Publications

Results 176–200 of 326

Search results

Jump to search filters

Diagnosing suprathermal ion populations in Z-pinch plasmas using fusion neutron spectra

Physics of Plasmas

Knapp, Patrick K.; Sinars, Daniel S.; Hahn, Kelly D.

The existence of suprathermal ion populations gives rise to significant broadening of and modifications to the fusion neutron spectrum. We show that when this population takes the form of a power-law at high energies, specific changes occur to the spectrum which are diagnosable. In particular, the usual Gaussian spectral shape produced by a thermal plasma is replaced by a Lorentz-like spectrum with broad wings extending far from the spectral peak. Additionally, it is found that the full width at half maximum of the spectrum depends on both the ion temperature and the power-law exponent. This causes the use of the spectral width for determination of the ion temperature to be unreliable. We show that these changes are distinguishable from other broadening mechanisms, such as temporal and motional broadening, and that detailed fitting of the spectral shape is a promising method for extracting information about the state of the ions. © 2013 AIP Publishing LLC.

More Details
TYPE Journal Article YEAR 2013
DOIOSTIScopus

Conceptual designs of 300-TW and 800-TW pulsed-power accelerators

Stygar, William A.; Fowler, William E.; Gomez, Matthew R.; Harmon, Roger L.; Herrmann, Mark H.; Huber, Dale L.; Hutsel, Brian T.; Bailey, James E.; Jones, Michael J.; Jones, Peter A.; Leckbee, Joshua L.; Lee, James R.; Lewis, Scot A.; Long, Finis W.; Lopez, Mike R.; Lucero, Diego J.; Matzen, M.K.; Mazarakis, Michael G.; McBride, Ryan D.; McKee, George R.; Nakhleh, Charles N.; Owen, Albert C.; Rochau, G.A.; Savage, Mark E.; Schwarz, Jens S.; Sefkow, Adam B.; Sinars, Daniel S.; Stoltzfus, Brian S.; Vesey, Roger A.; Wakeland, P.; Cuneo, M.E.; Flicker, Dawn G.; Focia, Ronald J.

Abstract not provided.

More Details
TYPE Conference YEAR 2013
OSTI

Electrothermal instability growth in magnetically driven pulsed power liners

Physics of Plasmas

Sinars, Daniel S.; Yu, Edmund Y.; Herrmann, Mark H.; Cuneo, M.E.; Slutz, Stephen A.; Smith, Ian C.; Atherton, B.W.; Knudson, Marcus D.; Nakhleh, Charles N.

This paper explores the role of electro-thermal instabilities on the dynamics of magnetically accelerated implosion systems. Electro-thermal instabilities result from non-uniform heating due to temperature dependence in the conductivity of a material. Comparatively little is known about these types of instabilities compared to the well known Magneto-Rayleigh-Taylor (MRT) instability. We present simulations that show electrothermal instabilities form immediately after the surface material of a conductor melts and can act as a significant seed to subsequent MRT instability growth. We also present the results of several experiments performed on Sandia National Laboratories Z accelerator to investigate signatures of electrothermal instability growth on well characterized initially solid aluminum and copper rods driven with a 20 MA, 100 ns risetime current pulse. These experiments show excellent agreement with electrothermal instability simulations and exhibit larger instability growth than can be explained by MRT theory alone. © 2012 American Institute of Physics.

More Details
TYPE Journal Article YEAR 2012
OSTIScopus
Results 176–200 of 326
Results 176–200 of 326