Drift wave excitation by inhomogeneous plasma ?ow in solar spicules

摘要

The stability of the drift waves is discussed within the two-?uid theory taking into account the ion temperature and thestress tensor effects.A dispersion equation is derived and the stability/instability conditions discussed in detail usingthe parameters appropriate for the solar spicules.The drift mode appears to be highly unstable for the characteristiclengths of the density and the shear ?ow gradients applicable for spicules.These imply the characteristic lengths in therange of a few hundred meters up to a few kilometers,yielding wave frequencies of the order of a few Hz.Hence,theunstable drift wave develops at time scales that may be taken as relatively short in comparison with the average lifetime of spicules that is measured in minutes.