: compact multi-planar and cylindrical wire arrays. The multi-planar wire arrays (PWA) were studied in open and closed configuration with Al, stainless...
Summary form only given. Optical emission from plasmas can be used to provide key parameters of the plasma such as the elemental composition, temperature, densities, charge states, expansion/implosion velocities and potentially estimates of plasma elemental mass values. Optical spectroscopy has been fielded for the first time on an explosively driven flat plate hydrodynamic experiment at AWE. The...
Summary form only given. Recent aluminum rod experiments driven by 1-MA Zebra generator at University of Nevada, Reno (UNR) have provided a benchmark for magnetohydrodynamic (MHD) modeling. The innovative 'hourglass' and 'barbell' load geometries used in the experiments made it possible to distinguish between plasma formation due to Ohmic heating, which can be studied numerically utilizing MHD codes,...
Summary form only given. The UV laser probing at 266 nm is a promising diagnostics for the Z-pinch plasma. Laser diagnostics at the wavelength 532 nm are not applicable for Z-pinches with an electron plasma density ne>5-1019 cm-3 because of the strong inverse bremsstrahlung absorption and refraction of the probing beam. UV laser probing has a significant advantage because the absorption increment...
Summary form only given. EUV spectroscopy is a feasible tool for diagnosing of Z-pinch plasma before and after stagnation in complement to X-ray spectroscopy, which is conventionally used in studying of the stagnating hot dense plasmas. A collection of aluminum EUV spectra from implosions of traditional cylindrical wire arrays and new planar wire arrays (PWA) on the 1 MA Zebra generator at UNR are...
Summary form only given. A general overview of Mo planar wire array implosions (single, double, and triple) from the past three years on the 1 MA, 100 ns UNR Zebra generator is presented. Mo planar wire arrays on Zebra have radiated high peak powers and yields (up to 1 TW and 24 kJ) as well as produced high-temperature L-shell plasmas (up to 1.4 keV), indicating the importance in connection with inertial...
Summary form only given. The double-planar wire array (DPWA) is the most promising Z-pinch load studied on the Zebra generator for application to radiation physics and inertial confinement fusion studies. These loads radiate powers and energies up to ~1 TW and ~25 kJ, respectively, in a versatile pulse shape on the 1 MA Zebra generator. Recent studies show that radiation yields of this load scale...
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