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In-air APPLE II undulators are the favorite sources for variably polarized synchrotron radiation in many laboratories. The technology for short period in-vacuum and cryogenic planar devices was not transferred to APPLE II devices yet, because several design challenges must be solved. Among them are a precise gap and phase drive on the micrometer level in the presence of strong tree-dimensional forces. Various methods of vertical force compensation for planar devices have been proposed and realized. We present a new dedicated force compensation scheme, which handles the three-dimensional APPLE II forces and permits a conventional in-air motion control. Within an R&D project at HZB all key components for an in-vacuum APPLE II are developed. Utilizing the results of the R&D study, HZB will start the fabrication of a full scale APPLE II end of 2018. [ABSTRACT FROM AUTHOR]

A laser plasma accelerator is under development at the Max-Planck-Institut für Quantenoptik in Garching. This accelerator will be part of an X-ray table top FEL in the future. The FEL radiation will be produced with a small period in-vacuum undulator. The coercivity of the magnetic material has to be sufficiently high in order to avoid demagnetization due to electron losses. The best performance can be achieved with a cryogenic permanent magnet undulator design. (Nd0.2Pr0.8)2Fe14B magnets are suited for low temperatures since they do not suffer from a spin reorientation. A new (Nd0.2Pr0.8)2Fe14B material has been characterized at various temperatures and the results are presented. Based on this material a 20 period prototype with a period length of 9 mm and a magnetic gap of 2.5 mm is currently under construction. [ABSTRACT FROM AUTHOR]

BESSY plans to go to topping up operation in the near future. A high injection efficiency is essential to avoid particle losses inside the undulator magnets and to ensure a low radiation background in the beamlines. Dynamic and static multipoles of the insertion devices have to be minimized to accomplish this requirement. APPLE II devices show strong dynamic multipoles in the elliptical and vertical polarization mode. Measurements before and after shimming of these multipoles are presented. The static multipoles of the BESSY UE56-2 which are due to systematic block inhomgeneities have successfully been shimmed recovering the full dynamic aperture. © 2007 American Institute of Physics [ABSTRACT FROM AUTHOR]

BESSY plans to build a SASE-FEL facility for the energy range from 20 eV to 1000 eV. The energy range will be covered by three APPLE II type undulators with a magnetic length of about 60 m each. This paper summarizes the basic parameters of the FEL-undulators. The magnetic design will be presented. A modified APPLE II design will be discussed which provides higher fields at the expense of reduced horizontal access. GENESIS simulations give an estimate on the tolerances for the beam wander and for gap errors. © 2004 American Institute of Physics [ABSTRACT FROM AUTHOR]

A beamline for circularly polarized radiation from a Sasaki type elliptical double undulator has been recently commissioned at BESSY-II. The PGM (Plane Grating Monochromator) based beamline works with collimated light and employs only one set of optical elements for steering and monochromatising the two (circularly) polarized, angularly separated, beams. The first commissioning results are presented here to illustrate the capabilities of this undulator-beamline concerning photon flux, photon energy resolution and polarization characteristics. © 2000 American Institute of Physics. [ABSTRACT FROM AUTHOR]