Development of Stand-Off Imaging Systems Using Low Cost Plasma Detectors That Work in the GHz to THz Range

Technologies used to detect mm-wave/Terahertz (THz) radiation range from those that are based on temperature changes, direct/indirect transitions or those that detect through the applied electric field. However, many commercially available detectors have limitations in terms of speed and responsivity and are quite expensive. For these reasons, commercially available indicator lamps which are called glow discharge detectors (GDDs) can be a good alternative since they are low cost and can detect microwave to mm-wave radiation with high sensitivity. These detectors have shown a good response in the mm wave region of the spectrum below ~100GHz, and here we show that their sensitivity even extends far into the THz region. To allow for such a broad frequency sensitivity we studied the detection mechanism behind the glow discharge, and find that it is as a non-local thermal equilibrium plasma whereby it can be simulated using a kinetic approach. The validity of such an approach is shown by obtaining plasma discharge parameters which agree well with experimental observations. The sensitivity of these lamps to frequencies which range from gigahertz to terahertz region allowed us to investigate the possibility of using these lamps in array configurations for low-cost active imaging purposes.