Stuttgart 2012 – wissenschaftliches Programm
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MS: Fachverband Massenspektrometrie
MS 8: Ion Trap and FT-ICR-MS, Molecules, Clusters and Reactions
MS 8.3: Vortrag
Donnerstag, 15. März 2012, 15:00–15:15, V57.06
Electrostatic ion beam traps: self-bunching, intrabeam scattering, and RF-bunching — •Michael Froese1, Manfred Grieser1, Oded Heber2, Michael Lange1, Felix Laux1, Sebastian Menk1, Roland Repnow1, Yoni Toker2, Robert von Hahn1, Andreas Wolf1, and Klaus Blaum1 — 1Max Planck Institute for Nuclear Physics, 69117 Heidelberg — 2Weizmann Institute of Science, Rehovot 76100, Israel
The Cryogenic Trap for Fast ion beams (CTF) has been used to investigate the properties of ion bunches in electrostatic ion beam traps (EIBTs). The main ion loss mechanism in these traps (collisional detachment) has been made negligible via our high vacuum levels. For the self-bunching trapping mode achievable with EIBTs, the longitudinal ion bunch density distribution has been measured by photo-detaching aluminum dimer anions, which also revealed the presence of a DC ion beam component co-existing with the oscillating bunch. Stable coherent bunch observation in self-bunching mode was extended from 100 ms in room-temperature EIBTs to times as long as 12 s using N2+ and Al2− with kinetic energies of 6-7.1 keV. The decay of the bunch signal amplitude was observed to be intensity dependent. A model employing intrabeam scattering as well as the expansion of the bunch with time is found to well reproduce the data. This model was also found to reproduce the decay of the bunch signal when RF bunching was applied in agreement with the newly developed EIBT bunch dynamics. These bunches were observed for 600 s placing correspondingly small upper limits on all other EIBT losses.