Publications

Simpson, Sean S.; Coats, Rebecca S.; Hjalmarson, Harold P.; Jorgenson, Roy E.; Pasik, Michael F.

This report documents work conducted in FY13 on electrical discharge experiments performed to develop predictive computational models of the fundamental processes of surface breakdown in the vicinity of high-permittivity material interfaces. Further, experiments were conducted to determine if free carrier electrons could be excited into the conduction band thus lowering the effective breakdown voltage when UV photons (4.66 eV) from a high energy pulsed laser were incident on the rutile sample. This report documents the numerical approach, the experimental setup, and summarizes the data and simulations. Lastly, it describes the path forward and challenges that must be overcome in order to improve future experiments for characterizing the breakdown behavior for rutile.

Pasik, Michael F.; Coats, Rebecca S.; Jorgenson, Roy E.; Hjalmarson, Harold P.

Abstract not provided.

Kotulski, J.D.; Coats, Rebecca S.; Ulrickson, M.A.

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Kotulski, J.D.; Coats, Rebecca S.; Ulrickson, M.A.

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Pasik, Michael F.; Coats, Rebecca S.; Jorgenson, Roy E.; Hjalmarson, Harold P.

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Jorgenson, Roy E.; Pasik, Michael F.; Coats, Rebecca S.; Hjalmarson, Harold P.; Lehr, J.M.; DiAntonio, Christopher D.; Wallace, Zachariah R.

Abstract not provided.

Kotulski, J.D.; Coats, Rebecca S.

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Kotulski, J.D.; Coats, Rebecca S.

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Kotulski, J.D.; Coats, Rebecca S.; Ulrickson, M.A.

Abstract not provided.

Warne, Larry K.; Martinez, Leonard E.; Jorgenson, Roy E.; Merewether, Kimball O.; Jojola, John M.; Coats, Rebecca S.; Bystrom, Edward B.

A lightning flash consists of multiple, high-amplitude but short duration return strokes. Between the return strokes is a lower amplitude, continuing current which flows for longer duration. If the walls of a Faraday cage are made of thin enough metal, the continuing current can melt a hole through the metal in a process called burnthrough. A subsequent return stroke can couple energy through this newly-formed hole. This LDRD is a study of the protection provided by a Faraday cage when it has been compromised by burnthrough. We initially repeated some previous experiments and expanded on them in terms of scope and diagnostics to form a knowledge baseline of the coupling phenomena. We then used a combination of experiment, analysis and numerical modeling to study four coupling mechanisms: indirect electric field coupling, indirect magnetic field coupling, conduction through plasma and breakdown through the hole. We discovered voltages higher than those encountered in the previous set of experiments (on the order of several hundreds of volts).

Digest of Technical Papers-IEEE International Pulsed Power Conference

VanDevender, J.P.; Langston, William L.; Pasik, Michael F.; Coats, Rebecca S.; Pointon, Timothy D.; Seidel, David B.; Jennings, C.A.; McKee, G.R.; Schneider, Larry X.

We have developed a new type of convolute called the Clam Shell MITL (CSMITL) to couple multi-level accelerators to a common load. The CSMITL has magnetic nulls only at large radius where the cathode electric field is kept below the threshold for emission, has only a simply connected magnetic topology to avoid plasma motion along magnetic field lines into highly stressed gaps, and has electron injectors that ensure efficient electron flow even in the limiting case of self-limited MITLs. We report the first experimental results on a CSMITL, which convolutes two disk feeds on the Saturn accelerator into a single disk feed. Experiments with a high impedance electron beam load operating at twice the self-limited impedance of the CSMITL confirm key design features and demonstrate robust operation. © 2011 IEEE.

Digest of Technical Papers-IEEE International Pulsed Power Conference

Glover, Steven F.; Davis, Jean-Paul D.; Schneider, Larry X.; Reed, Kim W.; Pena, Gary P.; Hall, Clint A.; Hanshaw, Heath L.; Hickman, Randy J.; Hodge, K.C.; Lemke, Raymond W.; Lehr, J.M.; Lucero, D.J.; McDaniel, Dillon H.; Puissant, J.G.; Rudys, Joseph M.; Sceiford, Matthew S.; Tullar, S.J.; Van De Valde, D.M.; White, F.E.; Warne, Larry K.; Coats, Rebecca S.; Johnson, William Arthur.

