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Department Library

2018

Mitchell Clingo (Capstone, May 2018, Advisor: Grant Hart )

Abstract

Non-neutral plasma in a Malmberg-Penning trap has been shown computationally to exhibit nonlinear mode coupling between Trivelpiece-Gould modes. We used a computational model that shows similar mode coupling between the nz=1 and nz=2 modes. This occurs because of the nonlinear terms found in the momentum and the continuity equations. By driving both modes, we can get large enough magnitudes to see the coupling. If the magnitude of either mode is not large enough, coupling factors become insignificant. Also, a relation exists between the relative phase difference between modes and the direction of energy transfer in coupling.

2015

Emma Hoggan (Capstone, April 2015, Advisor: Grant Hart )

Abstract

Landau damping is a fundamental behavior of plasma physics in which density waves propagating in a collisionless plasma become damped as individual particles exchange energy with the wave. While this process is well-documented experimentally, we still have more to learn about how discrete particle interactions contribute to the damping. We use MATLAB to visualize and analyze electron plasma simulations to gain insights into these particle interactions. These visualization techniques include animations of particle mid-plane velocities and animations of particle positions versus wave amplitudes.

2013

Natalie Muhlestein (Senior Thesis, August 2013, Advisor: Grant Hart )

Abstract

2011

Austin Parker (Capstone, December 2011, Advisor: Grant Hart )

Abstract

The use of novel materials in conventional armor solutions has been difficult due to extant processing methods and expensive methods. This is especially apparent in the use of aluminum oxynitride (AlON), currently being researched for its application in transparent ceramic armors. Development of a reaction sintering process utilizing unique additives in the direct sintering of alumina and aluminum nitride powders can reduce costs and provide a more practical manufacturing process for the delivery of next generation armor to the military in a timely fashion. Using a liquid sintering process and aluminum phosphate as an additive it is possible to sinter AlON directly while decomposing phosphate and alumina from the sample. It was found that this approach formed the requisite γ-AlON phase and the densities of samples could approach 3.63 g/cc. Based on the these results, and subsequent ballistic testing of larger scale samples, it was concluded that AlPO4 is a viable additive in a reaction sintering process to improve density and transparency of AlON.

2010

Michael Takeshi Nakata (PhD Dissertation, April 2010, Advisor: Grant Hart )

Abstract

Beryllium-7 (Be-7) only decays by electron capture into lithium-7 (Li-7) with a half life of 53 days. We study the effect of ionization on this decay rate. We do so by trapping a Be-7 ion plasma in a cylindrical Malmberg-Penning trap and measuring Be-7 and Li-7 concentrations as functions of time by using Fourier transform ion cyclotron resonance mass spectrometry (FTICR-MS). We have simulated these signals in a 2-dimensional electrostatic particle-in-cell (PIC) code. The two spectrum peaks merge at high ion densities whereas at low ion densities they can be resolved. The merged peak shifts linearly according to the relative abundances of these species. We have also simulated singly-ionized beryllium-7 hydride (BeH+) and Li-7 ion plasmas at high densities. These two separate peaks shift according to their relative abundances. We describe an analytical model that explains how these peaks shift.

2008

Jeremy Carter (Capstone, August 2008, Advisor: Grant Hart )

Abstract

The intention of this project was to develop and assemble two sets of identical magnetic coils for the Beryllium based plasma chamber at Brigham Young University. These coils, assembled simply with 12 gauge wire, power sources, and aluminum channeling (to support the wire), will correct for two very significant anomalies. The first is the Earth’s intrinsic magnetic field, and the other, misalignment between the interior of the device and the solenoid surrounding it. These coils, appearing to be very simple, underwent a complex designing process as well. They were developed via a three dimensional analysis that implemented the computing power of Matlab. Completed, these coils will help in furthering plasma based research at BYU by reducing the number of complications affecting the functionality of this particular plasma chamber.

