Effects of magnetic and collisional viscosity on the E x B gradient drift instability. Memorandum report

Technical Report · Thu Apr 27 04:00:00 EDT 1989

OSTI ID:5723442

Zalesak, S T; Huba, J D; Satyanarayana, P

The role of magnetic viscosity (i.e., Larmor radius effects) and collisional viscosity on the ExB gradient drift instability is investigated in both the collisional and inertial regimes. The equations describing the time evolution of small perturbations to an equilibrium two dimensional (x,y) magnetized plasma are derived where the equilibrium electron density is an arbitrary function of y. The equations are then solved iteratively in time to obtain the growth rate of the fastest-growing eigenmode for a given Fourier wavenumber k in the x direction. Results are compared for appropriate profiles with two asymptotic results: the long-wavelength limit, valid for kL less than 1, and the short-wavelength or local limit, valid for kL greater than 1, where L is the gradient scale length of the equilibrium profile. It is found that although the long- and short-wavelength limits do indeed provide accurate growth rates for kL less than 1 and kL greater than 1, respectively, neither provides reliable growth rates for kL approx. 1. In comparing these results to the long-wavelength limit, in addition to affecting gamma in an absolute sense, increasing L to a finite value decreases k sub max, the value of k for which gamma(k) maximizes, and also affects the sharpness of the peak of gamma(k) about k sub max. Both of these phenomena have large effects on freezing models.

• Research Organization: Naval Research Lab., Washington, DC (USA)
• OSTI ID: 5723442
• Report Number(s): AD-A-207975/4/XAB; NRL-MR-6438
• Country of Publication: United States
• Language: English

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71 CLASSICAL AND QUANTUM MECHANICS
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