HF Plasma Research Articles

Optimization and preparation for the start-up of the plasma ICR heating system at the KTM tokamak

The paper presents and discusses the results of the research on the preparation of the HF plasma heating system of the KTM tokamak for the start-up. The calculations have been performed to determine the parameters at which the most effective absorption of the HF radiation by the plasma of the KTM tokamak was expected, the results of measurements of the frequency response of the antenna-feeder device of the HF heating system generator of the KTM tokamak plasma have been presented. The result of the carried out work have shown that more efficient plasma heating on a KTM tokamak can be obtained at a frequency of 14 MHz.

Optimizing the Design of an HF Plasma Discharge Powder Processing System for Enhanced Tail Flame Stabilization: A Mathematical Modeling Approach

Optimizing the Design of an HF Plasma Discharge Powder Processing System for Enhanced Tail Flame Stabilization: A Mathematical Modeling Approach

Technology for cleaning glass substrates in glow discharge plasma for microfluidics applications

The production of microfluidic chips is increasing every year because the technology using the chip allows you to make an express test to obtain the analysis, as well as economically viable. Often microfluidic chips are based on glass in which the microchannels are formed. Accurate production of a microfluidic device requires careful preparation of the glass substrate to improve adhesion for further application of functional layers. The choice of cleaning mode strongly affects the output product, so a clear understanding of what factors affect the quality of cleaning in HF plasma is needed. Mathematical modeling of dependence between plasma power of the glow discharge, time and gas medium first of all gives understanding which cleaning mode is optimal and which parameter affects stronger very relevant for development of this potentially promising technology of quality products.

QGC606: A Best-in-Class Orally Active Centrally Acting Aminopeptidase A Inhibitor Prodrug for Treating Heart Failure Following Myocardial Infarction.

Blockade of brain renin-angiotensin system (RAS) overactivity by firibastat, the first centrally acting aminopeptidase A (APA) inhibitor prodrug, has already demonstrated its effectiveness in improving cardiac function after myocardial infarction (MI). We developed QGC606, a more potent and more selective APA inhibitor prodrug and studied its effects after long-term oral administration in mice post-MI. Two days after MI induced by the left anterior descending artery ligation, adult male mice were randomized into 4 groups to receive oral treatment during 4 weeks with vehicle; QGC606; firibastat; or the angiotensin-I converting enzyme inhibitor ramipril, used as positive control. Four weeks post-MI, brain APA was overactivated in vehicle-treated MI mice. QGC606 treatment normalized brain APA hyperactivity to control values measured in sham-operated mice. Four weeks post-MI, QGC606-treated mice had higher left ventricular (LV) ejection fractions, significantly smaller LV end-systolic diameter and volume, significantly lower HF biomarkers mRNA expression (Myh7 and Anf) and plasma N-terminal pro B-type natriuretic peptide (NT-pro-BNP) and noradrenaline levels than saline-treated mice. QGC606 treatment significantly improved the dP/dt max and min, LV end-diastolic pressure without affecting blood pressure (BP), whereas we observed a decrease in BP in ramipril-treated mice. We observed also a reduction of cardiac fibrosis, highlighted by lower connective tissue growth factor mRNA levels and a reduction of both the fibrotic area and MI size in QGC606-treated mice. Chronic oral QGC606 administration in post-MI mice showed beneficial effects in improving cardiac function and reducing cardiac remodeling and fibrosis but, unlike ramipril, without lowering BP.

Modeling the wavelength of unresolved transition arrays in the extreme ultraviolet region from Sn to Hf ions by combining theoretical and experimental spectral data

This paper proposes a method to determine the wavelength of unresolved transition arrays (UTAs) in the extreme ultraviolet (EUV) wavelength region from Sn to Hf plasma by combining calculated and experimental data. Based on a computational analysis of the atomic structure, we show that the wavelength of UTAs can be explained using the screening theory by a simple quadratic formula using the effective core charge and the screening constant for 4d electrons as parameters. The results from the model were compared with experiments to reproduce the trend of the spectrum, which has a minimum wavelength with respect to the ion charge. The wavelength is shown to agree with experiment over Pd- to Sr-like ions by applying a small shift that was determined using the spectrum observed in the electron beam ion trap. The present model would allow us to calculate the opacity of Sn plasmas with much smaller computational time than using present large-scale collisional radiative models, with fewer energy levels and parameterized rate coefficients, which will be also useful to investigate the efficiency of the EUV light source.

