Sinusoidal Voltage Pulses Research Articles

Tuning plasma chemistry by various excitation mechanisms for the H2O2 production of atmospheric pressure plasma jets

Abstract Atmospheric pressure plasmas (APPJs) are widely used for research purposes or industrial applications. There are plenty of different APPJs designed with various geometries and excitation frequencies ranging from kHz over RF (MHz) to fast ns pulses. A direct comparison of these APPJs is often challenging as the different geometries or the different excitation frequencies are not the same and can strongly influence plasma behaviour. In this work, this challenge is met and overcome by the use of an APPJ which can be operated at various excitation frequencies. kHz pulsing with a high voltage peak with µs rise time, sinusoidal voltage pulse at 13.56 MHz and fast high voltage ns pulse were applied to the plasma jet used. The production of H 2 O 2 was investigated by treating liquids and measuring the H 2 O 2 concentration in the treated liquid. Fast ns pulses and RF excitation show similar results, while the kHz excitation is less effective in the H 2 O 2 production.

Spectroscopic diagnostics of a high-frequency dielectric barrier discharge of atmospheric pressure in mixtures of cadmium diiodide vapor with neon and small additions of xenon

Diagnostics of the emission spectra of a gas-discharge plasma of a barrier discharge of atmospheric pressure in mixtures of cadmium diiodide vapor with neon and small additions of xenon is carried out. A gas-discharge plasma was created and the components of the working mixture were excited by a high-frequency barrier discharge at a sinusoidal voltage pulse repetition rate of up to 140 kHz. Emission of exciplex molecules of cadmium monoiodide with a maximum emission at a wavelength of λ = 655 nm and xenon iodide with a maximum of radiation at wavelengths λ = 253 and λ = 320 nm, excimer molecules of iodine, lines of atoms of cadmium, iodine, neon and xenon was revealed. It was found that at temperatures of the mixtures under study above 150 0C, the predominance of radiation from exciplex molecules of cadmium monoiodide is observed. The reason for the increased brightness of the emission of exciplex molecules of cadmium monoiodide in mixtures of cadmium diiodide vapor with neon and xenon additive is established. The regularities in the spectral characteristics of radiation in the mixtures under study are discussed. A high-frequency barrier discharge of atmospheric pressure in mixtures of cadmium diiodide vapor with neon and xenon is of interest for creating a multi-wavelength excilamp in the UV and visible spectral ranges

Barrier Bucket Studies in the CERN PS

Part of the residual beam loss during the Multi-Turn Extraction (MTE) of fixed target beams from the CERN Proton Synchrotron (PS) can be attributed to kicker magnets switching while the beam is coasting with the main radio frequency (RF) systems off before extraction. Generating a barrier bucket to deplete the longitudinal line density of the coasting beam during the kicker rise time can reduce these losses. Beam tests have been performed with an existing Finemet® cavity in the PS, which is normally operated as a wide-band feedback kicker. To drive the cavity, a beam synchronous waveform synthesizer based on programmable logic has been developed. It produces a pre-distorted signal which ideally results in a single period sinusoidal voltage pulse with programmable parameters at the gap of the cavity, once or multiple times per revolution. The modelling of the behaviour of the power amplifier and the cavity is essential to achieve an anti-symmetric voltage pulse with little pre- and post-pulse ripple. The design of the beam-synchronous waveform generator is presented together with results from initial beam studies with the created barrier buckets in the PS.

Mathematical Model of the Frequency Converter Based on the Resonant Inverter with Pulse-Density Control

