Field Value Language dc.contributor.author Maj, Ronald dc.date.accessioned 2019-07-09 dc.date.available 2019-07-09 dc.date.issued 2018-12-21 dc.identifier.uri http://hdl.handle.net/2123/20700 dc.description.abstract The practicality of detecting thermal Langmuir waves, charged particle impacts (i.e. shot noise”) and impacts from dust particles on a CubeSat in the Earth’s ionosphere are investigated in this thesis. The voltage power spectra predicted for thermal Langmuir waves (QTN) and particle shot noise are modelled for a dipole antenna, and shown to provide two good, independent, passive, in situ methods of measuring the plasma density and temperature in the ionosphere. If implemented, these data would be more frequent and cover a much greater domain than current ground-based methods, improving empirical ionospheric models. Antenna lengths 20 – 40 cm are found to be ideal for ionospheric conditions with QTN peaks and shot noise at the microvolt level, nicely matching CubeSat sizes. A monopole antenna response function is derived and QTN spectra are enhanced by an order of magnitude over the dipole. However, the function breaks down predicting shot noise and remains an area for future work. Using a NASA dust environment model, predictions for dust detection using the power spectrum show it useful only for large (approx. 4 microns or larger) single-particle impact events, which are rare. Assuming a CubeSat in a polar orbit at 300, 800, and 1,500 km altitude, the average dust spectrum is 3 times larger than the shot noise spectrum only once every 2,150, 110, and 225 min, respectively. Lastly, an amplifier circuit was built to detect the plasma wave signals inside a plasma chamber with conditions modelled on the lower ionosphere. An electron gun was used to produce the plasma and 3 exposed wires to simulate antennas. The amplifier was found to linearly amplify the weak signals inside the chamber across 0.1 – 1.5 MHz. Multiple peaks were measured and those at approx. 1.6 and 4 MHz were concluded to be the electron cyclotron frequency and Langmuir waves, respectively, albeit from the electron gun. Future work will require a less impactful plasma generator such as extreme UV light. en_AU dc.publisher University of Sydney en_AU dc.publisher Faculty of Science en_AU dc.publisher School of Physics en_AU dc.rights The author retains copyright of this thesis. It may only be used for the purposes of research and study. It must not be used for any other purposes and may not be transmitted or shared with others without prior permission. en_AU dc.subject CubeSat en_AU dc.subject Ionosphere en_AU dc.subject Antenna en_AU dc.subject Shot-noise en_AU dc.subject QTN en_AU dc.subject Monopole en_AU dc.title Voltage Power Spectroscopy on a CubeSat in Earth's Ionosphere en_AU dc.type PhD Doctorate en_AU dc.type.pubtype Doctor of Philosophy Ph.D. en_AU dc.description.disclaimer Access is restricted to staff and students of the University of Sydney . UniKey credentials are required. Non university access may be obtained by visiting the University of Sydney Library. en_AU
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