Plasmolysis of methane using a high-frequency plasma torch

The possibility of converting methane into hydrogen using a high-frequency induction plasma torch at the atmospheric pressure has been experimentally studied. The dependencies of the degree of methane conversion and the rate of hydrogen production were studied depending on the process conditions. It has been demonstrated that the degree of the methane-to-hydrogen conversion can reach values close to 100%. Keywords: methane plasmolysis, HF plasma torch, hydrogen.

Infrared spectrometric (FTIR) studies of fur semi-finished product modified by HF plasma in the medium of active plasma-forming gases

Infrared spectrometric (FTIR) studies of fur semi-finished product modified by HF plasma in the medium of active plasma-forming gases

Total Blood Exosomes in Breast Cancer: Potential Role in Crucial Steps of Tumorigenesis.

Exosomes are crucial players in cell-to-cell communication and are involved in tumorigenesis. There are two fractions of blood circulating exosomes: free and cell-surface-associated. Here, we compared the effect of total blood exosomes (contain plasma exosomes and blood cell-surface-associated exosomes) and plasma exosomes from breast cancer patients (BCPs, n = 43) and healthy females (HFs, n = 35) on crucial steps of tumor progression. Exosomes were isolated by ultrafiltration, followed by ultracentrifugation, and characterized by cryo-electron microscopy (cryo-EM), nanoparticle tracking analysis, and flow cytometry. Cryo-EM revealed a wider spectrum of exosome morphology with lipid bilayers and vesicular internal structures in the HF total blood in comparison with plasma. No differences in the morphology of both exosomes fractions were detected in BCP blood. The plasma exosomes and total blood exosomes of BCPs had different expression levels of tumor-associated miR-92a and miR-25-3p, induced angiogenesis and epithelial-to-mesenchymal transition (EMT), and increased the number of migrating pseudo-normal breast cells and the total migration path length of cancer cells. The multidirectional effects of HF total blood exosomes on tumor dissemination were revealed; they suppress the angiogenesis and total migration path length of MCF10A, but stimulate EMT and increase the number of migrating MCF10A and the total path length of SKBR3 cells. In addition, HF plasma exosomes enhance the metastasis-promoting properties of SKBR3 cells and stimulate angiogenesis. Both cell-free and blood cell-surface-associated exosomes are involved in the crucial stages of carcinogenesis: the initiation of EMT and the stimulation of proliferation, cell migration, and angiogenesis. Thus, for the estimation of the diagnostic/prognostic significance of circulating exosomes in the blood of cancer patients more correctly, the total blood exosomes, which consist of plasma exosomes and blood cell-surface-associated exosomes should be used.

Equipments for Treatment in High Frequency Plasma Discharge

This article presents five alternative plasma equipments patented by the author, designed for specific applications like activation, cleaning, decontamination, or monomer polymerization on surfaces. Two equipments perform HF cold plasma treatment of highly adherent powdery materials (pigments, plastics, drugs, and so on), that are used to modify the physical-chemical characteristics of surfaces. Another HF plasma equipment is employed for the treatment of nonwoven stratified materials used as filters for gaseous media. A specially designed afterglow plasma equipment is used for decontamination and cleaning of highly fragile flat or 3-D cultural heritage items. An equipment for producing HF torch plasma is also described.

Physical processes in capillary- porous material and coating in HF plasma at decreased pressure

When implementing the high-energy ions into an open pore and their movement from the material surface deep into a capillary-porous object, the ions are capable to tear both the strong covalent bindings and the numerous weak intermolecular bindings in the structure of capillary-porous material. In this connection, a combination of processes on suppression of kinetic energy, recombination of ions, release of the new charged particles occurs, which results in modification of internal pores’ surface in the capillary-porous material.

Thermal atomic layer etching of crystalline GaN using sequential exposures of XeF2 and BCl3

Gallium nitride (GaN) is a wide-bandgap semiconductor that is useful for optoelectronics and high speed and high power electronics. Fabrication of GaN devices requires etching for many processing steps. Gas phase thermal atomic-layer-controlled etching is desirable for damage-free isotropic etching. In this letter, the thermal atomic layer etching (ALE) of crystalline GaN was demonstrated using sequential exposures of XeF2 and BCl3. GaN ALE was achieved with an etch rate of 0.55 Å/cycle at 195 °C using XeF2 exposures for 20 s at 40 mTorr and BCl3 exposures for 0.5 s at 50 mTorr. At the same reactant exposures, GaN etch rates varied with temperature from 0.18 Å/cycle at 170 °C to 0.72 Å/cycle at 300 °C. The GaN etch rates increased slowly with increasing XeF2 exposure. In addition, the GaN etch rate was self-limiting with respect to both increasing BCl3 pressures and BCl3 exposure times. This self-limiting behavior for BCl3 is consistent with a ligand-exchange mechanism for GaN ALE. Alternative fluorination reactants were also investigated including HF, SF4, and NF3 plasma. Sequential exposures of NF3 plasma and BCl3 yielded GaN etch rates of 2.5–2.9 Å/cycle at 250 °C. In contrast, the HF and SF4 fluorination reactants could not etch crystalline GaN.

