Study of conceptual deep space monitor communications systems using a single earth satellite. Volume III - Appendix Final report

Condensed technical survey for deep space monitor communications system using earth satellit

MAARSS: Magnet Architectures and Active Radiation Shielding Study

Protecting humans from space radiation is a major hurdle for human exploration of the solar system and beyond. Like on Earth, large magnetic fields surrounding a spaceship would deflect charged particles away from the habitat region and reduce the radiation dose to acceptable limits. The objective of this study is to determine the feasibility of current state of the art (SOA) high temperature superconducting (HTS) magnets as a means to protect crew from space radiation exposure on long duration missions beyond Low Earth Orbit (LEO). The study will look at architecture concepts to deflect high energy Galactic Cosmic Radiation (GCR) and Solar Proton Events (SPEs). Mass, power, and shielding efficiency will be considered and compared with current passive shielding capabilities. This report will walk the reader through several designs considered over the one year study and discuss the multiple parameters that should be evaluated for magnetic shielding. The study team eventually down-selects to a scalable light weight solenoid architecture that is launchable and then deployable using magnetic pressure to expand large diameter coils. Benefitting from the low temperature and high vacuum environment of deep space, existing high-temperature superconductors make such radiation shields realistic, near-term technical developments

Development of EMC antennas and their application in on-line SE measurement of conductive composite plastic materials

The development of three new EMC antennas, namely the V-conical-lens antenna (VCLA), half of a Transverse Electromagnetic-T (TEM-T) cell (acting as an antenna) and the Q-loop antenna (a quarter of a loop antenna in front of 90 ° comer reflector) is described. These antennas, when calibrated, are designed with a view to employing them in the measurement of on-line Shielding Effectiveness (SE) of conductive composite materials. Test devices incorporating those newly developed antennas for measuring SE against high impedance and low impedance wave are introduced. The theoretical model of the VCLA is developed and design features are presented as a state-of-the-art project with a view to developing this technique in the near future for measuring the plane wave SE of conductive plastics during their production process. A modified TEM-T cell designed to simulate a high impedance field on the material under test (MUT) in its (TEM-T cell's) near field region is presented. The field simulated by this device in the test location is studied theoretically. The device measures the high impedance field SE o f planar sheet-like conductive plastic materials in a situation that attempts to reconstruct the on-line environment likely to prevail in the manufacture o f such plastics. This test device is calibrated by taking into account the background noise, indirect path signal infringement and radiation losses. The newly developed Q-loop antenna is designed to be used to measure the low impedance field SE of conductive plastic materials. An analytical model of the Q-loop antenna is developed using image theory and the theory of pattern multiplication. This model is verified experimentally. Calibration experiments are performed to facilitate applying the antenna in an on-line SE measurement technique. A new class of filled composite material with a two dimensional regular array of conductive flakes (like a Frequency Sensitive Surface (FSS)) in plastic resin is proposed. A theoretical model of the suggested configuration is formulated and used to predict SE values. The SE of such material is also determined experimentally and compared with the theoretical predictions. This SE is compared with the SE o f an available filled composite in which the flakes are randomly distributed. The improvement in the shielding capability of the new class of material is highlighted. Relative radiation patterns of the developed antennas are measured and compared with predictions. Apart from the anomalies which can be attributed to (simplifying) assumptions made in the development of the theoretical analysis, the measured radiation patterns and other antenna parameters are in good agreement with predictions

Modelling the Electromagnetic Properties of Conductive Nonwoven Fabrics

This thesis presents micro-structure models of wet-laid conductive nonwoven fabrics allowing the sheet conductance and shielding effectiveness to be simulated and compared to experimental measurement. Conductive nonwoven fabrics are used within the aerospace and defence industries to provide lightweight, functional electromagnetic enhancement to composite structures. They are materials borne from stochastic processes with anisotropic distributions of fibre and parameters that vary from point to point on the local scale. Monte Carlo models of the material’s micro-structure have been constructed by writing a series of algorithms which pseudo-randomly generate the material’s structure by incorporating key physical parameters such as the density, areal concentration and fibre angle distribution. To define the last of these parameters, a completely new optical method has been developed making use of the Hough Transform. These models have predicted the anisotropic sheet conductance to within 1-2% of experimental values, with an estimated inter-fibre contact resistance of Rj = 8.6kΩ, and a measured geometry factor of Φx = 0.727, Φy = 0.273. Analytic models of the material are derived from first principles enabling the rapid calculation of the sheet conductance, whilst also providing an understanding between the key parametric relationships. The analytic model, Monte Carlo model and experimental measurements are compared and give good correspondence. The micro-structure models are finally applied to a full wave electromagnetic simulation technique and shown to produce close correlation to polarisation specific measurements of the shielding effectiveness. High frequency (up to 200GHz) simulations of lightweight nonwoven structures suggest an eventual fall in the shielding effectiveness, attributed to the material’s sub-wavelength apertures

Electromagnetic Interference Shielding Effectiveness of Interlayered Systems Containing Metal-Oxide, Conducting Polymer and Carbon Nanotube Reinforced Polymeric Composites

