Plasma Sensing Using Terahertz Waves

Abstract

The terahertz (THz) region of the electromagnetic spectrum, the far-infrared, has numerous applications towards characterizing low-energy phenomena in a number of wide and diverse materials. One of these exciting new areas is in plasma diagnostics. There are many experimental and theoretical methods to determine plasma parameters in a dc glow discharge. Pulsed terahertz (THz) techniques such as THz-Time Domain Spectroscopy (THz-TDS) can offer a non-contact solution towards characterizing various plasma properties. Further studies in the area of millimeter and microwave radiation have shown that the interaction of the THz radiation with fundamental plasma such as DC glow discharge plasma can be utilized towards development of inexpensive detection schemes and detectors. Here we discuss the importance of these schemes in lieu of imaging systems and describe experiments we have conducted which support these results. In particular we find that a typical Drude model approach is insufficient in describing the transmission of the THz waves through the “cold” plasma. Results are given in the area of this promising research.