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Glover S.F.,Sandia National Laboratories | Foster P.J.,Defense Nuclear Facilities Safety Board | McDaniel D.H.,Sandia National Laboratories | White F.E.,SAIC | And 2 more authors.
Proceedings of the 2012 IEEE International Power Modulator and High Voltage Conference, IPMHVC 2012 | Year: 2012

Dynamic materials properties research at Sandia National Laboratories has resulted in research that is advancing capabilities in precision programmable pulsed power systems operating in multi-mega amp regimes. Programmable pulse shaping capabilities require the gas switches in these systems to perform over a large range of dynamic operating conditions. Runtime, jitter, and the number of channels formed are all impacted by the conditions of these switches at the time of trigger. This paper provides a model and analysis of a 200 kV gas switch designed for linear transformer drivers operating at percentages of self break ranging from 45% to 100%. This work expands on the research performed by T.H. Martin and S.I. Braginskii. © 2012 IEEE.

Glover S.F.,Sandia National Laboratories | White F.E.,SAIC | Pena G.E.,Sandia National Laboratories | Foster P.J.,Defense Nuclear Facilities Safety Board
Proceedings of the 2012 IEEE International Power Modulator and High Voltage Conference, IPMHVC 2012 | Year: 2012

Development of solid dielectric insulation concepts has enabled an ultra-low impedance high current driver concept called Genesis. A prototype demonstration called Protogen includes interfaces for up to twelve modules and can be operated in a repetitive mode to generate reliability data. Initial operation of Protogen is focusing on the integration of key solid dielectric concepts, dielectric lifetime, and integrated system performance. Multiple configurations of Protogen have already been tested demonstrating the flexibility of Genesis technology. This paper expands on previously published results paying particular attention to versatility, reliability, and modeling of the Protogen system. © 2012 IEEE.

Zutavern F.J.,Sandia National Laboratories | Glover S.F.,Sandia National Laboratories | Mancuso A.P.,Sandia National Laboratories | Foster P.J.,Defense Nuclear Facilities Safety Board | White F.E.,SAIC
Digest of Technical Papers-IEEE International Pulsed Power Conference | Year: 2013

Pulsed power gas switches operate under extreme conditions holding off voltages at millions of volts and greater, conducting currents at 100's of kiloamps, and can reliably trigger with less than 10ns of jitter at optimal operating conditions. However as Martin and Braginskii had noted the impedance of these switches is dynamic and a function of many parameters such as gas pressure, current, and the number of channels. In systems such as Protogen or Ursa Minor many gas switches are utilized to enable optimal performance and pulse shaping. A challenge with either system is that, if the switches are tightly coupled and one switch triggers early, then the fields on the second switch change dramatically and can move the second switch into a new operating regime that will result in a different dynamic resistance. This paper presents a least squares approach to extracting the Martin and Braginskii switch resistance with field dependent carrier recombination from measured data. © 2013 IEEE.

Mossman K.L.,Defense Nuclear Facilities Safety Board
Health Physics | Year: 2014

Management of radiological risks typically encountered in environmental and occupational settings is challenging because of uncertainties in the magnitude of the risks and the benefits of risk reduction. In practice, radiation dose instead of risk is measured. However, the relationship between dose and risk is not straightforward because cancer (the major health effect of concern at low doses) is a disease of complexity. Risks at small doses (defined as less than 100 mSv) can never be known exactly because of the inherent uncertainties in cancer as a complex disease. Tumors are complex because of the nonlinear interactions that occur among tumor cells and between the tumor and its local tissue environment. This commentary reviews evidence for cancer complexity and what complexity means for radiation protection. A complexity view of cancer does not mean we must abandon our current system of protection. What it does mean is that complexity requires new ways of thinking about control of cancer - the ideas that cancers can occur without cause, cancers behave unpredictably, and calculated cancer risks following small doses of radiation are highly uncertain. © 2014 Health Physics Society.

Andersen D.K.,University of Illinois at Urbana - Champaign | Andersen D.K.,Defense Nuclear Facilities Safety Board | Vakakis A.F.,University of Illinois at Urbana - Champaign | Bergman L.A.,University of Illinois at Urbana - Champaign
Conference Proceedings of the Society for Experimental Mechanics Series | Year: 2011

The influence of adding a geometrically nonlinear viscous damper to a system of coupled oscillators with essential nonlinear stiffness will be discussed. All nonlinear terms are restricted to the coupling terms between a linear oscillator and light attachment. We show that the addition of the nonlinear damper introduces dynamics not observed with linear damping. In fact, we find the surprising result that the nonlinear damper introduces new dynamics into the problem, and its effect on the dynamics is far from being purely parasitic - as one would expect in the case of weak linear viscous dissipation. Similar to essential nonlinear stiffness, geometrically nonlinear damping of the type considered in our work is physically realizable by means of linear viscous damping elements. Numerical work examining this problem will be discussed. ©2010 Society for Experimental Mechanics Inc.

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