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The surface structure of Ni plating films that were reacted with methane at 800°C was investigated using scanning electron microscopy and transmission electron microscopy (TEM). The surface of the Ni plating film was eroded by the reaction with methane, resulting in a nano‐roughened surface with a hexagonal close‐packed structure with a thickness of ~ 3 nm. The carbon layer deposited on the Ni plating...
For near-future large-scale space programs, high-power Hall thruster cluster systems are required. At Gifu University, based on the prior studies of magnetic-layer thruster discharge characteristics, a study to investigate interference effects on discharge characteristics for the cluster system was initiated. To characterize cluster operations, a side-by-side (SBS) system comprising two anode layer...
At Gifu University, to understand unsteady operation phenomena including plasma generation and exhaust processes on a coaxial pulsed plasma thruster (PPT), the luminescence behavior has been studied. In this study, spatial velocity distributions were compared with the results of electrostatic measurement and high-speed photography, and the applicability of a photosensor system to the plume measurements...
To evaluate the effects of inflowing-high-energy electrons on the grid erosion, three-dimensional full-PIC analyses of ion engine were conducted. A comparison of the results of full-PIC results show that the inflowing high energy electrons expand the sheath region downstream and blurs the sheath edge. However, only a slight influence of the electrons on grid currents is observed.
Numerical evaluations of grid erosions in ion engines are required to estimate the lifetimes of long-term space missions. In this study, to investigate the characteristics of ions colliding with neutrals and impacting the accel grid surface, including ions that collide with neutrals more than once, three-dimensional particle analyses using a full-PIC (Particle in Cell) code were performed. The distributions...
Twenty kHz-range discharge current oscillation with a large amplitude is observed in Hall thrusters, causing unstable operation. In our previous studies, the effects of the anode orifice configuration on the current oscillation have been investigated. Using the results of neutral particle simulations, the relationship between the neutral distribution and the propellant inlet condition was analyzed...
Parametric estimations of propulsion performances were conducted through numerical analysis and experiment in closed drift accelerators, the so-called hall thrusters. At high-voltage mode of DC regime which is ordinary operation region, the large-amplitude discharge current oscillation in the tens of kHz has been a serious problem that should be solved with a view to improving the stability of operation...
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