FAR-INFRARED AND MICROWAVE PLASMA DIAGNOSTICS

The theory of electromagnetic wave propagation in a cold plasma is onl y briefly treated. Optical approximations made for diagnostic applicat ions are mentioned. Refractive index measurements via FIR-interferomet ry are discussed and an electron density profile evaluation is illustr ated. The principle of microwave reflectometry is presented and exampl es from fixed frequency and pulsed radar reflectometry are shown. The theoretical background of electron cyclotron emission is given in a si mplified version and examples of electron temperature measurements on TEXTOR are presented. Scattering of mm-waves from high temperature pla smas is shortly sketched. An example of a rapidly growing density fluc tuation in a critical operational situation is illustrated by collecti ve wave scattering on a turbulent plasma. Magnetic field fluctuation s tudies carried out by cross-polarisation scattering of microwaves are reported.