Experimental and analytical studies of merging plasma loops on the Caltech solar loop experiment

Abstract

Of crucial importance for magnetized plasmas is magnetic helicity, a topological quantity that measures the knottedness or twistedness of the magnetic field. A universal relaxation theory, applicable to astrophysical and laboratory plasmas, dictates the evolution of plasmas towards an equilibrium state based solely on helicity content. The Caltech Solar Loop Experiment creates plasma with injected helicity to study this evolution, which can involve the merging of two plasma loops into a single structure. This thesis studies the merging using two techniques. The first is the construction of an array of vacuum photodiodes to measure extreme ultraviolet radiation from the experiment; the data provides information concerning non-equilibrium radiation losses and magnetic reconnection. The second is a Hamiltonian study of particle orbits to explain how particles can transition from being localized from one plasma loop to being shared among two neighboring loops. This shows how the merging process may initiate and also leads to a general theorem where the action variable serves as a Hamiltonian for the orbit-averaged system.