Undulators for BESSY III

Helmholtz Zentrum Berlin is engaged in the conceptual design of the BESSY III facility. The BESSY III storage ring will be a fourth generation synchrotron light source with an emittance of about 100 pm rad and an energy of 2.5 GeV. It will be equipped with advanced undulators to provide users with tailor-made light. So far cryogenic permanent magnet undulators, hybrid planar undulators and a variety of APPLE II undulators - conventional (in-air) and in-vacuum are planned to meet user requirements in terms of spectral range, flux and polarisation. In this paper we give an overview of the planned undulators, discuss some of the design aspects and present their expected performance.