Scaled Experiment to Investigate Auroral Kilometric Radiation Mechanisms in the Presence of Background Electrons
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Auroral Kilometric Radiation (AKR) emissions occur at frequencies similar to 300kHz polarised in the X-mode with efficiencies similar to 1-2% [1,2] in the auroral density cavity in the polar regions of the Earth's magnetosphere, a region of low density plasma similar to 3200km above the Earth's surface, where electrons are accelerated down towards the Earth whilst undergoing magnetic compression. As a result of this magnetic compression the electrons acquire a horseshoe distribution function in velocity space. Previous theoretical studies have predicted that this distribution is capable of driving the cyclotron maser instability. To test this theory a scaled laboratory experiment was constructed to replicate this phenomenon in a controlled environment, [3-5] whilst 2D and 3D simulations are also being conducted to predict the experimental radiation power and mode, [6-9]. The experiment operates in the microwave frequency regime and incorporates a region of increasing magnetic field as found at the Earth's pole using magnet solenoids to encase the cylindrical interaction waveguide through which an initially rectilinear electron beam (12A) was accelerated by a 75keV pulse. Experimental results showed evidence of the formation of the horseshoe distribution function. The radiation was produced in the near cut-off TE01 mode, comparable with X-mode characteristics, at 4.42GHz. Peak microwave output power was measured similar to 35kW and peak efficiency of emission similar to 2%, . A Penning trap was constructed and inserted into the interaction waveguide to enable generation of a background plasma which would lead to closer comparisons with the magnetospheric conditions. Initial design and measurements are presented showing the principle features of the new geometry.
McConville , S L , Ronald , K , Speirs , D C , Gillespie , K M , Phelps , A D R , Cross , A W , Bingham , R , Robertson , C W , Whyte , C G , He , W , King , M , Bryson , R , Vorgul , I , Cairns , R A & Kellett , B J 2014 , Scaled Experiment to Investigate Auroral Kilometric Radiation Mechanisms in the Presence of Background Electrons . in 15th International Congress on Plasma Physics (ICPP2010) & 13th Latin American Workshop on Plasma Physics (LAWPP2010) . Journal of Physics Conference Series , vol. 511 , IOP Publishing Ltd. , Bristol , 15th International Congress on Plasma Physics (ICPP) / 13th Latin American Workshop on Plasma Physics (LAWPP) , Chile , 8-13 August . DOI: 10.1088/1742-6596/511/1/012061conference
15th International Congress on Plasma Physics (ICPP2010) & 13th Latin American Workshop on Plasma Physics (LAWPP2010)
© 2013 The Authors. Published under licence by IOP Publishing Ltd. The following article appeared in S L McConville et al 2014 J. Phys.: Conf. Ser. 511 012061 and may be found at http://iopscience.iop.org/1742-6596/511/1/012061. Content from this work may be used under the terms of the Creative Commons Attribution 3.0 licence. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI.