Advanced Plasma Diagnostics

Phase Contrast Imaging on DIII-D

Cutaway diagram of DIII D (Diagram courtesy of General Atomics)

It is now widely believed that microturbulence in magnetically confined fusion plasmas results in excessive loss of particles and heat.

To better understand such turbulence, Professor Miklos Porkolab and graduate students have developed a new diagnostic using Carbon Dioxide lasers and a special imaging technique widely used in microscopy, phase contrast imaging (PCI). This diagnostic, which provides detailed measurements of the density fluctuations with extraordinary sensitivity and fine spatial and temporal resolution, is being used on the DIII-D tokamak in San Diego, in collaboration with General Atomics scientists, as well as on C-Mod. Recent upgrades will allow tests of some of the latest theoretical predictions regarding the origin of microturbulence, and related transport. This diagnostic is also used on C-Mod to measure RF wave propagation in the hot plasma core.