Collecting a Sample of Solar Wind: An Experimental Study of Its Capture in Metal Films

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Abstract
Foils of Al, Mg, Mo, Pt, Au, and MYLAR were bombarded with known fluxes of ions (3H, 4He, 22Ne, 37Ar, 85Kr), and accelerated to 1–40 keV in an electromagnetic isotope separator to determine the usefulness of a hypothetical experiment to bring home a sample of solar wind by exposing foils to the solar plasma current outside the earth's geomagnetic cavity. The amounts retained in such foils after bombardment and after subjecting them to particular heating cycles in vacuum and in air (1 atm) were determined. The problems of the loss of ions in space during the proposed space experiment and of extraction of ions in the laboratory subsequent to recovery were thus studied. Aluminum seems to be an acceptable collector material for solar-wind ions. The trapping efficiency for other materials studied is variable and appreciably smaller than unity in some cases. However, since commercial aluminum can contain significant amounts of trapped rare gases, care must be taken to prepare the collector surfaces in their absence.