Glow Discharge Detector Research Articles

Fast and Enhanced MMW Imaging System Using a Simple Row Detector Circuit with GDDs as Sensor Elements and an FFT-Based Signal Acquisition System.

The relatively high atmospheric propagation of millimeter-waves (MMW) was found to be one of the most critical reasons for the development of reliable sensors for MMW detection. According to previous research works, it has been already shown that incident MMW radiation on a glow discharge detector (GDD) can increase the discharge current. Hence, the electrical mode of detection can be employed to detect the presence of MMW radiation. In this article, a new design of a row detector using GDDs as pixel elements, and the influence of MMW incidence on GDD's discharge current, were acquired using an elementary data acquisition (DAQ) platform. The DAQ system computes the averaged Fast Fourier Transform (FFT) spectrum of the time signal and returns the FFT results as magnitude based on the level of detection. An FFT-based signal acquisition proved to be a better alternative to the lock-in detection that was commonly used in MMW detection systems. This improved detection circuit provides enhanced noise filtering, thereby resulting in better MMW images within a short time. The overhead expense of the entire system is very low, as it can avoid lock-in amplifier stages that were previously used for signal enhancement. A scanning mechanism using a motorized translation stage (step motor) is involved to place and align the row detector in the image plane. The scanning can be carried out vertically to perform the imaging, by configuring the step motor after selecting the desired step size and position. A simplified version of the MMW detection circuit with a dedicated over-voltage protection facility is presented here. This made the detection system more stable and reliable during its operation. The MMW detection circuit demonstrated in this work was found to be a milestone to develop larger focal plane arrays (FPA) with very inexpensive sensor elements.

Response of a Glow Discharge Detector to Far Infrared Radiation

Today, the fact that THz and mm-waves can be used in many areas of our daily lives reveals the necessity for devices that can efficiently detect these waves. Due to the low energies with respect to ambient conditions, it has been a challenge to develop sensitive, fast detectors using conventional approaches. The plasma medium offers a unique way to detect this radiation. Many conflicting theories have been offered historically on the details of the detection mechanism of the experimentally observed interaction between plasma and THz/mm-wave by using classical analytical approaches. Nevertheless, inexpensive neon glow lamps realized as glow discharge detectors (GDDs) continue to be a region of great interest for the mm-wave and THz community. Here, the nature of the plasma in the glow discharge lamp is investigated for the first time using the particle in cell/Monte Carlo collision (PIC/MCC) method based on a kinetic approach. After obtaining the distribution of the entire glow discharge, its interaction with THz/mm-waves is simulated and compared with experiments. Excellent agreement for the observed changes in current and spatial distribution of the negative glow is further aided by the observed increase in responsivity with increasing modulation frequency, which, to the best of our knowledge, has not been explained before. In this context, the effect of radiation frequency and modulation frequency on this interaction is examined separately, and the situations required for the efficient use of neon indicator lamps as detectors are discussed.

Performance Enhancement of Inexpensive Glow Discharge Detector Operating in Up-Conversion Mode in Millimeter Wave Detection for Focal Plane Arrays

Performance enhancement of a very inexpensive millimeter-wave (MMW)/terahertz (THz) sensor for MMW/THz imaging systems is experimentally demonstrated in this study. The MMW sensor is composed of a glow discharge detector (GDD) and a light-to-frequency (LTF) converter combination. The experimental results given in this study show an improvement in the performance parameters of the detector element, such as the minimum detectable signal, as well as the signal to noise ratio (SNR) and the noise equivalent power (NEP), when a NIR long-pass filter was inserted between the GDD and the LTF combination. A detailed derivation of the NEP of this unique sensor is presented in this work. Based on this derivation and the experimental measurements, the NEP value was calculated.

Terahertz Radiation Detection Using Glow Discharge Detectors by Electrical and Optical Modes

Based on the phenomenon that the incident terahertz (THz) radiation can increase the discharge current and luminescent intensity of a glow discharge detector (GDD), the electrical and optical modes were used to detect the THz wave. The influence of GDD’s discharge current, orientation, size, phosphor coating, and polarization sensitivity were investigated in detail. The results show that the electron density, the receiving efficiency to THz wave and effectively collecting the output signals of GDD are important to improve the responsivity of GDD.

Comparison between Up-Conversion Detection in Glow-Discharge Detectors and the Schottky Diode for MMW/THz High-Power Single Pulse

Generally, glow-discharge detectors (GDD), acting on miniature neon indicator lamps, and Schottky diode detectors serve as efficient, fast, and room-temperature millimeter wave (MMW)/THz detectors. Previous studies on GDD implemented a repetition of terahertz sources, and low-power radiation, and showed good results in terms of detection, responsivity, and noise-equivalent power. This paper presents a comparison between a detector based on a GDD lamp and a Schottky diode detector for the detection of a high-power single pulse. With this comparison, we touch upon two GDD detection methods, the visual light emitting from the GDD and the electrical current of the GDD detector. Results showed better response time and better sensitivity for the GDD detection method compared to with the Schottky diode.

