Now showing items 27-44 of 44

    • A model for IS spectra for magnetized plasma with arbitrary isotropic velocity distributions 

      Enger, Eirik Rolland (Mastergradsoppgave; Master thesis, 2020-06-27)
      The plasma line in the incoherent scatter spectrum is known to provide information about the state of the ionosphere. However, it is weak in signal strength and therefore difficult to measure reliably and consistently. When high-energetic electrons (suprathermal electrons) are present in the ionosphere the plasma line echo power is enhanced and detectable by more radars. Recent measurements made by ...
    • Multifractals and their application to geospace data 

      Østvand, Lene (Master thesis; Mastergradsoppgave, 2008-06-02)
      In this thesis I first introduce multifractal theory and mathematical concepts for multifractal analysis. Different methods for different uses are described, with focus on a differentiating between coarse and fine theory approaches. Methods for analysing time series are also described, more specificly a direct method based on the coarse theory analysis, the wavelet transform modulus maxima ...
    • Na lidar measurements during the ECOMA/Geminids campaign with focus on Na peak density and temperature 

      Østerpart, Jørgen Olai Kristensen (Master thesis; Mastergradsoppgave, 2011-02)
      Using a resonance lidar, atomic Na (sodium) can be observed in the 80-110 km altitude range of the atmosphere. Na belongs to the alkali metal group and is highly reactive, so one could expect that it would quickly react with other particles and leave its atomic state. Its actual behaviour however includes the formation of relatively dense layers which, from the perspective of a stationary lidar, ...
    • Natural occuring oil seepages as a consequence of bottom trawling? 

      Hindenes, Sander (Mastergradsoppgave; Master thesis, 2023-05-31)
      Bottom trawling is used to capture fish species that live in the seabed. The damage on the seabed trawling causes has been discussed for many years. This thesis aims to investigate whether bottom trawling for sand eels can be a cause for some of the detected oil seepages in the North Sea. We investigated this using manual delineation of oil seepages in Synthetic Aperture Radar (SAR) satellite ...
    • A new Method for Estimating 3-Dimensional Ionospheric Currents from Ground-Based Magnetometers 

      Thom, Erik (Mastergradsoppgave; Master thesis, 2022-07-17)
      The ionosphere is a region of the upper atmosphere where a significant rate of photo-ionisation from solar ultraviolet radiation cause an increased plasma density. In this region a system of electrical currents flow, driven by electric fields generated by fluctuating dynamics within the Earths magnetosphere. These fluctuating dynamics are caused by interactions between the magnetosphere and the solar ...
    • On the Distribution of Meteoric Smoke Particles above Andøya, Norway, and Estimated Collection During a Summer Rocket Campaign 

      Larsen Greaker, Herman (Master thesis; Mastergradsoppgave, 2023-12-21)
      As meteoroids enter the Earth’s atmosphere, the majority will fully evaporate in the altitude region 70–110 km, due to the frictional heating from atmospheric interactions. The evaporated material is thought to re-condense and coagulate into nanometer sized particles called meteoric smoke particles (MSP). These particles are thought to be a central component in the formation of noctilucent clouds ...
    • On the internal physical conditions in dust probes: transport, heating and evaporation of fragmented dust particles 

      Antonsen, Tarjei (Master thesis; Mastergradsoppgave, 2013-12-13)
      We study the conditions within, and dynamics of fragmented mesospheric dust particles inside, the Faraday-cup type dust probe MUDD using numerical simulations with a dedicated model. The transport of singly charged fragments from impacting NLC particles on the main grid in MUDD, have been calculated on the basis of supplementary models of the neutral gas conditions and electric field structure within ...
    • On the Meteoric Smoke Particle Detector SPID: Measurements and analysis from the G-chaser rocket campaign 

      Trollvik, Henriette Marie Tveitnes (Master thesis; Mastergradsoppgave, 2019-06-01)
      The Smoke Particle Impact Detector (SPID), newly designed at the University of Tromsø, was launched from Andøya 09:13 UTC the 13. January 2019. SPID is designed to detect meteoric smoke particles (MSPs) in winter mesospheric conditions. The rocket had a velocity of 1600 ms-1 at ~55 km where the nosecone was separated. At ~ 60km, SPID detected a signal of 17nA on the middle plate. The dynamics of the ...
    • On Trapped Particle Dynamics in Rotating Frames 

      Helgeland, Aurora Driveklepp (Mastergradsoppgave; Master thesis, 2021-07-01)
      The rapid rotation of Jupiter and Saturn, combined with internal source of plasma provided by their moons Io and Enceladus respectively, creates a magnetodisk structure of the planetary magnetic field. The magnetodisk looks like a stretched dipole magnetic field in the equatorial region, where centrifugal force is largest. The centrifugal force, originating in the rotating frame, is known to have ...
    • Plasma cloud detection and diagnostics from arcing by conditional averaging 

