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1. Varying the aspect ratio of toroidal ion traps: Implications for design, performance, and miniaturization

   Hettikankanange, Praneeth M.; Austin, Daniel E. (January 2021, International journal of mass spectrometry)

   null (Ed.)

   A large aspect ratio (AR) leads to higher ion capacity in miniaturized ion trap mass spectrometers. The AR of an ion trap represents the ratio between an extended trapping dimension and the characteristic trapping dimension. In contrast to linear and rectilinear traps, changing the AR of a toroidal ion trap(TorIT) results in changes to the degree of curvature and shape of the trapping potential, and hence, on performance as a mass analyzer. SIMION simulations show that higher-order terms in the trapping potential vary strongly for small and moderate AR values (below ~10), with the effects asymptotically flattening for larger AR values. Because of the asymmetry in electrode geometry, the trapping center does not coincide with the geometric center of the trap, and this displacement also varies with AR. For instance, in the asymmetric TorIT, the saddle point in the trapping potential and the geometric trap center differ from þ0.6 to 0.4 mm depending on AR. Ion secular frequencies also change with the AR. Whereas ions in the simplified TorIT have stable trajectories for any value of AR, ions in the asymmetric TorIT become unstable at large AR values. Variations in high-order terms, the trapping center, and secular frequencies with AR are a unique feature of toroidal traps, and require significant changes in trap design and operation as the AR is changed. 

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2. Tandem mass spectrometry using continuous‐wave infrared multiphoton dissociation in an electrostatic linear ion trap

   https://doi.org/10.1002/rcm.9698  

   Carrick, Ian_J; Fabijanczuk, Kimberly_C; Rong, Jiayue; McLuckey, Scott_A (January 2024, Rapid Communications in Mass Spectrometry)

   RationaleThe electrostatic linear ion trap (ELIT) can be operated as a multi‐reflection time‐of‐flight (MR‐TOF) or Fourier transform (FT) mass analyzer. It has been shown to be capable of performing high‐resolution mass analysis and high‐resolution ion isolations. Although it has been used in charge‐detection mass spectrometry (CDMS), it has not been widely used as a conventional mass spectrometer for ensemble measurements of ions, or for tandem mass spectrometer. The advantages of tandem mass spectrometer with high‐resolution ion isolations in the ELIT have thus not been fully exploited. MethodsA homebuilt ELIT was modified with BaF₂viewports to facilitate transmission of a laser beam at the turnaround point of the second ion mirror in the ELIT. Fragmentation that occurs at the turnaround point of these ion mirrors should result in minimal energy partitioning due to the low kinetic energy of ions at these points. The laser was allowed to irradiate ions for a period of many oscillations in the ELIT. ResultsDue to the low energy absorption of gas‐phase ions during each oscillation in the ELIT, fragmentation was found to occur over a range of oscillations in the ELIT generating a homogeneous ion beam. A mirror‐switching pulse is shown to create time‐varying perturbations in this beam that oscillate at the fragment ion characteristic frequencies and generate a time‐domain signal. This was found to recover FT signal for protonated pYGGFL and pSGGFL precursor ions. ConclusionsFragmentation at the turnaround point of an ELIT by continuous‐wave infrared multiphoton dissociation (cw‐IRMPD) is demonstrated. In cases where laser power absorption is low and fragmentation occurs over many laps, a mirror‐switching pulse may be used to recover varying time‐domain signal. The combination of laser activation at the turnaround points and mirror‐switching isolation allows for tandem MS in the ELIT. 

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3. An accessible planar charged particle trap for experiential learning in quantum technologies

   https://doi.org/10.1119/5.0243389  

   Thomas, Robert E; Wolfram, Cole E; Warren, Noah B; Fouch, Isaac J; Blinov, Boris B; Parsons, Maxwell F (July 2025, American Journal of Physics)

   We describe an inexpensive and accessible instructional setup that explores particle trapping with a planar linear ion trap. The planar trap is constructed using standard printed circuit board manufacturing and is designed to trap macroscopic charged particles in air. Trapping, shuttling, and splitting are demonstrated to students using these particles, which are visible to the naked eye. Students control trap voltages and can compare properties of particle motion with an analytic model of the trap using a computer vision program for particle tracking. Learning outcomes include understanding the design considerations for planar AC traps, mechanisms underpinning particle ejection, the physics of micromotion, and methods of data analysis using standard computer vision libraries. 

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4. Status of CHIP-TRAP: The Central Michigan University High-Precision Penning Trap

   https://doi.org/10.3390/atoms11100127  

   Redshaw, Matthew; Bhandari, Ramesh; Gamage, Nadeesha; Hasan, Mehedi; Gamage, Madhawa Horana; Keblbeck, Dakota K; Limarenko, Savannah; Perera, Dilanka (October 2023, Atoms)

   Precise and accurate atomic mass data provide crucial information for applications in a wide range of fields in physics and beyond, including astrophysics, nuclear structure, particle and neutrino physics, fundamental symmetries, chemistry, and metrology. The most precise atomic mass measurements are performed on charged particles confined in a Penning trap. Here, we describe the development, status, and outlook of CHIP-TRAP: the Central Michigan University high-precision Penning trap. CHIP-TRAP aims to perform ultra-high precision (∼1 part in 1011 fractional precision) mass measurements on stable and long-lived isotopes produced with external ion sources and transported to the Penning traps. Along the way, ions of a particular m/q are selected with a multi-reflection time-of-flight mass separator (MR-TOF-MS), with further filtering performed in a cylindrical capture trap before the ions are transported to a pair of hyperbolic measurement traps. In this paper, we report on the design and status of CHIP-TRAP and present results from the commissioning of the ion sources, MR-TOF-MS, and capture trap. We also provide an outlook on the continued development and commissioning of CHIP-TRAP. 

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5. Particle-in-Cell Simulation of Quasi-Neutral Plasma Trapping by RF Multipole Electric Fields

   https://doi.org/10.3390/physics1030028  

   Hicks, Nathaniel K.; Bowman, Amanda; Godden, Katarina (December 2019, Physics)

   Radio-frequency (RF) charged particle traps, such as the Paul trap or higher order RF multipole traps, may be used to trap quasi-neutral plasma. The presence of positive and negative plasma species mitigates the ejection of particles that occurs due to space charge repulsion. For symmetric species, such as a pair plasma, the trapped particle distribution is essentially equal for both species. For plasma with species of disparate charge-to-mass ratio, the RF parameters are chosen to directly trap the lighter species, leading to loss of the heavier species until sufficient net space charge develops to prevent further loss. Two-dimensional (2D) electrostatic particle-in-cell simulations are performed of cases with mass ratio m+/m− = 10, and also with ion–electron plasma. Multipole cases including order N = 2 (quadrupole) and higher order N = 8 (hexadecapole) are considered. The light ion-heavy ion N = 8 case exhibits particles losses less than 5% over 2500 RF periods, but the N = 8 ion–electron case exhibits a higher loss rate, likely due to non-adiabaticity of electron trajectories at the boundary, but still with low total electron loss current on the order of 10 μA. The N = 2 ion-electron case is adiabatic and stable, but is subject to a smaller trapping volume and greater initial perturbation of the bulk plasma by the trapping field. 

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