Date of Award
2024
Document Type
Dissertation
Degree Name
Doctor of Philosophy (PhD)
Department
Mechanical Engineering
Committee Chair
Jason T. Cassibry
Committee Member
Gabriel Xu
Committee Member
Bill Emrich
Committee Member
Chang-kwon Kang
Committee Member
Joshua L. Rovey
Committee Member
Ryan McBride
Research Advisor
Jason T. Cassibry
Subject(s)
Fusion, Fusion reactor walls--Design and construction, Plasma (Ionized gases), Hydrodynamics
Abstract
The goal of achieving net energy production from fusion reactions would have many positive and transformational impacts upon society and is therefore of great interest. Magneto-Inertial Fusion may be a path to achieving the high energy density requirements. One possible method for reaching the necessary plasma conditions is through a z-pinch driving a magnetized liner to compress and heat the fusion fuel. Progress has been made through both modeling and experiment, largely through Sandia National Laboratories, in recent years in developing this process and achieving neutron yields in the range of 1013 neutrons per pulse. Magnetized liner z-pinch experiments have largely used beryllium liners. This is in part because materials adjacent to the fuel will mix during the implosion and reduce yield. Higher atomic number materials are also more inclined to radiation energy loss due to higher rates of bremsstrahlung radiation. However, alternate materials may have advantages to the implosion or in the context of a wider system level design. This work seeks to investigate several materials across the periodic table in the context of a magnetized liner z-pinch implosion. This work investigates the implosion dynamics and resulting thermodynamic conditions and yield. The work presented uses a smooth particle hydrodynamic method in a newly developing multi physics code that solves the resistive magnetohydrodynamic equations with a tabular equation of state and transportation models (e.g., radiation, electron thermal conduction, neutron, and fusion reactions). This work has found similar dynamic structures in the liner across materials and driving currents that agree with existing literature. The z-pinches are dominated by large wavelength Rayleigh-Taylor instabilities on the order of 1 to 3 mm with amplitudes reaching similar values around 1 to 2 mm. Liner areal densities are found to reach 0.025 and 0.8 g/cm2 for 4 and 16 MA peak cases. With a constant liner mass at a given driving current, timing of stagnation deviates in some cases up to approximately 25 ns due to the characteristic properties of the liner materials. Changing liner material results in a changing equation of state and resulting material properties leading to altered implosion dynamics. The baseline model in this work reaches a similar temperature of approximately 1.8 keV to that of a reference 16 MA peak current z-pinch experiment at Sandia National Laboratories. The corresponding pressure and neutron yield are an order of magnitude less than the referenced experiment at about 1 terapascal and 1011 neutrons while confinement time is found to be similar at about 2 ns. Fuel density in the baseline model is found to peak at about 1000 kg/m3. As liner materials were changed to gallium and tungsten, peak temperature in the model was seen to drop to 0.8 and 0.6 keV respectively while peak density reached 500 and 300 kg/m3 respectively. Peak pressure for the gallium case was similar at 1 terapascal while tungsten reached a higher peak pressure of 4.5 terapascal. The confinement times were of a similar magnitude of about 1.6 and 1.25 ns while neutron yields were similar at 4x1011 and decreased to 7.5x109 for gallium and tungsten respectively. The model was also extended to a 4 MA peak current case with the same time to peak current of 100 ns. Temperatures were found to peak at 1, 0.5, and 0.7 keV, densities peaked at 25, 3.5, and 10 kg/m3, and pressures peaked at 0.3, 0.14, and 0.45 terapascal for beryllium, gallium and tungsten respectively. The neutron yields were found to drop to 3x109, 1.5x109, and 1.5x109 while burn durations were found to be about 4.4, 2.7, and 3.75 ns for beryllium, gallium, and tungsten respectively.
Recommended Citation
Taylor, Brian Dale, "Liner implosion of magneto-inertial fusion plasmas across the periodic table" (2024). Dissertations. 429.
https://louis.uah.edu/uah-dissertations/429