Small and large scale magnetic structures involved in the development of the 1992 October 28 solar flare

We report spatially resolved observations of a solar flare, obtained in a w ide range of wavelengths including soft and hard X-rays, decimeter-meter an d millimeter radio emissions. This unique combination of data (including th e simultaneous fast localization of emission at millimeter wavelengths) all ows us to conclude that, even if the 1992 October 28 flare is a moderate on e in terms of the amount of energy contained in the thermal plasma and in n on thermal electrons, the magnetic configuration involved in the flare deve lopment is complex at all spatial scales. Furthermore, it is shown that ste pwise temporal evolutions of the amount of energy release in non thermal el ectrons are closely related to stepwise changes of the magnetic structures of all spatial scales illuminated either by hot plasma or by non-thermal el ectrons. This provides some evidence that different episodes of energy rele ase are triggered by loop-loop interaction and that the site of particle ac celeration changes rapidly within the energy release volume. These findings are discussed in the context of flare models as well as with respect to th e fragmented nature of energy release in solar flares.