New methods of measuring emittance using beam position monitors

Stripline position monitors can be used as a nonintercepting emittance monitor and it is independent of the beam distribution. Usually, difference/sum ratio method is used to pick up the second moment. Two new methods are put forward, which are a log-ratio method and a combined method. The analysis and comparing of these methods are introduced. Change the current of quadrupole magnets m times (mges6) upstream from BPM to change the Transfer matrix, and then the emittance can be calculated.