1. Steven R. Spangler University of Iowa
Observations of Density Fluctuations Near the Sun Using Radio Scintillations
Steven R. Spangler
University of Iowa

2. Basic physics of extracting information on coronal turbulence: radio refractive index
Radio propagation effects primarily diagnose density fluctuations
Are secondary indicators of B

4. Example: Phase Scintillations of a VLBI Interferometer

5. Types of Scintillation Phenomena
Frequency scintillation
Intensity cross-correlation

6. Principal Papers In This Area
Deduction of plasma physical properties from radio observations
Harmon & Coles 2005, JGR 110, H
Hollweg et al 1982, JGR 87, 1

7. Radio Results on Coronal Turbulence I:
Speed of irregularities << VA : Irregularities are non-propagating or oblique AIC waves

8. Radio Results on Coronal Turbulence II:
Density spectrum power law with “bulge” at ion inertial length (Coles and Harmon, 1989ff)

9. Radio Results on Coronal Turbulence III:
Smooth variation of turbulent intensity with heliocentric distance; no coronal “Kumasphere”. Not unanimous; see Lotova

10. Open Questions and Issues for Discussion
Why no fast mode waves in corona? (Harmon and Coles). Similar situation in ISM.
What are the amplitudes of velocity and magnetic fluctuations?
Is the turbulence sufficiently strong to heat and accelerate?
How is the turbulence generated?
Thanks