
Proceedings Paper
Solar EUV/FUV line polarimetry: observational parameters and theoretical considerationsFormat | Member Price | Non-Member Price |
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Paper Abstract
Several mechanisms can induce a detectable amount of linear polarization (□ 1%) in spectral lines
emitted by the outer solar atmosphere at EUV/FUV wavelengths (100 A< A < 1500 A):
(1) Polarization in FUV lines (up to 20%) can be originated by resonance scattering of radiation anisotropically
illuminating the emitting atoms. Modifications of this polarization can then result from the
presence of a magnetic field (Hanle effect);
(2) Impact line polarization can arise from anisotropic collisional excitation of the EUV emitting atoms by
particles (electrons, protons) with non-Maxwellian velocity distributions.
We suggest how new technological developments associated with the production of ultra-smooth, low
scatter flow-polished mirror substrates and high quality multilayer and interference film coatings can make
possible some exciting new optical instruments which should permit observations of these polarization effects.
Polarization measurements have not previously been obtained in these wavelength regimes.
We give the observational parameters for the development of all refledive FUV coronagraph/polarimeter
and EUV imaging polarimeter instruments. A coronagraph/polarimeter, operating at hydrogen Lyman a,
could provide - via the Hanle effect - the first direct measurements of coronal vector magnetic fields, of
relevance to numerous fundamental questions in modern solar physics. A multilayer EUV imaging polarimeter,
operating at EUV helium lines (e.g., 304 A, 584 A), could provide information on impact polarization
phenomena, relevant to questions concerning the relative importance of thermal and non-thermal processes
in solar flares.
The reflecting polarization analyzers for these instruments will operate at the Brewster angle and will
be coated with advanced thin film interference coatings or EUV multilayer coatings. We describe some new
types of EUV/FUV polarimeters based on these polarization optics.
Paper Details
Date Published: 1 February 1991
PDF: 13 pages
Proc. SPIE 1343, X-Ray/EUV Optics for Astronomy, Microscopy, Polarimetry, and Projection Lithography, (1 February 1991); doi: 10.1117/12.23208
Published in SPIE Proceedings Vol. 1343:
X-Ray/EUV Optics for Astronomy, Microscopy, Polarimetry, and Projection Lithography
PDF: 13 pages
Proc. SPIE 1343, X-Ray/EUV Optics for Astronomy, Microscopy, Polarimetry, and Projection Lithography, (1 February 1991); doi: 10.1117/12.23208
Show Author Affiliations
Silvano Fineschi, NRC-NASA/Marshall Space Flight Ctr. (Italy)
Richard B. Hoover, NASA/Marshall Space Flight Ctr. (United States)
Richard B. Hoover, NASA/Marshall Space Flight Ctr. (United States)
Juan M. Fontenla, Univ. of Alabama in Huntsville (United States)
Arthur B. C. Walker II, Stanford Univ. (United States)
Arthur B. C. Walker II, Stanford Univ. (United States)
Published in SPIE Proceedings Vol. 1343:
X-Ray/EUV Optics for Astronomy, Microscopy, Polarimetry, and Projection Lithography
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