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Proceedings Paper

An EUV spectrometer for mapping the heliopause and solar wind
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Paper Abstract

The He+ ion provides a valuable tracer of solar wind dynamics and the heliospheric boundary. Mapping the heliosphere in the 30.4 nm resonance line of the He+ ion with high spectral resolution will open access to the heliopause and reveal the three-dimensional flow of the solar wind. The emission fluxes are however faint, just a few mR, which poses a serious limitation on the mapping rate at high signal-to-noise ratio. We have developed a spectrometer configuration for narrowband EUV emission that offers important advantages over previous designs: high throughput (~1cps/mR), high resolution (several thousand), no moving parts, and modest instrument size and mass. The concept combines a conventional normal-incidence Rowland mount grating and an efficient multilayer coating, with a microchannel plate detector performing two dimensional photon counting. One key innovation is the use of a large-area multi-slit at the spectrometer entrance. This multislit is a one dimensional sequence of open and opaque zones, against which pattern the accumulated spectral image can be correlated to recover the incident spectrum. The other innovation is arranging that each member of the multislit group is curved in such a way that the off-plane grating aberrations (which extend and rotate the image of each object point) do not introduce significant wavelength broadening. The curved slit arrangement yields a large well-corrected image field, and a high throughput for diffuse emission is achieved. The curved-multislit Rowland spectrometer may have a variety of other applications sensing diffuse fluxes with high spectral resolution.

Paper Details

Date Published: 18 August 2005
PDF: 8 pages
Proc. SPIE 5898, UV, X-Ray, and Gamma-Ray Space Instrumentation for Astronomy XIV, 589810 (18 August 2005); doi: 10.1117/12.615553
Show Author Affiliations
M. Lampton, Univ. of California/Berkeley (United States)
J. Edelstein, Univ. of California/Berkeley (United States)
T. Miller, T-Stop Design (United States)
M. Gruntman, Univ. of Southern California (United States)


Published in SPIE Proceedings Vol. 5898:
UV, X-Ray, and Gamma-Ray Space Instrumentation for Astronomy XIV
Oswald H. W. Siegmund, Editor(s)

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