<p> Optimization criteria for trap design were established and a qualitative optimization program on the design of two of the most promising series of traps was carried out. </p> <p> An evaluation of several existing traps was carried out using Johnston's technique. Two traps were calibrated and an impact testing device was designed and built for future research work to be conducted at Guelph University. </p> / Thesis / Master of Engineering (MEngr)

Unwanted gas bubbles are a challenge for microfluidic-based systems, as adherence to channel networks can disrupt fluid delivery. This is especially true for devices with biological applications, as the presence of a single bubble creates thin fluid films with extremely high shear stresses, which can damage biological samples. Current strategies to remove bubbles require complicated fabrication or off-chip components. This thesis describes an on-chip microfluidic strategy utilizing permeation for in-plane trapping and removal of occasional gas bubbles. The trap was demonstrated with nitrogen bubbles, which were consistently removed at a rate of 0.14 µL/min for a single trap, and shown to have long-term operation capability by removing approximately 4,000 bubbles during one day without failure. The trap was integrated with a microfluidic system for the study of small blood vessels. Experiments were complemented with analytical and numerical models to characterize the bubble removal process.

Unwanted gas bubbles are a challenge for microfluidic-based systems, as adherence to channel networks can disrupt fluid delivery. This is especially true for devices with biological applications, as the presence of a single bubble creates thin fluid films with extremely high shear stresses, which can damage biological samples. Current strategies to remove bubbles require complicated fabrication or off-chip components. This thesis describes an on-chip microfluidic strategy utilizing permeation for in-plane trapping and removal of occasional gas bubbles. The trap was demonstrated with nitrogen bubbles, which were consistently removed at a rate of 0.14 µL/min for a single trap, and shown to have long-term operation capability by removing approximately 4,000 bubbles during one day without failure. The trap was integrated with a microfluidic system for the study of small blood vessels. Experiments were complemented with analytical and numerical models to characterize the bubble removal process.

The three-dimensional quadrupole ion trap (QIT) is an extraordinary device. It functions both as an ion store in which gaseous ions can be confined for a period of time and as a mass spectrometer of considerable mass range and variable mass resolution. Over the past few decades, it has evolved into a powerful tool for both research and routine analysis. The basic objective of this thesis is the development of a three-dimensional quadrupole ion trap with cylindrical symmetry in laminar approximation. The laminar construction allows hyperbolic geometry to be well approximated with minimal construction effort and also provides more access into the trap through interlaminar spaces without disruption of the field. The performance of the trap is examined in the mass selective trapping mode and mass-selective instability mode. Fourier detection is also done. Resolution of our instrument is limited by the external hardware. There is not good enough data quality and so not a good enough spectrum to predict its resolution accurately. A few changes to the instrumentation of the trap will improve the resolution.

Portable mass spectrometers provide convenience for applications where conventional mass spectrometers are not suitable. However, a series of miniaturization issues show up in small mass spectrometers, specifically mass analyzers, that need to be thoroughly addressed before further miniaturization. The work in this dissertation focuses on miniaturization issues of ion trap mass analyzers. Space-charge is one of the major issues in small ion traps affecting their analytical performance. It limits ion trapping capacity when ion-ion repulsion causes spreading of a packet of ions. Simulation studies on the relationship between different trap dimensions and trapping capacity was done on a geometry-optimized cylindrical ion trap. A reasonable way of scaling the two important operating parameters (trapping voltage and trapping frequency as functions of the trap dimension) was discussed and applied in the simulation. The trapping capacity (N) decreased with the physical trap dimension (r0) as expected, and N is scaled exponentially as r0. Scaling laws for trapping parameters are proposed, confirmed by SIMION simulations that evaluate the space charge issue in small ion traps. This effect represents a practical limit in ion trap miniaturization.Geometry deviation is another issue that cannot be neglected in miniaturized ion traps, especially in small linear ion traps (LIT). The LIT our group is working on consists of an assembly of two plates, of which each was made by lithographically patterning a series of electrodes on an insulating plate. It is a promising way of expanding the trap capacity at a small trap dimension. However, misalignment of the two plates might seriously affect its performance, specifically resolution and signal intensity. Simulations were done on the misalignment of two-plate planar LIT in the six possible degrees of freedom (DOF) of misalignment between the two plates. Each DOF's influence on the mass resolution and the ion detection efficiency were discussed. Preliminary data from a previous ceramic plate design was collected while most of the misalignment experiments were done on an improved version. A platform was designed incorporating four motorized stages to precisely control the alignment of the ion trap in vacuum. The new plate design was demonstrated to achieve a better than unit resolution for toluene and deuterated toluene after the plates were aligned. The impact on the resolution and signal intensity from pitch, x-, y- and z-displacement were also experimentally studied.

