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Astron. Astrophys. 357, 1073-1085 (2000)

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9. Conclusions

The main conclusions of the present paper are:

  1. Phase mixing of finite-amplitude Alfvén waves in the corona gives rise to nonlinear coupling of AWs and to spectral energy redistribution. The strongest coupling in the plasma, which is uniform along [FORMULA], includes counter-propagating waves.

  2. The nonlinear effects of a non-zero ion Larmor radius on the finite-amplitude Alfvén waves comes into play at length scales which are much longer than the dissipation length-scale [FORMULA]. In the coronal holes, the phase-mixing switches to the nonlinear phase at the heights equal to 10-100 parallel wavelengths [FORMULA], where the transverse wavelength [FORMULA] m while the dissipation length-scale is [FORMULA] m.

  3. Nonlinear coupling introduces a spectral redistribution of the wave energy, thus changing the rate of the dissipation of wave flux. The influence of the nonlinear interaction on the actual dissipation of the wave flux and consequent plasma heating depends on the frequency of the waves and is a subject of further investigations. The part of wave energy which is transferred to smaller scales can be damped rapidly by collisional dissipation.

  4. The distance at which the phase-mixing undergoes a transition from a laminar to a nonlinear stage depends on the wave frequency and amplitude. In the case of the decay into counterstreaming waves this distance is proportional to [FORMULA] and is given by (64).

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© European Southern Observatory (ESO) 2000

Online publication: June 5, 2000