The Electromagnetic Interference (EMI) Shielding Effectiveness (SE) has become one of the important requirements for the devices associated with telecommunication systems consisting of large frequency bands. The degradation of the quality of transmitting signal influenced by frequencies emitting from external sources can be reduced by covering the circuits of the devices by EMI Shielding materials like polymer composites, metal-based nanofiber mats, the metal of oxide films, etc. The investigation strives for the attenuation of EMI by introducing two composite mats from conducting polymer-based, multiwalled carbon nanotubes (MWCNTs) coated Nylon 6 nanofiber composites. Two other composite mats are also developed by the Forcespinning® method using sol solution of functionalized multiwalled carbon nanotubes (f-MWCNTs) and magnetite (Fe3O4) into as-prepared polyacrylonitrile (PAN) which is then carbonized at elevated temperature to convert it into carbon nanofiber (CNF). A total of four layers of mats are stacked and compression molded together to develop one multilayered composite (MLC 1). The Fe3O4 has higher magnetic properties which may provide a good magnetic loss effect. The focus is to investigate the synergistic effects between higher magnetic Fe3O4, conductive MWCNTs nanofillers with the dielectric CNF, conducting polymer, and functionalized MWCNTs coated nanofiber composite which can provide information about the dominating mechanism. (Absorption, reflection, or multiple reflections) for EMI SE. The multilayered composite (MLC 2) consisting 8 layers (repeating the stacking sequence again) has given the highest obtained value more than 40 dB EMI SE in the frequency range from 300–500 MHz. The results will bring some findings of optimized materials yielding good EMI SE in lightweight applications

Modelling the Electromagnetic Properties of Conductive Nonwoven Fabrics

This thesis presents micro-structure models of wet-laid conductive nonwoven fabrics allowing the sheet conductance and shielding effectiveness to be simulated and compared to experimental measurement. Conductive nonwoven fabrics are used within the aerospace and defence industries to provide lightweight, functional electromagnetic enhancement to composite structures. They are materials borne from stochastic processes with anisotropic distributions of fibre and parameters that vary from point to point on the local scale. Monte Carlo models of the material’s micro-structure have been constructed by writing a series of algorithms which pseudo-randomly generate the material’s structure by incorporating key physical parameters such as the density, areal concentration and fibre angle distribution. To define the last of these parameters, a completely new optical method has been developed making use of the Hough Transform. These models have predicted the anisotropic sheet conductance to within 1-2% of experimental values, with an estimated inter-fibre contact resistance of Rj = 8.6kΩ, and a measured geometry factor of Φx = 0.727, Φy = 0.273. Analytic models of the material are derived from first principles enabling the rapid calculation of the sheet conductance, whilst also providing an understanding between the key parametric relationships. The analytic model, Monte Carlo model and experimental measurements are compared and give good correspondence. The micro-structure models are finally applied to a full wave electromagnetic simulation technique and shown to produce close correlation to polarisation specific measurements of the shielding effectiveness. High frequency (up to 200GHz) simulations of lightweight nonwoven structures suggest an eventual fall in the shielding effectiveness, attributed to the material’s sub-wavelength apertures

Investigation on shielding effectiveness of reverberant enclosures with contents

Shielding is a method to protect electronic devices from electromagnetic interference and the protection is usually provided by using an enclosure. This ability of protection is quantified by shielding effectiveness (SE). Most of methods to predict SE are about empty enclosures. It has been shown that the presence of contents affects the SE and hence they should be considered. The power balance (PWB) method is widely used for analysing shielding problems of populated enclosures. By using this method, the contents are represented by their absorption cross sections (ACS). Previous ACS measurements were performed when the contents were unpowered. This might be a problem if the contents contain active devices. In order to investigate the influence of power states on ACS, we measured the ACS of some computer components when they were powered on and off. Comparison suggests that their ACS barely change in different power states. Therefore, it can be concluded that power state has little effect on ACS measurements. The PWB method assumes that in the steady state, the internal field of an enclosure is uniform, which is not true when the internal loss is high. In order to overcome this limitation, a 2D diffusion model has been proposed. It stems from acoustics and is a generalization of the PWB method. In this work, the 2D model has been expanded to a 3D one. The 3D diffusion model was verified by using it to predict the power density in a populated enclosure and compare the predictions with those obtained by full wave simulation and measurement. The result indicates that when the loss in an enclosure is high, the internal field is not uniform and the 3D diffusion model is able to describe the variation of field

A feasibility study of the mass spectrometer instrumentation for the analysis of the Martian atmosphere Final report

Mass spectrometer instrumentation for analysis of Mars atmospher

Lightning protection of aircraft

The current knowledge concerning potential lightning effects on aircraft and the means that are available to designers and operators to protect against these effects are summarized. The increased use of nonmetallic materials in the structure of aircraft and the constant trend toward using electronic equipment to handle flight-critical control and navigation functions have served as impetus for this study

Development and evaluation of the elastic recovery concept for expandable space structures

Elastic recovery of expandable space structure