Making an X-ray Undulator Ready for Commissioning: Procedures Subsequent to Fabrication until Tunnel Installation

In this study, sequence of events for an X-ray undulator generating Free Electron Laser (FEL) pulses down to hard X-rays of the electromagnetic spectrum, are discussed in detail. As soon as an undulator arrives to a Magnetic Measurements Hutch (MMH), a series of treatment steps start to make it ready for commissioning, beginning with a high-precision magnetic alignment procedure. Once Hall probe and undulator are accurately aligned to each other, then gap-dependent measurements begin to create tuning lists. After completion of mechanical tuning of poles, MMH 3D-coordinates have to be transformed to the coordinates of tunnel, where many undulator cells will be sequenced one after another along a linear path. Here, all optical, mechanical and magnetic procedures that an X-ray undulator experiences before commissioning, are thoroughly explained. Furthermore, effects of different types of Hall probes on magnetic measurements, are discussed as well. Finally, whole algorithm subsequent to fabrication until tunnel installation (i.e. optical and magnetic alignment, pole tuning, phase jitter therapy etc.), are summarized by means of the results of magnetic measurements taken in three identical MMHs of European XFEL facility