Gyrokinetic linear theory of the entropy mode in a Z pinch

The linear gyrokinetic theory of the entropy mode is presented in a Z-pinch configuration in the regime of plasma β ≪ 1, focusing primarily on the parameter regime in which the ideal interchange mode is stable. The entropy mode is a small-scale, nonmagnetohydrodynamic mode that typically has peak growth rates at kρ s∼1[ρ s2=(T 0e+T 0i)/(mΩ ci2)], with magnitudes comparable to those of ideal modes. The properties of this mode are studied as a function of the density and temperature gradients, plasma collisionality, and electron to ion temperature ratio. © 2006 American Institute of Physics