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Indexed by:期刊论文

Date of Publication:2011-03-01

Journal:NUCLEAR FUSION

Included Journals:Scopus、SCIE、EI

Volume:51

Issue:3

ISSN No.:0029-5515

Abstract:Scaling laws of fast growth of collisionless double tearing modes in the linear phase are studied numerically by a reduced magnetohydrodynamics model in a cylindrical plasma. It is found that in the case rho(s) << d(e), with d(e) the electron inertial skin depth and rho(s) the ion sound gyroradius, the scaling of the linear growth rate changes gradually from gamma similar to d(e)(1) to gamma similar to d(e)(3) as the rational surface separation Delta r(s) increases. In the case d(e) << rho(s), on the other hand, the scaling shifts gradually from gamma similar to d(e)(1/3) or gamma similar to rho(2/3)(s) to gamma similar to d(e)(1) or gamma similar to rho(1)(s) as Delta r(s) increases. In the small Delta r(s) regime, furthermore, it is shown that for short wavelength unstable modes, the scaling on d(e) and rho(s) as their poloidal mode number varies is similar to that as Delta r(s) does. In addition, rho(s) is found to play an important role in reducing the scaling dependence on d(e). These numerical scaling laws are testified to be reasonable in comparison with previous analytical theories, based on the similarity of physical characteristics of the same Delta' categories in tearing modes, where Delta' is the linear instability parameter for tearing modes. Finally, the characteristics of the second unstable eigenmode with different mode numbers, under the influence of d(e) and rho(s), are obtained and analysed.