The article is dedicated to the development of the mathematical model of the resonant frequency converter with pulse-density control in the part of determining the functional of the carrier voltage pulses, which allows calculating the time sequence of the inverter’s control pulses. The authors have determined that the functional here is the dependence of the average value of the carrier voltage pulse of the resonant capacitor on its duration. Its duration, on its turn, depends on the instantaneous filter current value at the beginning of the control pulse for the half-bridge transistors. The analytic expressions for determining the exact and approximate average values of the quasi-sinusoidal voltage pulses at the resonant capacitor during the time interval between two serial control pulses are obtained. Due to the gotten expressions, the error in the application of the approximate model is estimated.Comparing the average value of the carrier resonant voltage pulse with the average value of the desired output voltage during the time interval between two serial control pulses, allowed to obtain the frequency converter pulse-density control law, which considered and compensated the inaccuracy of the approximate value of the chosen functional. To observe the functionality of the frequency converter, which operates according to the designed control law, its load characteristics were built and compared to the characteristics of the converter, which control law used the approximate model but did not consider its inaccuracy.In the case of the resonant current amplitude exceeding 1.2 times over the load current one, the maximum calculating error of the average value of the carrier voltage pulses is 0.01%. This makes possible to simplify the real time calculation of the control pulses sequence by using the approximate average value of the resonant voltage to ensure the hard pattern of the load characteristic in the case of load resistance varying within two orders. The comparison of the frequency converters load characteristics in the cases of various control laws shows the prolonged hard pattern of the load characteristic in the case of considering the inaccuracy of the chosen functional.The research results can be applied in the design of the highly efficient secondary power supplies with improved electromagnetic compatibility with the load and the network. Thus, the received functional of the carrier sinusoidal voltage pulses allows the real time calculation of the control pulses time sequence for the power transistors of the resonant inverter in accordance to the developed pulse-density control law.Ref. 10, fig. 5.

Control of magnetic vortex polarity by the phase difference between voltage signals

Using micromagnetic simulations, we investigate the voltage control of magnetic vortex polarity based on a designed multiferroic heterostructure that contains two separate piezoelectric films beneath a magnetostrictive nanodisk. The results show that controllable switching of vortex polarity can be achieved by proper modulation of the phase difference between two sinusoidal voltage pulses V1 and V2, which are applied to the two separate piezoelectric films, respectively. The frequencies of V1 and V2 are set at the gyrotropic eigenfrequency fG of the nanodisk, and the vortex polarity switching is completed via the nucleation-annihilation process of the vortex-antivortex pair. Our findings provide an additional effective means for ultralow power switching of the magnetic vortex, which lays the foundation for voltage-controlled vortex random access memory.

Experimental and theoretical characterization of a multi-wavelength DBD-driven exciplex lamp operated with mercury bromide/rare gas mixtures

Emission spectra from an atmospheric-pressure dielectric barrier discharge (DBD) with HgBr2/He or HgBr2/Xe/Kr mixtures, as well as the electrical characteristics, were investigated at repetition frequencies of sinusoidal voltage pulses up to 125 kHz. In the spectra, the study revealed radiation from HgBr(B–X, C–X) exciplex molecules, atomic lines of mercury and rare gases, and in mixtures with xenon, radiation of XeBr(B–X, B–A) exciplex molecules. Regularities in the spectral characteristics of the radiation from the gas-discharge plasma were discussed. The electron energy distribution function, the specific energy lost in the processes involving electrons, the electron temperature and density, and the rate constants of elastic and inelastic electron scattering by the components of the working mixture were calculated as functions of the reduced field E/N. The high-frequency atmospheric-pressure barrier discharge in mixtures of mercury dibromide with gases can be used in multi-wavelength exciplex lamps, operating in the UV and visible regions.

Characterization of a white-colour DBD-driven cadmium bromide exciplex lamp

The emission spectra from an atmospheric-pressure gas-discharge plasma in mixtures of cadmium dibromide vapour with gases (Ne, Ar, Kr, Xe and N2), as well as the temporal characteristics of voltage and current, have been investigated. A dielectric barrier discharge at a repetition frequency of sinusoidal voltage pulses up to 140 kHz was used to create the gas-discharge plasma. The discharge radiation has been analysed in the spectral range 200–900 nm with a resolution of 0.05 nm. In the spectra, the study has revealed radiation from CdBr(B–X, C–X) exciplex molecules, atomic lines of cadmium and rare gases, and in mixtures with xenon, radiation of XeBr(B–X, B–A) exciplex molecules. The most intense CdBr(B–X) radiation was observed in CdBr2/Xe mixtures. A discharge radiation of a silvery-white colour was observed when the temperature of the mixture was above 250 °C. The XeBr(B–X) radiation predominated in the spectra at temperatures of the mixture up to 200 °C. A further increase in the temperature resulted in the prevalence of the CdBr(B–X) radiation. Regularities in the spectral characteristics of the radiation from the gas-discharge plasma are discussed. The high-frequency atmospheric-pressure barrier discharge in mixtures of cadmium dibromide with gases can be used in multiwave exciplex lamps, operating in the UV and visible regions.

