×
Department Library

2018

Ryan Doel (Capstone, January 2018, Advisor: Bryan Peterson )

Abstract

A single-stage parallel wire ionic wind device was investigated in an effort to further elucidate thrust dependencies. An attempt to measure the strength of the relationship between the geometrical constant C and the ratio of the emitter and collector diameters, C proportional to de/dc, was undergone. Consequently a 1m long assembly was created wherein electrode gap distance, applied voltage, and diameter of emitter and collector wire were varied. We found that the collector size has a larger impact on thrust than emitter diameter. It was observed that the lengthened device reduced end effects witnessed by other researchers. The relationship C proportional to de/dc was never quantified due to the propagation of errors in our results. In an effort to reduce these errors, future research should acquire force measurements at 30+ different voltages for each configuration. Also, further studies should combine 4+ collector sizes and 4+ emitter sizes, in order to paint a broader picture of the force dependence on electrode size.

2015

Daniel Eliason (Senior Thesis, April 2015, Advisor: Bryan Peterson )

Abstract

In this research, ionized boron carbide is used as the current choice ionic plasma. A powerful electric pulse must be generated to ionize and inject the sample into a cylindrical Malmberg-Penning trap, the goal being to approach the Brillouin density limit. Utilizing inductors and capacitors, a pulse forming network (PFN) was designed and made to provide a longer pulse to generate sufficient plasma. After further development of the PFN and insertion into the trap, the anticipated electrical behavior did not match the actual resulting waveform. The system and the PFN are being studied and will be modified to obtain correct functionality.

2012

William Hall (Senior Thesis, April 2012, Advisor: Bryan Peterson )

Abstract

Bernstein modes are modes that propagate perpendicular to the magnetic field near the ion cyclotron frequency. The BYU Ion Experiment is in a unique position to measure the m = 0 azimuthally symmetric Bernstein mode in a pure ion non-neutral plasma, which has yet to be measured experimentally. Work on the experiment has developed some of the tools necessary for this measurement. However the experiment is still not able to reach a fraction of the Brillouin density limit necessary to measure the modes, and other problems with timing and density consistency remain barriers to this measurement. Steps to rectify these problems are underway, most notably implementing a pulse forming network to lengthen arc times at the source, thereby increasing plasma densities.

Mark Andrew Hutchison (Masters Thesis, December 2012, Advisor: Bryan Peterson )

Abstract

Axisymmetric radial Bernstein modes are known to exist in non-neutral plasmas and have been studied theoretically and computationally in 1D, but detection of these modes has still proven to be difficult due to self-shielding. To help advance the work on this front we created a 2D particlein-cell (PIC) code that simulates a non-neutral plasma in a Malmberg-Penning trap. A detailed description of the PIC code itself has been included that highlights the benefits of using an r 2–z grid and how it can be tested. The focus of the PIC simulation was to discover how best to drive and detect these modes. While it is improbable that radial Bernstein modes will be detected in long plasmas, we show that it may be a possible due to the axial nodal structure in the potential and electric field generated by confining plasmas of any finite-length. Additionally, we find that for a short plasma the strongest detection signal along the trap wall occurs at the plasma’s midpoint rather than near the ends. Results show that oscillating the confinement potentials is sufficient to excite the fundamental radial Bernstein mode, but not any of the higher order modes. The higher order modes can be seen in the simulation, however, by sinusoidally driving the radial electric field. Unfortunately, the individual modes are difficult to isolate which we suspect is due to mode mixing. Finally, we report frequencies and mode shapes for the fundamental mode and the (lower) first higher order mode.

David Johnson (Senior Thesis, August 2012, Advisor: Bryan Peterson )

Abstract

We measure the magnetic field of a set of Helmholtz coils designed to maintain a flat magnetic field in our plasma chamber. We show that the field of the Helmholtz coils is sufficiently large to correct for the magnetic field of the earth (approximately 50 µT) and probably other irregularities as well. We also show that the field is sufficiently flat to distinguish a beryllium-7 plasma from a lithium-7 plasma using FTICR with a central field of 0.43 T in the plasma chamber. This requires the field created by the Helmholtz coils to be uniform to within about 60 µT. The standard deviation of a 630 µT field produced by the coils was found to be approximately 30 µT.

2011

Chad Williams (Senior Thesis, August 2011, Advisor: Bryan Peterson )

Abstract

In order to increase the confinement time of a non-neutral Be-7 ion plasma in a Malmberg- Penning trap we have implemented an electron dump system to expel electrons from the plasma. Ridding the plasma of electrons is important because it allows the ion plasma to respond correctly to the implemented rotating wall, which is designed to increase the ion central density and confinement time. The electron dump shifts the voltages on the plasma confinement rings to make them all negatively charged, thus forcing the electrons to leave. Theoretically, this can be accomplished without disrupting the ion plasma. We built an AC coupling box to coordinate the ring shifts and arranged the system to be run automatically through LabVIEW. After extensive tests of our system we have found that it decreases the electron density by a factor of 100, though issues, such as the disruption of the ion plasma, still remain.

