Air core coils for deflecting micron-size electron beams

Bobbin-type air core coils have been designed and experimentally evaluated for astigmatic properties in line scan operation over deflection angles of ± 20°. The approximate design technique is successful in specifying the proper operating focal distance when this is comparable to the coil length. Line fields in excess of 20 000 spot diameters have been measured using a 10 kV beam having a 5 × 10-³radian convergence half-angle.