MICRO-TURBULENCE IN THE SOLAR-WIND AT 5-76 RS OBSERVED WITH INTERPLANETARY SCINTILLATION

We study the properties of micro-turbulence in the solar wind using in terplanetary scintillation (IFS) observations made with the single dis h antenna operating at 2.3 GHz and 8.5 GHz. Our IFS observations were made during September-October in 1992 and 1993 and covered a radial di stance range of 5-76 solar radii (Rs). We apply the spectral-fitting m ethod to obtain properties of solar wind turbulence, such as axial rat io of anisotropy, inner scale of dissipation length, power-law spectra l index, and solar wind velocity. We also examine the velocity depende nce of the turbulence near the sun, and find the following results. (1 ) Both low-speed and high-speed solar-wind hows show acceleration at t he distance range of 10-30 Rs, which is consistent with previous works . (2) The radial dependence of anisotropy and spectral index show no s ignificant difference between the low-speed and high-speed solar wind. (3) Only the inner scale length shows a dependence on flow speed: the inner scale in the high-speed wind is 1.4 +/- 0.3 times larger than t hat in the low-speed wind.