2010

Daniel Erickson (Senior Thesis, December 2010, Advisor: Bryan Peterson )

Abstract

The rotating wall is a technique that creates an asymmetrical electric field that rotates and couples with the plasma, exerting a torque on it to counteract the drag caused by collisions with neutral atoms. Hardware has been constructed and software has been written to operate the rotating wall, and their proper operation has been verified. However, the ions in our trap are being Debye shielded from the rotating wall signal by the presence of electrons. Attempted methods for removing the electrons, as well as future plans for such, are discussed.

2009

Mark Hutchison (Honors Thesis, August 2009, Advisor: Bryan Peterson )

Abstract

The actual decay constant for neutral beryllium 7 (7Be) is unknown because it has always been measured with a substantial loss of its 2s electrons due to bonding or interstitial effects. By considering free 7Be ions (such as may appear in a low density non-neutral plasma) we can potentially calculate the electron charge density at the nucleus with more accuracy and this can be used to calculate relative changes in the decay constant for ionized states of 7Be. We use both Hartree–Fock self-consistent field (HF SCF) and Density Functional Theory (DFT) methods for calculating the relative changes in the decay constants for 7Be, 7Be+, and 7Be++ and find that there is a non-linear relationship between the decay constant and the fractional amount of 2s electrons still present in the nucleus.

Jordan Stutz (Senior Thesis, April 2009, Advisor: Bryan Peterson )

Abstract

Beryllium-7 (7Be) is the lightest element that decays only by electron capture. The half-life can measurably change depending on the density of electrons available for capture. This density is a ected by chemical bonding, insertion into a lattice, or the application of high pressure. We hope to determine the half-life of singly ionized 7Be where the electron con guration is well known. We will measure this by trapping a 7Be plasma in a Malmberg-Penning trap. To measure any di erences in the half-life, we must contain it for up to one accepted half-life of 53.3 days. This will give a precise half-life which can then be used to compare with other measurements of the half-life. I will discuss the hardware and software needed to properly sequence the creation and characterization of the plasma as well as some preliminary results.

2008

Colby Dawson (Senior Thesis, April 2008, Advisor: Bryan Peterson )

Abstract

In order to determine the relative ion density in a confined, non-neutral plasma, I have designed and built circuitry used to add up the amount of charge in nine annular regions expanding radially outward from the axis of the confinement region. The plasma is dumped by grounding the side of the confinement system closest to charge-collecting rings, causing ions to collect on each region. Accumulating charges cause a current to ow to a corresponding integrator circuit where the amount of charge on each region is quantifed. A sample- and-hold circuit is appended to each integrator circuit to minimize error due to output drift. The integrator circuits are externally read and controlled by computer through a logic circuit. Ion density information will be used to fine-tune system confinement pa- rameters to retain as many ions as possible.

Brent Hicks (Senior Thesis, April 2008, Advisor: Bryan Peterson )

Abstract

This paper discusses the development of a Fourier transform ion cyclotron res- onance mass spectrometry (FT-ICR/ms) system capable of differentiating and finding the relative abundances of different ion species in a plasma confined in a Malmberg-Penning trap. FT-ICR is a mass spectrometry technique fre- quently used by chemists to identify protein components with masses of several thousand amu. Unique to this system is its ability to identify lightweight ions with masses near 10 amu, corresponding to cyclotron frequencies near 1 MHz, and its ability to differentiate between cyclotron frequencies differing by about 20 Hz. Ultimately this system will be used to determine the effect of ionization on the half-life of 7Be and the formation of its daughter 7Li during long term confinement.

2007

David K Olson (Masters Thesis, July 2007, Advisor: Bryan Peterson )

Abstract

We have designed a new type of plasma gun ion source for a Malmberg–Penning trap based on Metal Vapor Vacuum Arc (MeVVA) ion source designs. Our primary intent with this MeVVA–type source is to create a confinable beryllium-7 ( 7Be) plasma. 7Be is a peculiar isotope due to its varying radioactive decay half-life in different electro-chemical configurations. It is also found in an unexpected abundance at high altitudes of the Earth’s atmosphere. It is possible ioniziation affects the radioactivity of the isotope, partly explaining this discrepancy with atmospheric models. The short half-life of 7Be requires us to replace the sample inside the ion source on a regular basis. Our design makes it possible to easily remove the cathode of the ion source from an ultra-high vacuum trap and exchange 7Be samples while only needing to repressurize a small chamber rather than the entire trap. This design has an added benefit of being capable of generating plasmas from a wide variety of metals by sim- ply exchanging the source target in the removable cathode. Because of this wide compatibility, we will be able to use our trap for studying any number of different plasmas, including other radioactive types. Testing of the ion source design shows we are able to extract more than a sufficient number of ions at reasonable energies for confinement.

2005

David Olson (Senior Thesis, August 2005, Advisor: Bryan Peterson )

Abstract

n/a

Samuel Tobler (Senior Thesis, April 2005, Advisor: Bryan Peterson )

Abstract

n/a