The success of dynamic materials properties research at Sandia National Laboratories has led to research into ultra-low impedance, compact pulsed power systems capable of multi-MA shaped current pulses with rise times ranging from 220-500 ns. The Genesis design consists of two hundred and forty 200 kV, 80 kA modules connected in parallel to a solid dielectric disk transmission line and is capable of producing 280 kbar of magnetic pressure (>500 kbar pressure in high Z materials) in a 1.75 nH, 20 mm wide stripline load. Stripline loads operating under these conditions expand during the experiment resulting in a time-varying load that can impact the performance and lifetime of the system. This paper provides analysis of time-varying stripline loads and the impact of these loads on system performance. Further, an approach to reduce dielectric stress levels through active damping is presented as a means to increase system reliability and lifetime. © 2011 IEEE.

Proceedings - Symposium on Fusion Engineering

Kotulski, Joseph D.; Coats, Rebecca S.; Ulrickson, M.A.

The prediction of electromagnetic loads on the ITER blanket modules during a plasma disruption is considered for two different blanket modules and different disruption events. © 2011 IEEE.

Glover, Steven F.; Lemke, Raymond W.; Lehr, J.M.; Lucero, Diego J.; McDaniel, Dillon H.; Rudys, Joseph M.; Sceiford, Matthew S.; Davis, Jean-Paul D.; Warne, Larry K.; Coats, Rebecca S.; Johnson, William Arthur.; Schneider, Larry X.; Pena, Gary P.; Hall, Clint A.; Hanshaw, Heath L.; Hickman, Randy J.

Abstract not provided.

Coats, Rebecca S.; Ulrickson, M.A.

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Coats, Rebecca S.; Ulrickson, M.A.

Abstract not provided.

Glover, Steven F.; Rudys, Joseph M.; Sceiford, Matthew S.; Warne, Larry K.; Coats, Rebecca S.; Johnson, William Arthur.; Davis, Jean-Paul D.; Schneider, Larry X.; Reed, Kim W.; Pena, Gary P.; Hall, Clint A.; Hickman, Randy J.; Lehr, J.M.; McDaniel, Dillon H.

Abstract not provided.

Langston, William L.; Pasik, Michael F.; Coats, Rebecca S.; Pointon, Timothy D.; Seidel, David B.; McKee, George R.; Schneider, Larry X.

Abstract not provided.

Kotulski, J.D.; Coats, Rebecca S.; Ulrickson, M.A.

Abstract not provided.

Pasik, Michael F.; Coats, Rebecca S.; Ulrickson, M.A.

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Fusion Science and Technology

Coats, Rebecca S.; Pasik, Michael F.; Ulrickson, M.A.

Abstract not provided.

IEEE Transactions on Plasma Science

Warne, Larry K.; Jorgenson, Roy E.; Martinez, Leonard E.; Jojola, John M.; Coats, Rebecca S.; Merewether, Kimball O.

Abstract not provided.

Physical Review Special Topics in Accelerators and Beams

Langston, William L.; Pasik, Michael F.; Coats, Rebecca S.; Pointon, Timothy D.; Seidel, David B.; McKee, George R.; Schneider, Larry X.

Abstract not provided.

Coats, Rebecca S.; Pasik, Michael F.; Ulrickson, M.A.

Abstract not provided.

Jorgenson, Roy E.; Warne, Larry K.; Coats, Rebecca S.

This report documents calculations conducted to determine if 42 low-power transmitters located within a metallic enclosure can initiate electro-explosive devices (EED) located within the same enclosure. This analysis was performed for a generic EED no-fire power level of 250 mW. The calculations show that if the transmitters are incoherent, the power available is 32 mW - approximately one-eighth of the assumed level even with several worst-case assumptions in place.