Matthias Geissel, T. Awe, D. Bliss, M. Campbell, M. Gomez, E. Harding, A. Harvey-Thompson, S. Hansen, C. Jennings, M. Kimmel, P. Knapp, S. Lewis, R. McBride, K. Peterson, M. Schollmeier, D. Scoglietti, A. Sefkow, J. Shores, D. Sinars, S. Slutz, I. Smith, C. Speas, R. Vesey, J. Porter
Sandia National Laboratories is pursuing a variation of Magneto-Inertial Fusion called Magnetized Liner Inertial Fusion, or MagLIF. The MagLIF approach requires magnetization of the deuterium fuel, which is accomplished by an initial external B-Field and laser-driven pre-heat. While magnetization is crucial to the concept, it is challenging to couple sufficient energy to the fuel, since laser-plasma instabilities exist, and a compromise between laser spot size, laser entrance window thickness, and fuel density must be found. Nonlinear processes in laser plasma interaction, or laser-plasma instabilities (LPI), complicate the deposition of laser energy by enhanced absorption, backscatter, filamentation and beam-spray. Key LPI processes are determined, and mitigation methods are discussed. Results with and without improvement measures are presented.
Annular wire array implosions on the Sandia Z-machine can produce
>200 TW and 1-2 MJ of soft x rays in the 0.1-10 keV range. The
x-ray flux and debris in this environment present significant
challenges for radiographic diagnostics. X-ray backlighting
diagnostics at 1865 and 6181 eV using spherically-bent crystals
have been fielded on the Z-machine, each with a ~ 0.6 eV
spectral bandpass, 10 μm spatial resolution, and a 4 mm by 20
mm field of view. The Z-Beamlet laser, a 2-TW, 2-kJ Nd:glass laser
(λ=527 nm), is used to produce 0.1-1 J x-ray sources for
radiography. The design, calibration, and performance of these
diagnostics is presented.
The application of the X pinch x-ray source for phase-contrast x-ray radiography of low absorption materials is demonstrated. The X pinch is a source of radiation in the 1-10 keV x-ray band with extremely small size and short pulse duration. The small source size provides high spatial coherence of the imaging x-ray beam, enabling it to be used to image low absorption, low contrast objects with excellent spatial resolution. Images with spatial resolution better than 3 micrometers of exploded, insulated 25 micrometers W wire and biological objects are presented. The advantages of the X-pinch over other x-ray sources are discussed.
Several methods of using the X pinch as a source of x-ray radiation for the radiography of dense plasmas and other objects are presented. These methods do not use pinholes, instead taking advantage of the small source size and short x-ray emission duration of the X pinch radiation. Detailed measurements of the emission characteristics of X pinches made using different wire materials and in different energy ranges using a set of x-ray diagnostics with high temporal and spatial resolution are presented. Several applications of the X pinch are discussed.
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