Multidimensional Visualization of MHD and Turbulence in Fusion Plasmas

Abstract

Quasi-optical imaging at sub-THz frequencies has a major impact on fusion plasma diagnostics. Millimeter-wave imaging reflectometry utilizes microwaves to actively probe fusion plasmas, inferring the local properties of electron density fluctuations. Electron cyclotron emission imaging is a multichannel radiometer that passively measures the spontaneous emission of microwaves from the plasma to infer local properties of electron temperature fluctuations. These imaging diagnostics work together to diagnose the characteristics of turbulence and magnetohydrodynamic activity. Important quantities, such as amplitude and wavenumber of coherent fluctuations, correlation lengths and decorrelation times of turbulence, and poloidal flow velocity of the plasma, are readily inferred.

Microwave Imaging Reflectometry for the study of Edge Harmonic Oscillations on DIII-D

“…The Microwave Imaging Reflectometer (MIR) [8,9] on DIII-D is an X-mode imaging reflectometer, with tunable frequency range from 56 to 74 GHz and 20 cm poloidal coverage. MIR is well suited for measuring density fluctuations in the steep gradient pedestal region of H mode and has been used to compare the poloidal wavenumber spectra of both the coherent and so-called broadband EHO types [10] .…”

Millimeter-wave imaging of magnetic fusion plasmas: technology innovations advancing physics understanding

“…ECE radiometry and ECEI. Microwave imaging reflectometry (MIR) is a radar technique employed to infer electron density, n e , and electron density fluctuations by probing the density dependent plasma cutoff layer with an injected microwave beam [7][8][9][10][11]. The injected beam, or probing microwave source, is reflected back to a receiving antenna and mixed with a reference signal.…”