PETRA III - Betrieb 2015 | July, 2015 | 1 PDE Magnet PETRA III. PETRA III Team DESY Meeting mit MEA PETRA III - Betrieb 2015 | July, 2015 | 2 PXN, 2 nd cell PU64, PU65 PETRA III - Betrieb 2015 | July, 2015 | 3 Problems with the fringe field of the PDE Dipole PU64PDE Dipole 20 mrad correction coils correction windings Fringe field of the dipole Gap PU mm 30 mm Orbit distortion: rms orbit 0.3 mm 1.7 mm Kick ~ 0.1 mrad or B*L = 2.2 T mm (Measurements: Sep 9, 2015 ) PETRA III - Betrieb 2015 | July, 2015 | 4 Field measurements in the tunnel Length of coil ~ 55 mmMeasurements of the magnetic field versus gap with Dipole on and off and the difference The magnetic field measurements agree with the measured orbit distortion if one extrapolates the results further into the undulator region. The coil is too short to cover the whole fringe field. PETRA III - Betrieb 2015 | July, 2015 | 5 Correcting the orbit distortion with a feed forward Setting the PDE correction coil according to a Feed Forward table Feed Forward + Fast Orbit Feedback Orbit distortion is very small But the spectral properties of the undulator radiation have been not yet measured ! Feed Forward max. horz. Orbit distortion ~ 200 m BPM horizontal vertical PETRA III - Betrieb 2015 | July, 2015 | 6 Improved magnet design A new coil configuration gives good results but requires a new support structure for the vacuum chamber. PDE Magnet in the equivalent position on the Extension East (no undulators yet) with absorber in the magnet gap. Fring field shielding New coil configuration PETRA III - Betrieb 2015 | July, 2015 | 7 Fotos PDE NN PETRA III - Betrieb 2015 | July, 2015 | 8 Dipoles Extension sections Einbaupositionen Magnete #004 = spare PETRA III - Betrieb 2015 | July, 2015 | 9 PDD Spulenhalterung NN PETRA III - Betrieb 2015 | July, 2015 | 10 PDE Magnet PDE #04 PETRA III - Betrieb 2015 | July, 2015 | 11 PDE #05 PETRA III - Betrieb 2015 | July, 2015 | 12 PDE #4 Randfeld PDE PETRA III - Betrieb 2015 | July, 2015 | 13 NN PETRA III - Betrieb 2015 | July, 2015 | 14 Thank you for your attention !