| 摘要 |
PROBLEM TO BE SOLVED: To simply and accurately find in a short time a ratio of an purposive componental ion contained in an ion beam extracted from an ion source. SOLUTION: In this measuring method, a deflector 24 to receive the ion beam 10 extracted from the ion source 2 and bend it by a magnetic field, and a Faraday cup 30 provided at a position where the ion beam 10 making a straight advance in the deflector 24 is injected are used. When magnetic field strength in the deflector 24 is reduced to zero, an ion current I0 passing through the Faraday cup 30 is measured, and when the magnetic field strength in the deflector 24 is gradually increased, ion currents I1 and I2 on two flat parts where the change of the ion current I passing through the Faraday cup 30 becomes almost zero near the magnetic field strength corresponding to the purposive componental ion are individually measured. Thereby, a ratio of|I1-I2|/I0 is found.
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