Inexpensive Millimeter-Wave Communication Channel Using Glow Discharge Detector and Satellite Dish Antenna

A full proof of concept for low-cost millimeter wave (MMW) communication link is demonstrated in this study. The suggested MMW channel is based on a very inexpensive commercially available off-axis dish antenna usually used for TV satellites, two Arduino Uno micro controller boards, and glow discharge detectors (GDD). The GDD is a robust and inexpensive room-temperature plasma device which was found to be a sensitive MMW radiation detector. The Arduino micro controllers are used to encode a text message into serial bits and also decode it. Those serial bits were used to modulate the MMW radiation in On-Off keying. The detection of MMW radiation was performed using a simple and inexpensive GDD. The suggested MMW channel can be used as point to point backhaul wireless communication for the 5th generation of cellular communication.

QPSK detection using glow discharge detector and a photodiode for millimeter‐wave and terahertz communication

AbstractThe terahertz gap (0.1‐10 THz) is an attractive frequency band for new applications. In wireless communication, it can serve as a high capacity link. The lack in use of that gap exists due to a lack of available commercial communications technology systems in that region. We have found that neon indicator lamps or glow discharge detectors (GDD) can be used as simple and very inexpensive detectors in that frequency gap. In modern modulation techniques, the signal phase should be recovered. This article is a proof of concept of detection of quadratic amplitude modulated millimeter‐wave signals by a GDD and photodiode using a heterodyne detection method.

Ultra-wideband and inexpensive glow discharge detector for millimeter-wave wireless communication based on upconversion to visual light.

Data traffic is increasing rapidly, especially on wireless channels, pushing the carrier frequency to the X, K, and millimeter-wave (MMW) bands. This requires development of new technologies and communication components operating at those bands. The detectors and receivers for those bands are very expensive, have high sensitivity to electrostatic discharge, and can be damaged by high incident power. An ultra-wideband and inexpensive glow discharge detector (GDD) is presented here. The GDD was found to be an excellent microwave and MMW radiation detector. The detection mechanism presented here is based on upconversion of microwave and MMW radiation to visual light. The experimental results demonstrate ultra-wideband detection at X and at MMW bands. These results present a proof of concept for the ability of our system to be used as a detector in wireless communication for the 5th generation.

Robust, Sensitive, and Inexpensive 2D Focal Plane Array Upconverting MMW Imaging Into the Visible

A new concept of millimeter-wave (MMW) imaging system is demonstrated in this letter. The new concept is based on glow discharge detector (GDD) focal plane array (FPA) and a basic CMOS camera. The GDD elements emit optical light as a function of the incident MMW radiation intensity. By synchronizing the modulation of the MMW source with the exposure time of the CMOS camera in a way that every two consecutive frames were captured with the influence of the MMW radiation and without it, we were able to observe the effect of the MMW radiation alone on the GDD FPA without the light deriving from the GDD DC bias.

Digital Signal Detection by a Glow Discharge Detector

A glow discharge detector (GDD) is a plasma neon bulb originally designed for lighting. However, it was demonstrated that it can be used for the detection of electromagnetic radiation in a wide range of frequencies up to millimeter and submillimeter waves. It is shown here that the device can be used not only as a detector but also as a heterodyning mixer. Experimental measurements confirm an analytical derivation, demonstrating that quadrature modulated signals can be downconverted to an intermediate frequency (IF) without distortions, even if the amplitude and phase are modulated simultaneously, as in quadrature amplitude modulation (QAM) waveforms. Digital QAM waves at the microwave frequencies were directly illuminated onto the GDD and mixed with radiation produced by a local oscillator. The resulted GDD current was analyzed to verify that the product maintains its QAM constellation also at the IF. The GDD detects both the magnitude as well as the phase in a manner that allows the complete demodulation of the digital data using several modulation methods. The experimental setup, as well as the results, is presented. It is concluded that the GDD can be employed also as a direct mixer in a digital receiver chain. The notation “GDM” is proposed for it which stands for “glow discharge mixer.”

