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dc.contributor.authorMaj, Ronald
dc.date.accessioned2019-07-09
dc.date.available2019-07-09
dc.date.issued2018-12-21
dc.identifier.urihttp://hdl.handle.net/2123/20700
dc.description.abstractThe 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.publisherUniversity of Sydneyen_AU
dc.publisherFaculty of Scienceen_AU
dc.publisherSchool of Physicsen_AU
dc.rightsThe 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.subjectCubeSaten_AU
dc.subjectIonosphereen_AU
dc.subjectAntennaen_AU
dc.subjectShot-noiseen_AU
dc.subjectQTNen_AU
dc.subjectMonopoleen_AU
dc.titleVoltage Power Spectroscopy on a CubeSat in Earth's Ionosphereen_AU
dc.typePhD Doctorateen_AU
dc.type.pubtypeDoctor of Philosophy Ph.D.en_AU
dc.description.disclaimerAccess 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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