Printed-Circuit Steering Coils

Beam steering coils utilizing "turns" etched on printed-circuit boards have been constructed and tested. This approach offers an economical method for achieving high-quality, compact steering coils. The circuit-boards are rolled into a cylinder and inserted inside a short steel tube. Boards for vertical and horizontal steering are located in separate layers. For our application, three coil sizes were constructed with inside diameters of 25 cm. 20.6 cm, and 17.3 cm respectively. Active length is 0.6 of the inside diameter in all cases. The coils produce an integrated deflection field in either the vertical or horizontal direction of ~ 316 Gauss-cm when excited with 5 A at ~ 30V. The conductor pattern on the circuit-board was designed to produce a nearly uniform angular deflection for all rays transmitted, in spite of the short length/diameter ratio. The magnetic field integrated over a length of 152 cm was measured at several radii and azimuths. Values at 0.4 and 0.8 of bore radius were within ~ 0.5% and ~ 1.5% respectively of the central value. Suggestions for further refinement of deflection uniformity are presented.