Magnetic Measurements of the Drift Tube Quadrupole Magnets for the PEFP 100-MeV DTL

To accelerate the proton beam up to 100 MeV, a conventional drift; tube linac (DTL) is under development for the Proton Engineering Frontier Project, (PEFP) proton accelerator. Ab electroquadrupole magnet is installed in each drift tube for focusing the proton beam. Front the view point of beam dynamics, one of the most important parameters of the quadrupole magnet, is the integrated field gradient and 1.75 T is required for the PEFP 100-MeV DTL electromagnet. To measure the integrated field gradient, we developed it rotating coil system, which consists of a rotating probe coil, a DC motor for driving the probe coil, a rotary encoder and an oscilloscope for measuring the voltage induced in the probe coil. The measured signals were analyzed by rising the. Fast Fourier Transform (FFT), from which the integrated field gradient and the magnetic center offset could be found. In this paper, the measurement system setup and the measurement results, as well as the data analysis procedure, are given in detail.