Sökning: "laboratory discharges"

Visar resultat 1 - 5 av 21 avhandlingar innehållade orden laboratory discharges.

  1. 1. Measurements of X-Ray Emission from Laboratory Sparks and Upward Initiated Lightning

    Författare :Pasan Hettiarachchi; Vernon Cooray; Mats Leijon; Mahbubur Rahman; Marcos Rubinstein; Uppsala universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; X-ray; upward lighting; laboratory discharges; energy distribution;

    Sammanfattning : In 1925 Nobel laureate R. C. Wilson predicted that high electric fields of thunderstorms could accelerate electrons to relativistic energies which are capable of generating high energetic radiation. The first detection of X-rays from lightning was made in 2001 and from long sparks in 2005. LÄS MER

  3. 2. Numerical modelling of positive electrical discharges in long air gaps

    Författare :Oscar Diaz; Vernon Cooray; Raul Montano; Uppsala universitet; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; high voltage techniques; numerical modeling; electrical discharge in gases; streamer mechanism; leader channel; Engineering Science with specialization in Atmospheric Discharges; Teknisk fysik med inriktning mot atmosfäriska urladdningar;

    Sammanfattning : This dissertation deals with research on the numerical modelling of electrical discharges in laboratory long air gaps excited with positive switching impulses. It begins with the preliminary work of several scientists during the last decades, making a detailed analysis of different approaches for modelling all the stages in a full discharge. LÄS MER

  4. 3. NOx Production by Ionisation Processes in Air

    Författare :Mahbubur Rahman; Vernon Cooray; Pierre Laroche; Uppsala universitet; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Engineering physics; Nitrogen oxides; Lightning; Electrical Discharges; Cosmic Rays; Troposphere; Teknisk fysik; Engineering physics; Teknisk fysik;

    Sammanfattning : The study presented in this thesis was motivated by the large uncertainty on the concentration of atmospheric electrical discharges to the global nitrogen budget. This uncertainty is partly due to the fact that information concerning the NOx production efficiency of electrical discharges having current signatures similar to those of lightning flashes is not available in the literature. LÄS MER

  5. 4. Atomic Spectroscopy for Applications in Energy Technology

    Författare :Thomas Lennartsson; Astronomi - Genomgår omorganisation; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; atomic structure; plasma diagnostics; branching fractions; gas discharges; highly charged ions; extreme ultraviolet spectra; time-resolved spectroscopy;

    Sammanfattning : This thesis intends to provide spectroscopic information which may be of use in the investigation of low-density plasmas. Developed since the 19th century, the spectroscopic approach has proven to be a versatile method for measuring properties in hot gases, such as electron and ion temperatures and densities, the abundance of various elements in the gas, etc. LÄS MER

  7. 5. Development and application of laser diagnostics - from laboratory devices towards practical combustion engines

    Författare :Zhenkan Wang; Förbränningsfysik; []
    Nyckelord :Combustion diagnostics; Laser induced fluorescence LIF ; Ultra-high-speed; Burst-mode laser; Ballistic imaging; Particle imaging velocimetry; Laser Doppler anemometry; Turbulent premixed combustion; Plasma; Internal combustion engine; Partially premixed combustion PPC ; Auto-ignition; OH radical; CH2O formaldehyde ; Fysicumarkivet A:2018:Wang;

    Sammanfattning : For many decades, research work on combustion has been focused on improving combustion efficiency and reducing harmful emissions. Laser diagnostics is one of the best ways to investigate the combustion process and emission formation as it is non-intrusive and it has high spatiotemporal resolution. LÄS MER