Experiments with stable confined electron columns

Abstract

Gabor Lenses were invented for focusing ion beams by the electric field of a confined electron column. In synchrotrons spontaneously occurring electron clouds have an influence on the beam dynamics. Instabilities of single or multi bunches, emittance growth, excessive energy deposition, particle losses, interferences with diagnostic and gas desorption from chamber walls can appear. As a consequence of these interactions between ions and electrons, the beam is deflected or, in worst case, lost. If an ion beam bunch passes a confined electron column in a Gabor Lens these impacts can be studied as well. Collisions of the ions with the electron ensemble will lead to oscillation eects on the cloud and have an influence on the bunch train. These interaction effects will be increased by the number of bunches and their frequency and can be modified by the plasma parameters, temperature and density, of the electron column. If it is possible to damp the excitation of the confined electron column space charge compensation could be provided.
To study these impacts and interactions Gabor Lenses are built. In 2018 a new lens called Gabor Lens 2000 is constructed. This 2 m long lens can hold an electron column with an aspect ratio smaller than 0.1. Single pass experiments with ion beams will be performed under dierent temperature and density of the plasma and also dierent frequencies of the train.