P. Lubiński

This work concerns the experimental study of the plasma emitted by a Hall effect thruster in the context of chaotic behavior. Its aim was to check whether low-dimensional deterministic chaos could explain the fluctuations observed in the current waveforms: discharge current and ion current measured by a planar probe with a guarding ring. The discharge voltage was used as a control parameter, and the dependence of the thruster efficiency on this parameter was studied. Several standard chaos diagnosis tools, such as the presence of attractors with non-integral dimensions, the specific shape of Poincaré cross sections, and the positive values of the largest Lyapunov exponent, provided a strong evidence for deterministic chaos in the tested current waveforms. This chaotic behavior occurred when the thruster was operating in the global mode of oscillations dominated by so-called breathing oscillations, adversely affecting the operation of the device.