Transient Growth Mechanisms of Resistive Drift-Waves

Normal mode analysis has been applied to many fluid dynamic stability problems with great success. However, there are some notable cases where the predictions of normal mode analysis fail to correspond to observed phenomena. In particular, normal mode analysis predicts a transition to turbulence for some flows at a much higher Reynolds numbers than that seen in experiment. Recent studies have shown that for some problems, normal mode analysis only gives a partial description of the properties of the linear perturbation equation [1, 2]. When the eigenmodes of the linear system are not orthogonal and complete, or equivalently when the system is nonnormal, general solutions of the system may present behavior quite different from that suggested by normal mode analysis [3]. Drift-wave turbulence is considered to be a possible cause of anomalous transport in the cool plasma edge region of tokamaks. Here, nonnormal analysis methods are used to study the linear properties of the Hasegawa-Wakatani drift-wave turbulence model [4].