There is no shortage of simulation software in accelerator physics. Faced with the myriad of options, a researcher will typically select one or two reliable codes, learn them well, and stand by them. It is the very nature of computer simulation that different codes have various strengths and differences. This reality underscores the importance of benchmarking multiple codes against one another. This philosophy holds especially true in accelerator modeling, where nonlinearities and the sheer complexity of the simulated scenarios make analytic verification of results difficult, if not impossible. An excellent methodology to confirm that the results of a simulation represent real physics is to run the same test across multiple codes and compare the results.While pursuing my graduate studies at MSU, I have been able to implement this multi-code strategy in several contexts. Simulating the COSY-Julich storage ring in MAD8 and Zgoubi, the dynamic aperture seemed acceptable. However, upon porting the lattice to COSY Infinity, we discovered the surprising result that the lattice as specified was unstable when fringe fields were taken into account. This result would not have been apparent had we limited our simulations to only the original two codes. A similar analysis was performed on the HESR storage ring to be constructed at FAIR. There it was discovered that the nonlinearities which limit dynamic aperture were not visible while using impulse approximation modes in the codes MAD8 and MADX. Porting the lattice to COSY INFINITY, we were able to model the nonlinearities to a high degree of accuracy. This time, we had the positive result of determining that fringe fields did not affect the stability of the lattice. Often when codes disagree in their predictions, the cause of the discrepancy is not immediately apparent. Such was the case when comparing the codes LISE++ and COSY INFINITY in their modeling of spherical and cylindrical electrostatic deflectors. Disagreement in the second order aberration initiated a full analytic investigation into the nature of these aberrations. New physics clarified by that work is also presented here for the first time. Finally, an analysis of the Oak Ridge Isomer/Isotope Spectrometer/Separator (ORISS), was performed. ORISS is an electrostatic multiply reflecting time-of-flight (MRTOF) mass separator that was built by the University Radioactive Ion Beam Consortium (UNIRIB). The device was never fully commissioned due to the Oak Ridge group losing funding, and ended up at Michigan State University for use at the Facility for Rare Isotopes and Beams (FRIB). MRTOF devices are typically used at very low particle intensities due to strong Coulomb repulsion at the particle turning points. Questions were opened on whether the device could operate effectively in a high resolution mass separation mode at high particle intensities. Simulations performed on the iCER High Performance Computing Cluster at MSU show that the device can be operated effectively in this mode at high intensities if voltages are adjusted properly. This was the first analysis of the device to take the effects of intense space charge into consideration and the results are presented here for the first time.
Read
