On processing of Controlled Source Electromagnetic (CSEM) Data

In this paper, we present a fast and robust scheme of controlled source electromagnetic data processing. We specify in detail various types of noise that affect measurements and show how these noise components can be suppressed. We promote an improved algorithm to process noisy data. We demonstrate that our method can recover response functions from extremely noisy field data. The proposed software can be adapted to new data sets and noisy environments. We apply our processing method to field data from Kola Peninsula, Norilsk region and Pechora province (Russia)

Synchrotron radiation from a runaway electron distribution in tokamaks

The synchrotron radiation emitted by runaway electrons in a fusion plasma provides information regarding the particle momenta and pitch-angles of the runaway electron population through the strong dependence of the synchrotron spectrum on these parameters. Information about the runaway density and its spatial distribution, as well as the time evolution of the above quantities, can also be deduced. In this paper we present the synchrotron radiation spectra for typical avalanching runaway electron distributions. Spectra obtained for a distribution of electrons are compared to the emission of mono-energetic electrons with a prescribed pitch-angle. We also examine the effects of magnetic field curvature and analyse the sensitivity of the resulting spectrum to perturbations to the runaway distribution. The implications for the deduced runaway electron parameters are discussed. We compare our calculations to experimental data from DIII-D and estimate the maximum observed runaway energy.Comment: 22 pages, 12 figures; updated author affiliations, fixed typos, added a sentence at the end of section I

Quasi-linear analysis of the extraordinary electron wave destabilized by runaway electrons

Runaway electrons with strongly anisotropic distributions present in post-disruption tokamak plasmas can destabilize the extraordinary electron (EXEL) wave. The present work investigates the dynamics of the quasi-linear evolution of the EXEL instability for a range of different plasma parameters using a model runaway distribution function valid for highly relativistic runaway electron beams produced primarily by the avalanche process. Simulations show a rapid pitch-angle scattering of the runaway electrons in the high energy tail on the $100-1000\;\rm \mu s$ time scale. Due to the wave-particle interaction, a modification to the synchrotron radiation spectrum emitted by the runaway electron population is foreseen, exposing a possible experimental detection method for such an interaction