Download or read book Computational Investigations of Characteristic Performance Improvements for Subkilogram Laser Micropropulsion written by Richard Joel Thompson and published by . This book was released on 2009 with total page 89 pages. Available in PDF, EPUB and Kindle. Book excerpt: Experimental investigations have evaluated the feasibility of using laser-driven plasma microthrusters for small-thrust, high-specific-impulse space maneuvers, particularly for micro- and nanosatellite missions. Recent work made use of the Mach2 hydromagnetics code for the construction of an adequate computational model of the micro-thruster operation. This thesis expounds on this previous work by extending the computational modeling capabilities, allowing for the determination of plasma plume properties and characteristic performance assessment of the microthruster; this allows for further computational investigation of the performance improvements achieved by new design considerations. Two particular design changes are implemented and measured: (i) the simulation of microthruster performance intentionally achieving laser-supported detonation of energetic polymer fuels for higher-thrust capabilities, and (ii) the implementation of an axisymmetric nozzle to improve passive solid-fuel performance. The Mach2 hydromagnetics code with the new performance assessment capabilities was used to examine the performance improvement of these new modes of operation; results of the simulations are presented and then evaluated for their use in the overall design of the plasma microthruster. Laser-supported detonation shows a tremendous potential increase in the laser momentum coupling coefficient C[subscript m], and demonstrates a much higher thrust; the axisymmetric nozzle varies with nozzle half-angle and length, but still demonstrates expected nozzle trends and improves the laser momentum coupling coefficient, C[subscript m], by up to 230% for some designs considered.

Download or read book Spaceborne Antennas for Planetary Exploration written by William A. Imbriale and published by John Wiley & Sons. This book was released on 2006-08-04 with total page 594 pages. Available in PDF, EPUB and Kindle. Book excerpt: JPL spacecraft antennas-from the first Explorer satellite in 1958 to current R & D Spaceborne Antennas for Planetary Exploration covers the development of Jet Propulsion Laboratory (JPL) spacecraft antennas, beginning with the first Explorer satellite in 1958 through current research and development activities aimed at future missions. Readers follow the evolution of all the new designs and technological innovations that were developed to meet the growing demands of deep space exploration. The book focuses on the radio frequency design and performance of antennas, but covers environmental and mechanical considerations as well. There is additionally a thorough treatment of all the analytical and measurement techniques used in design and performance assessment. Each chapter is written by one or more leading experts in the field of antenna technology. The presentation of the history and technology of spaceborne antennas is aided by several features: * Photographs and drawings of JPL spacecraft * Illustrations to help readers visualize concepts and designs * Tables highlighting and comparing the performance of the antennas * Bibliographies at the end of each chapter leading to a variety of primary and secondary source material This book complements Large Antennas of the Deep Space Network (Wiley 2002), which surveys the ground antennas covered in support of spacecraft. Together, these two books completely cover all JPL antenna technology, in keeping with the JPL Deep Space Communications and Navigation Series mission to capture and present the many innovations in deep space telecommunications over the past decades. This book is a fascinating and informative read for all individuals working in or interested in deep space telecommunications.