Reduction of the growth rate of the m = 1 resistive magnetohydrodynamic mode by finite gyroradius effects
The reduction in the growth rate of the m = 1 resistive magnetohydrodynamic (MHD) mode due to finite gyroradius effects is determined. Specifically, equilibrium diamagnetic flows, the Hall (or diamagnetic) term in Ohm's law, and ion viscosity are taken into account. The analysis is carried out in cylindrical geometry; toroidal corrections are included in only a very restricted sense. The calculation is valid in the limit where Braginskii's two-fluid equations are valid, i.e., where collision frequencies are large compared to the mode frequency and mean free paths are shorter than the relevant scale lengths. It is shown that the decrease in the mode growth rate due to ion viscosity is small for present-day tokamak parameters. On the other hand, diamagnetic drifts can significantly reduce the growth rate in both the ideal MHD and the resistive limits. In fact, in the ideal MHD limit, the mode can be completely stabilized if the pure MHD growth rate is less than half the ion diamagnetic drift frequency. Although the mode cannot be stabilized in the resistive limit, the growth rate is reduced by a factor of ..gamma../sup 2//sub T//parallel ..omega../sub *i//..omega../sub *e/parallel, where ..gamma.. /sub T/ is the purely resistive (tearing) growth rate and ..omega../sub *i/ and ..omega../sub *e/ are respectively the ion and electron diamagnetic drift frequencies.
- Research Organization:
- Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
- Sponsoring Organization:
- US Energy Research and Development Administration (ERDA)
- DOE Contract Number:
- W-7405-ENG-26
- OSTI ID:
- 7096954
- Report Number(s):
- ORNL/TM-5968; TRN: 77-015459
- Country of Publication:
- United States
- Language:
- English
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