| 摘要 |
<p>A mass spectrometer is provided comprising a first ion trap 2 arranged upstream of an analytical second ion trap 5. The charge capacity of the first ion trap 2 is set at a value such that if all the ions stored within the first ion trap 2 up to the charge capacity limit of the first ion trap 2 are then transferred to the second ion trap 5, then the analytical performance of the second ion trap 5 is not substantially degraded due to space charge effects. The charge capacity of the first ion trap 2 may be set by the strength of the potential provided to the end gate electrode of the trap such that when the space charge approaches the maximum columbic forces mean that ions start escaping through the gate and are detected. The detection of these escaping ions allows the transfer of the ions from the first trap 2 to the analytical trap 5. Other means involve the setting of a filling time T, during which if ions are detected as leaking from the first ion trap 2, filling of trap 2 is stopped and the ions stored in the first trap 2 are transferred to analytical trap 5. A further embodiment utilizes a single trap which is filled in a first mode and on detection of the space charge reaching capacity the potentials are varied so that it then function in a second mode as an analytical trap.</p> |
