| Paper | Title | Page |
|---|---|---|
| WEPC096 | APPLE Undulator for PETRA III | 2219 |
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| Currently, the storage ring PETRA is being rebuilt to a light source with an ultra low emittance of only 1nm rad. The undulator radiation will take full advantage of this high performance. PETRA III will also provide circularly polarized light and linearly polarized light under arbitrary angles (inclined mode) within the energy range of 250-3000eV. The light will be produced with an APPLE II undulator which is under construction at BESSY at present. The total length of 5m and a minimum gap of only 11mm cause strong 3D forces. Due to the small good field region in an APPLE undulator and a small stay clear between the magnets and the vacuum chamber a sophisticated mechanical layout is required. The design will be presented, the expected residual mechanical deformations will be given and the consequences for the spectral performance will be discussed. |