Laboratory reproduction of auroral magnetospheric radio wave sources

Research output: Contribution to conferencePaper

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Abstract

Auroral Kilometric Radiation, AKR, occurs naturally in the polar regions of the Earth's magnetosphere where electrons are accelerated by electric fields into the increasing planetary magnetic dipole. Here conservation of the magnetic moment converts axial to rotational momentum forming a horseshoe distribution in velocity phase space. This distribution is unstable to cyclotron emissions and radiation is emitted in the X-mode. In the laboratory a 75-85kV electron beam of 5-40A was magnetically compressed by a system of solenoids. Results are presented for an electron beam gyrating at cyclotron frequencies of 4.42GHz and 11.7GHz resonating with near cut-off TE01 and TE03 modes respectively. Measurements of the electron transport combined with numerical simulations demonstrated that a horseshoe distribution function was formed in electron velocity space. Analysis of the experimental measurements allowed the inference of the 1D number density as a function of the electron beam pitch angle. The total power emitted experimentally was ~19-35 kW with a maximum RF emission efficiency of ~2%. These results were compared to those obtained numerically using a 2D PiC code KARAT with a maximum efficiency of 2% predicted for the same mode and frequency, consistent with astrophysical and theoretical results.
Original languageEnglish
Pages188-196
Number of pages8
Publication statusPublished - 15 Oct 2008
Event2008 ICTP International Workshop on the Frontiers of Modern Plasma Physics - Trieste, Italy
Duration: 14 Jul 200825 Jul 2008

Conference

Conference2008 ICTP International Workshop on the Frontiers of Modern Plasma Physics
CityTrieste, Italy
Period14/07/0825/07/08

Keywords

  • auroral kilometric radiation
  • cyclotron instabilities
  • magnetosphere

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