Počet záznamů: 1  

Kinetic modelling of runaway electron avalanches in tokamak plasmas.

  1. 1.
    0473161 - ÚFP 2017 RIV GB eng J - Článek v odborném periodiku
    Nilsson, E. - Decker, J. - Peysson, Y. - Granetz, R.S. - Saint-Laurent, F. - Vlainic, Milos
    Kinetic modelling of runaway electron avalanches in tokamak plasmas.
    Plasma Physics and Controlled Fusion. Roč. 57, č. 9 (2015), č. článku 095006. ISSN 0741-3335. E-ISSN 1361-6587
    GRANT EU: European Commission(XE) 633053 - EUROfusion
    Institucionální podpora: RVO:61389021
    Klíčová slova: plasma physics * runaway electrons * knock-on collisions * tokamak * Fokker-Planck * runaway avalanches
    Obor OECD: Fluids and plasma physics (including surface physics)
    Impakt faktor: 2.404, rok: 2015

    Runaway electrons can be generated in tokamak plasmas if the accelerating force from the toroidal electric field exceeds the collisional drag force owing to Coulomb collisions with the background plasma. In ITER, disruptions are expected to generate runaway electrons mainly through knock-on collisions (Hender et al 2007 Nucl. Fusion 47 S128-202), where enough momentum can be transferred from existing runaways to slow electrons to transport the latter beyond a critical momentum, setting off an avalanche of runaway electrons. Since knock-on runaways are usually scattered off with a significant perpendicular component of the momentum with respect to the local magnetic field direction, these particles are highly magnetized. Consequently, the momentum dynamics require a full 3D kinetic description, since these electrons are highly sensitive to the magnetic non-uniformity of a toroidal configuration. For this purpose, a bounce-averaged knock-on source term is derived. The generation of runaway electrons from the combined effect of Dreicer mechanism and knock-on collision process is studied with the code LUKE, a solver of the 3D linearized bounce-averaged relativistic electron Fokker-Planck equation (Decker and Peysson 2004 DKE: a fast numerical solver for the 3D drift kinetic equation Report EUR-CEA-FC-1736, Euratom-CEA), through the calculation of the response of the electron distribution function to a constant parallel electric field. The model, which has been successfully benchmarked against the standard Dreicer runaway theory now describes the runaway generation by knock-on collisions as proposed by Rosenbluth (Rosenbluth and Putvinski 1997 Nucl. Fusion 37 1355-62). This paper shows that the avalanche effect can be important even in non-disruptive scenarios. Runaway formation through knock-on collisions is found to be strongly reduced when taking place off the magnetic axis, since trapped electrons can not contribute to the runaway electron population.
    Trvalý link: http://hdl.handle.net/11104/0270327

     
     
Počet záznamů: 1  

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