Sökning: "space physics"

Visar resultat 16 - 20 av 635 avhandlingar innehållade orden space physics.

  1. 16. The Auroral Large Imaging System : design, operation and scientific results

    Författare :Urban Brändström; Umeå universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Space and plasma physics; Aurora; Artificial airglow; HF-pump enhanced airglow; Multistation measurements; Polar Stratospheric clouds; Radio-Induced optical emissions; Spectroscopic imaging observations; Tomography; Rymd- och plasmafysik; Space physics; Rymdfysik; rymdfysik; Space Physics;

    Sammanfattning : The Auroral Large Imaging System (ALIS) was proposed in 1989 by Åke Steen as a joint Scandinavian ground-based nework of automated auroral imaging stations. The primary scientic objective was in the field of auroral physics, but it was soon realised that ALIS could be used in other fields, for example, studies of Polar Stratospheric Clouds (PSC), meteors, as well as other atmospheric phenomena. LÄS MER

  3. 17. Turbulence and scalar flux modelling applied to separated flows

    Författare :Johan Gullman-Strand; Arne V. Johansson; Suad Jakirlic; KTH; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Space and plasma physics; fluid physics; plasma physics; applied mechanics; aerospace; Rymd- och plasmafysik; Space physics; Rymdfysik;

    Sammanfattning : The turbulen flow in an asymmetric diffuser has been en studied by the means of Reynold average Navier-Stokes equations with both differential and explict algebraic expressions to model the Reynolds stress tensor. Modifications to the differential stress model have been derived, using the inverse turbulence timescale to obtain the dissipation of turbuence kinetic energy. LÄS MER

  4. 18. The Polar Cusp and its Ionospheric footprint : Dynamics and Transients

    Författare :Frédéric Pitout; Ryoichi Fujii; Uppsala universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Space and plasma physics; Solar wind - magnetosphere - ionosphère interactions; polar ionosphere; Rymd- och plasmafysik; Space physics; Rymdfysik; Space Physics; rymdfysik;

    Sammanfattning : The magnetopause, the boundary layer between the solar wind and the Earth’s magnetosphere, is not closed as we have long thought. Transfers of energy, particles and momentum from the solar wind to the magnetosphere actually take place. LÄS MER

  5. 19. Neural Networks Applications and Electronics Development for Nuclear Fusion Neutron Diagnostics

    Författare :Emanuele Ronchi; Sean Conroy; Basilio Esposito; Uppsala universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; Neural networks; tomography; unfolding; real time; pulse shape discrimination; PSD; neutron spectroscopy; MPRu; TOFOR; KN3; neutron camera; LED; summing amplifiers; electronics; JET; Plasma physics; Plasmafysik; Computational physics; Beräkningsfysik; Applied Nuclear Physics; Tillämpad kärnfysik; Elektronik; Electronics;

    Sammanfattning : This thesis describes the development of electronic modules for fusion neutron spectroscopy as well as several implementations of artificial neural networks (NN) for neutron diagnostics for the Joint European Torus (JET) experimental reactor in England.The electronics projects include the development of two fast light pulser modules based on Light Emitting Diodes (LEDs) for the calibration and stability monitoring of two neutron spectrometers (MPRu and TOFOR) at JET. LÄS MER

  7. 20. Diagnosing Fuel Ions in Fusion Plasmas using Neutron Emission Spectroscopy

    Författare :Carl Hellesen; Göran Ericsson; Sean Conroy; William W Heidbrink; Uppsala universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; fusion; plasma diagnostics; neutron spectroscopy; NBI heating; ICRF heating; energetic ions; Fusion; Fusion; Nuclear physics; Kärnfysik; Applied Nuclear Physics; Tillämpad kärnfysik;

    Sammanfattning : Neutron emission spectra, measured with the time of flight spectrometer TOFOR, at the joint European torus (JET) are presented in this thesis. TOFOR has been in use since 2005, routinely measuring the neutron emission from JET plasmas. LÄS MER