Milli Arcsecond Imaging of the Solar Corona

Joseph, Davila
Öktem, Sevinç Figen
Farzad, Kamalabadi
Dissipation in the solar corona is believed to occur in extremely thin current sheets of order 1-100 km. Emission from these hot but thin current sheets is visible in coronal EUV emission lines, however, this spatial scale is unresolved in existing imaging instruments. Conventional optics cannot be easily manufactured with sufficient surface figure accuracy to obtain the required resolution. A photon sieve, a diffractive imaging element similar to a Fresnel zone plate, can be manufactured to provide a few milli-arcsec (mas) resolution, with much more relaxed tolerances than conventional imaging technology. Images from photon sieves will not only show the structure of the corona at a resolution never before obtained, they will also allow a study of the temperature structure in the dissipation region. Several photon sieves have been designed, fabricated, and tested by us at Goddard Space Flight Center. To fully exploit the potential of these devices two new technologies, (1) formation flying and (2) computational image deconvolution must be used. Recent progress on photon sieve development as well as these issues will be discussed. A simple design for a sounding rocket payload is presented that obtains 80 mas (0.080 arcsec) imaging with a 100 mm diameter photon sieve to image Fe XIV 334 and Fe XVI 335 which would provide a demonstration of this technology.


Milli Arcsecond MAS Imaging of the Solar Corona
Davila, Joseph M; Öktem, Sevinç Figen; Kamalabadi, Farzad; Oneill, John; Gradac, Anne Marie Novo; Daw, Adrian N; Rabin, Douglas M (2016-05-01)
Dissipation in the solar corona is believed to occur in extremely thin current sheets of order 1-100 km. Emission from these hot but thin current sheets should be visible in coronal EUV emission lines. However, this spatial scale is far below the resolution of existing imaging instruments, so these dissipation sites have never been observed individually. Conventional optics cannot be manufactured with sufficient surface figure accuracy to obtain the required spatial resolution in the extreme-ultraviolet whe...
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Measurements of total solar radiation and bright sunshine hours in six different climatological locations in Turkey are used to develop an Angstrom type equation. The coefficients are found for a linear equation from regression analysis for these locations. A simple overall equation, which yields the solar radiation in any location in Turkey for bright sunshine hours, is developed. The results of this equation, together with the results obtained from five similar, internationally accepted correlations, are ...
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Citation Formats
D. Joseph, S. F. Öktem, and K. Farzad, “Milli Arcsecond Imaging of the Solar Corona,” presented at the 41st COSPAR Scientific Assembly, İstanbul, Türkiye, 2016, Accessed: 00, 2021. [Online]. Available: