Creation, diagnostics and manipulation of a non-neutral one-component plasma

The sympathetic cooling of ions with electrons is a well-established technique that is routinely used on negative particles ranging from antiprotons to molecules. An electron beam can be captured and confined in a Penning trap, forming a non-neutral onecomponent plasma. Due to the high frequency of their cyclotron motion, the electrons then quickly cool to the temperature of the cryogenic environment and can be used as a cooling agent for other particles. In the course of this thesis, an electron gun based on a commercial electron source was designed, built and put into operation. The resulting electron beam was captured in a cylindrical Penning trap and stored for extended periods. A plasma modes diagnostics system was installed and used to obtain information on all relevant plasma properties, such as geometric extent, density and particle number. Two different techniques, both making use of plasma excitation by time-varying electric fields, were used to test the diagnostics system, measure the synchrotron cooling rate, and modify the plasma properties. In this way, a significant increase in the plasma storage time was achieved