      Nilsen, Kenneth (Master thesis; Mastergradsoppgave, 2017-06-06)
      Plasma cloud formation from arcing is experimentally studied. The arcs are formed by a high voltage set-up in the space simulation chamber at UiT. The plasma clouds are observed as large structures in the time series recorded by Langmuir probe and reference probe. By using the method of conditional averaging, the structures are accentuated. The electron cloud formed by arcing was found to be ...
    • Plasma line studies in relation to Naturally Enhanced Ion Acoustic Lines (NEIALs) 

      Knutsen, Joachim Sveia (Master thesis; Mastergradsoppgave, 2008-06-02)
      New to the ESR common programmes is the inclusion of plasma lines along with the standard ion power density spectrum. Using data from the IPY common programme, a programme that has been run all through the International Polar Year, we have gone through large amounts of analysed data trying to find periods in time that fulfils the known criteria for finding Naturally Enhanced Ion Acoustic Lines ...
    • Polar Mesospheric Winter Echoes - an analysis of selected cases 

      Ettestad, Kristine (Mastergradsoppgave; Master thesis, 2022-05-31)
      Polar Mesospheric Winter Echoes (PMWE) are strong coherent radar echoes, from the upper mesosphere at 55-85 km that are observed typically from end of August until beginning of May. Some models to explain PMWE formation suggest that they form because of turbulence in the atmosphere. Other models suggest that the PMWEs form like summer polar mesospheric echoes (PMSE) where charged dust particles ...
    • Predicting the Auroral Oval Boundaries by Means of Polar Operational Environmental Satellite Particle Precipitation Data 

      Breedveld, Mikkel Jelle (Master thesis; Mastergradsoppgave, 2020-06-29)
      New empirical Kp-based models for the equatorward and poleward boundaries of the auroral oval in the Northern and Southern Hemispheres were developed, with the purpose of reviewing the auroral ovals predicted by well-established Feldstein auroral oval model. The new models were derived from particle and energy flux measurements from six low-altitude (800-900 km) POES/MetOp satellites. The equatorward ...
    • Radar observations of space debris in polar orbits 2018–2021. A study on the evolution of the Microsat-R fragments 

      Paulsen, Martinius Ekeland (Master thesis; Mastergradsoppgave, 2021-07-02)
      Orbits are an invaluable resource for the global community. However, space pollution is becoming more pronounced as the accumulation of debris continues. Deliberate collisions are a relevant source contributing to this development. When Microsat-R was destroyed with a missile in 2019, it ejected numerous fragments into orbit. Based on observations made with EISCAT UHF, this thesis will investigate ...
    • Review and test of funnel shape geometries in solar wind acceleration 

      Trollebø, Robert (Master thesis; Mastergradsoppgave, 2009-12-15)
      The origin and heating of the solar wind is still a puzzle. We review in this study the idea that the solar wind originates in coronal funnels. We place emphasis on the fast solar wind. This study provides primarily a historic overview over the development of the idea of funnel expansion. We present examples of recent solar wind studies that investigate the funnel geometry. These studies include ...
    • Spectral observations of Polar Mesospheric Summer Echoes (PMSE) 

      López Muñoz, Aquilino (Master thesis; Mastergradsoppgave, 2007-06-15)
      We present spectral measurements of PMSE under the influence of HF heating cycles. The data has been obtained with EISCAT VHF radar, during the EISCAT campaign 2004 in Tromsø. Examples where the PMSE overshoot appears when the electrons are heated with a specific cycle are shown. A detailed analysis of PMSE spectral width during the heating cycles concluded that there is no evidence of a possible ...
    • Survey and simulation of space debris using EISCAT UHF 

      Røynestad, Elisabeth Kristina (Master thesis; Mastergradsoppgave, 2018-06-01)
      This thesis starts with a review of the evolution of space debris, what is consists of, how it is made, how it is detected and tracked, and why it is such an important topic. Some of the worst collisions have contributed to causing 49% of the total space debris. If the launch rate continues, the "Kessler Syndrome" might become a reality destroying our future outlook for space communication and ...
    • A theoretical study of the coupling between minor ions and protons in the solar transition region 

      Byhring, Hanne Sigrun (Master thesis; Mastergradsoppgave, 2007-06-01)
      We have used a numerical model to calculate the flow velocities of six minor ion species, using two different background models for the fast solar wind, one with a slow expansion, and one with a very rapidly expanding geometry. By comparing the flow velocity of the minor ions and the protons, we have investigated the degree of coupling between minor ions and the background solar wind in the solar ...