Plasma state supervision utilizing millimeter wave radar systems

Abstract

This work introduces a method for plasma state supervision, based on a frequency-modulated continuous wave radar sensor and a suitable signal evaluation enabling a continuous supervision method for the plasma state. Highly precise phase evaluation of the signal allows us to detect and visualize smallest changes in the plasma state. 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. Broadband measurements are carried out at center frequencies of 80 and 140 GHz in a low-pressure plasma. The radar-based setup can be used for a very flexible application, capable for spatially resolved measurements in the plasma bulk. At the same time, the high measurement rate allows for quasi real-time monitoring, so that transient processes in the plasma are recorded. Due to the simple setup, this approach is most suitable for industrial applications to improve process control. The chosen different frequencies will show a change in the influence of the plasma on the electromagnetic wave demonstrating the advantages of multi-frequency approaches in future applications.

Radar-Enabled Millimeter-Wave Sensing of Fire Interactions

“…With f min as the start frequency of the emitted frequency ramp and the time of flight (TOF), also known as the round trip time of the emitted signal, τ = 2R/c m , with c m as the speed of light in a specific medium, R as the distance of an object that can be determined. An exact description of the derivation and implementation of the signal processing can be found in [31] and [32]. The reason for higher accuracy of the phase evaluation is illustrated by the Cramer-Rao lower bound (CRLB).…”

“…Consequently it affects the propagation velocity and change the TOF of the signal. So the effect on the phase ϕ IF of the transceived signal can be evaluated [31]:…”

Optimizing Accumulator Performance in Hydraulic Systems through Support Vector Regression and Rotational Factors

“…Optical sensors provide high detection precision and are unaffected by the electrical characteristics of the medium; however, they cannot penetrate in dusty and smoky environments and their use is limited in liquid media detection. Radar sensors are highly accurate and can adapt to extreme conditions, featuring non-contact measurement, making them suitable for the detection environment of high-viscosity and corrosive liquids, and are the preferred choice in industries such as chemical smelting [5,6].…”