FAST BPM DAQ SYSTEM USING WINDOWS OSCILLOSCOPE-BASED EPICS IOC

The KEK linac is a 600-m-long injector that delivers electron/positron beam to the four independent rings (KEKB e-/e+, PF, PF-AR). The non-destructive beam position monitor (BPM) is an indispensable diagnostic tool for a long-term stable beam operation. In the KEK linac, around one hundred BPMs with the four strip-line type electrodes are used for the beam orbit measurement. The beam orbit data is used for the beam orbit and energy feedback loops. The previous BPM data acquisition (DAQ) system consists of a VME-CPU and a digital oscilloscope, and it has been installed more than decade ago. Although the maximum linac beam repetition rate is 50-Hz, the maximum BPM DAQ rate is about 1-Hz limited by an oscilloscope performance. Recently, we have the on-going linac upgrade project aiming a fast beam-mode switch operation, in which the fast beam position measurement of 50-Hz is strongly required. For this purpose, we developed a new BPM DAQ system using a Windows-based fast digital oscilloscope. In this paper, the system description of the new DAQ system and the results of performance test will be presented in detail.