Ion beam extraction phenomenon is one of the most important processes in an ion propulsion system because ion beam current and beam accelerating voltage dominate thrust. In order to evaluate the beam extraction capability, which is determined by the interrelation between discharge plasma properties and beam accelerating conditions, there is a need to understand the problems of ion sheath formation. This study has been performed to develop a numerical simulation code which is capable of investigating the ion beam extraction phenomena in the ion thruster. In the calculation, both ions and electrons were treated as particles in a particle-in-cell routine to determine the ion sheath self-consistently. The calculation results of electric potential contours and extracted currents were compared with the experimental ones and they were found to be in good agreement. In addition, it was confirmed that the ion beam extraction capability can be simulated in a wide range of beam accelerating voltage.

An innovative engine, designated "Volterra," has been developed and the thrust performance, thrust, beam divergence angle, and ion energy distribution function were investigated using a 1 kW class magnetic-layer-type Hall thruster developed at Kyushu University. The thrust of this engine is superior to that of the thruster with 150 V constant voltage operation, but the ion energy distribution function is wider. Plume divergence is almost the same as for the thruster with 150 V constant voltage operation.

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Angular distributions of photoelectrons (ADPs) from the 2σ g shell of a fixed-inspace N 2 molecule have been measured for left-and right-elliptically polarized, as well as for linearly polarized, light. From these data a set of dipole matrix elements and phase shift differences characterizing the process has been determined taking into account the acceptance angles of both electron and ion detectors, i.e. the complete experiment has been performed. Good agreement between the experimental and the relevant theoretical values calculated in the random phase approximation is obtained. Based on the results of the complete experiment, three-dimensional ADPs and ions are predicted for different light polarizations.

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