Self-correction coil: operation mechanism of self-correction coil
K. Hosoyama · 1983
We discuss here the operation mechanism of self-correction coil with a simple model. At the first stage, for the ideal self-correction coil case we calculate the self-inductance L of self-correction coil, the mutual inductance M between the error field coil and the self-correction coil, and using the model the induced curent in the self-correction coil by the external magnetic error field and induced magnetic field by the self-correction coil. And at the second stage, we extend this calculation method to non-ideal self-correction coil case, there we realize that the wire distribution of self-correction coil is important to get the high enough self-correction effect. For measure of completeness of self-correction effect, we introduce the efficiency eta of self-correction coil by the ratio of induced magnetic field by the self-correction coil and error field. As for the examples, we calculate L, M and eta for two cases; one is a single block approximation of self-correction coil winding and the other is a two block approximation case. By choosing the adequate angles of self-correction coil winding, we can get about 98% efficiency for single block approximation case and 99.8% for two block approximation case. This means that by using the self-correction coil we can improve the field quality about two orders.