EDP Sciences, Astronomy & Astrophysics, 2(371), p. 738-747, 2001
DOI: 10.1051/0004-6361:20010411
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Cyclotron resonance with high-frequency Alfvén waves has been proposed as an ion heating mechanism for producing high-speed winds and large ion temperatures in coronal holes. In the simplest version of the model (cyclotron sweep model), the waves propagate without interacting until they hit a resonance with the plasma ions at distance, where the ion cyclotron frequency becomes comparable to the wave frequency. We calculate the energetic test-particle mean free path lambda in solar corona heated by this mechanism. The primary result of our study is that energetic particles are efficiently coupled to the high-frequency MHD waves and may, thus, provide important feed back to wave-heating models. Detailed calculations are presented for a solar-wind stream of intermediate speed driven by the cyclotron sweep mechanism applying an extended quasi-linear theory for the mean free path. A local maximum of lambda is located near r=2 R_&sun; , but lambda is very small at distances close to the Sun ( r