High-Power Millimeter Wave Direct Detection by Glow Discharge Detector

Glow discharge detector (GDD) composed of a commercial miniature neon tube is utilized for direct detection of high-power millimeter waves. The detector was exposed directly to 95-GHz high power emitted from a gyrotron and the detector readings were recorded as a function of the incident power. The response of the GDD was examined for ~35-dB range. A linear regime was observed followed by a saturation regime. The detection was done without an amplifying stage as done for low power detection. The detector handling of high power without damage was experimentally demonstrated, even when exposed directly to high power. A dependence of the detector rise time on the measured power was observed. This detector can be used in a diagnostic setup of high power devices such as gyrotrons and free electron lasers. Since the cost of such detector is approximately three orders of magnitude less than a commercial W-band crystal detector, an array of detectors can be made for spatial analysis of a high power device output.

Detection and upconversion of three-dimensional MMW/THz images to the visible

We present an inexpensive technique to obtain a three-dimensional (3D) millimeter wave (MMW) and terahertz (THz) image using upconversion. In this work we describe and demonstrate a method for upconversion of MMW/THz radiation to the visual band using a very inexpensive miniature glow discharge detector (GDD) and a silicon photodetector. We present MMW/THz upconversion images based on measuring the visual light emitting from the GDD rather than its electrical current. The results show better response time and better sensitivity compared to the electronic detection performed previously. Furthermore, in this work we perform frequency modulation continuous wave (FMCW) radar detection based on this method using a GDD lamp, with a photodetector to measure GDD light emission. By using FMCW detection, the range in addition to the intensity at each pixel can be obtained, thus yielding the 3D image. The GDD acts as a heterodyne mixer not only electronically but also optically. The suggested 3D upconversion technique using the GDD is simple and inexpensive and has better performance compared to other MMW/THz imaging systems suggested in the literature. This method provides minimum detectable signal power that is about 6 orders of magnitude better than similar plasma systems due to the very large internal signal gain deriving from the much smaller electrode separation and resulting in much higher plasma electric field.

Detection of far-infrared radiation using glow discharge detectors

The plasma medium, created inside the neon indicator lamp, enables the detection of a wide wavelength range of differential or modulated EM signals. The interaction between the plasma and various frequency EM waves are still being investigated and in the mm-wave/terahertz range the interaction mechanism is still not well understood. In this study commercially available neon indicator lamps are studied using both time-domain and continuous wave mm-wave/THz measurement systems. The glow discharge detector response is similar to other commercially available room temperature direct detection mm-wave/THz detectors and performs at a fraction of their cost. Using a W-band Schottky diode multiplied source the detection behavior of the detector was investigated using lock-in detection techniques at modulation frequencies up to 90 kHz. These measurements also show that the orientation of the electrode structure was sensitive to the polarization of the incident field. The polarization sensitive behavior indicates a strong coupling between the incident and native field in the plasma. Furthermore, the interaction of the lamp structure with the mm-wave/THz field was investigated between 260 and 380 GHz using both a home-made time-domain THz spectroscopy system as well as a commercially available mm-wave/THz source. Within the constraints on the maximum modulation frequency of the source (<100 Hz–1 kHz), certain mm-wave/THz frequencies are attenuated suggesting the electrode structure of the detector can play a role in the detection. Overall, the measurements show that certain types of indicator lamps perform better than others and future studies in detection and imaging can benefit from their use.

Terahertz Frequency Modulated Continuous Wave Radar using Glow Discharge Detector

A well-known method for range applications is chirped frequency modulated continuous wave (FMCW) radar. We offer a simple way to measure the distance to the object target with high resolution based on very inexpensive glow discharge detectors (GDDs) at terahertz (THz) band frequencies. Proof of concept of THz FMCW radar using a GDD is experimentally demonstrated in this paper. The advantage of FMCW in the THz band is its better range resolution compared with FMCW radar in the microwave band due to wider frequency swing. Such a system using a GDD has the following advantages: very inexpensive and simple to realize, rigid components, room temperature operation, fast response time, and high power radiation immunity. Those properties are very important in the realization of high resolution 3-D imaging in the THz band. Depth resolution on the order of 7.5 mm can be achieved by the proposed system.

Switching and Fast Operation of Glow Discharge Detector for Millimeter Wave Focal Plane Array Imaging Systems

Applications of millimeter waves (MMWs), especially MMW imaging, are required in medicine, homeland security, communication, and space technology. The lack of a fast and inexpensive room temperature detector makes it difficult to realize those applications. Recently we found that the commercially available miniature neon lamps, known as glow discharge detectors (GDD), can be used as room temperature, sensitive, and inexpensive MMW detectors. Furthermore, they have shown a fast response time of about one microsecond. The disadvantages of using the GDD are high power consumption and for relatively large bias current, aging of the electrode coating due to electrode bombardment by heavy ions inside the plasma. Those disadvantages can be overcome by electronically switching on the detector bias current during detection period only, leaving the detector OFF most of the time. In this paper, the influence of the detector aging on the responsivity is investigated experimentally, and an electronic circuit for fast ON/OFF switching operation is demonstrated.

