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Accretion disk dynamics, photoionized plasmas, and stellar opacities
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View: Figures


Image of FIG. 1.
FIG. 1.

Schematics of experiment configurations used for laboratory astrophysics at the Z facility. The diagram in (a) shows the dynamic Hohlraum x-ray source used to investigate stellar interior opacities. The source is created when the annular tungsten wire arrays implode onto the foam, generating and trapping radiation that heats the sample. The CH-tamped Fe/Mg sample located above the source is shown in an expanded scale for clarity. The diagram in (b) shows a bare Z-pinch configuration used to study photoionized plasma kinetics. The gas located from the pinch is photoionized by x rays that emerge from the diagnostic viewing slots when the pinch implodes on axis. The top pinch electrode structure is not shown.

Image of FIG. 2.
FIG. 2.

Charge state distribution calculated for iron in the solar interior. The indicated radii, electron temperature, and electron density are from Ref. 6 and the calculations were performed with PRISMSPECT (Ref. 7).

Image of FIG. 3.
FIG. 3.

Transmission measured for a mixed Fe/Mg plasma at electron temperature and density . The transmission in the 800–987 eV range corresponds to a thin Fe sample and the transmission in the 992–1790 eV range corresponds to a thicker Fe sample (see Ref. 10). The Mg K-shell transitions are used to diagnose the plasma, enabling tests of opacity model calculations for the -shell transitions.

Image of FIG. 4.
FIG. 4.

Transmission measured for a photoionized neon plasma. PRISMSPECT model calculations are superimposed on the data.

Image of FIG. 5.
FIG. 5.

Schematic of the dog-bone shaped Hohlraum cavity and backlighter source for laser-driven photoionized plasma experiments.

Image of FIG. 6.
FIG. 6.

Comparison of fractional populations for a nitrogen photoionized plasma with results computed with the NIMP code (Ref. 19).

Image of FIG. 7.
FIG. 7.

Absorption line spectrum recorded by Chandra from AGN NGC3738 in the wavelength range from 1.25 to 13.8 A.

Image of FIG. 8.
FIG. 8.

Ionization balance distributions for oxygen, neon, magnesium, silicon, sulfur, and iron. Each plot displays the total fractional population per ionization stage as a function of the ionization parameter in .

Image of FIG. 9.
FIG. 9.

Schematic illustration of the main dynamical features seen in accretion disk simulations. From Ref. 41 [J. F. Hawley and J. H. Krolik, Astrophys. J. 641, 103 (2005)], copyright © The American Astronomical Society. Reprinted by permission of The American Astronomical Society.

Image of FIG. 10.
FIG. 10.

Evolution of magnetic field (white contours) and gas density (color contours) in a three-dimensional simulation beginning with an orbiting gas torus containing dipole magnetic field loops. (a) The initial condition. (b) At time the field has been brought down to the black hole and has begun to fill the axial region. (c) By time the field has become highly tangled within the accretion disk and coronal region, but along the axis the field is regular and mostly radial with a toroidal component due to the rotation of the black hole.

Image of FIG. 11.
FIG. 11.

Schematic of a possible experiment in which a laser heats a block of aerogel foam at subcritical density into which is doped the emitting material (for this experiment we choose the doped material to be sodium) in a region of a chosen (in this case planar) geometry. Thomson scattering determines the electron and ion temperature (both are needed: the first determines the kinetics and the second determines the line width and thereby the optical depth). The doped region remains unaffected until it is disrupted by the rarefaction wave that moves inwards from the outside of the foam. Calculations show that for sodium doped into the central region, the kinetics reach a steady state in a few hundreds of picoseconds which shows that the doped plasma has long enough to reach a steady state before it is disrupted. The spectroscopic observation of the line intensity ratio is conducted at a variety of angles and for a number of different dopant concentrations.


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752b84549af89a08dbdd7fdb8b9568b5 journal.articlezxybnytfddd
Scitation: Accretion disk dynamics, photoionized plasmas, and stellar opacities