Iwasaki, Y. JACoW Publishing Geneva, Switzerland 978-3-95450-200-4 10.18429/JACoW-ICAP2018-TUPAF16 English 227-228 TUPAF16 power-supply electron storage-ring acceleration data-acquisition Contribution to a conference proceedings 2019 2019-01 https://doi.org/10.18429/JACoW-ICAP2018-TUPAF16 http://jacow.org/icap2018/papers/tupaf16.pdf The accelerator of the SAGA Light Source consists of 255 MeV injector linac　and 1.4 GeV storage ring. The accumulated electron beam current of the　storage ring is about 300 mA. The energy of　the electrons are raised up to 1.4 GeV in 4 minutes in the storage ring. At the moment of the　beam acceleration (the beam energy is lower than 300 MeV), the electron　beam is lost like the step function. The lost beam current is normally　about 5 mA to 30 mA. The beam loss at the energy ramp-up is not observed, when the beam current is lower than 200 mA. To understand the beam loss mechanism, which depend on the beam current, we developed high-speed logging system of 100 kHz for monitoring the beam current and the magnets power supplies using National Instruments PXI. We investigated the relationship between the beam loss and the betatron tune shifts. The tune shifts during the beam acceleration were analyzed from the measured data of the output current of the magnets power supplies by using beam tracking code of TRACY2. By adopting the new high-speed logging system, the time structure of the beam loss process was clearly observed. We will present the high-speed logging system developed for monitoring the beam current and the power supplies at this meeting. The results of the investigation to find the relationship of the beam loss and the tune shifts will be also shown.