Preliminary Power Spectra of the Interplanetary Plasma

Spacecraft observations of the solar-wind plasma have been used to estimate power spectra of the denisty of solar-wind protons. An average frequency dependence of f-1.3 in the frequency range 1 to 1[h Hz and a plasma-density correlation length of 106 km or more for the structure of turbulence are implied. Both estimates are consistent with results from direct observations of the interplanetary magnetic field and the solar-wind speed and also with data on interplanetary scintiliations.