Insertion Devices Development Projects

The photon sources for the MAX IV beamlines are based on Insertion Devices (ID) that cover the photon energy range from 4- 40 000 eV at the three accelerators. The soft x-ray beamlines at the 1.5 GeV and 3 GeV rings are based on APPLE II type undulator, except FlexPES, to provide full polarization control at the fundamental harmonic. A room temperature In-vacuum undulators (IVU) are the sources for the hard x-ray beamlines at the 3 GeV ring and Short Pulse Facility (SPF).

All IDs are delivering light up to specifications at the current 16 beamlines at MAX IV, and continuous improvement is being made to enable operation excellence, such as motion upgrade, introducing the continuous photon energy scanning modes of operation at the different beamlines, and transparent operation in terms of the effect on the electron beam orbit and optics. 

We have recently finished characterizing a full-scale APPLE X prototype undulator with a compact structure intended for use at single-pass machines and fourth-generation storage rings where a small round vacuum chamber can be accommodated. It is part of the enabling technology development for the future upgrade of the 3 GeV ring and soft X-ray FEL at MAX IV as a source with full polarization control. The compactness of its structure considerably reduces the overall cost by 40 % and the weight by a factor of 6 compared to an APPLE II undulator with similar parameters.  

Another direction in ID development involves implementing a Cryogenic Permanent Magnet Undulator (CPMU) technology to achieve a shorter period undulator of the order of 13–14 mm. This short-period CPMU is designed to leverage the emittance reduction from the proposed 3 GeV ring upgrade, serving as a source of high coherent flux and brilliance for photon energies up to 65 keV. 

The near-term R&D of the Insertion Devices at MAX IV consists of:

  1. Compact APPLE X undulator with a round aperture for the generation of Soft X-ray. A cost-effective solution compared to the existing APPLE II and provides full polarization control with constant effective K-value as a function of phase, i.e. polarization state. The APPLE X is an ideal source for the proposed soft X-ray FEL at MAX IV and gives the possibility to extend the energy range below 2 keV at the FemtoMAX beamline at the SPF. In addition, it offers higher energy range with full polarization tunability at the 3 GeV MAX IV ring compared to the APPLE II undulators.
  2. Short period Cryogenic Permanent Magnet Undulator CPMU for future hard X-rays beamlines. Period length of 12 – 14 mm and physical gap in the range of 3 – 3.5 mm to extend the hard X-rays range beyond 65 keV with high brilliance at the 3 GeV MAX IV ring.
Apple X
APPLE-X Prototype Undulator at the magnetic measurement laboratory at MAX IV

Ongoing Research Activities

  • Universal Polarization Mode of Operation
  • Continuous ID-Mono Scanning
  • Machine Learning
  • Beam Loss Monitors in 3 GeV Storage Ring
  • Magnetic Measurement Laboratory