Recirculating linac as an injector for small storage rings or free electron lasers

There is an increasing interest in the use of small storage rings to produce synchrotron radiation for such purposes as lithography. Clearly, such rings need injectors and the provision of these can add significantly to the overall cost of a storage ring project in terms of both hardware and space requirements. There is a need, therefore, to consider the most cost-effective way of providing for injection. It is suggested that the recirculating linac (or double-sided microtron) design meets this aim at least for injection energies up to about 450 MeV and maybe higher. The concept on which the proposal is based was first given by Kaiser, who called it a bicyclotron. The concept is described