Design and Construction of an Atmospheric Pressure HF Plasma Source

Atmospheric pressure plasma sources used in many industrial, environmental, light sources, biological, and medical applications. Aiming these prospects, an effort has been remunerated for the design and construction of a cost-effective atmospheric pressure high frequency (30 KHz) plasma source. The major sections include in this source are, (i) DC power suppliers, (ii) A set of Class A push-pull power amplifiers, (iii) Ferrite core high-frequency power transformer, (iv) Impedance matching network, and (v) Electrode design for plasma production. Two power suppliers have been considered; one is a 12V DC for biasing the base of the 2N3055 power, and the other is a 90V DC for biasing the Class A push-pull power amplifier. Class A push-pull power amplifier is chosen because of its high efficiency of about 50% concerning other types of amplifiers. Ferrite core high-frequency power transformer is designed with a turn ratio of 1:3 in order to step up the voltage to a certain level for producing atmospheric pressure plasma. An impedance matching network is designed to transfer maximum power from the source to the plasma load.

Effective surface treatment for GaN metal–insulator–semiconductor high-electron-mobility transistors using HF plus N2 plasma prior to SiN passivation

An effective surface cleaning technique is demonstrated for the GaN metal–insulator–semiconductor high-electron-mobility transistor (MIS-HEMT) passivation process. In this study, dilute HF solution and in situ N2 plasma treatments were adopted to remove the native oxide and recover the nitrogen-vacancy defects at the GaN surface before device passivation. To investigate the correlation between the properties of the SiN/GaN interface and the device performance, the GaN MIS-HEMTs were characterized using current–voltage (I–V) measurement, capacitance–voltage (C–V) measurement, and X-ray photoelectron spectroscopy (XPS) analysis. With the application of this surface treatment technique, the device exhibits improved I–V characteristics with low leakage current, low dynamic ON-resistance, and good C–V response with a steep slope. Overall, the results reveal that the oxide-related bonds and nitrogen-vacancy defects at the SiN/GaN interface are the root cause of the GaN MIS-HEMTs performance degradation.

17pCP-10 高周波プラズマ中に浮遊した多数微粒子のスピン運動、円運動、ペアダンス運動

17pCP-10 高周波プラズマ中に浮遊した多数微粒子のスピン運動、円運動、ペアダンス運動

Effects of Untreated and Thermally Treated Lupin Protein on Plasma and Liver Lipids of Rats Fed a Hypercholesterolemic High Fat or High Carbohydrate Diet

Lupin protein is capable of reducing plasma lipids in hypercholesterolemic man and animals. Whether lipid-lowering properties of lupin protein will be influenced by thermal treatment or by other nutrients has not been elucidated. In a two-factorial study, rats were fed hypercholesterolemic diets based on high amounts of carbohydrates (HC) or fat (HF), which contained either (20.4% of energy) untreated or thermally treated lupin protein (steam: 120 °C, 30 min) or casein as control protein. Lupin protein lowered plasma lipid concentrations in rats fed the HF diet but not in those fed the HC diet (P<0.05). Among rats fed the HF diet, plasma and VLDL triglyceride concentrations were lower in rats fed thermally treated (-46% and -44%, P<0.05) and untreated lupin protein (-47% and -46%, P<0.05) than in those fed casein; whereas liver triglycerides were reduced only in rats fed untreated lupin protein (P<0.05). Compared to casein, untreated lupin protein had slightly stronger cholesterol-lowering effects in plasma, LDL and HDL (-34%, -37%, -35%; P<0.05) than thermally treated lupin protein (-23%, -29%, -31%, P<0.10). In conclusion, the lipid-lowering effect of lupin protein strongly depends on composition of the basal diet, and thermal treatment is accompanied by a slight reduction of its hypocholesterolemic properties.

