Off-axial plasma displacement suitable for antihydrogen production in AEgIS experiment

Abstract

Antihydrogen experiments are currently based on non neutral electron, positron or antiproton plasma manipulation techniques in cylindrical Malmberg-Penning traps. An experimental study of a plasma manipulation technique based on off-axis diocotron displacement is presented. The use of the autoresonant excitation of (1, 0) diocotron mode of pure electron plasma allows a precise positioning of the plasma by moving it across the magnetic field and allows dumping such plasma in a desired angular position. The experimental procedure described here will pave the way to positron loading into an off-axial Penning trap terminated with a positronium converter target as it is proposed for the AEgIS experimental apparatus. The technique was studied over a range of confining magnetic field values and reproduces experimental conditions similar to most of the currently running antihydrogen experiments. The efficiency of the autoresonant excitation – in terms of plasma expansion rate and particle loss – is analyzed, studying the behaviour of electron plasma subjected to large off-axial displacements, showing that this method fulfills the requirements imposed by the AEgIS experiment.