| 摘要 |
PURPOSE:To improve the uniqueness in corresponding relation between a magnetic field value and coil current by hunting the coil current near the objective magnetic field value and bringing the coil current close to the objective magnetic field value while the amplitude of the hunting is diminished gradually. CONSTITUTION:Secondary ions generated from a sample 1 are accelerated with an acceleration electrode 2, detected with an ion detector 10 through an electric field 3 and a magnetic field 4, and the results are output on an output device 12 through an arithmetic unit 11. On the other hand, all mass numbers required to analyse are obtained by calculation or measurement, and are previously memorised in a memory 13. When, the magnetic field 4, a magnetic field detecting element 5, magnetic field detecting circuit 6, magnetic field controller 8, and magnetic field generating circuit 9 form a feedback loop which is to obtain the magnetic field intensity corresponding to output of a magnetic field setting devive 7, a coil current is hunted near the objective magnetic field value by its dynamic characteristics, and the coil current is brought rapidly close to the objective magnetic field value while the amplitude of hunting is being gradually diminished. |
