Recent Developments in Electron Cyclotron Emission Research on Magnetically Confined Plasmas
Author: Gary Taylor
Date of PPPL Report: December 2006
Submitted to: Fusion Science and Technology.
Electron cyclotron emission (ECE) has been an important diagnostic for measuring the temporal evolution of the electron temperature profile in magnetically confined plasma devices for more than 25 years. Recent advances in ECE measurements, such as 2-D ECE imaging and ECE intensity correlation techniques, have provided detailed information on sawtooth reconnection, neoclassical tearing mode behavior, electron heat transport, fast electron dynamics, and fast particle-driven Alfvén eigenmodes. ECE spectral analysis is benefiting from improved ECE modeling and significant increases in computational power that allow fast, real-time, temperature measurements. Mode-converted electron Bernstein wave emission (EBE) diagnostics are being developed to study overdense (ωpe >> ωce) plasmas, a regime where conventional ECE diagnostics cannot be applied and one commonly encountered in high β devices, such as the spherical torus and reversed-field pinch. While ECE diagnostic techniques are now well established on many existing magnetically confined plasmas, significant challenges lie ahead for applying ECE techniques to reactor-grade plasmas, such as ITER where Te(0) is expected to reach 20–40 keV. This paper reviews the recent advances in ECE, electron cyclotron absorption and EBE diagnostics and discusses the challenges for ECE measurements on ITER.