A new linear high electric field radiofrequency quadrupole (RFQ) ion trap, dubbed HVTrap, was developed and tested to study the phase space properties of confined particles and determine the suitability of such a device as an ion source/delivery system for high-resolution time-of-flight (TOF) mass spectrometry and to test the possibility of high field RFQ beam cooling in an ion guide. / A segmented quadrupole rod structure was built and shown to easily withstand over 4kV between adjacent electrodes placed 1mm apart in 1x10 -4 Torr of helium buffer gas. An innovative resonating circuit design using hollow air-cored induction coils was used to simultaneously deliver the necessary RF and DC trapping potentials to the linear RFQ system as well as deliver the extraction voltages used to eject test ions (Cs+, m/z = 133) produced by a surface ionization source. The resulting ion bunches were delivered to a TOF system for time profile analysis using a multichannel plate detector. Optimal trapping parameters were found to vary with applied RF potentials and extraction voltages. The presence of helium buffer gas at pressures of 10-4 Torr and long cooling times, in the range of 500ms, were found to improve the number of detected ions. / A thermodynamic model of the confined ions was used to simulate the extraction process and follow the phase space evolution of the ejected particles through the TOF region. Analysis of the experimental data showed that confined Cs + ions reached equilibrium temperatures as low as 0.45 eV after 500ms cooling periods in 1x10-4 Torr of helium buffer gas. These equilibrium temperatures were also found to be dependent on the number of detected ions and applied RF potentials. Harmonic frequencies in the resonant circuit are thought to play an important role in determining the thermal energies of the trapped ions. / This thesis has shown that high field RFQ confinement of ions in buffer gas is indeed feasible and that trapped particles can be manipulated using DC fields superimposed on the RF. In its present form, the HVTrap would be capable of mass resolutions of roughly 1000. Beam cooling using a high field RFQ would also be possible and could potentially accommodate beam currents of up to 100nA. If the ion temperature could be reduced to 0.05 eV, TOF mass resolutions of 30 000 would be possible.
| Identifer | oai:union.ndltd.org:LACETR/oai:collectionscanada.gc.ca:QMM.100609 |
| Date | January 2005 |
| Creators | Gianfrancesco, Omar. |
| Publisher | McGill University |
| Source Sets | Library and Archives Canada ETDs Repository / Centre d'archives des thèses électroniques de Bibliothèque et Archives Canada |
| Language | English |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Format | application/pdf |
| Coverage | Doctor of Philosophy (Department of Physics.) |
| Rights | © Omar Gianfrancesco, 2005 |
| Relation | alephsysno: 002339287, proquestno: AAINR25155, Theses scanned by UMI/ProQuest. |
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