ENERGY-TRANSPORT AND DYNAMICS

We report findings concerning energy transport and dynamics in flares during the impulsive and gradual phases based on new ground-based and space observations (notably from Yohkoh). A preheating sometimes occur s during the impulsive phase. Ca XIX line shifts are confirmed to be g ood tracers of bulk plasma motions, although strong blue shifts are no t as frequent as previously claimed. They often appear correlated with hard X-rays but, for some events, the concept that electron beams pro vide the whole energy input to the thermal component seems not to appl y. Theory now yields: new diagnostics of low-energy proton and electro n beams; accurate hydrodynamical modeling of pulse beam heating of the atmosphere; possible diagnostics of microflares (based on X-ray line ratio or on loop variability); and simulated images of chromospheric e vaporation fronts. For the gradual phase, the continual reorganization of magnetic field lines over active regions determines where and when magnetic reconnection, the mechanism favoured for energy release, wil l occur. Spatial and temporal fragmentation of the energy release, obs erved at different wavelengths, is considered to be a factor as well i n energy transport and plasma dynamics.