Dynamic Vortex Drag

This thesis explores the concept of dynamic vortex drag resulting from Kelvin wave excitations on vortex cores in thin lms of super uid 4He. In this system, vortex drag is commonly accepted as a signi cant mechanism for the dissipation of third sound wave motion; however, current models implementing a static drag force have been unable to quantitatively explain anomalous third sound free decay results found in the literature. In this thesis, many possible manifestations of Kelvin wave agitation are explored and are shown to correct the de ciencies of existing static drag theories. It is therefore concluded that vortex drag in thin lms of super uid 4He is most likely a dynamic, and not a static, process. Acknowledgements: I would like to extend my gratitude to the Wesleyan University Physics Department for teaching me the physics that is at the backbone of this project and will underpin my development as a scientist in the years to come. In particular, I would like to thank Professor Fred Ellis for his support and encouragement in pursuing this project, his general academic and life advice during my time as an undergraduate, and his dedication towards encouraging an appreciation of dynamic climates in a southern Californian. I would also like to thank Professor Brian Stewart for inculcating an interest in sustainability, renewable energy, and broader energy/resource issues that I will carry with me throughout graduate school and the rest of my life. Additionally, I would like to thank the Wesleyan University Financial Aid Department for their generosity and thoughtfulness in my family's times of need.