MICROWAVE INTERFEROMETRY - NONCONTACT TECHNIQUE FOR PLASMA DENSITY MEASUREMENTS 

Miwitron offers microwave interferometry systems for measurements of plasma electron density and plasma flow velocity in various experiments with the low temperature plasma in basic and applied research and in the plasma technology.

Microwave interferometry is based on investigation of propagation characteristics of microwave radiation passing plasma and proved to be reliable technique for plasma density measurement. 

The main feature of the microwave interferometry - noncontact character of the measurements - makes this diagnostics commonly used in such an application as high-temperature plasma in fusion experiments.

As to low temperature plasma which is employed for scientific and technological purposes, microwave interferometry is not generally accepted in this field. Traditional diagnostics for plasma density there is the Langmuir probe. It faces however significant difficulties in the reactive plasma due to very fast contamination of the probe surface, which makes measurements practically impossible. Probe application is also problematic in aerothermodynamics experiments with supersonic and hypersonic plasma flow in the wind tunnels due to strong thermal load on the probe. In these cases, microwave interferometer can be a good alternative to the Langmuir probe, taking into account also the fact that it has also some others advantages over the probe (see Application note). Nevertheless, microwave interferometry has received little use for these applications as well. One of the reasons is a poor offer of the systems on the market. Microwave assemblies for the microwave part of the interferometer, which are offered by some producers of microwave components, imply in fact special knowledge in the field and demand additional efforts from user for data acquisition.      

Microwave interferometers offered by Miwitron are cost effective and completely ready-to-use systems. They do not demand any special knowledge to put them into operation. Advanced construction of the systems with flexible coaxial cables instead of rigid waveguides makes the system very flexible and easy to set up on plasma devices of various designs and sizes.