MESUREMENT OF MACROSCOPIC ELECTRIC FIELDS IN SOLAR PLASMA STRUCTURES

MACROSCOPIC ELECTRIC FIELDS PLAY A CENTRAL ROLE IN THE PROCESSES OF RECONNECTION AND PARTICLE ACCELERATION THAT FIGURE PROMINENTLY IN SOLAR-TERRESTRIAL PHYSICS STUDIES OF FLARES AND FILAMENT ERUPTIONS. DETECTION OF THESE FIELDS AND MEASURMENT OF THEIR MAGNITUDE, ORIENTATION, SPATIAL DISTRIBUTION, AND TIME DEPENDENCE WOULD OPEN A NEW AREA OF INVESTIGATION IN SOLAR PLASMA DIAGNOSTIC TECHNIQUES. WE HAVE DEVELOPED A NEW TECHNIQUE FOR REMOTE SENSING THE MAGNITUDE AND ORIENTATION OF MACROSCOPIC ELECTRIC FIELDS HAVING A SUBSTANTIAL COMPONENT IN THE SKY PLANE, USING THE POLARIZATION-DEPENDENCE OF BALMER LINE STARK BROADENING. RESULTS SO FAR SUGGEST A DETECTABLE FIELD POSSIBLY ASSOCIATED WITH RECONNECTION IN AN EXCELLENT SET OF OBSERVATIONS OF A POST-FLARE LOOP. THE PHASE I WORK WE PROPOSE HERE WOULD EXTEND THESE SOLAR OBSERVATIONS TO A LARGER SAMPLE OF SOLAR STRUCTURES, AND TO THE PASCHEN LINES IN THE NEAR IR WHERE THE TECHNIQUE SHOULD BE MORE SENSITIVE. WE ALSO INTEND TO CARRY OUT LABORATORY MEASUREMENTS AT THE MIT TARA MIRROR MACHINE TO FURTHER REFINE AND CALIBRATE THIS TECHNIQUE OF PROBING PLASMA ELECTRIC FIELDS. OUR RESULTS WILL BE COMPARED TO THEORETICAL MODELS OF STATIC AND OSCILLATORY MACROSCOPIC E-FIELDS ASSOCIATED WITH RECONNECTION, PARTICLE ACCELERATION, AND PLASMA WAVES IN SOLAR STRUCTURES.