A time-accurate 2D axisymmetric Hybrid PIC-MCC model is used to simulate the plasma flow in the acceleration channel and near-field plume of a Hall thruster. The model is applied to the P5 Hall thruster due to known magnetic configuration and the availability of experimental data on the plasma properties in the interior and near-field plume for this thruster. Results for thruster performance an...

A fault-tolerant control scheme with thruster redundancy is developed and applied to perform attitude tracking manoeuvres for an orbiting flexible spacecraft. Based on the assumption of bounded elastic vibrations, an adaptive sliding mode controller is proposed to guarantee that all the signals of the resulting closed-loop attitude system are uniformly ultimately bounded in the presence of an u...

This paper reports two speci c improvements in the nite-dimensional nonlinear dynamical modeling of marine thrusters. Previously reported four-quadrant models have employed airfoil theory considering only axial uid ow and using sinusoidal lift/drag curves. First, we present a thruster model incorporating the e ects of rotational uid velocity and inertia on thruster response. Second, we report a...

We present a single fiber reflectance confocal microscope with a two dimensional MEMS gimbaled scanner. Achieved lateral and axial resolutions are 0.82 mum and 13 mum, respectively. The field of view is 140 x 100 mum at 8 frames/second. Images and videos of cell phantoms and tissue are presented with sub-cellular resolution.

A systems-level trade study is presented comparing the propulsion requirements and associated Ž nal masses for different architectural implementations of the Terrestrial Planet Finder mission. The study focuses on the millinewton-level propulsion chores associated with rotating and repointing an array.Three interferometer conŽ gurations, free  ying, monolithic, and tethered, lead to estimates ...

MIT's fully kinetic particle-in-cell Hall thruster simulation is adapted for use on parallel clusters of computers. Significant computational savings are thus realized with a predicted linear speed up efficiency for certain large-scale simulations. The MIT PIC code is further enhanced and updated with the accuracy of the potential solver, in particular, investigated in detail. With parallelizat...

Optical emission spectroscopy is employed to correlate BN insulator erosion with highpower operation of the NASA 300M Hall-effect thruster. Actinometry leveraging excited xenon states is used to normalize the emission spectra of ground state boron as a function of thruster operating condition. Trends in the strength of the boron signal are correlated with thruster power, discharge voltage, disc...

This paper reports a comparative experimental evaluation of proportional derivative and adaptive modelbased control for underwater vehicles. To the best of the authors’ knowledge, this is the first such evaluation of modelbased adaptive tracking control for underwater vehicles during simultaneous dynamic motion in all 6 degrees-of-freedom. This experimental evaluation revealed the presence of u...

Abstract. A heave compensation system is one of the absolutely necessary instruments to secure mining operation. The heave compensation system includes a heave compensated platform which is to compensate heave motion and a gimbaled platform which is to accommodate pitch and roll. The simulation of a nonlinear model based on fuzzy PID control is performed. The results show that the compensation ...

Over the last decade, miniature ion thruster development has remained an active area of research do to its low power, low thrust, and high efficiency, however, due to several technical issues; a flight level miniature ion thruster has proved elusive. This thesis covers the design, fabrication, assembly, and test of an altered version of the Miniature Xenon Ion thruster (MiXI), originally develo...