The structure of the mind.

MacDougall, William

doi:10.1037/10542-003

Cited by 1 publication

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“…Stability analyses (Stern 1960;Schmitt 1979) establish that the salt-fingers are observed in the supercritical regime well beyond the scope of the linear stability analysis. More elaborate treatment of the double diffusive convection is considered in many papers (Monchick & Mason 1967;McDougall 1981a;Kunze 1987;McDougall 1981b;Ozgökmen, M. & E. 1998;Radko 2008Radko , 2010. It interests us to note that double diffusive convection has been invoked in the astrophysical contexts to investigate convection in steller interiors (Ulrich 1972), photospheric composition of low mass giants (Charbonnel & Zahn 2007b), and galactic evolution of 3 He (Charbonnel & Zahn 2007a).…”

Section: Introductionmentioning

confidence: 99%

On the helium fingers in the intracluster medium

Sadhukhan¹,

Gupta²,

Chakraborty³

2017

Monthly Notices of the Royal Astronomical Society

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In this paper we investigate the convection phenomenon in the intracluster medium (the weakly-collisional magnetized inhomogeneous plasma permeating galaxy clusters) where the concentration gradient of the Helium ions is not ignorable. To this end, we build upon the general machinery employed to study the salt finger instability found in the oceans. The salt finger instability is a form of double diffusive convection where the diffusions of two physical quantities-heat and salt concentrations-occur with different diffusion rates. The analogous instability in the intracluster medium may result owing to the magnetic field mediated anisotropic diffusions of the heat and the Helium ions (in the sea of the Hydrogen ions and the free electrons). These two diffusions have inherently different diffusion rates. Hence the convection caused by the onset of this instability is an example of double diffusive convection in the astrophysical settings. A consequence of this instability is the formation of the vertical filamentary structures having more concentration of the Helium ions with respect to the immediate neighbourhoods of the filaments. We term these structures as Helium fingers in analogy with the salt fingers found in the case of the salt finger instability. Here we show that the width of a Helium finger scales as one-fourth power of the radius of the inner region of the intracluster medium in the supercritical regime. We also determine the explicit mathematical expression of the criterion for the onset of the heat-flux-driven buoyancy instability modified by the presence of inhomogeneously distributed Helium ions.

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