Laboratory Reproduction of Auroral Magnetospheric Radio Wave Sources
- SUPA Department of Physics, John Anderson Building, 107 Rottenrow, University of Strathclyde, Glasgow, G4 0NG (United Kingdom)
- Space Science and Technology Department, STFC Rutherford Appleton Laboratory, Didcot, OX11 0QX (United Kingdom)
- School of Mathematics and Statistics, University of St Andrews, St Andrews, KY16 9SS, Scotland (United Kingdom)
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 {approx}19-35 kW with a maximum RF emission efficiency of {approx}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.
- OSTI ID:
- 21251515
- Journal Information:
- AIP Conference Proceedings, Vol. 1061, Issue 1; Conference: 2008 ICTP international workshop on the frontiers of modern plasma physics, Trieste (Italy), 14-25 Jul 2008; Other Information: DOI: 10.1063/1.3013767; (c) 2008 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA); ISSN 0094-243X
- Country of Publication:
- United States
- Language:
- English
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