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.

 

• A18.2 Test Set-Up
• A18.3 Data
• A18.4 Results
• A18.5 Addenda