Authors: B R Dennis G K Skinner M J Li A Y Shih
Publish Date: 2012/06/12
Volume: 279, Issue: 2, Pages: 573-588
Abstract
This paper describes the development of Xray diffractive optics for imaging solar flares with better than 01 arcsec angular resolution Xray images with this resolution of the ≥ 10 MK plasma in solar active regions and solar flares would allow the crosssectional area of magnetic loops to be resolved and the coronal flare energy release region itself to be probed The objective of this work is to obtain Xray images in the ironline complex at 67 keV observed during solar flares with an angular resolution as fine as 01 arcsec – over an order of magnitude finer than is now possible This line emission is from highly ionized iron atoms primarily Fe xxv in the hottest flare plasma at temperatures in excess of ≈ 10 MK It provides information on the flare morphology the iron abundance and the distribution of the hot plasma Studying how this plasma is heated to such high temperatures in such short times during solar flares is of critical importance in understanding these powerful transient events one of the major objectives of solar physics We describe the design fabrication and testing of phase zone plate Xray lenses with focal lengths of ≈ 100 m at these energies that would be capable of achieving these objectives We show how such lenses could be included on a twospacecraft formationflying mission with the lenses on the spacecraft closest to the Sun and an Xray imaging array on the second spacecraft in the focal plane ≈ 100 m away Highresolution Xray images could be obtained when the two spacecraft are aligned with the region of interest on the Sun Requirements and constraints for the control of the two spacecraft are discussed together with the overall feasibility of such a formationflying missionWe thank John Krizmanic and Keith Gendreau for supporting the lens design and testing effort Kenneth Phillips for providing the spectra shown in Figure 1 and for help with the solar objectives and Amil Patel Gang Hu and Thitima Suwannasiri for their work fabricating the lenses in Goddard’s Detector Development Lab This project was supported with funding from the Goddard Internal Research and Development IRAD program CHIANTI is a collaborative project involving George Mason University the University of Michigan USA and the University of Cambridge UK
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