Abstract The effects of gas composition on gliding arc (glidarc) electrical discharge reactors with pure water have been studied. The glidarc reactors utilized AC electrical discharges with two different electrode configurations. In one case a set of two stainless steel electrodes connected to a single power supply was placed in the gas phase over the liquid surface (power=250–300 W, maximum voltage=12 kV). The second experimental arrangement utilized a reactor with a set of three stainless steel electrodes supplied by two identical high-voltage transformers, where the electrodes were placed over the water surface or with the water sprayed directly in the plasma formed between the electrodes (power=500–600 W, maximum voltage=12 kV). The variation of pH and conductivity and the formation of hydrogen peroxide, ozone, nitrate, and hydrogen were measured. The effects of the type of gas, including pure oxygen, pure nitrogen, and dry air, were determined.

Formation of Reactive Species in Gliding Ark Discharge with Liquid Watet

Recently pharmaceuticals are emerging as a major source of pollution for the environment. It has been well observed that the effluent discharge from hospitals has an eminent quantity of chemical waste as antibiotics, disinfectants and other treatments wastes. Pharmaceutical effluents are bioactive and their existence in the environment has been found harmful to both aquatic life and humans. In developing countries, untreated wastewaters are discharged to local water bodies by just following the local regulations. The current global challenges including high population growth rate and climate change have contributed to the widespread epidemics and emergence of diseases. Besides intractable and decaying antibiotic system, hospitals emit pathogenic waste during treatment process that can lead to situations where a total ban on hospital effluent are needed, for instance in multiple cases where discharge lead to strain on nature and quality of water. In case of pharmaceutical residues, it has been observed that only 18–32% of the pharmaceutical residues could be degraded by the secondary treatment of these seven technologies and it has been increased to 30–65% by tertiary treatment. As far as the pharmaceutical residues are concerned, it has been observed that MBR removes the residues with the efficiency of 28–100%, varying for each pharmaceutical. This paper reviews the existing treatment processes, their advantages and future perspective of this emerging area.

Recent trends in disposal and treatment technologies of emerging-pollutants- A critical review

The analysis of a solid-state Marx modulator (S2M2) topology, which have been developed for repetitive high-voltage (in kilovolts) applications, needing positive or negative rectangular pulses, is presented. The proposed topology benefits from the intensive use of semiconductors, allowing kilohertz operation with different load conditions. In addition to resistive loads, capacitive loads can be discharged to ground after each pulse and inductive loads can be clamped and the energy recovered to the main capacitors. Furthermore, the presented topology and proposed switching sequence enables the use of typical half-bridge semiconductor structures currently integrated in modular packages, which is advantageous for circuit assembling and triggering the semiconductors. Discussion on the advantages and limitation will be given. Finally, experimental results of some modulator features will be presented.

Repetitive High-Voltage Solid-State Marx Modulator Design for Various Load Conditions

A review on non-thermal plasma treatment of water contaminated with antibiotics.

Organic contaminants removal by the technique of pulsed high-voltage discharge in water.

Repetitive high voltage pulsed power system proposed in this study originates from conventional Marx generators. This newly developed Marx modulator employs high voltage (HV) insulated gate bipolar transistors (IGBT) as switches and series- connected diodes as isolated components. Self-supplied IGBT drivers and optic signals are used in the system to avoid insulation problem. Experimental results of 20 stages generating pulses with 60 kV, 20-100 mus and 50~500 Hz are presented to validate the performance of the system in the paper.

Repetitive and High Voltage Marx Generator Using Solid-state Devices

By utilizing power semiconductor switches, especially high-voltage insulated gate bipolar transistors (IGBTs), as main switches, Marx modulators have demonstrated many advantages such as variable pulse length and pulse-repetition frequency, snubberless operation, and inherent redundancy. However, the relatively slow turn-on speed of the IGBT influences the pulse rise time of the Marx modulator. In this paper, a newly developed all-solid-state pulsed-power generator is proposed. This generator consists of a Marx modulator based on discrete IGBTs and a magnetic pulse-sharpening circuit, which is employed to compress the rising edge of the Marx output pulse. The experimental results are presented with a maximum voltage of 20 kV, a rise time of 200 ns, a pulse duration of 500 ns (full-width at half-maximum), and a repetition rate of 5 kHz on a 285- resistive load. The output power of the generator is 2.5 kW, and the average power in one pulse is 1 MW. The design methods of the IGBT drive circuits and the parameter calculation of the magnetic pulse-sharpening circuit are introduced in detail in this paper. The factors influencing the performance of the generator are also discussed.

All-Solid-State Repetitive Pulsed-Power Generator Using IGBT and Magnetic Compression Switches

Microstructure and properties of aging Cu–Cr–Zr alloy

A newly developed bipolar high voltage adder is proposed for generating fast narrow pulses The new circuit topology enables the use of typical half-bridge semiconductor structures on the basis of conventional unipolar all-solid-state pulse adder Magnetic ring transformers were employed for isolating the charge loop from the high-voltage pulse discharge loop, which simplified the isolation arrangement Certain measures were implemented to resolve the EMI caused by the pulse adder arrangement A laboratory prototype was assembled with 8 stages and each stage was made of 800 V MOSFETs The modulator operating at 21 kHz repetition rate gives 2 kV bipolar pulses, with 200 ns positive/negative pulse widths, 37 ns rise time, 50 ns fall time, and 40 ns relaxation time into a 50 Ω resistive load The adopted design is an all-solid-state approach with a simple control method, long maintenance-free lifetime, and high reliability

All-solid-state pulse adder with bipolar high voltage fast narrow pulses output

In order to develop an efficient and reliable pulsed power supply for excimer dielectric barrier discharge (DBD) ultraviolet (UV) sources, a pulse generator using Marx topology is adopted. MOSFETs are used as switches. The 12-stage pulse generator operates with a voltage amplitude in the range of 0–5.5 kV. The repetition rate and pulsewidth can be adjusted from 0.1 to 50 kHz and 2 to 20 $\mu \text{s}$ , respectively. It is used to excite KrCl* excilamp, a typical DBD UV source. In order to evaluate the performance of the pulse generator, a sinusoidal voltage power supply dedicated for DBD lamp is also used to excite the KrCl* excilamp. It shows that the lamp excited by the pulse generator has better performance with regard to radiant power and system efficiency. The influence of voltage amplitude, repetition rate, pulsewidth, and rise and fall times on radiant power and system efficiency is investigated using the pulse generator. An inductor is inserted between the pulse generator and the KrCl* excilamp to reduce electromagnetic interference and enhance system reliability. The experimental results show that it also helps to improve radiant power and system efficiency.

Kefu Liu

Papers

Repetitive and High Voltage Marx Generator Using Solid-state Devices

All-Solid-State Repetitive Pulsed-Power Generator Using IGBT and Magnetic Compression Switches

Microstructure and properties of aging Cu–Cr–Zr alloy

All-solid-state pulse adder with bipolar high voltage fast narrow pulses output

Repetitive High-Voltage All-solid-state Marx Generator for Excimer DBD UV Sources