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Project: Understanding the Interaction of THz waves with Cold Plasmas: Applications using Glow Discharge Detectors

Acronym: GDD-THZ
Main Objective:
Glow Discharge Detectors (GDD) offer a low cost solution for the detection of THz and millimeter waves with high sensitivity and fast
response at room temperature. This work aims to contribute with a detailed study on the role of frequency dependent resonant effects in
the detection mechanism of GDDs and present an optimal design for detection. It has a laboratory component (TD-THz spectroscopy and
CW High Frequency THz measurements) supported by theoretical and numerical analysis of THz wave propagation in these devices.
A research field, started in the 70s, which consisted in using glow discharge lamps to detect THz and millimeter waves has become
relevant again in the international arena due to the high interest in developing THz technologies. By forming the discharge in a gas kept
at high pressure between two leads, the lamp generates light and a plasma is formed inside the device which drives it to be sensitive,
and consequently to detect, THz and/or millimeter waves. Our research not only support this, but using the METU-Ankara Turkey
home-built THz pulsed spectrometers we also see frequency resonant effects as the THz pulse passes through the plasma. We believe
that these are due to the structure of the plasma glow discharge region and the physical structure of the cathode and anode. Our goal is
to understand the role of these resonant effects in the detection mechanism of the glow discharge lamp. We intend to investigate this by
using the time-domain THz spectroscopy systems as well as CW high frequency THz measurements, available at the laboratories in
METU-Ankara, coupled with simulations of the THz wave propagation through the discharge structure which will be aided by the team in
IT-Lisbon Portugal. This work will focus on the development of a variable GDD structure where we can control the pressure and nature of
discharge gases, as well as electrical properties such as the applied bias on the anode and cathode. The aim of this is to find the best
combination of materials, spacing between electrodes and pressure inside the GDDs for optimal detection. By modeling the plasma
medium and discharge structure, simulations will be carried out based on proprietary software such as CST-Microwave Studio and
ANSYS-HFSS. The proven ability of this method to detect THz waves with high sensitivity at room temperature, and the observed
frequency dependent resonant effects, show that these devices can be used in a variety of civilian and defense applications. This
research will allow us to understand the effects of the interaction of the gas lamp with the THz field and of these observed resonances for
THz detection and aid us in developing these technologies.
Reference: TUBITAK/0002/2014
Funding: FCT
Start Date: 01-03-2017
End Date: 01-03-2020
Team: Marco Alexandre Ribeiro
Groups: Radio Systems – Lx
Local Coordinator: Marco Alexandre Ribeiro

Associated Publications