2. RHESSI-Nessie II WG 3: “From sites of radiation to particle sources” Three sub-groups, to have appointed times in the program Specific educational questions to be shared and perhaps answered by Friday Collaborations leading to meaningful papers to be encouraged

3. Focus area #1: propagation “Realistic” magnetic fields: drifts, scattering, energy losses, trapping, Neupert effect Interested members? Fletcher, Galloway, Gordovskyy, Hannah, Hudson, Melnikov, Petrosian, Veronig

4. Null? Separatrices? Anzer-Pneuman, 1982

6. Focus area #2: Radiation 1.“Realistic” magnetic fields: Microwave and X-ray luminosity, coronal emission, Alfven speeds, “cornucopia effect” Interested members? Fletcher, Gallagher, Hudson, Mann, McTiernan, Veronig, Warmuth

7. Focus area #3: Footpoint physics Particle penetration into the lower atmosphere. Positron creation and decay. DEM. Interested members? Allred, Brown, Fletcher, Hudson, Murphy, Ryan, Veronig, Woods

8. Bastille day 2000 (Fletcher & Hudson, 2001)

9. Tentative schedule, Team 3 Wednesday 11:00 - lunch Team organization; Propagation theme Wednesday 14:00 - 16:00 Focus area #1: Radiation theme Wednesday 16:30 - supper Focus area #2: Events Thursday 09:30 - 10:30 Discussion of corona Thursday 11:00 - lunch Focus area #3: Footpoint physics Thursday 14:00 - 16:00 Propagation: answers to questions Thursday 16:30 - supper Radiation: answers to questions Friday 09:00 - 10:30 Footpoints: answers to questions Friday 11:00 - lunch Working session(s) Friday 14:00 - 16:00 Recap, followed by working session(s)

10. RHESSI current sheet? Sui & Holman, ApJ 2001 Homologous flare to that discussed by Astrid Signature appears in two other events Current-sheet signatures in UVCS data

14. Radiative hydrodynamics en train

17. Propagation Questions To what extent are electron footpoints smeared out by drift motions? Being studied… maybe? To what extent can ions and electrons be separated spatially? Considerably Do separatrices correspond to ribbons, or (Metcalf et al, 2003) are they intriguingly related? Being studied Does trapping and Coulomb loss explain 34-GHz looptop sources? Being studied… probably?! At what time scale does the steady-state approximation break down? Experts discussing

18. Cartoon by Jakimiec

20. Radiation Questions Does trapping and Coulomb loss explain 34-GHz looptop sources? Being studied… probably?! Can a coronal loop be dense enough to stop 60 keV electrons? Yes; new input to models Do RHESSI observatinos suggest a coronal current sheet? Yes… being studied Can “realistic” field extrapolations help to understand flare X-ray sources? Being studied

21. Footpoint Questions Do electron-heated atmospheres produce thick enough transition regions to explain the 511-keV line width? No Do proton-heated atmospheres produce thick enough transition-region material to explain the 511-keV line width? Being studied Do we understand footpoint DEMs well enough to explain ribbon radiation? Being studied Do we understand why hard X-ray footpoint structures are so concentrated in the ribbons? Being studied

22. Slide 8 April 21, 2002: Brian Dennis, of course!

24. Collaborative projects Inputs for radiative hydrodynamics models, for example the return current Proton beam simulations and 511 line Intercomparison of B-cubes for AR 486 and others “Realistic” magnetic models applied to flare radiation sources