First Beam Experiments at ISIS with a Low Output-impedance Second Harmonic Cavity

First beam test with the low output-impedance second harmonic cavity (LOI), was performed in April, 2011 using the ISIS synchrotron at 2.1×10 protons per pulse, which corresponds to the circulating beam current of 2.3~5.2A. The LOI was proven to be stable under such a high intensity beam. The output impedance of LOI was derived from the beam induced voltage across the cavity gap, resulting in 35ohm at 3.4MHz, which agrees well with the measurement by the network analyzer. Issues on the present LOI system and a plan for further beam experiments are also described.