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Full-Text Articles in Physical Sciences and Mathematics
Numerical Modeling Of Hohlraum Radiation Conditions: Spatial And Spectral Variations Due To Sample Position, Beam Pointing, And Hohlraum Geometry, David H. Cohen, O. L. Landen, J. J. Macfarlane
Numerical Modeling Of Hohlraum Radiation Conditions: Spatial And Spectral Variations Due To Sample Position, Beam Pointing, And Hohlraum Geometry, David H. Cohen, O. L. Landen, J. J. Macfarlane
Physics & Astronomy Faculty Works
View-factor simulations are presented of the spatially varying radiation conditions inside double-ended gold Hohlraums and single-ended gold Hohlraums ('' halfraums '') used in inertial confinement fusion and high-energy density physics experiments [J. Lindl, Phys. Plasmas 11, 339 (2004); M. D. Rosen, Phys. Plasmas 3, 1803 (1996)]. It is shown that in many circumstances, the common assumption that the Hohlraum '' drive '' can be characterized by a single temperature is too simplistic. Specifically, the radiation conditions seen by an experimental package can differ significantly from the wall reemission measured through diagnostic holes or laser entrance holes (LEHs) by absolutely calibrated …
Chandra Hetgs Multiphase Spectroscopy Of The Young Magnetic O Star Theta(1) Orionis C, M. Gagné, M. E. Oksala, David H. Cohen, Stephanie Korinne Tonnesen , '03, A. Ud-Doula, S. P. Owocki, R. H.D. Townsend, J. J. Macfarlane
Chandra Hetgs Multiphase Spectroscopy Of The Young Magnetic O Star Theta(1) Orionis C, M. Gagné, M. E. Oksala, David H. Cohen, Stephanie Korinne Tonnesen , '03, A. Ud-Doula, S. P. Owocki, R. H.D. Townsend, J. J. Macfarlane
Physics & Astronomy Faculty Works
We report on four Chandra grating observations of the oblique magnetic rotator theta(1) Ori C (O5.5 V), covering a wide range of viewing angles with respect to the star's 1060 G dipole magnetic field. We employ line-width and centroid analyses to study the dynamics of the X-ray - emitting plasma in the circumstellar environment, as well as line-ratio diagnostics to constrain the spatial location, and global spectral modeling to constrain the temperature distribution and abundances of the very hot plasma. We investigate these diagnostics as a function of viewing angle and analyze them in conjunction with new MHD simulations of …
Diagnostics Of Disks Around Hot Stars, David H. Cohen, M. H. Hanson, R. H.D. Townsend, K. S. Bjorkman, M. Gagné
Diagnostics Of Disks Around Hot Stars, David H. Cohen, M. H. Hanson, R. H.D. Townsend, K. S. Bjorkman, M. Gagné
Physics & Astronomy Faculty Works
We discuss three different observational diagnostics related to disks around hot stars: absorption line determinations of rotational velocities of Be stars; polarization diagnostics of circumstellar disks; and X-ray line diagnostics of one specific magnetized hot star, theta(1) Ori C. Some common themes that emerge from these studies include (a) the benefits of having a specific physical model as a framework for interpreting diagnostic data; (b) the importance of combining several different types of observational diagnostics of the same objects; and (c) that while there is often the need to reinterpret traditional diagnostics in light of new theoretical advances, there are …