Alfven velocity

Magneto-Hydrodynamic Behavior of Plasma Alfven Velocity and Magnetic Reynolds Number... 

The maximum gas rotation velocity v a is referred to as the Alfven velocity for plasma centrifuges. The rotation velocities in plasma centrifuges reach 2-3 10 cm/s in the case of light atoms, which exceed those of mechanical centrifuges by about 50-fold. The fast gas rotation in a plasma centrifuge can be applied for the separation of isotopes with small differences in atomic masses - M2) ... 

Magnetic fields introduce hydromagnetic waves, which are transverse modes of ion motion and wave propagation that do not exist in the absence of an apphed B field. The first of these are Alfven, A, waves and their frequency depends on B and p, the mass density. Such waves move parallel to the apphed field having the following velocity ... 

Alfven number (Al) - A dimensionless quantity used in plasma physics, defined by Al = v(pp) /5, where p is density, v is velocity, p is permeability, and B is magnetic flux density. [2] Alfven waves - Very low frequency waves which can exist in a plasma in the presence of a uniform magnetic held. Also called magnetohydrodynamic waves. 

The study of the chemical and physical processes occurring in T Tauri outflows is of great importance as these stars have been proposed as the energy source of Herbig-Haro objects (Schwartz 1978 Canto 1978) and turbulence in molecular clouds (Norman and Silk 1980, Franco 1983). In this work, the physical model of the outflow is taken from Hartmann, Edwards and Avrett (1982) in which the primary stellar wind (i.e. wind that has not interacted with its environment) is ionized and heated by Alfven waves in the star s convection zone to reach a terminal velocity (of about 230 kms ) and a maximum temperature (of 20,000 K, cf. Hartmann et al. model no. 2) at z = 3 to 5, where z is the radial ordinate in units of stellar radii (r t 2 x 10 cm). Thereafter the wind expands and cools radlatively and adiabatically. Other parameters for the model are the initial wind density at z = 1 (oq lO - cm ), the density at z = 5 (n < 5 X 10 to 10 cm ) and the stellar photospheric temperature 4000 E). The cooling rate of the wind is obviously dependent on the physical conditions within the ejecta and in any case is by no means certain. Hartmann et al. suggest a... 

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