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Ulysses HISCALE Data Analysis Handbook


Appendix 18. Preliminary Solar Polar Magnet Study


Applicable Document: Preliminary Solar Polar Magnet Study, John W. Kohl, May 9, 1980.


A18.1 Introduction


Studies were carried out to determine a mechanical yoke/magnet/detector configuration to preferentially select for low-energy electrons at the detector surface and still meet residual magnetic field specifications.


Initial tests were run with a stainless steel yoke (designated as SST416/APL) which had no opening in the side wall for a detector mount and had interchangeable magnet-pole pieces. Magnetic field surveys were taken in both the yoke/pole-piece/magnet configuration and the yoke/magnet/pole-piece configuration, labeled Configurations I and II respectively. No tests were run on this yoke using an electron beam to determine the low energy electron paths and impact points within the yoke.


Then a series of tests were run on another stainless steel yoke (designated as SST416/UCB) which was basically identical to SST416/APL except that there was an opening in the side wall to accommodate a detector housing. Again, only magnetic field surveys were run on SST416/UCB; no electron beam data was obtained. For both stainless steel yokes the residual magnetic field at 1 meter exceeded specifications.


To decrease the leakage field from the yoke, another yoke was constructed of a higher permeability material-Carpenter 49. The first Carpenter 49 yoke, designated C49/APL, was identical to SST416/APL in that it did not have a hole in the yoke for a detector housing. Again only magnetic field surveys were run on C49/APL; no electron beam data was obtained.

Because of the higher permeability of Carpenter 49, the sidewalls of the C49/APL yoke were thinned down to 0.10 inches thick, which were still calculated to be able to carry as much flux as the original SST walls. Also, there was a hole for the detector housing. This yoke was designated C49/Mod I. Magnetic field surveys for C49/Mod I were obtained for both magnet configurations I and II. Electron beam measurements were also made for C49/Mod I in both magnet/pole-piece configurations.


Based on the magnetic field survey and the electron beam measurements, the magnet/pole-piece assembly was repositioned within the yoke and the pole-pieces designed as an integral part of the yoke. This yoke assembly was designated as C49/Mod II. Both magnetic field surveys and electron beam measurements were made on C49/Mod II. As of this writing, C49/Mod II is considered to be the flight version of the Solar Polar magnet.




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Updated 8/8/19, Cameron Crane


Manufacturer: ESA provided the Ulysses spacecraft, NASA provided the power supply, and various others provided its instruments.

Mission End Date: June 30, 2009

Destination: The inner heliosphere of the sun away from the ecliptic plane

Orbit:  Elliptical orbit transversing the polar regions of the sun outside of the ecliptic plane