Commissioning of the Alba Injector With 67 Mev Single Klystron Linac

The 3 GeV ALBA booster normally accelerates an injected beam of 110 MeV, delivered by the linac operating with two independent klystrons. On 2014, the linac waveguide system was upgraded and commissioned to allow operating with either klystron and providing a reduced beam energy of 67 MeV. The commissioning of the booster to capture the beam at a reduced energy and ramp it up to 3 GeV has required a long set-up process of the magnets at 67 MeV beam energy. Due to the dominant effect of the remnant magnetic field in the low energy regime, the scaling of the magnet settings at the beginning of the ramp did not allow to capture the beam, and more precise calibrations were measured on spare quadrupoles to ease its fine tuning. The effect of higher eddy currents induced when the dipoles start ramping, combined with the lower beam rigidity, has been also an issue to tune the dipole waveforms for the 67 MeV - 3 GeV cycle. The encountered problems and their solutions to commission the ALBA injector in this new mode of operation are here presented.