An Experimental Investigation of the Auroral Kilometric Radiation Emission Mechanism

Summary form only given. In this presentation we discuss a laboratory experiment for the investigation of instabilities associated with an electron beam subject to a magnetic compression of up to a factor of 30. Experimental results will be presented showing emission at a frequency of 11.7 GHz, corresponding to the relativistic cyclotron frequency, from a 42 keV electron beam subject to magnetic compression ratios in the range of 10 to 30. In addition, data from particle-in-cell code simulations will be presented showing the instability growth and saturation in an experimentally consistent geometry. A scenario analogous to this occurs in the terrestrial auroral zone, where particles are accelerated into the polar regions of the Earth's magnetic dipole. The resultant horseshoe shaped velocity distribution has been shown to be unstable to a cyclotron-maser type instability. This instability has been postulated as being responsible for the auroral kilometric radiation and also nonthermal radiation from other astrophysical objects including stars with a suitable magnetic field configuration