Characterization of Chaotic Instabilities in an Electron-Hole Plasma in Germanium

Abstract

Helical instabilities in an electron-hole plasma in Ge in parallel dc electric and magnetic fields are known to exhibit chaotic behavior. By fabricating probe contacts along the length of a Ge crystal we study the spatial structure of these instabilities, finding two types: (i) spatially coherent and temporally chaotic helical density waves characterized by strange attractors of measured fractal dimension d ~ 3, and (ii) beyond the onset of spatial incoherence, instabilities of indeterminately large fractal dimension d ≥ 8. In the first instance, calculations of the fractal dimension provide an effective means of characterizing the observed chaotic instabilities. However, in the second instance, these calculations do not provide a means of determining whether the observed plasma turbulence is of stochastic or of deterministic (i.e., chaotic) origin.KeywordsPhase SpaceFractal DimensionChaotic SystemChaotic DynamicStrange AttractorThese keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.