Investigation of VLF and HF waves showing seismo-ionospheric anomalies induced by the 29 September 2009 Samoa earthquake (&amp;lt;i&amp;gt;M&amp;lt;/i&amp;gt;&amp;lt;sub&amp;gt;w&amp;lt;/sub&amp;gt;=8.1)

Abstract. In Samoa Islands, a powerful earthquake took place at 17:48:10.99 UTC (06:48:10.99 LT) on 29 September 2009 with a magnitude Mw=8.1. Using ICE (Instrument Champ Electrique) and IMSC (Instrument Magnetic Search Coil) experiments onboard the DEMETER (Detection of Electromagnetic Emissions Transmitted from Earthquake Regions) satellite we have surveyed possible variations in electromagnetic signals transmitted by the ground-based VLF transmitter NPM in Hawaii and in HF plasma waves close to the Samoa earthquake during the seismic activity. The indices Dst and Kp were used to distinguish pre-earthquake anomalies from the other anomalies related to the geomagnetic activities. In a previous study we have shown that anomalies in IAP (plasma analyzer) and ISL (Langmuir probe) experiments onboard the DEMETER and also TEC (Total Electron Content) data appear 1 to 5 days before the Samoa earthquake. In this paper we show that the anomalies in the VLF transmitter signal and in the HF range appear with the same time scale. The lack of significant geomagnetic activities indicates that these anomalous behaviors could be regarded as seismo-ionospheric precursors. It is also shown that comparative analysis is more effective in seismo-ionospheric studies.

The Irritation Potential of Nonthermal Atmospheric Pressure Plasma in the HET‐CAM

AbstractTo determine a reliable test and validate the use of nonthermal atmospheric pressure plasma on wounds, we selected the Hen's Egg Test–chorioallantoic membrane (HET‐CAM) as an alternative method to the Draize rabbit test to determine the irritation potential of plasma. Irritations of varying intensities provoked by using a dielectric barrier discharge (DBD) and an HF Plasma Jet corresponded to treatment frequencies and exposure times. Pulsed plasma led to the mildest irritations. Depending on the intensity of the irritations, the effects were partially or completely reversible. In the latter case, it may be assumed that this plasma mode can be applied to living tissue without harm. To conclude, the HET‐CAM is suitable for screening plasma sources and parameters for the medical applications of plasma.magnified image

Kinetic Theory of Plasma Waves – Part I: Introduction

The kinetic description of linear waves in plasmas is succinctly presented, with emphasis on applications to highfrequency (hf) wave heating and current drive. The Maxwell-Vlasov system of equations is introduced. Its twotimescale analysis yields the linearized Vlasov and the quasilinear Fokker-Planck equations. The standard guiding centre and Hamiltonian formalisms are presented. Two formulations of the hf plasma wave equation are given: as a partial differential equation to hold at each position, and as a global Galerkin (‘variational’) form.

Spectroscopic measurements of high frequency plasma in supercritical carbon dioxide

Spectroscopic measurements of high frequency (hf) plasma were performed under high pressure conditions (5 and 7 MPa) and supercritical (sc) CO2 conditions (8–20 MPa). Temperature evaluated from C2 Swan bands (d 3Πg→a 3Πu) increased from 3600 to 4600 K with an increase in pressure. The first observation of broadening and shifting of the O I line profile (3p5 P3,2,1→3s5 S20) of hf plasma under sc CO2 conditions was carried out. However, the origin of broadening and the shifting cannot be understood because the present theory explaining them is not valid for such high pressure conditions.

Optical, radar, and magnetic observations of magnetosheath plasma capture during a positive IMF &amp;lt;I&amp;gt;B&amp;lt;sub&amp;gt;z&amp;lt;/sub&amp;gt;&amp;lt;/I&amp;gt; impulse

Abstract. We present a multi-instrument study of the ionospheric response to a northward turning of the IMF. The observations were made in the near-noon (11:00 MLT) sector on Svalbard (at 75° MLAT). The data set includes auroral observations, ionospheric flows obtained from the EISCAT and CUTLASS radars, the spectral width of the HF radar backscatter, particle precipitation and plasma flow data from the DMSP F13 satellite, and Pc1 frequency band pulsations observed by induction magnetometers. Careful collocation of all the observations has been made with the HF radar backscatter located by a ray-tracing procedure utilizing the elevation angle of arrival of the signals and an ionospheric plasma density profile. Prior to IMF turning northward, three auroral arcs were observed at the poleward boundary of the closed llbl, inside the llbl, and in the equatorward part of the llbl, respectively. The northward IMF turning was accompanied by enhanced HF radar returns with a broad Doppler spectrum collocated with the arcs. The auroral arcs shifted poleward whereas the backscatter region moved in the opposite direction, which is consistent, respectively, with reconnection beyond the cusp and the capturing of magnetosheath plasma during northward IMF. Locally, magnetic noise enhancement in the Pc1 frequency band occurred simultaneously with the anomalous radar backscatter, and the absence of such signals at more remote magnetic observatories indicates a local generation of the Pc1 turbulence, which is collocated with the radar backscatter. Finally, we discuss possible interpretation errors which may be caused by limited observational data.