| Zugriffsnummer |
12019 |
| Dokumenttyp |
Zeitschriftenartikel
|
| Sprache |
Englisch
|
| Titel |
A transversal earth magnetic field compensating coil system and its comparison with conventional systems |
| Autor(in); Institution |
Ahlers, Heiko; 2.23, Magnetische Messtechnik, PTB-Braunschweig
|
| Quelle/Jahr |
PTB-Mitteilungen: 109
(1999), 3, 131
- 137
|
| ISSN |
0030-834X
|
| Zusammenfassung |
The coercive field strength of a soft magnetic specimen can be determined by magnetizing and demagnetizing it in a solenoid. However, for a precise measurement, the transversal component of the earth magnetic field has to be compensated. For this purpose, a coil consisting of eight parallel straight electrical conductors has been designed. The conductors are positioned on the surface of a cylinder. The angles of the first and second conductors are 42 degrees and 78 degrees related to the direction of the field to be compensated. The angles of the other 6 conductors ensue from the symmetry. The coil constant is . An elongated, almost homogeneous field region was obtained. The cross section of this region is approximately circular with a diameter of 22 % of the total diameter of the coil, the relative deviation of the field strength being smaller than 10-4. A compensation to less than 32 mA/m can be achieved in a cylindrical space 100 mm in diameter and 2 m in length. This degree of precision requires considerable high accuracy in mechanical construction. For less strict requirements, the formulas for two-conductor and four-conductor systems are indicated. |
