ALFVENIC FLUCTUATIONS IN FAST AND SLOW SOLAR WINDS

We compute properties of Alfvenic fluctuations within a wide frequency range (i.e., 10(-6) s(-1) less than or similar to f less than or simi lar to 10(-2) s(-1)) in both high-and low-speed magnetized radial sola r winds. In particular, the radial and frequency variations of the nor malized cross helicity sigma(c), the Alfven ratio R-A, and other relev ant quantities associated with Alfvenic fluctuations are presented and analyzed. Because of the existence of the Alfven critical radius r(A) and a characteristic frequency f, for a given magnetized solar wind p rofile, continuous reflection effects are clearly manifest at frequenc ies lower than several times f,. Since outward propagating fluctuation s which many authors consider Alfvenic fluctuations have been detected in the high-latitude solar wind (which is fast and steady), such cont inuous reflection effects in the low-frequency end of the fluctuation spectrum may be found in the Ulysses data. In order to strengthen our case comparisons are carried out between our theoretical results and p revious data analyses of observations from the Hellos 1 and 2 spacecra ft in the radial range of 0.29 AU less than or similar to r less than or similar to 1.0 AU. Stronger evidence for continuous reflection effe cts of low-frequency Alfvenic fluctuations is found in the high-speed solar wind close to the Sun than in the low-speed solar wind in genera l.