An electrograph for measurement of macroscopic electric fields in prominences and flares

✍ Scribed by T. Moran; P. Foukal

• Publisher: Springer
• Year: 1991
• Tongue: English
• Weight: 623 KB
• Volume: 135
• Category: Article
• ISSN: 0038-0938
• DOI: 10.1007/bf00146705

✦ Synopsis

We describe an 'electro~aph' instrument designed for measurement of macroscopic electric fields in solar plasmas, using the polarization dependence of line width in Stark-broadened hydrogen Paschen emission lines. Observations of quiescent prominences and limb chromosphere with our electrograph at the NSO/Sac Peak Evans Coronal Facility provide upper limits of 5-10 Vem i for transverse macroscopic electric fields in these structures, averaged over an area of about 5 x 7 arc sec. Random thermal motions of hydrogen ions across magnetic field lines generate a quasi-static electric field, which should be distinguishable from pressure broadening in the intensely magnetized chromosphere over a sunspot, given an electrograph sensitivity a factor 2-3 better than that achieved here. Future electrograph measurements of limb flares, post-flare loops and eruptive prominences, even at 5 V cm -~ sensitivity, could provide a useful new test of reconnection and discharge effects in such dynamic structures.