Interplanetary scintillation measurements of the electron density power spectrum in the solar wind

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Abstract
The Spatial spectrum of electron density in the solar wind is estimated over the frequency range 2 × 10−3 to 3 × 10−2 km−1 by using 74 MHz observations of interplanetary scintillation. The inversion technique by which the spatial spectrum is estimated from the observed temporal spectrum requires weak scattering. Hence at 74 MHz it can only be applied for solar elongations greater than 40°. The shape of the spectrum is best described by a two‐component power law (P(q) ∝ q−α) where α ≅ 2.7 at low wave numbers and α ≅ 3.2 at higher wave numbers. Occasionally, a single α ≅ 3.0 gives a satisfactory description. The shape of the spectrum varies significantly from day to day, but no mean variation with solar distance has been observed.