1 / 9

NSI model for the production of runaway electrons in streamer discharges .

NSI model for the production of runaway electrons in streamer discharges. Olivier Chanrion, Torsten Neubert National Space Institute / Danish Technical University chanrion@space.dtu.dk.

toni
Télécharger la présentation

NSI model for the production of runaway electrons in streamer discharges .

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. NSI model for the production of runaway electronsin streamer discharges. Olivier Chanrion, Torsten Neubert National Space Institute / Danish Technical University chanrion@space.dtu.dk

  2. Outline - Introduction : Streamer discharges Thermal runaway mechanism Terrestrial Gamma-ray Flashes - The Danish model - Result example - Plans …

  3. Streamer dischargeStreamers : - filaments of weakly ionised plasma propagating both along and against the electric field - present in leader tips of lightning, in mesospheric discharge ( sprites ) … Enhancement of the field in the streamer heads Can ‘push’ thermal electrons into the runaway regime => Role in TGF ?

  4. On the production of runaway electrons Electric field = 3 Ek Ionization threshold Friction force X-ray -ray thermal electrons runaway electrons Are streamers responsible for the recently observed Terrestrial -ray Flashes ? Numerical difficulty : Few high energy electrons % low energy ones

  5. The Danish ModelChanrion&Neubert, JGR, 115 (2010) • Physical model : Fully kinetic • - movement of electrons in a background electric field • - collision with neutral ( attachment, excitation, ionization, photoionization ) • - total cross section comes from Phelps ( BOLSIG ) • - extrapolation to high energies follows Murphy (LANL Rep. 2002) • - scattering angle follows Okhrimovsky (PhysRevE,65,2002) • - Ionisation energy partitionning follows Opal (J. Chem. Phys., 55, 1971) • Numerical model • 3D like geometry (2D cylindrical) • - Based on the standard Birdshall Particle in Cell • + Monte Carlo Collision • - Advanced resampling technique for high energy electron • Features • - Allow to study the acceleration of cold electron in the runaway regime - Unprecedented precision allows to calculate the probability to runaway

  6. The Danish Model • distribution function with the • runaway branch • Threshold for runaway • Probability • to runaway

  7. The Danish ModelIn a background field of 3Ek Estimate of runaway in agreement with Moss(JGR,111,2006) and Gurevich (Phys.Lett.A, 361, 2007) work=> lead to agreement with TGF observations.

  8. Plans • Nb of electrons • 1/Probability to runaway First runaway appears when the field in the tip is about 5 Ek At t > 1.8 µs, 1012 electrons drift in a field > 5Ek => Above the precision limit a standard MCC code

  9. Plans • Main goal : • Simulate the production of X- and Gamma ray • Understand the impact on the streamer propagation • Deniz Cinar, a PhD student will start next month • Preliminary studies with 1D code • Implementation of advance in the quasi-3D code • Collaboration with • CWI/TU Eindhoven (Ute Ebert, L. van Deursen) • RFNC ( Babich )

More Related