Gradient coil design using active magnetic screening.

Active magnetic screening allows the production of gradient coils which are magnetically decoupled from their surroundings. Using such coils the eddy current problems associated with the generation of large, rapidly switched gradients within the confines of a superconductive magnet can be eliminated. In this paper the principles of active screening are outlined and some of the methods of designing screened gradient coils are described. Problems relating to the construction of screened gradient coils are also addressed.