Development of a Rapid Beam Emittance Measurement System using a Real-Time Beam Profile Monitor

We have developed a rapid beam emittance measurement system for the injection beam of the K140 azimuthally varying field (AVF) cyclotron at Research Center for Nuclear Physics (RCNP). So far, a conventional emittance monitor has been used in a section of a medium energy beam transport (MEBT) system to evaluate the quality of the injected beam to the K400 ring cyclotron. Two kinds of emittance monitors were supplemented in the low energy beam line for evaluation of ion beams from ion sources. One of them is a conventional type consisting of two sets of position-variable slits and a three-wire profile monitor (TPM), similar to the one installed in the MEBT system of the AVF cyclotron. It takes about 30 min to get emittances in both the horizontal and vertical planes. For quick emittance measurements, we have developed a new system equipped with a set of fast moving slits with a fixed gap and a real-time beam profile monitor (BPM83) with a rotating helical wire. With this system the measurement time was considerably reduced to 70 s for both the horizontal and vertical emittances. Moreover the data analysis and graphical processing were completely automated. The overall measurement and analysis time was successfully minimized within 75 s. This rapid emittance measurement system has contributed to improve the beam quality by optimizing parameters of ion sources and the beam transport system.