The PTB electromagnetic undulator for BESSY II

Area of Science:

• Synchrotron Radiation and Particle Accelerators
• Metrology and Scientific Instrumentation

Background:

• The BESSY II storage ring is a key facility for generating synchrotron radiation.
• Radiometry requires precisely controlled photon sources for accurate measurements.

Purpose of the Study:

• To present the design and parameters of a novel electromagnetic undulator for radiometric applications.
• To detail the undulator's tunable energy range and operational modes.

Main Methods:

• Design and simulation of an electromagnetic undulator with specific period length and magnetic field parameters.
• Measurement of magnetic field data to validate design specifications.
• Calculation of the first harmonic tuning range based on undulator parameters and electron beam energy.

Main Results:

• The undulator features a period length of 180 mm, 21 periods, and a maximum magnetic induction of 0.46 T.
• A tuning range of 5 to 150 eV for the first harmonic is achieved at 1.7 GeV electron energy.
• An alternative mode with a doubled period length (360 mm) shifts the tuning range to lower energies.

Conclusions:

• The electromagnetic undulator is optimized for radiometry at the BESSY II facility.
• The dual-mode operation provides flexibility for radiometric measurements across a wider energy spectrum.