scholarly journals The Effect of Field‐Aligned Currents and Centrifugal Forces on Ionospheric Outflow at Saturn

2020 ◽  
Vol 125 (7) ◽  
Author(s):  
C. J. Martin ◽  
L. C. Ray ◽  
M. Felici ◽  
D. A. Constable ◽  
C. T. S. Lorch ◽  
...  
Keyword(s):  
Centrifugal Forces ◽  
Ionospheric Outflow

Ionospheric Outflow at Jupiter and Saturn

2020 ◽  
Author(s):  
Carley Martin ◽  
Licia Ray ◽  
David Constable ◽  
David Southwood ◽  
Marianna Felici ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Fluid Model ◽  
Plasma Source ◽  
Atmospheric Plasma ◽  
Atmospheric Conditions ◽  
Centrifugal Forces ◽  
Mass Source ◽  
Auroral Emission ◽  
Ionospheric Outflow ◽  
Field Lines

<p>Ionospheric outflow is the outward flow of atmospheric plasma, initiated by a loss of equilibrium along the magnetic field. Terrestrial ionospheric outflow presents as a polar wind triggered by the Dungey cycle, which drives much of Earth’s magnetospheric dynamics. At Saturn, Felici et al. [2016] observed ionospheric outflow in the lobes at 36 R<sub>S</sub>. Interestingly, at Jupiter, Valek et al. [2019] reported ionospheric outflow on magnetic field lines with invariant latitudes between Io’s auroral signatures and the main auroral emission, lower than the polar cap.</p><p>At Jupiter and Saturn, the rapid rotation of the planet, coupled with an internal plasma source inside each magnetosphere, results in the Vasyliunas cycle, by which material is circulated throughout the system, eventually being lost down the magnetotail. This constant churning likely results in a system where ionospheric outflow occurs more readily at mid-to-high planetary latitudes that map to the middle magnetosphere, rather than solely at polar latitudes. Furthermore, ionospheric outflow at the Jupiter and Saturn will be affected by strong centrifugal forces and auroral currents, which are near omnipresent in each magnetosphere.</p><p>Using a 1-dimensional, hydrodynamic, multi-fluid model, we determine the ionospheric outflow in the jovian and saturnian systems. Our model includes the effect of centrifugal forces and auroral field-aligned currents, both of which act to enhance outflow rates from previous studies. We find that ionospheric outflow may provide a significant contribution to the jovian and saturnian systems, with the mass source rates of 18.7 – 31.7 kg s<sup>-1</sup>and 5.5-17.7 kg s<sup>-1</sup>, respectively, where the range reflects the sensitivity to the assumed initial atmospheric conditions.</p>

CONVECTING THRESHOLD IN NANOFLUID DRIVEN BY CENTRIFUGAL FORCES IN A ROTATING ANNULAR HELE-SHAW

2017 ◽  
Vol 9 (1) ◽  
pp. 49-62
Author(s):  
K. Souhar ◽  
M. Kriraa ◽  
L. Bammou ◽  
S. Alami ◽  
J. Bouchgl ◽  
...  
Keyword(s):  
Centrifugal Forces

scholarly journals On Population III Star Formation

1983 ◽  
Vol 104 ◽  
pp. 119-120
Author(s):  
A. Kashlinsky ◽  
M. J. Rees
Keyword(s):  
Background Radiation ◽  
Free Fall ◽  
Compact Objects ◽  
Centrifugal Forces ◽  
Tidal Interactions ◽  
Geometrical Cross Section ◽  
Spin Parameter ◽  
Small Density ◽  
Major Factors ◽  
Population Iii

If primordial fluctuations were isothermal their amplitude at recombination would be non-linear on scales Mo ≃ 106÷9 M⊙. Since the Jeans mass after recombination is MJo ≃ 8 × 105 Ω−1/2 M⊙ the clouds of mass Mo would be able to form the first generation of compact objects, the so-called Population III. These clouds would acquire angular momentum via tidal interactions with their neighbours. The importance of rotation can be conveniently characterised by the spin parameter λ = Vrotation/Vfree-fall and tidal interactions lead to a spin λo = 0.07 ± 0.03. As the cloud collapses λ increases as r−1/2. Any fragment forming in a rotating cloud would have the same spin λ as the whole cloud. It could therefore collapse only by ≃ λo2 in radius before centrifugal forces intervened, thus leaving a large geometrical cross-section for coalescence to be important. At radii r ≲ λo8/5 (Mo/MJo)2/15 ro the coalescence time is shorter than the free-fall time and no fragmentation is possible below this radius. In the primordial clouds two major factors prevent fragmentation at larger radii. First, the background radiation is still ‘hot’ and the trapping of it would prevent fragmentation until the whole cloud has collapsed to a radius 10−2 x−2/3 ro. Here x = 10−2(M/107 M⊙)1/3 is the ionization fraction given by the balance between gravitational contraction and recombination cooling. Furthermore, any small density fluctuation would lead to fragmentation only after the paternal cloud had collapsed by a factor (δ/5)2/3 in radius. For these reasons fragmentation is unlikely until centrifugal forces halt the collapse and a disk forms. The disk will be initially at T ≃ 104K but after a small fraction of H2 forms it will cool to T3 ≃ T/103K ≃ 1 and the final fragments mass could be as low as ≃ 0.2(λo/0.07)4 T32(MJo/Mo)1/3 M⊙.

Investigation into the spatial and temporal coherence of ionospheric outflow on January 9–12, 1997

2002 ◽  
Vol 64 (15) ◽  
pp. 1659-1666 ◽  
Author(s):  
W.K. Peterson ◽  
H.L. Collin ◽  
M. Boehm ◽  
A.W. Yau ◽  
C. Cully ◽  
...  
Keyword(s):  
Temporal Coherence ◽  
Ionospheric Outflow

Structural Response of Fiber Composite Fan Blades

1975 ◽  
Author(s):  
C. C. Chamis ◽  
M. D. Minich
Keyword(s):  
Quantitative Data ◽  
Fiber Composite ◽  
Structural Response ◽  
Aerodynamic Heating ◽  
Analysis Method ◽  
Centrifugal Forces ◽  
The Core ◽  
Composite Mechanics ◽  
Composite Blades ◽  
Load Conditions

A fiber composite airfoil, typical for high-tip speed compressor applications, is subjected to load conditions anticipated to be encountered in such applications, and its structural response is theoretically investigated. The analysis method used consists of composite mechanics embedded in pre- and post-processors and coupled with NASTRAN. The load conditions examined include thermal due to aerodynamic heating, pressure due to aerodynamic forces, centrifugal, and combinations of these. The various responses investigated include root reactions due to various load conditions, average composite and ply stresses, ply delaminations, and the fundamental modes and the corresponding reactions. The results show that the thermal and pressure stresses are negligible compared to those caused by the centrifugal forces. Also, the core-shell concept for composite blades is an inefficient design (core plies not highly stressed) and appears to be sensitive to interply delaminations. The results are presented in graphical and tabular forms to illustrate the types and amount of data required for such an analysis, and to provide quantitative data of the various responses which can be helpful in designing such composite blades.

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