Plasma ion source mass spectrometer

Abstract

Simplified measurements may be conducted using a plasma ion source mass spectrometer by performing an ion count while scanning an ion beam and setting voltages applied to electrodes of at least an ion lens and a deflector at values which maximize the count value. The mass spectrometer comprises a plasma ion source for ionizing a sample in a plasma, a vacuum vessel containing deflection, detection and monitoring devices, a sampling interface for introducing the ionized sample into the vacuum vessel, and a data processing unit. An ion lens collects and condenses the ionized sample. A mass filter separates ions in the ion beam by mass. A deflector deflects the ion beam by 90 degrees to prevent light from the plasma from entering the mass filter. A scanning electrode scans the ion beam, and a detector detects ions that have passed through the mass filter and provides a corresponding output signal. A power supplies a scanning signal to the scanning electrode, and applies predetermined voltage signals to the ion lens and the deflector. The data processing unit counts output signals from the detector in synchronism with the scanning signal applied to the scanning electrode. Based upon the voltage applied to the scanning electrode and the output signal of the detector, the data processing unit calculates optimum values of voltages to be applied to the deflector, the scanning electrode and the ion lens.