Mass Spectroscope and its Adjusting Method

A mass spectroscope comprising:

• a sample introduction chamber for introducing therein a sample;
• an ionization chamber for ionizing the sample which has been introduced into the sample introduction chamber;
• an ion trap section for separating the sample ionized in the ionization chamber according to the mass of the ions;
• a detector for detecting ions having predetermined mass among the ions separated in the ion trap section;
• and
• a data processing unit for processing data obtained as the result of detecting the ions by the detector, wherein:
• the ion trap section includes:
• a rod electrode section having two pairs of rod electrodes (four rod electrodes in total), each pair of rod electrodes being disposed in such a manner that the rod electrodes of the pair face each other;
• an RF signal source for generating an RF signal;
• a resonance circuit unit for resonating and amplifying the RF signal generated by the RF signal source to generate a high-voltage RF signal, applying the high-voltage RF signal to one of the two rod electrode pairs, and applying the high-voltage RF signal, the phase of which is reversed from that of the high-voltage RF signal applied to the one of the two rod electrode pairs, to the other of the two rod electrode pairs, the rod electrodes of each of the rod electrode pair facing each other with respect to the central axis of the four rod electrodes of the rod electrode section;
• a resonance frequency/amplitude difference measuring unit for measuring an amplitude difference between the high-voltage RF signal applied to the one of the two rod electrode pairs and the reversed-phase high-voltage RF signal applied to the other of the two rod electrode pairs, and measuring a resonance frequency of the resonance circuit unit;
• and
• a control unit for adjusting the resonance circuit unit on the basis of information about the amplitude difference between the high-voltage RF signals and the resonance frequency of the resonance circuit unit;
• the resonance circuit unit includes:
• a frequency synchronizing section for synchronizing the drive frequency of the RF signal source and the resonance frequency of the resonance circuit with each other;
• and
• an amplitude difference adjustment section for adjusting the amplitude difference between the high-voltage RF signals to a predetermined value;
• and
• the control unit includes:
• an amplitude difference control section for controlling the amplitude difference adjustment section of the resonance circuit unit on the basis of the information about the amplitude difference between the high-voltage RF signals and the resonance frequency of the resonance circuit unit;
• and
• a frequency synchronization control section for controlling the frequency synchronizing section of the resonance circuit unit.

A method for adjusting a mass spectroscope, the method comprising the steps of:

• resonating and amplifying, by a resonance circuit, an RF signal generated by an RF signal source to generate a high-voltage RF signal;
• providing a rod electrode section with two pairs of rod electrodes (four rod electrodes in total), each pair of rod electrodes being disposed in such a manner that the rod electrodes of the pair face each other with respect to the central axis of the four rod electrodes, applying the generated high-voltage RF signal to one of the tow rod electrode pairs, and applying the generated high-voltage RF signal to the other of the two rod electrode pairs with the phase of the high-voltage RF signal reversed from that of the high-voltage RF signal applied to the one of the two rod electrode pairs;
• measuring an amplitude difference between the high-voltage RF signal applied to the one of the two rod electrode pairs and the reversed-phase high-voltage RF signal applied to the other of the two rod electrode pairs, and a resonance frequency of the resonance circuit;
• and
• adjusting the resonance circuit on the basis of information about the measured amplitude difference between the high-voltage RF signals and the measured resonance frequency of the resonance circuit, wherein:
• on the basis of the information about the amplitude difference between the high-voltage RF signal applied to the rod electrodes and the reversed-phase high-voltage RF signal applied to the rod electrodes, and the information about the resonance frequency of the resonance circuit, the resonance circuit is adjusted in such a manner that the amplitude difference decreases, and in such a manner that the resonance frequency of the resonance circuit is aligned with a frequency of the RF signal.

A method for adjusting a mass spectroscope that includes a rod electrode section having two pairs of rod electrodes (four rod electrodes in total), each pair of rod electrodes being disposed in such a manner that the rod electrodes of the pair face each other, the method comprising the steps of:

• detecting a resonance frequency of a resonance circuit which resonates and amplifies an RF signal generated by an RF signal source to generate a high-voltage RF signal;
• setting a drive frequency of the RF signal source in such a manner that the drive frequency is synchronized with the detected resonance frequency of the resonance circuit;
• resonating and amplifying, by the resonance circuit, an RF signal generated by the RF signal source at the set drive frequency, thereby generating a high-voltage RF signal;
• providing the rod electrode section with two pairs of rod electrodes, each pair of rod electrodes being disposed in such a manner that the rod electrodes of the pair face each other with respect to the central axis of the four rod electrodes, applying the generated high-voltage RF signal to one of the two rod electrode pairs, and applying the generated high-voltage RF signal to the other of the two rod electrode pairs with the phase of the high-voltage RF signal reversed from that of the high-voltage RF signal applied to the one of the two rod electrode pairs;
• detecting an amplitude difference between the high-voltage RF signal applied to the one of the two rod electrode pairs and the reversed-phase high-voltage RF signal applied to the other of the two rod electrode pairs;
• comparing the detected amplitude difference with a predetermined value;
• when the detected amplitude difference is larger than the predetermined value, adjusting the resonance circuit in such a manner that the amplitude difference decreases;
• and
• when the detected amplitude difference is smaller than or equal to the predetermined value, setting a correction coefficient of a mass spectrum according to the drive frequency.