  The concept of a fixed field alternating gradient (FFAG) accelerator was
invented in the 1950s. Although many studies were carried out up to the late
1960s, there has been relatively little progress until recently, when it
received widespread attention as a type of accelerator suitable for very fast
acceleration and for generating high-power beams. In this paper, we describe
the principles and design procedure of a FFAG accelerator.
