On the existence of Weibel instability in a magnetized plasma. II. Perpendicular wave propagation: The ordinary mode.

In a magnetized plasma with a temperature anisotropy T||>T⊥ (where || and ⊥ denote directions with respect to the uniform magnetic field B0), the nonresonant Weibel instability can develop and destabilize purely growing, ordinary plasma modes (k=k⊥). This paper presents a rigorous extended analysis of this instability on the basis of a new threshold b0(k), which enables to determine the instability conditions as well as the upper limits of the growth rates. Accurate analytical forms of the threshold conditions are provided here for the first time and for the full physical range of the temperature anisotropy and the parallel plasma beta. The marginal and threshold conditions for the plasma parameters, which directly lead to an instability of the ordinary mode, are explicitly derived numerically and analytically. The new analytical tools developed here provide premises for a comprehensive investigation of the interplay of this instability with the firehose instability, as they both can develop in the same conditions. [ABSTRACT FROM AUTHOR]