The effect of the shape of single, sub-ms voltage pulses on the rates of surfaceimmobilization and hybridization of DNA

Electric fields generated by single square and sinusoidal voltage pulses withamplitudes below 2 V were used to assist the covalent immobilization ofsingle-stranded, thiolated DNA probes, onto a chemically functionalizedSiO2 surface and to assist the specific hybridization of single-stranded DNA targets withimmobilized complementary probes. The single-stranded immobilized DNA probeswere either covalently immobilized (chemisorption) or electrostatically adsorbed(physisorption) to a chemically functionalized surface. Comparing the speed of electricfield assisted immobilization and hybridization with the corresponding controlreactions (without electric field), an increase of several orders of magnitude isobserved, with the reaction timescaled down from 1 to 2 h to a range between100 ns and 1 ms. The influence of the shape of the voltage pulse (square versussinusoidal) and its duration were studied for both immobilization and hybridizationreactions. The results show that pulsed electric fields are a useful tool to achievetemporal and spatial control of surface immobilization and hybridization reactions ofDNA.

Characteristics of a high-frequency barrier discharge in mixtures of mercury diiodide vapor with gases

The spectral and electric characteristics of atmospheric-pressure high-frequency barrier discharge plasma based on mixtures of mercury diiodide with neon and admixtures of argon, xenon, and nitrogen are analyzed. A repetition rate of sinusoidal voltage pulses of about 100 kHz is used both to produce the gas discharge plasma and to excite the components of the working mixture. The radiation of the discharge in the range 200–900 nm is analyzed with a high resolution. It is found that, in the range 400–900 nm, the system of bands of excimer molecules HgI(B → X) emits 85% of the barrier discharge radiation. It is established that the radiation intensity of HgI(B → X) molecules is maximal in the mixture HgI2/Xe/Ne = 0.6/10/90 kPa. In this mixture, UV radiation of molecules XeI(B → X) and XeI(B → A) is observed. The regular features of the spectral and electric characteristics of the gas discharge plasma are discussed. An atmospheric-pressure high-frequency barrier discharge in mixtures of mercury diiodide with gases is of interest for use in a selective (Δλ = 438–446 nm) excilamp with a cylindrical working aperture.

Spectroscopic Diagnostics of Barrier Discharge Plasmas in Mixtures of Zinc Diiodide with Inert Gases

The spectral characteristics of the emission of gas discharge atmospheric pressure plasmas in mixtures of zinc diiodide vapor with inert gases (He, Ne, Ar, Kr, and Xe) are investigated. The formation of a gas discharge plasma and the excitation of the components of a working mixture were performed in a high-frequency (with a repetition frequency of sinusoidal voltage pulses of 100 kHz) barrier discharge. The gas discharge emission was analyzed in the spectral range 200–900 nm with a resolution of 0.05 nm. Emission bands of ZnI(B-X) exciplex molecules and I2* excimer molecules, lines of inert gases, and emission bands of XeI* exciplex molecules (in Xe-containing mixtures) were revealed. It is ascertained that the strongest emission of ZnI* molecules is observed in ZnI2/He(Ne) mixtures. The regularities in the spectral characteristics of the gas discharge plasma emission are considered.

Pulse excitation method for measurement of high frequency magnetic properties of large cores (abstract)

It is very important to obtain saturated magnetic properties from reverse saturation (full B-H curve) of ferromagnetic cores to design magnetic switches which are used in high power pulse generators. The magnetic switch is excited in the high frequency range (∼MHz). But, it is extremely difficult to measure full B-H curve of large toroidal cores of which diameter is some hundreds of mm, using the conventional ac excitation method at high frequency. The main reason is poor output ability of power source for core excitation. Therefore we have developed pulse excitation method to get high frequency magnetic properties. The measurement circuit has two sections. One is excitation part composed by charge transfer circuit. The others is reset part for adjustment initial point on direct B-H curve. The sample core is excited by sinusoidal voltage pulse expressed as 1−cos(2π ft). Excitation frequency f is decided by the constants of the elements of the charge transfer circuit. The change of magnetic flux density ΔB and magnetic field H are calculated, respectively, by measuring the induced voltage of search coil and magnetizing current. ΔB-H characteristics from reverse saturation of four different kinds of large cores were measured in frequency range from 50 kHz to 1 MHz. Core loss increases in proportion to Nth powers of the frequency, where the index N depends on each of cores. N is about 0.5 in case of winding ribbon cores, such as Fe-based amorphous, Co-based amorphous, and Finemet, but N is about 0.2 in case of the Ni-Zn ferrite.