NASA Scientific and Technical Aerospace Reports

20040120896 Georgia Inst. of Tech., Atlanta, GA, USA
Annual Report of the Fusion Research Center, Georgia Institute of Technology, 2003
Stacey, W. M.; Mandrekas, J.; Dec. 2003; 24 pp.; In English
Report No.(s): PB2004-105911; No Copyright; Avail: CASI; A03, Hardcopy
Contents include the following: Next Step Option Design Studies (DOE Grant ER54350) (Fusion Transmutation of
Nuclear Waste; Toroidal Rotation and Radial Electric Field in Edge Pedestal).
NTIS
Nuclear Fusion; Radioactive Wastes
20040120923 Princeton Univ., NJ
MHD Ballooning Instability in the Plasma Sheet
Cheng, C. Z.; Zaharia, S.; Oct. 2003; In English
Report No.(s): DE2004-820113; PPPL-3890; No Copyright; Avail: National Technical Information Service (NTIS)
Based on the ideal-MHD model the stability of ballooning modes is investigated by employing realistic 3D
magnetospheric equilibria, in particular for the substorm growth phase. Previous MHD ballooning stability calculations
making use of approximations on the plasma compressibility can give rise to erroneous conclusions. Our results show that
without making approximations on the plasma compressibility the MHD ballooning modes are unstable for the entire plasma
sheet where beta (sub)eq is greater than or equal to 1, and the most unstable modes are located in the strong cross-tail current
sheet region in the near-Earth plasma sheet, which maps to the initial brightening location of the breakup arc in the ionosphere.
However, the MHD beq threshold is too low in comparison with observations by AMPTE/CCE at X= -(8 - 9)R(sub)E, which
show that a low-frequency instability is excited only when beq increases over 50. The difficulty is mitigated by considering
the kinetic effects of ion gyrorad ii and trapped electron dynamics, which can greatly increase the stabilizing effects of field
line tension and thus enhance the beta(sub)eq threshold (Cheng and Lui, 1998). The consequence is to reduce the equatorial
region of the unstable ballooning modes to the strong cross-tail current sheet region where the free energy associated with the
plasma pressure gradient and magnetic field curvature is maximum.
NTIS
Magnetohydrodynamic Stability; Plasmas (Physics)
20040120925 Princeton Univ., NJ
Turbulence Spreading into Linearly Stable Zone and Transport Scaling
Hahm, T. S.; Diamond, P. H.; Lin, Z.; Itoh, K.; Itoh, S. I.; Oct. 2003; In English
Report No.(s): DE2004-820109; PPPL-3887; No Copyright; Avail: National Technical Information Service (NTIS)
We study the simplest problem of turbulence spreading corresponding to the spatio-temporal propagation of a patch of
turbulence from a region where it is locally excited to a region of weaker excitation, or even local damping. A single model
equation for the local turbulence intensity I(x, t) includes the effects of local linear growth and damping, spatially local
nonlinear coupling to dissipation and spatial scattering of turbulence energy induced by nonlinear coupling. In the absence of
dissipation, the front propagation into the linearly stable zone occurs with the property of rapid progression at small t, followed
by slower subdiffusive progression at late times. The turbulence radial spreading into the linearly stable zone reduces the
turbulent intensity in the linearly unstable zone, and introduces an additional dependence on the rho* is always equal to rho
i/a to the turbulent intensity and the transport scaling. These are in broad, semi-quantitative agreements with a number of
global gyrokinetic simulation results with zonal flows and without zonal flows. The front propagation stops when the radial
flux of fluctuation energy from the linearly unstable region is balanced by local dissipation in the linearly stable region.
NTIS
Turbulence; Spreading; Nonlinearity; Energy Dissipation
76
SOLID-STATE PHYSICS
Includes condensed matter physics, crystallography, and superconductivity. For related information see also 33 Electronics and
Electrical Engineering; and 36 Lasers and Masers.
20040111142 Lockheed Martin Corp., Syracuse, NY, USA
Wafer-Bonded Internal Back-Surface Reflectors for Enhanced TPV Performance
Wang, C. A.; Murphy, P. G.; O’Brien, P. W.; Shiau, D. A.; Anderson, A. C.; Aug. 2002; In English
Report No.(s): DE2004-821703; LM-02K065; No Copyright; Avail: National Technical Information Service (NTIS)
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