Kellen Giraud (Senior Thesis, April 2008, Advisor: Grant Hart )

Abstract

A quadrupole mass filter (QMF) has been simulated and manufactured. The quadrupole is part of an ion trap system that will isolate a plasma of ionized beryllium-7 (7Be) for months at a time. Through this experiment, the half- life of ionized 7Be will be measured. The function of the QMF is to filter out unwanted ions and allow wanted ions to penetrate into the region of high magnetic field. Voltages are applied to the conducting rods of the QMF based on the stability curve generated by the Mathieu equations. The motion of 7Be ions in an ideal QMF has been simulated. Our QMF has been altered from the ideal QMF, and the motion of ions in the modified QMF has also been simulated. A quadrupole was built based on the results of the simulations, and was installed into the experimental system. Tests on the manufactured quadrupole have indicated that significant changes must yet be made for the experimental QMF to match the simulations.

2005

Reed Jensen (Senior Thesis, April 2005, Advisor: Grant Hart )

Abstract

n/a

2004

Brent Cannon (Capstone, April 2004, Advisor: Grant Hart )

Abstract

When designing and constructing a model rocket, forehand knowledge of the performance is extremely helpful. With such knowledge, measures can be taken to ensure the rocket is recovered safely and has an optimal flight. I have created a software tool that allows the user to simulate their rocket design before physically building it. Written in Java, this simulator makes use of the fourth-order Runge-Kutta method as well as cubic spline interpolation. A method of estimating drag coefficients is also implemented.

2003

Patrick William Ross (Senior Thesis, April 2003, Advisor: Grant Hart )

Abstract

2002

Michael Takeshi Nakata (Masters Thesis, April 2002, Advisor: Grant Hart )

Abstract

A simple, non-destructive diagnostic for the temperature of non-neutral plasma is desirable as plasma lifetime increase and the confined species become more exotic. If the confinement system includes an isolated wall sector, the motion of the charges beneath that sector will result in a noise signal that can be directly related to the velocity distribution of the confined particles. Care must be taken to differentiate the resulting plasma signal from the instrumental noise spectrum and the strong signals from plasma oscillation modes. The theoretical basis of the relationship between the noise spectrum and the temperature as well as experimental results will be presented.

1995

Craig Reeves Baker (Masters Thesis, December 1995, Advisor: Grant Hart )

Abstract

A brief description of the ionosphere is given. The linear stability of the nighttime equatorial ionosphere is examined. Account is made for realistic ionospheric conditions, including variations along two-dimensional magnetic field lines, the effect of an east-west electric field and neutral winds, and vertical gradients in the collision frequencies. A damping term, overlooked by assuming a one-dimensional magnetic field, is presented and a numerical method is proposed for further exploration of the instability.

1992

Lei Chen (Masters Thesis, December 1992, Advisor: Grant Hart )

Abstract

The effects of a titled magnetic field on a cold, non-neutral plasma are studied. The plasma is assumed to be finite length, in a state of equilibrium and confined within a cylindrically symmetric system by the use of electrostatic and magnetic forces. Linear perturbation theory is used to analyze the properties of non-neutral plasma in a titled field. The equations for the perturbed quantities are established using the assumption of cold plasma and step function density profiles. General solutions matching the titled plasma boundary conditions have been given by a Bessel function series. Within the plasma and far away from the resonance region of the perturbation, linear perturbation analysis can be interpreted using the rigid tilt first order Taylor expansion. The resonance effects have also been found to match previous work done by Keinigs, and Spencer and Hart. From the analytical solution of perturbed we can find solutions to the perturbed flow, although of very small magnitude compared to the E x B drift flow. The solved perturbed flow reveals that the tilted plasma column spins around the tilted magnetic fields with a constant angular velocity. No parallel axis perturbed velocity exists along the tilted magnetic field.

1991

Paul Nathan Barnes (Masters Thesis, August 1991, Advisor: Grant Hart )

Abstract

The lab dip is explored through computer modeling as an accurate and precise technique for examining the transition frequencies in ions of a nonneutral plasma. The experiment is also designed. Singly ionized magnesium was considered as the ion for use. Ion plasmas eliminate many causes of broadening and shift in the transitions. A comparison is made between second-order Doppler broadening and Stark broadening in the Lamb dip method and this is then compared to the same broadening mechanisms in the laser cooling method.