Cyclotron resonance in coronal holes 3. A five-beam turbulence-driven model

Following Hollweg and Johnson [1988], Isenberg [1990], and Li et al. [1999a ], we postulate that the Sun launches a flux of low-frequency Alfven waves, which dissipate via a turbulent cascade to high frequencies where the ener gy is absorbed by ion cyclotron resonant interactions. The plasma consists of two proton beams, which are proxies for the resonant and nonresonant hal ves of their distribution function, two He++ beams, which are proxies for t he strongly and weakly resonant halves of their distribution, and a single beam of O+5 with vanishing density. The level of the power spectrum at the high resonant frequencies is determined by the condition that the protons a nd He++ resonantly absorb energy at the same rate at which the low-frequenc y waves are dissipating. Once the level of the high-frequency power spectru m is determined, the resonant heating and acceleration of the O+5 can be ca lculated. For both Kolmogorov and Kraichnan scalings of the turbulent dissi pation the model yields results for the protons that are in reasonably good agreement with the UVCS/SOHO results. The He++ becomes; more than mass pro portionally heated and flows faster than the protons, close to the Sun. How ever, our model is unable to reproduce the UVCS/SOHO observation that the O +5 temperature is still increasing with heliocentric distance r out to 3.5 r(s). Instead, the O+5 becomes very hot initially, experiences a strong mir ror force, and accelerates to high speed, which in turn leads to rapid adia batic cooling. Put another way, the O+5 observations imply that (dT(perpend icular to)/dt)(res) must bean increasing function of r, while it is the nat ure of the resonant interactions to make (dT(perpendicular to)/dt)(res) dec rease with increasing r.