Publications

Plasma State Supervision Utilizing 140 GHz Radar Measurements

Schenkel, F. and Schulz, C. and Baer, C. and Rolfes, I.

2021 18TH EUROPEAN RADAR CONFERENCE, EURAD 2021
Volume: Pages: 25-28
DOI: 10.23919/EuRAD50154.2022.9784522
Published: 2021

Abstract
In this contribution a novel approach of plasma diagnostic is introduced. Measurements based on high precise phase evaluations of a FMCW radar sensor are able to detect small changes of the process state in low-pressure plasmas. Assuming the plasma to act like a frequency dependent dielectric material, the propagation of the electromagnetic wave depends on the plasma state and hence, also the measured phase. Measurements are carried out at a frequency of 140 GHz, so that theoretically a change of 1 degree of the detected phase corresponds to a change in relative permittivity of 4e-14 for a propagation length of 1 m. It is shown, that transient processes in plasmas can be measured in quasi-real-time and that the measurement system offers the possibility to be suitable for industrial purposes like process control. © 2022 European Microwave Association (EuMA).

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