A Fast Way of Electron Orbit Simulation in Complex Magnetic Fields
Vertical cut through a quadrupole magnet: Black: Field distribution at a fixed vertical distance to the midplane. Magenta: Electron trajectories for various initial coordinates. © C. Rethfeldt/HZB
The design of advanced synchrotron radiation sources requires precise algorithms for the simulation of electron trajectories in complex magnetic fields. However, multi-parameter studies can be very time consuming. Now, a team of the HZB has developed a new algorithm which significantly reduces the computation time. This approach is now published in the renowned journal “Physical Review Special Topics Accelerator & Beams”.
In a storage ring like BESSY II electrons circulate nearly with the speed of light passing complex magnetic structures. These magnets guide the electron beam and focus it on the ideal orbit. They are comparable to optical lenses which focus the light. To evaluate the stability of the electron trajectories in the magnetic fields, several thousands of turns need to be simulated. After each revolution the trajectories are slightly different, passing the magnets at slightly different positions. These combined and complex orbit and field calculations require a precise algorithm which could easily result in time consuming simulations.
Already in 2011, a team out of the HZB undulator group and of the HZB-institute of accelerator physics has published a first paper of a new simulation algorithm [2], which drastically speeds up the simulation time for trajectories in complex undulator fields. This simulation routine was implemented into the public domain code “elegant“ of the Advanced Photon source / Argonne, and it is available, worldwide.
Now, Malte Titze together with Johannes Bahrdt and Godehard Wüstefeld could extend this method to another important class of three dimensional magnets: multipoles such as quadrupoles or sextupoles [1].
“The paper demonstrates, that this method yields very precise results, particularly within the fast changing fringing fields of the magnets”, Malte Titze explains. He is now engaged in research activities at CERN. “Such simulation methods are of great interest for future light sources, especially for diffraction limited storage rings, which may include combined function magnets and exhibit significant cross talking between neighboring magnets” comments Johannes Bahrdt. “This is of clear relevance for a successor of BESSY II”. The scientists describe their methods in the renowned journal of “Physical Review Special Topics Accelerator & Beams“.
[1] M. Titze, J. Bahrdt, G. Wüstefeld, „Symplectic tracking through straight three dimensional fields by a method of generating functions“
DOI: 10.1103/PhysRevAccelBeams.19.014001
[2] J. Bahrdt, G. Wüstefeld, “Symplectic tracking and compensation of dynamic field integrals in complex undulator structures”, Phys. Rev. ST Accel. Beams 14, 040703 (2011).
- Battery research with the HZB X-ray microscopeNew cathode materials are being developed to further increase the capacity of lithium batteries. Multilayer lithium-rich transition metal oxides (LRTMOs) offer particularly high energy density. However, their capacity decreases with each charging cycle due to structural and chemical changes. Using X-ray methods at BESSY II, teams from several Chinese research institutions have now investigated these changes for the first time with highest precision: at the unique X-ray microscope, they were able to observe morphological and structural developments on the nanometre scale and also clarify chemical changes.
- BESSY II: New procedure for better thermoplasticsBio-based thermoplastics are produced from renewable organic materials and can be recycled after use. Their resilience can be improved by blending bio-based thermoplastics with other thermoplastics. However, the interface between the materials in these blends sometimes requires enhancement to achieve optimal properties. A team from the Eindhoven University of Technology in the Netherlands has now investigated at BESSY II how a new process enables thermoplastic blends with a high interfacial strength to be made from two base materials: Images taken at the new nano station of the IRIS beamline showed that nanocrystalline layers form during the process, which increase material performance.
- Hydrogen: Breakthrough in alkaline membrane electrolysersA team from the Technical University of Berlin, HZB, IMTEK (University of Freiburg) and Siemens Energy has developed a highly efficient alkaline membrane electrolyser that approaches the performance of established PEM electrolysers. What makes this achievement remarkable is the use of inexpensive nickel compounds for the anode catalyst, replacing costly and rare iridium. At BESSY II, the team was able to elucidate the catalytic processes in detail using operando measurements, and a theory team (USA, Singapore) provided a consistent molecular description. In Freiburg, prototype cells were built using a new coating process and tested in operation. The results have been published in the prestigious journal Nature Catalysis.