No description available.

New measurements of the masses of the isotopes⁸,⁹,¹¹Li were made using recently commissioned TITAN Penning trap mass spectrometer at TRIUMF. The measurement of the halo nucleus ¹¹Li represents a new standard in Penning trap mass spectrometry, as it is the shortest lived, t₁/₂ = 8.8 ms, isotope ever weighed using this technique. Low energy, E = 20 keV, beams of these radioactive isotopes were produced using the ISAC facility. These were subsequentlycooled and bunched using a square-wave-driven Radio- Frequency Quadrupole (RFQ) ion guide, which was filled with hydrogen gas. The cooled ion bunches were then passed into a Penning trap where the mass measurements were made. A description of the RFQ in the ISAC hall is given along with some results from the commissioning of the device. A new set of harmonic deceleration optics is presented which have been successfully used to inject ions into the RFQ. Cooling of lithium ions with high DC efficiencies of 20%, in helium, and 40%, in hydrogen, are shown. Extraction of extremely short ion bunches, 30 ns FWHM, is also demonstrated. Storage times for stable lithium ions in helium and hydrogen were investigated. It was found that lithium ions could be cooled in hydrogen for up to 30 ms without significant losses whereas cooling in helium lead to exponential losses with a half-life of 5.7(1)ms. The TITAN Penning trap is described and the ⁸,⁹,¹¹Li data presented. Final values for the mass excess of ∆(⁸Li) = 20945.70(38) keV, ∆(⁹Li) = 24954.80(60) keV and ∆(¹¹Li) = 40728.1(12) keV are obtained. The ⁹,¹¹Li results are then used to obtain a new value for two neutron separation energy of ¹¹Li, S₂n = 369.3(1.3) keV. This agrees with the recent measurement from the MISTRAL spectrometer, 376(5) keV, at the two sigma level, but shows over three standard deviations from the most recent atomic mass evaluation, 300(20) keV

A high frequency, large amplitude helium filled RFQ (Radio Frequency Quadrupole) beam cooler and buncher was developed and tested for use in the TITAN (TRIUMF's Ion Trap for Atomic and Nuclear science) Penning trap mass spectrometer facility. This device will cool and bunch radioactive ion beams for use in TITAN's high precision mass measurements of short-lived isotopes and other experiments. A test stand was built to test the transmission and properties of ions from a surface ion source through injection optics, the linear Paul trap RFQ and the extraction optics in both continuous and pulsed modes. The efficiency of the device was determined to be on the order of 60% in continuous mode. The present measurements confirm a transverse emittance of the extracted beam in bunched mode operation of 4 pi-mm-mrad at an extraction energy of 4 keV.

New measurements of the masses of the isotopes⁸,⁹,¹¹Li were made using recently commissioned TITAN Penning trap mass spectrometer at TRIUMF. The measurement of the halo nucleus ¹¹Li represents a new standard in Penning trap mass spectrometry, as it is the shortest lived, t₁/₂ = 8.8 ms, isotope ever weighed using this technique. Low energy, E = 20 keV, beams of these radioactive isotopes were produced using the ISAC facility. These were subsequentlycooled and bunched using a square-wave-driven Radio- Frequency Quadrupole (RFQ) ion guide, which was filled with hydrogen gas. The cooled ion bunches were then passed into a Penning trap where the mass measurements were made. A description of the RFQ in the ISAC hall is given along with some results from the commissioning of the device. A new set of harmonic deceleration optics is presented which have been successfully used to inject ions into the RFQ. Cooling of lithium ions with high DC efficiencies of 20%, in helium, and 40%, in hydrogen, are shown. Extraction of extremely short ion bunches, 30 ns FWHM, is also demonstrated. Storage times for stable lithium ions in helium and hydrogen were investigated. It was found that lithium ions could be cooled in hydrogen for up to 30 ms without significant losses whereas cooling in helium lead to exponential losses with a half-life of 5.7(1)ms. The TITAN Penning trap is described and the ⁸,⁹,¹¹Li data presented. Final values for the mass excess of ∆(⁸Li) = 20945.70(38) keV, ∆(⁹Li) = 24954.80(60) keV and ∆(¹¹Li) = 40728.1(12) keV are obtained. The ⁹,¹¹Li results are then used to obtain a new value for two neutron separation energy of ¹¹Li, S₂n = 369.3(1.3) keV. This agrees with the recent measurement from the MISTRAL spectrometer, 376(5) keV, at the two sigma level, but shows over three standard deviations from the most recent atomic mass evaluation, 300(20) keV

No description available.