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To compare mm-wave and X-ray diagnostics of solar flare plasma, five flares observed in 1980–1991 in Metsahovi at 22 and 37 GHz and with GOES, SMM, and GRO are studied. The first impulsive peak of the mm-wave bursts under investigation coincides in time with hard X-ray emission. The second gradual component in mm-wave emission coincides with the maximum of the soft X-ray emission measure. The bremsstrahlung mm-wave radiation from hot chromospheric plasma and gyrosynchrotron radiation driven by common population of superthermal electrons are calculated. It is shown that for mm-wave events with the first peak intensity ≤ 100 s.f.u., the thermal bremsstrahlung is more important than the gyrosynchrotron emission. The total energy of fast electrons deduced from the first peak of mm-wave bursts is one to two orders of magnitude less than that determined from the hard X-ray emission in the approximation of a thick-target nonthermal model. That can testify in favour of the hybrid thermal/nonthermal model proposed by Holman and Benka (1992). The emission measure and the energy of evaporated plasma using both mm-wave and soft X-ray data are also determined. For events investigated here the energy of evaporated chromospheric plasma is larger than the total energy of fast electron beams. We have concluded that, for evaporation, additional energy release in the chromosphere is needed. The possibility of such energy release in the framework of an advanced circuit model for solar flares is discussed.

The dynamical model of a solar prominence taking into account plasma motion in the form of a cumulative flux was developed. Of great importance is the fact that the prominence plasma is partially ionized. Ion-neutral collisions in nonsteady flux conditions radically change the energetics and dynamics of the prominence model. In this case the equilibrium state described by the Kippenhahn-Schluter solutions becomes unstable, and various dynamic regimes of plasma compression, as well as monotonic or quasi-periodic expansion of the plasma can exist in the prominence.