VARIABLE-PERIOD MAGNETOSTATIC UNDULATOR DESIGNS BASED ON IRON-FREE CURRENT CONFIGURATIONS

The recent availability of high-energy storage rings (≥5 GeV) with long straight sections (≥20 m) for generating synchrotron radiation (SR) has provided a suitable context for initiating the development of weak-field insertion devices with relatively long periods. This, in turn, has led to the introduction of static-field undulators with variable periods, which are superior in many respects to conventional fixed-period undulators. In prior work, a segmented-wire electrostatic undulator with a widely variable period and the ability to produce arbitrarily polarized soft X-rays on the Stanford Positron Electron Project (PEP) has been introduced. In this paper, we develop the design of a magnetostatic analog of this device and derive the equations describing its performance. Based on this exercise, it is shown that other types of variable-period magnetostatic structures with significantly stronger fields could be implemented, and a specific design for a variable-period dipole configuration with the potential for generating moderate fields on medium-energy (2–4 GeV) storage rings is proposed. © 1990 IEEE