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M.J. Aschwanden (LMSAL)
The Frequency-Agile Solar Radiotelescope (FASR) is designed to produce simultaneous images of solar phenomena at many frequencies. A data cube with a stack of multiple frequency images can be used for tomographic reconstruction of the 3D density and temperature distribution of flares, based on the free-free emission at cm and mm wavelengths.
We simulate a set of multi-frequency images for the Bastille-Day flare of 2000-July-14, based on EUV observations from TRACE and soft X-ray observations from Yohkoh. The 3D model consists of some 200 postflare loops with observationally constrained densities and temperatures. The temporal evolution involves flare plasma heating, a phase of conductive cooling, followed by a phase of radiative cooling. The images simulated at different microwave frequencies reveal a sequence of optically-thick free-free emission layers, which can be "pealed off" like onion shells with increasing radio frequency. We envision a tomographic method that yields information on the density and temperature structure of flare systems and their evolution. Comparison with EUV and soft X-ray based 3D models will also allow to quantify wave scattering at radio frequencies and provide information on small-scale inhomogeneities and wave turbulence.
Besides the thermal free-free emission, radio images contain also information on coherent emission processes, such as plasma emission from electron beams and loss-cone emission from gyroresonant trapped particles, conveying information on particle acceleration processes.
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The author(s) of this abstract have provided an email address for comments about the abstract: aschwanden@lmsal.com
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Bulletin of the American Astronomical Society, 34
© 2002. The American Astronomical Soceity.