A new technique is presented for measuring the spatial and momentum distributions of a buffer-gas cooled ion cloud in a Paul trap by extracting it from the trap and fitting the time profile of the extracted ion signal. A thermodynamic model based on the Gibbs distribution has been developed which describes the initial ion cloud phase space volume and fits the measured time distributions of the extracted cloud using only one parameter: temperature. A time-of-flight system has been built to systematically vary the ion extraction conditions and compare predictions of the model to various measurements of the ion cloud time profile. A new numerical method using a multipole expansion was developed to compute the extraction fields. Agreement between the ion simulations and the time-of-flight data is better than 2% of the total flight time. / Ion cloud temperatures were measured for seven different trap loadings of potassium ions and four loadings of sodium ions, in both cases down to clouds of about 1000 ions. This is the first time that temperature measurements have been made for such small numbers of buffer-gas cooled ions. The results show that the temperature of the ions above the buffer gas temperature appears to be proportional to the two-thirds power of the number of ions in the cloud. / Dynamic manipulation of the extracted ion cloud phase space volume was also accomplished using a time-varying acceleration voltage to change the ion cloud energy spread in flight. / A concept is also outlined to measure the detailed phase space area of the extracted cloud using the projection-slice theorem of tomographic imaging. / These measurements have applications for the use of ion traps as beam collectors for nuclear physics experiments at isotope separator facilities and possibly for nano-circuit fabrication.
| Identifer | oai:union.ndltd.org:LACETR/oai:collectionscanada.gc.ca:QMM.39462 |
| Date | January 1992 |
| Creators | Lunney, Matthew David Norwood |
| 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 Electrical Engineering.) |
| Rights | All items in eScholarship@McGill are protected by copyright with all rights reserved unless otherwise indicated. |
| Relation | alephsysno: 001318784, proquestno: NN80474, Theses scanned by UMI/ProQuest. |
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