The production of laminar fields with permanent magnets

With the increasing demands upon millimeter/microwave devices with regard to miniaturization, power, frequency range, etc., there have arisen requirements for strong (kOe) magnetic fields of unusual shape, confined to small regions by permanent magnetic configurations of minimal bulk. The present work describes several novel permanent magnet structures that produce uniform fields of up to several kOe confined to spaces with thicknesses an order of magnitude smaller than the other two dimensions. Such structures are potentially useful for focusing ribbonlike electron beams in devices such as orotrons. The structural principles used to accomplish this can also be used to shorten long, but efficient, (permanent magnet) transverse field sources, without loss of field strength or incurrence of flux leakage. Examples of proposed structures are discussed and analyzed.