9316972 Kundu This effort continues research at the University of Maryland centered around the study of solar flares using radiowave techniques. The investigators will use observations made by the Very Large Array (VLA) of the National Radio Astronomy Observatory, and the Berkeley-Illinois-Maryland Millimeter Array (BIMA) at Hat Creek. The investigators will compare the observed magnetic structure of sunspot-associated microwave sources with model computations and determine the vertical and horizontal components of the magnetic field at specific locations in the low corona. The study will also make use of X-ray and EUV data obtained by the Yohkoh satellite. The combined data will be used to estimate the electron temperature and magnetic field in coronal loops, and the temperature and density structure of the active region in three dimensions. VLA observations of flares at multiple centimeter wavelengths will be used to study the structure and cause of flaring. The BIMA observations will provide high spatial resolution measurements of flares at millimeter wavelengths. In particular, the millimeter imaging observations of MeV electrons will be used to study gamma ray sources sizes, structures and locations. The similarity of time profiles of impulsive emission by MeV electrons will permit us to analyze the fundamental characteristics of the acceleration mechanism responsible for MeV electrons. The delay of millimeter emission relative to cm, hard X-rays and gamma rays will provide important information on electron and proton acceleration. Additionally, the investigators will search for nanoflares and acoustic waves in the Sun's chromosphere and study chromospheric and coronal heating.***
