Joanna Pawlat

Measurement of Low Gas Concentrations Using Photonic Bandgap Fiber Cell

In this paper, we present a novel low-loss splice for use between the photonic bandgap fiber (PBGF) and the conventional solid-core fiber to make PBGFs more functional. Furthermore, the hollow-core and the holes in the cladding of PBGF act as gas pipes. Using the proposed splice, a measurement system for low gas concentrations based on the PBGF cell has been developed and implemented. Experiments for measuring ammonia (NH3) gas at the ppm level were performed. The basic peak agreed well with the database of the Pacific Northwest National Laboratory (PNNL), meaning that this method can be used to accurately and effectively measure gas concentration. The constructed gas cells are compact and cost-effective for sensitive, rapid, and continuous measurement of gases.

Temperature Distribution in the Gliding Arc Discharge Chamber

Abstract Low temperature, non-equilibrium plasma was generated during gliding arc discharge in a multi-electrode reactor at atmospheric pressure. Various diagnostic methods to determine electrons and gas temperature were used. Hot electrons’ temperature has been determined by optical spectroscopy. In the case of gas temperature, which is much lower, it was determined directly by the thermovision camera to avoid tedious calculations from the spectral lines. The results of the plasma diagnostics generated by gliding arc for different process gases and their flow rates are presented and discussed. Simplified diagnostic method would be very perspective for monitoring of various technological processes where plasma is used such as treatment of flue gases, wastes utilization, deodorization, disinfection and sterilization, material processing and new material manufacturing for application in microelectronics and nanotechnologies.

Ozone Generation Using Plate Rotating Electrode Ozonizer- Effect Of Electrode Rotation And Discharge Analysis Method

Abstract An attempt to explain the phenomenon of the effect of electrode rotation on the ozone generation process is presented. A discharge photography method was applied and computer analysis method was used to find discharge differences between electrode rotational and non-rotational cases. The research presented shows that with electrode rotation the discharge was more uniform and the ozone generation efficiency increased about 15% compared to an ozonizer with a non-rotating electrode. In addition, during the research, the most suitable electrode rotational speed for the ozone generation process was estimated.

Power Systems of Plasma Reactors for Non-Thermal Plasma Generation

Abstract Recently, many different plasma sources are being investigated for exhaust gases treatment, odor abatement, VOC removal, soil conditioning, surface decontamination or tissue disinfection and sterilization. Among many different plasma reactors investigated in laboratories, gliding arc discharges (GAD), dielectric barrier discharges (DBD), pulsed discharges (PD), atmospheric pressure glow discharges (APGD) and atmospheric pressure plasma jets (APPJ) seem to be the most promising for high pressure low temperature applications. They can be designed as multi-electrodes’ high power system that can be used in environment protection processes, like decontamination of large surfaces and treatment of large volume of polluted gases, as well as small size and low power devices for biomedical applications, like plasma healing, disinfection and sterilization. Paper presents review of power supply systems for cold plasma reactors. Dielectric Barrier Discharge (DBD), Gliding Arc Discharge (GAD) and atmospheric pressure plasma jet (APPJ) reactors with their supply systems have been discussed from the point view of their characteristics, possibility to control power to the discharge and efficiency. Taking into account the plasma reactor characteristics and nature (nonlinear resistive and/or capacitive) different solutions of power suppliers have been presented: transformer type, AC/DC/AC inverter, RF-frequency system and frequency resonant inverter.

Fabrication of Photonic Bandgap Fiber Gas Cell Using Focused Ion Beam Cutting

In this paper, we present a novel low-loss splice for use between the photonic bandgap fiber (PBGF) and the conventional step index fiber to make PBGFs more functional. The gap between the butt-coupled fibers is the most important parameter for maintaining good output coupling efficiency and allowing gas diffusion. To achieve the small gap, a focused ion beam (FIB) milling technique was developed to clean the fiber surface. The gap is adjustable from 0 to 400 µm, and the typical connection loss at a gap of 20 µm is 1.6 dB. A measurement system for low gas concentrations based on the PBGF cell has been developed and implemented. Experiments for measuring ammonia gas at the ppm level were performed. The basic peak agreed well with the database of the Pacific Northwest National Laboratory (PNNL), meaning that this method can be used to accurately and effectively measure gas concentration.

Measurement of low gas concentration using photonic bandgap fiber

Abstract A high-sensitivity, compact set-up, enabling the precise measurement of a very low concentration of gas was designed. The micro-capillary gas flow phenomenon and the gas absorption inside fiber were estimated. Darcy - Weisbach equation for non-compressible flow and quasi - Panhandle equation for compressible gas flow were used for the calculation of the gas flow rate and gas velocity inside the photonic bandgap fiber. It was assumed that gas flowed mostly in the core. During the experimental part of work several types of optic fiber of various parameters were used. The core diameters ranged from 10.9 to 19.9 μm. It was possible to measure the flow rate of the nitrogen gas inside the fiber with various pressure differences on the opposite ends. Average velocity (Δp = 0.9 atm) ranged 0.17 m/s and was a little bit lower than expected.

Possibilities of Formaldehyde Removal by Discharge Plasma

Removal of formaldehyde by streamer corona discharge was studied experimentally. It was shown the removal efficiency as well as the by-products of the chemical process in the non-thermal plasma of the discharge depend on the initial concentration, gas flow rate, carrier gas, discharge polarity and discharge mode. A combined effect of plasma and catalytic pellets of various materials placed in the discharge reactor was investigated too.© 2003 ASME

Studies on electrical discharge effects in a foaming environment

A new apparatus called foaming column, which is potentially useful for polluted gas treatment, was constructed. Foam was created without addition of foaming agents, using only the kinetic energy of gas flow. During experiments, large quantities of gas and a small amount of pure water were required to generate foam between the main electrodes. Electrical discharge was obtained in the unique foaming environment. Various oxidants such as ozone, OH radicals and hydrogen peroxide were generated as an effect of electrical discharge. Several kinds of electrode materials and electrode set-ups were tested. Using the needle-to-plate electrode, which was made of stainless steel, higher concentrations were obtained for all oxidants.

Sterilization Techniques for Soil Remediation and Agriculture Based on Ozone and AOP

Abstract The sterilizing and remediation effects of the non-equilibrium atmospheric pressure plasmas are known for decades. Low temperature atmospheric pressure plasmas are considered as a promising alternative to conventional sterilizing methods, which have numerous drawbacks. Influence of various parameters such as discharge regimes, reactor geometries, gases, etc., on formation and effectiveness of plasma were investigated by many research groups. This paper presents the review of recently developed, environmentally safe technologies applied for the agriculture and soil remediation. The results of ozone soil sterilization and ozone influence on the DNA structure of Escherichia coli are described. The results of oxidants’ influence on humic acid are presented.

Generation of Oxidants with a Foaming System and its Electrical Properties

Abstract This works reports on electrical discharge performed in a foaming environment. This new method allows for an effective treatment of polluted gas by contacting the large streams of gas with small amount of liquid. The possibility of generation of oxidants in the foaming column was examined. Hydrogen peroxide (H2O2), hydroxyl radicals and the small amount of ozone were generated in the foam. It was possible to obtain 40 mgH2O2/dm3 at 14.5 kV of applied voltage and 5 dm3/min oxygen substrate gas flow. In case of air the maximum concentration was 35 mgH2O2/dm3 in the same applied voltage and gas flow conditions.