Various Studies at the CBETA 4-Turn FFA ERL

The CBETA ERL has a fixed-field (non-scaling FFA) return loop, which recirculates up to four different energies: 42, 78, 114, 150MeV.  Although most of the field is provided by permanent magnets, there are electromagnetic correctors that can superimpose a dipole field that can be changed during operation.  These dipole kicks affect the energies in different ways, since they have different cell tunes.  This allows independent control of the beams over a long distance by using combinations of correctors determined by Singular Value Decomposition (SVD).  To operate correctly in reality, at CBETA a "semi-empirical" response matrix was used in the SVD, which was adjusted to more exactly match the observed phase advances of the machine.  With this approach, all four beam orbits could be corrected.

First observations of beam halo, operational tooling, beam steering procedures and path length adjustment techniques developed for CBETA are also reported.