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Ion Extraction
The ions can be extracted in DC mode, that is, in overflow mode at which the
ions can escape from the trap over a reduced constant axial trap potential. However,
the obtainable charge state is limited to a certain extent.
But then they can be extracted in pulse mode. After a certain ion confinement time,
which is necessary to produce the designated charge state, the axial trap potential
at the third drift tube section is lowered.
The pulse frequency is determined by the ion trapping time, varying from some ten
ms to several seconds depending on the atomic number of the ion and the required charge state.
Ion pulse form
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The width of the ion pulse can be controlled by the magnitude of the potential at the third drift
tube section while the trap is open ranging from about 1 microsecond up to several tens of microseconds.
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After extraction from the trap the ions are guided by ion-optical elements to an analysing
magnet separating the ions according to their mass to charge ratios.
The ion pulse charge collected at the Faraday cup can be measured both
separately and cumulatively using a high-precision electrometer.
The emittance of the ion beam has been measured to be about 10 mm mrad.
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