Numerical and laboratory investigation of astrophysical cyclotron emission processes

Summary form only given. There are numerous types of astrophysical radio emission in association with non-uniform magnetic fields that have been the subject of particular interest and debate over the last thirty years. Such sources, including planetary and stellar auroral radio emission are spectrally well defined with a high degree of extraordinary (X-mode) polarisation. In particular, for the terrestrial auroral case it is now widely accepted that such emissions are generated by an electron cyclotron-maser instability driven by a horseshoe shaped electron velocity distribution formed through magnetic compression. Experiments have been conducted at the University of Strathclyde investigating the electrodynamics of an electron beam subject to significant magnetic compression within a bounding waveguide structure. More recently, a background plasma of variable density has been introduced to the interaction region of the laboratory experiment through use of a Penning discharge geometry. Corroboratory simulations have been conducted using the PiC code VORPAL to investigate the cyclotron emission process in the presence of a background plasma of variable density. The dynamics of the emission mechanism will be discussed for both bounded and unbounded interaction scenarios as a function of ωce / ωpe in line with recent laboratory experiments and earlier numerical simulations of unconstrained electron-cyclotron emission.