1. Inversions of Flaring Radio Emissions. Gregory D. Fleishman

2. Relevant Recent Discoveries 1.Pitch-angle anisotropy: - loop-top radio sources (NoRH) - variations of polarization (NoRH) - spectral variations (OVSA) 2.Dense flare environment - coronal loop HXR sources (RHESSI) - Razin effect in many radio bursts (OVSA) - resonant transition radiation in 10% of the bursts (OVSA) - cold dense flares (OVSA+ NoRH)

3. Implication for the radio burst modeling: take into account 1. For nonthermal electrons: - Anisotropic acceleration/injection, - Anisotropic transport effects, - Isotropisation due to collisions and wave-particle interactions, - Coronal losses of fast electrons 2.For emission generation and transport: - Free-free absorption - Razin suppression of the gyrosynchrotron emission - Source inhomogeneity - Other emission procersses (RTR, ECM…)

4. Simplfied model fitting Sequence of fitted spectra Derived parameters vs time Uniform, optically thin source with strong Razin-effect

5. 24 October 2001 AR 9672 Almost No SXRs!

6. 1 2 3 4 Images obtained for moments 1-4 17 GHz 35 GHz 9.4 GHz NoRP light curves

7. 1234 NoRH images 17 GHz I 17 GHz V 34 GHz I

8. Klein’s GS approxi- mation for isotropic electron distribu- tion

10. 10 March 2001

11. Exact GS formulae

12. Turbulence parameter a=2 * 10 -7

13. CONCLUSIONS 1.A number of recent discoveries calls for new, more detailed and sophisticated models of radio emission from solar flares. 2.Nonthermal radio emission depends not only on the magnetic field and energy distribution of fast electrons, but also on the pitch-angle anisotropy, background plasma density and temperature, source structure, and the turbulence level, thus, potentially it is a valuable source of information of the corresponding physical parameters and related processes. 3.The development of new reliable models and fitting algorithms is of primary importance and urgently needed to fully exploit the potential diagnostic capabilities of the planned project of a new solar dedicated radio instrument, Frequency Agile Solar Radiotelescope.