ION BEAM PURITY MONITORING DEVICE, METHOD AND PROGRAM

摘要

PROBLEM TO BE SOLVED: To provide an ion beam purity monitoring technique which makes possible to properly execute the purity monitoring in real time while continuing an output operation.SOLUTION: An ion beam purity monitoring device 30 comprises: an acquisition part 31 operable to take detection data 26 concerning ions emitted in a direction having an angle to a main axis X of an ion beam emitted from a target 12 irradiated with laser; a time counter 32 operable to repeat the counting of time according to the same cycle as that of laser oscillation; an allocation part 33 operable to allocate a signal value of the detection data 26 to a time of counting time; a setting part 35 operable to set a timing corresponding to each charge-to-mass ratio of impurity ions different from an intended ion forming the ion beam; a determination part 36 operable to make determination on whether or not the signal value of the detection data 26 in line with each timing of the impurity ions is above a threshold; and an output part 37 operable to output an abnormality signal on condition that the signal value is determined to be above the threshold.