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Copyright of Journal of Food Safety & Quality is the property of Journal of Food Safety & Quality Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Aiming at the discharge problem of inductively coupled plasma (ICP), a closed wave-transmitting cavi-ty configuration is designed, the fluid mechanics model of ICP is established, and the multi physical simulation software COMSOL is used for three-dimensional simulation research. The variation laws of typical parameters such as electron density, electron temperature and plasma potential with time in the discharge process are analyzed. On this basis, the power of radio frequency power supply, the air pressure in the cavity and other conditions are changed to obtain the parameter range and spatial gradient distribution of ICP. The results show that the discharge power mainly affects the numerical range of plasma parameters, and the change of air pressure has an effect on the numerical value and spatial distribution of plasma parameters. When the power of radio frequency power supply increases from 100 W to 300 W, the peak electron density increases from 2.54×1017 m-3 to 5.68×1017 m-3, and the electric potential induced in the heating zone and the corresponding electron temperature decrease slightly after the reaction is stable. Increasing the air pressure in the cavity within a certain range will significantly increase the electron density. The air pressure increases from 10 Pa to 30 Pa, and the electron density increases from 9.12×1017 m-3 to 3.62×1018 m-3. However, the uniformity of plasma parameter distribution will deteriorate if the air pressure is too high.

BackgroundThe ion source is one of the key components of the neutral beam injection system. Radio frequency (RF) ion source has the advantages of long life time, easy maintenance and long pules operation, which make it the main alternative source for the neutral beam ion source in the future.PurposeThis study aims to analyze equivalent impedance characteristics of a high power RF ion source driver with emphasis on the impedance matching network and effective tuning of matching network to achieve high-power and stable plasma discharge.MethodsFirst of all, the analytical model was established on the basis of transformer model. The plasma conductivity was obtained by estimating the ohmic heating frequency and stochastic heating frequency in the plasma. Then, the equivalent impedance of the plasma was coupled to the excitation coils with the transformer model, and the equivalent impedance of the driver was obtained. Finally, parameters of the single drive RF ion source of negative ion based neutral beam injection (NNBI) system of Comprehensive Research Facility For Fusion Technology (CRAFT) were taken as example to calculate variation of equivalent impedance of actuator with plasma electron density by MATLAB code.Results & ConclusionsComputation results show that the analytical model proposed in this study can be used to quickly and accurately calculate the electron temperature in the driver under different gas pressures, and the equivalent impedance under different gas pressures and electron densities, which provides a reference for the reasonable design and tuning of impedance matching network.

Copyright of Bulletin of the Chinese Ceramic Society is the property of Bulletin of the Chinese Ceramic Society Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Chinese Journal of Liquid Crystal & Displays is the property of Chinese Journal of Liquid Crystal & Displays and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal of Food Safety & Quality is the property of Journal of Food Safety & Quality Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Chinese Journal of Inorganic Analytical Chemistry / Zhongguo Wuji Fenxi Huaxue is the property of Beijing Research Institute of Mining & Metallurgy Technology Group and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Computational Fluid Dynamics (CFD) method coupled electromagnetic field is used to analyze thermal characters of inductively coupled plasma （ICP） with and without sampler. The ICP is modeled in an axisymmetric geometry, taking into account the gas streaming into a flowing ambient gas. The flow in the calculation region is assumed to be laminar and the well-known Navier-Stokes equations are used to determine the flow conditions. The time-averaged Axial and Radial Lorentz Force density is taken as Axial and Radial Momentum source respectively. Since the energy loss by emitted radiation is much lower than the coupled electric power density, it is negligible in this numerical simulation. The advantage of choosing CFD commercial software Ansys Fluent is that user-defined scalar (UDS) method can be applied to solve Maxwell's equations. On the other hand, user-defined function is a convenient way to add Ar-ICP's physical characters, which can be described by mathematic functions, like viscosity and thermal conductivity. Under the hypothesis of Local Thermal Equilibrium (LTE), electron density and electron temperature can be calculated based on gas temperature. The temperature of Nickel sampler interface cooled by water was set as 1700 K which is below the melting point of pure Nickel. The flaw of this numerical simulation method was the distribution of electrical conductivity σ(T) which is related to gas temperature. Because several equations need to be solved in the process of iterations, there is no other way to do it if σ(T) is unpredictable. In this case, the crucial parameter will be missing. But it is contradictory that if σ(T) is predictable then gas temperature can be predictable too. Although many references set σ(T) as a constant number at the beginning of iterations, a simple mathematical function will help to do better but not perfectly. Besides, the process of how tested element diffuses in ICP is hardly estimated by this model. Gas temperature is a little higher with sampler orifice because it becomes a relatively closed space between ICP torch and sampler. But the nearest area of sampler position has cooler temperature and the effect of plasma central tunnel is stronger. Gas temperature of central tunnel rises fast to about 8 000 K from axial position around 25 mm and drops down quickly to about 6 000 K from axial position around 1 mm in front of sampler position. To study how aerosols with different diameters affect the gas temperature of central tunnel, Discrete Phase Model (DPM) was used. Aerosols with diameters of several microns have higher probability to be ionized. [ABSTRACT FROM AUTHOR]

Copyright of Chinese Journal of Liquid Crystal & Displays is the property of Chinese Journal of Liquid Crystal & Displays and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Hidden components, ilegal additives in the pesticide, are serious threat to the safety of agricultural products. At present, the detection methods for hidden ingredients in pesticides do not cover the inorganic metal. In the paper, inorganic elements such as Pb, As, Hg, Cd, Cr, Ba, Mn, Cu, Ag, Sn and Zn in pesticides were determined by microwave digestion coupled with ICP-AES method. The results showed that good linearity in the concentration range of 0.1 -5.0 mg/L for the elements with correlation coefficients of 0. 999 5. The limits of quantification of 11 elements were 0.2 - 1.5 mg/kg. Its spiked recoveries were 91.0% - 107%, and the relative standard deviations ranged from 0. 58% to 4.42%. The method could be successfully applied for the determination of the 11 elements in pesticides. [ABSTRACT FROM AUTHOR]