Physics Commons^™

Most Probable Magnetohydrostatic Equilibria For Tokamaks And Reversed Field Pinches, John Joseph Ambrosiano

Dissertations, Theses, and Masters Projects

The determination of magnetohydrostatic equilibria usually requires that two of the equilibrium functions be given. as there is usually no a priori basis for specifying the form of these two functions, the functions and the equilibria they determine may be considered random.;In this dissertation, the author reviews a recent statistical method for determining the equilibrium of an axially symmetric cylindrical plasma which is most probable (in the maximum entropy sense) given four global constraints (i.e., energy, magnetic helicity, longitudinal magnetic flux, and longitudinal current flux). Previous results from this model have been limited to non-negative random equilibrium functions (B(,z), J(,z), …

Nonlinear Evolution Of The Magnetohydrodynamic Sheet Pinch, William H. Matthaeus

Dissertations, Theses, and Masters Projects

No abstract provided.

Stable Equilibrium Statistical States For Spheromaks, George Vahala, Linda L. Vahala

Electrical & Computer Engineering Faculty Publications

Incompressible nondissipative magnetohydrodynamic turbulence is treated for spherical systems. From the absolute equilibrium expectation values of the fields one can investigate those initially quiescent states for which no large mean square velocity will develop. This stable state is force-free and gives rise to the Hill vortex structure for the magnetic flux surfaces.

The Effects Of Electron Irradiation On Mosfets, Mark D. Skeldon

Physics Theses & Dissertations

The characteristics of n and p-channel MOSFETs have been investigated while irradiated with electron radiation from Strontium 9Ø. The drain current vs. gate voltage of the p-channel MOSFET and the threshold voltage changes in n and p-channel MOSFETs have been studied with and without aluminum shielding. The switching characteristics and threshold voltage changes of COS/MOS dual input NAND gates have been investigated while exposed to electron radiation. Various methods of annealing the radiation damage to these devices is discussed.

Cross Field Current Instabilites In A Vlasov Plasma, Don S. Lemons

Dissertations, Theses, and Masters Projects

No abstract provided.

Stability And Spectra Of The Bumpy Theta Pinch, Thomas E. Cayton

Dissertations, Theses, and Masters Projects

No abstract provided.

Pressure Anisotropy Effects On The Stability Of The Guiding Center Model Of The Bumpy Theta Pinch, Michael J. Schmidt

Dissertations, Theses, and Masters Projects

No abstract provided.

Studies Of Ion Wave Propagation In Inhomogeneous Plasmas, Shiew-Luan Y. Hsieh

Dissertations, Theses, and Masters Projects

No abstract provided.

Comments On 'Fluctuations In Guiding Center Plasma In Two Dimensions', George Vahala, Linda L. Vahala, David Montgomery, Glenn Joyce

Electrical & Computer Engineering Faculty Publications

It is stated that the principal result of the paper by Taylor and Thompson (see abstr. A14511 of 1973) on autocorrelations in density for the electrostatic guiding center plasma in two dimensions is wrong owing to an incorrect integration. It is further stated that there is no meaningful distinction between an `interaction cutoff' and a `fluctuation cutoff'.

A Two Dimensional Jet Flowing Into A Semi-Infinite Flow Field With An Ambient Velocity, Michael Leonard Crane

Dissertations, Theses, and Masters Projects

No abstract provided.

Lasing Conditions Of Elemental Sulfur In A Gas Discharge, David E. Egbert

Theses and Dissertations

The partial pressures from heated sulfur crystals and helium, and sulfur and nitrogen required for ionic sulfur laser action in a gas discharge were determined. Previous work with sulfur lasers is reviewed and population inversion mechanisms are presented for the ionic sulfur laser lines. Possible excitation mechanisms are presented for both electron and ion or atomic collision excitation. Transition diagrams for all the known ionic sulfur laser transitions and an approximate potential energy curve for the diatomic sulfur molecule are presented. Laser action was achieved only when a spark gap pulser was used with a laser tube especially designed to …

Crystal Structure Determination Of Β-Lactoglobulin From Electron Micrographs, Richard Roeter

Dissertations and Theses

Often electron micrographs exhibit a repeating structure. Sometimes this repeating structure satisfies the definition of a crystal in that it has a three dimensional repeating structure. If the unit cell structure of this repeating structure can be determined it can be used to help categorize different sections of a particular sample. In some cases, the use of optical diffraction analysis of electron micrographs with repeating structure is a method of determining the unit cell structure.

Samples of β-Lactoglobulin were prepared for viewing in the electron microscope using both the crystalline material and carbon replicas of the crystal surface. Because the …

Spectroscopic Measurement Of The Electron Temperature In The Tenuous Argon Ion Laser Plasma, Dane Danijel Bicanic

Physics Theses & Dissertations

The validity of the line intensity ratio technique for measuring the electron temperature was examined for an argon plasma with a "population inversion" i.e., the number of ions with electrons in the upper 4p levels was greater than in the lower 4s levels. The line intensities from these levels, the argon ion lasing transitions, were measured in a pulsed tenuous plasma at 110μ Hg produced by discharging a capacitor through a tube 2m long and 7mm inside diameter. The electron impact cross sections for simultaneous excitation and ionization as measured by Latimer and St. John were used and averaged over …

Electron Optical Study Of A Secondary Electron Multiplier, Chang Min Shen

Dissertations and Theses

Electron orbital theory was applied to the design of the geometrical structure of an electron multiplier for an image intensifier. A special structure satisfying production requirements was studied. Electron optical calculations consisted of determining the potential distribution and tracing the electron trajectories. Liebmann's procedure was used to solve Laplace's equation with constant potentials on the multiplier electrodes as boundary conditions. The trajectories were determined by solving the equation of motion in an electrostatic field using a Runge-Kutta procedure. The initial conditions for the trajectories were the initial energies, initial positions, and the initial directions of the secondary electrons. The plotted …