Final Report Radiation-magnetohydrodynamic evolution and instability of conductors driven by megagauss magnetic fields

We are pleased to report important progress in experimentally characterizing and numerically modeling the transformation into plasma of walls subjected to pulsed megagauss magnetic fields. Understanding this is important to Magnetized Target Fusion (MTF) because an important limitation to the metal liner approach to MTF comes from the strong eddy current heating on the surface of the metal liner. This has intriguing non-linear aspects when the magnetic field is in the megagauss regime as needed for MTF, and may limit the magnetic field in an MTF implosion. Many faculty, students, and staff have contributed to this work, and, implicitly or explicitly, to this report. Contributors include, in addition to the PIs

Advanced load current multiplier on Zebra generator

International audienceAn improved load current multiplier (LCM) was designed and tested on a high-voltage 100 ns, 0.8-1 MA generator Zebra. The new design allowed to achieve up to ~1.7 MA in plasma loads and up to 1.9 MA in static loads [1]. The previous LCM version provided 1.4 and 1.6 MA accordingly [2]. The load current increase results in the increase of X-ray yield and power from plasma radiation source loads [3]. The advanced LCM represents an integral part of Zebra, inside the generator vacuum section. The new low-inductance design of LCM-to-load connection ensured shielding of the multiplier convolute from load events. Experiments with plasma loads were thus possible without after-shot dismounting of LCM for load installation and diagnostics arrangement. Validation of LCM's on a high-voltage nanosecond generator suggests that the concept could be applicable to existing and future multi-MA fast pulse-power drivers. Anticipating these applications, we present first estimates supporting scaling-up of the LCM technique to multi-terawatt facilities

First Analysis of Radiative Properties of Moderate-atomic-number Planar Wire Arrays on Zebra at UNR at Higher Current of 1.7 MA

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Operation of a load current multiplier on a nanosecond mega-ampere pulse forming line generator

International audienceWe investigate the operation of a load current multiplier (LCM) on a pulse-forming-line nanosecond pulse-power generator. Potential benefits of using the LCM technique on such generators are studied analytically for a simplified case. A concrete LCM design on the Zebra accelerator (1.9 Ohm, ∼1  MA, 100 ns) is described. This design is demonstrated experimentally with high-voltage power pulses having a rise time of dozens of nanoseconds. Higher currents and magnetic energies were observed in constant-inductance solid-state loads when a better generator-to-load energy coupling was achieved. The load current on Zebra was increased from the nominal 0.8–0.9 MA up to about 1.6 MA. This result was obtained without modifying the generator energetics or architecture and it is in good agreement with the presented numerical simulations. Validation of the LCM technique at a nanosecond time scale is of importance for the high-energy-density physics research

Proton imaging of an electrostatic field structure formed in laser-produced counter-streaming plasmas

We report the measurements of electrostatic field structures associated with an electrostatic shock formed in laser-produced counter-streaming plasmas with proton imaging. The thickness of the electrostatic structure is estimated from proton images with different proton kinetic energies from 4.7 MeV to 10.7 MeV. The width of the transition region is characterized by electron scale length in the laser-produced plasma, suggesting that the field structure is formed due to a collisionless electrostatic shock.ISSN:1742-6588ISSN:1742-659

Vascular complications following intra-aortic balloon pump implantation: an updated review

BACKGROUND: The use of the intra-aortic balloon pump (IABP) as a support device remains controversial due to the fact that a number of studies have shown no benefit in end mortality whilst using this device. One of the reasons for this could be the increase in vascular complications when using the pump. Therefore, the aim of the present review was to assess the current literature available with regards to IABP vascular complications during the clinical situation. METHODS: A literature search was performed, searching for IABP complications in adult human studies between 1990 and 2016. RESULTS: A total of 20 reports were identified as fitting the criteria of this study. The majority of vascular complications were limb ischemia, bleeding or mesenteric ischemia. The overall incidence of vascular complications ranged from 0.94% to 31.1%. Diabetes, peripheral vascular disease and hypertension, as well as smoking were all identified as risk factors for complications following IABP. Furthermore, studies supported the use of sheathless balloon insertion to reduce the risk of complications. CONCLUSION: Major vascular complications, including limb and mesenteric ischemia as well as bleeding and hemorrhage, have been associated with IABP. However, the incidence of these complications was generally low. Further studies are still required to truly understand the risk/benefit associated with the use of IABP