Fusion plasma diagnostics with mm-waves - basic principles and recent developments

Microwave techniques play an important role in modern fusion plasma diagnostics. Both passive radiometry as well as active probing techniques are in use. Basically the confining magnetic field and the electron density of the plasma determine its dielectric properties and resonances. The probing wavelength in interferometry are in the infrared range without changing the basic principles of the microwave diagnostic techniques. The determination of the electron density and the electron temperature and their fluctuations both in the plasma core and the edge and gradient regions.