Low-Cost Millimeter Wave Imaging Using a Commercial Plasma Display

The use of glow discharge detectors to detect millimeter wave radiation is well documented and work is starting of the development of focal plane arrays to produce 2D images. This paper demonstrates the feasibility of using a low-cost commercial plasma display as an imager in the millimeter wave band. It shows that though the performance is not as good as that for individual glow discharge detectors, it is sufficiently good for short range imaging. This paper goes on to propose extending the modality to provide 3D images in near real time using each element of the array as a mixer in a frequency modulated continuous wave radar.

Capability of long distance 100 GHz FMCW using a single GDD lamp sensor.

Millimeter wave (MMW)-based imaging systems are required for applications in medicine, homeland security, concealed weapon detection, and space technology. The lack of inexpensive room temperature imaging sensors makes it difficult to provide a suitable MMW system for many of the above applications. A 3D MMW imaging system based on chirp radar was studied previously using a scanning imaging system of a single detector. The radar system requires that the millimeter wave detector will be able to operate as a heterodyne detector. Since the source of radiation is a frequency modulated continuous wave (FMCW), the detected signal as a result of heterodyne detection gives the object's depth information according to value of difference frequency, in addition to the reflectance of the 2D image. New experiments show the capability of long distance FMCW detection by using a large scale Cassegrain projection system, described first (to our knowledge) in this paper. The system presents the capability to employ a long distance of at least 20m with a low-cost plasma-based glow discharge detector (GDD) focal plane array (FPA). Each point on the object corresponds to a point in the image and includes the distance information. This will enable relatively inexpensive 3D MMW imaging.

Fourier imaging and distance approximation using time of flight method for terahertz wave imaging

An active terahertz wave imaging method is investigated for improved system simplicity, inexpensive implementation, and distance approximation. The proposed technique is composed of a single-pixel setup that allows acquiring the two-dimensional (2-D) Fourier transform intensity map of the imaged object and additional depth data using time of flight method. A raster scan is performed to achieve the object’s 2-D Fourier transform intensity and depth information. Iterative phase retrieval methods are employed to accomplish good image reconstruction using only the measured object’s Fourier transform magnitude. The proposed method uses a glow discharge detector (GDD) as its single millimeter wave pixel and offers a simple noncalibrating scheme for 2-D imaging and distance approximation. This work shows experimental results of using the GDD as a distance approximation detector and specifies the advantages, disadvantages, and constraints when using such a sensor. Basic aperture imaging (transmission imaging) experimental results are also shown, and complex aperture imaging simulations and their corresponding reconstructions are presented. Finally, both 2-D imaging and acquired depth data are fused into a single three-dimensional reconstructed image to reveal the potential of the proposed method.

Characterization of a Glow Discharge Detector With Terahertz Time Domain Spectroscopy

Recently, there has been much interest in the capability of low cost glow discharge detectors (GDDs) for detection of terahertz radiation. To utilize them in applications such as terahertz imaging these studies have typically focused on the response of the GDD at specific frequencies. To better understand the spectral behavior of glow discharges, we examine the interaction mechanism of GDDs with terahertz radiation using terahertz time domain spectroscopy in a broader range of frequencies between 0.05 and 0.5 THz. Our results show that in addition to terahertz-induced oscillations in the plasma charge density, the structure of the GDD itself plays an important role in the detection mechanism. We observe that by increasing the bias voltage on the gap, not only can we greatly reduce the transmission at a specific frequency, but we can also tune it as well, suggesting that these devices can be used as hybrid plasma filters.

Oversampling advances in millimeter-wave scan imaging using inexpensive neon indicator lamp detectors

In recent years, much effort has been invested to develop room temperature inexpensive, but sensitive, millimeter wave (MMW) and terahertz (THz) detectors that can be used as pixels in focal plane arrays, which is important for real-time imaging. A new 18×2 neon indicator lamp MMW/THz scanner was developed. The components of the camera include horizontally shifted two-column glow discharge detectors in a scanning array. The detectors, costing about 50 cents each, are wired to a preprocessing card, a VLSI board, and a motor for scanner movement. A description of the VLSI Verilog programmable hardware of the new scanner, the physical architecture, the software user interface, and imaging results at 97 GHz are presented. At this stage, the emphasis is focused on the lamp exposure time and spatial resolution when the scanning is performed horizontally. In the future it is planned to expose all pixels simultaneously for real-time imaging. New software capabilities allow the application of digital image enhancement algorithms. Fast scanning permits obtaining images in 1 to 5 s. Oversampling yields a sharper edge response and a higher signal-to-noise ratio.