NONLINEAR WAVES EXCITATION AND INTERACTION IN PURE ELECTRON PLASMAS

Abstract

Nonneutral plasmas are excellent subjects for well controlled studies on basic physics problems and industrial research over a wide range of parameters. For the long-time confinement, merger and recombination of antimatter, the method of choice is some variant of the Penning-Malmberg trap, and many of the techniques for the manipulation of charged particles, such as cooling, compression, transfer, and ultimately a stable confinement in a quiescent state, are based on methods first developed by the nonneutral plasma community using electron plasmas. Another fascinating properties of nonneutral plasmas is the fluid analogy: in a cold, magnetized, nonneutral plasma, the 2D transverse dynamics equations are isomorphic to the Euler equations for an ideal 2D fluid. Hence, a pure electron plasma in a Penning-Malmberg trap evolves as an inviscid, incompressible bidimensional fluid. The study and control of the various waves and instabilities is of great interest in physics, and it is often intertwined with non-linearity and turbulence. Experiments aimed at unveiling hidden dependencies between parameters or improve the control over non-equilibrium, unstable configurations can lead to the discover of new phenomena, and a more thorough understanding of basic plasma physics, like the excitation and interaction of different plasma modes in pure electron plasmas, is likely to be a useful tool for a range of applications. In this thesis work, we present the results of the experiments made on two different Penning-Malmberg traps on the excitation and interaction of nonlinear waves in pure electron plasmas. On the Eltrap device, located at the University of Milan, Italy, we perform experiments on the excitation and control of high order diocotron modes via the rotating electric field technique. On the CamV device, located at the University of California, San Diego, we investigate the newly discovered phenomenon of TG waves splitting due to the interaction with a diocotron mode.