Diagnostic of capacitively coupled radio frequency plasma from electrical discharge characteristics：comparison with optical emission spectroscopy and fluid model simulation

The capacitively coupled radio frequency（CCRF）plasma has been widely used in various fields.In some cases,it requires us to estimate the range of key plasma parameters simpler and quicker in order to understand the behavior in plasma.In this paper,a glass vacuum chamber and a pair of plate electrodes were designed and fabricated,using 13.56 MHz radio frequency（RF）discharge technology to ionize the working gas of Ar.This discharge was mathematically described with equivalent circuit model.The discharge voltage and current of the plasma were measured atdifferent pressures and different powers.Based on the capacitively coupled homogeneous discharge model,the equivalent circuit and the analytical formula were established.The plasma density and temperature were calculated by using the equivalent impedance principle and energy balance equation.The experimental results show that when RF discharge power is 50–300 W and pressure is 25–250 Pa,the average electron temperature is about 1.7–2.1 e V and the average electron density is about 0.5？×10^17–3.6？×10^17m^-3.Agreement was found when the results were compared to those given by optical emission spectroscopy and COMSOL simulation.

Carbon emission reduction analysis of CHP system driven by biogas based on emission factors

The cogeneration system of heat,power,and biogas(CHPB)driven by renewable energy provides an effective solution for carbon emission reduction in rural China.Starting from fully meeting the energy demand of 17 new rural residential households in Lanzhou,considering the annual dynamic local climate change,energy consump-tion characteristics,and environment parameters,a model of environmental benefit index for the CHPB system is constructed.The concept of emission factor is used to quantitatively analyze the environmental benefits of the system.The equivalent CO_(2)emission factor is defined to connect emissions with energy output,evaluating the environment-friendly potential of energy supply system.Compared with the conventional systems of indepen-dent power and thermal generation,the year-round characteristics of CO_(2)emission and emission structure chart of the proposed system are analyzed.The results show that the total CO_(2)emission and the average equivalent CO_(2)emission factors of the conventional and CHPB system are 85.45t,1.53 kg/kWh,and 308.46t,0.22 kg/kWh,respectively.The maximum CO_(2)emission reduction ratio of the CHPB system is 113.47%.Anaerobic digestion technology is employed to consume biomass feedstock,which reduced CH_(4)emission(equivalent to 86.36t of CO_(2)emission reduction).Five typical cities were selected to study the regional adaptability of the system and analyze environmental benefits.The results indicate that the CHPB system has the best environmental performance in Guangzhou,where the average CO_(2)emission reduction rate is 103.52%.

A new method for retrieving equivalent cloud base height and equivalent emissivity by using the ground-based Atmospheric Emitted Radiance Interferometer (AERI)

In the paper, we propose a new method of identifying the clear sky based on the Atmospheric Emitted Radiance Interferometer （AERI）. Using the Atmospheric Radiation Measurement （ARM） Mobile Facility （AFM） dataset in Shouxian in 2008, we sim- ulate the downwelling radiances on the surface in the 8-12 μm window region using Line-By-Line Radiative Transfer Model （LBLRTM）, and compare the results with the AERI radiances, The differences larger （smaller） than 3 mW （cm2 sr cm-1）-1 suggest a cloudy （clear） sky. Meanwhile, we develop the new algorithms for retrieving the zenith equivalent cloud base height （CBHe） and the equivalent emissivity （ee）, respectively. The retrieval methods are described as follows. （1） An infinitely thin and isothermal blackbody cloud is simulated by the LBLRTM. The cloud base height （H） is adjusted iteratively to satisfy the situation that the contribution of the blackbody to the downwelling radiance is equal to that of realistic cloud. The final H is considered as CBHe. The retrieval results indicate that the differences between the CBHe and observational cloud base height （CBH） are much smaller for thick low cloud, and increase with the increasing CBH. （2） An infinitely thin and isothermal gray body cloud is simulated by the LBLRTM, with the CBH specified as the observed value. The cloud base emissivity （co） is ad- justed iteratively until the contribution of the gray body to the downwelling radiance is the same as that of realistic cloud. The corresponding εc is εe. The average εe for the low, middle, and high cloud is 0.967, 0.781, and 0.616 for the 50 cases, respec- tively. It decreases with the increasing CBH. The retrieval results will be useful for studying the role of cloud in the radiation budget in the window region and cloud parameterizations in the climate model.