Sökning: "leader discharges"

Visar resultat 1 - 5 av 10 avhandlingar innehållade orden leader discharges.

  1. 1. Physics of Electrical Discharge Transitions in Air

    Författare :Lipeng Liu; Marley Becerra; Ute Ebert; KTH; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; electrical discharges; transition; streamers; glow corona; leader discharges; elektriska urladdningar; övergång; streamers; glöd-korona; ledarurladdningar; Electrical Engineering; Elektro- och systemteknik;

    Sammanfattning : Electrical discharges with a variety of different forms (streamers, glow corona, leaders, etc.) broadly exist in nature and in industrial applications. Under certain conditions, one electrical discharge can be transformed into another form. LÄS MER

  3. 2. Features of the Electric Fields Generated by Lightning with Special Attention to Positive Ground Flashes

    Författare :Dalina Johari; Vernon Cooray; Mahbubur Rahman; Fridolin Heidler; Uppsala universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; positive ground flashes; preliminary breakdown pulses; multiple-trains PBPs; positive leader; bidirectional leader; negative leader branch; subsequent return strokes; distant lightning; Engineering Science with specialization in Atmospheric Discharges; Teknisk fysik med inriktning mot atmosfäriska urladdningar;

    Sammanfattning : This thesis focuses on the main processes in positive ground flashes and the distant lightning environment for both positive and negative ground flashes. It presents the characteristics of the preliminary breakdown pulses (PBPs), the characteristics of the electric field pulses observed during leader propagation, and the characteristics of the electric fields produced by the first and the subsequent return strokes. LÄS MER

  4. 3. 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

  5. 4. On The Initiation of Upward Positive Leader Discharges During Lightning Strikes

    Författare :Marley Becerra; Uppsala universitet; []
    Nyckelord :TECHNOLOGY; TEKNIKVETENSKAP;

    Sammanfattning : .... LÄS MER

  7. 5. On the Attachment of Lightning Flashes to Grounded Structures

    Författare :Marley Becerra; Vernon Cooray; Rajeev Thottappillil; Mats Boman; Ivo Gallimberti; Uppsala universitet; []
    Nyckelord :Engineering physics; Lightning; Lightning attachment; Positive leader discharges; Lightning protection; Thunderstorms; Numerical modeling; Teknisk fysik;

    Sammanfattning : This thesis deals with the physical modeling of the initiation and propagation of upward positive leader discharges from grounded structures during lightning strikes. It includes the analysis of upward leaders initiated under the influence of the electric field produced by a dominant negative cloud charge and due to the combined action of a negative thundercloud and a descending downward stepped negative leader. LÄS MER