Target density effects on charge tansfer of laser-accelerated carbon ions in dense plasma

We report on charge state measurements of laser-accelerated carbon ions in the energy range of several MeV penetrating a dense partially ionized plasma. The plasma was generated by irradiation of a foam target with laser-induced hohlraum radiation in the soft X-ray regime. We used the tri-cellulose acetate (C$_{9}$H$_{16}$O$_{8}$) foam of 2 mg/cm$^{-3}$ density, and $1$-mm interaction length as target material. This kind of plasma is advantageous for high-precision measurements, due to good uniformity and long lifetime compared to the ion pulse length and the interaction duration. The plasma parameters were diagnosed to be T$_{e}$=17 eV and n$_{e}$=4 $\times$ 10$^{20}$ cm$^{-3}$. The average charge states passing through the plasma were observed to be higher than those predicted by the commonly-used semiempirical formula. Through solving the rate equations, we attribute the enhancement to the target density effects which will increase the ionization rates on one hand and reduce the electron capture rates on the other hand. In previsous measurement with partially ionized plasma from gas discharge and z-pinch to laser direct irradiation, no target density effects were ever demonstrated. For the first time, we were able to experimentally prove that target density effects start to play a significant role in plasma near the critical density of Nd-Glass laser radiation. The finding is important for heavy ion beam driven high energy density physics and fast ignitions.Comment: 7 pages, 4 figures, 35 conference

Design and achievement of superfilling electroless silver deposition for micrometer trenches.

Electroless silver bottom-up filling has been designed and investigated by linear sweep voltammetry. It was found that the addition of polyethylene glycol 4000 (PEG 4000) had a good inhibitory effect on the electrode reaction. Experiments showed that PEG 4000 had a strong depressing action in electroless silver deposition. Specifically, when the PEG 4000 concentration was 1.0 mg/L, the plating rate of electroless silver decreased from 5.7 to 2.3 μm/h. The bottom-up silver fillings for different-sized trenches were achieved in an electroless plating bath with the addition of PEG 4000. The trenches analysis showed that all microtrenches with different widths were completely filled by electroless silver plating

Frost Resistance of Desert Sand Concrete

Demand for medium sand has increased greatly with increasing infrastructure construction items. The shortage of construction sand resources has become a serious problem in many districts. It not only increases the engineering cost, and the overexploitation of river sand and mountain as medium sand also brings a series of serious environment problems. There are abundant desert sand (DS) resources in western China. If DS resources can be used to substitute medium sand to produce desert sand concrete (DSC), which was suitable for engineering practice, the environment can be improved and engineering cost can be reduced. Although many researchers had focused on the mechanical performance of DSC, there were few documents on the frost resistance of DSC. Frost resistance experiments of DSC with 50% desert sand replacement ratio (DSRR) and ordinary concrete (OC) were performed in this paper. Influence of freeze-thaw cycles on the mechanical properties of OC and DSC was analyzed. Experimental results showed that, with increasing freeze-thaw cycles, the damage, peak strain, and porosity increased, while elastic modulus, Poisson's ratio, and peak stress declined, the stress-strain curves tended to be flat. Under the same condition of freeze-thaw cycles, the frost resistance of DSC with 50% DSRR was higher than that of OC. Constitutive model of DSC after different freeze-thaw cycles was formulated. The results predicted by constitutive model agreed well with experimental results, which can provide technical support for DSC engineering practice

Characteristics of Unorganized Hydrogen Sulfide Dispersion for Industrial Building Layout Optimization

Hydrogen sulfide (H2S) is the main toxic pollutant emitted to the atmosphere from auto-coating wastewater. Its unorganized dispersion poses a health challenge for workers. Defining safe working distance, which transfers the H2S occupational exposure limit into industrial construction design regulation, would be a useful approach for reducing H2S exposure risk. Therefore, in this study, an H2S dispersion prediction, within 25 m, was performed by a computational fluid dynamics (CFD) method to explore the influence of temperature and wind speed on H2S dispersion. With the temperature changes from 288 K to 303 K, the H2S concentration at different observing points decreased. With wind speed changes from 2 m/s to 20 m/s, the plume layer structure was studied in the whole process. According to the H2S distribution characteristics, when the sedimentation tank treatment capacity is less than or equal to 10 m3/h, the safe working distance of H2S unorganized dispersion is 10 m. Hence, when there are workplaces within 10 m of the tank, closed measures should be taken for the sedimentation tank, or the manufacturer layout should be optimized to protect the environment and human health

Dust Dispersion Characteristics of Open Stockpiles and the Scale of Dust Suppression Shed

The storage of bulk materials in open yards can easily lead to contamination in the form of suspended particles. The creation of enclosed spaces for open yards is an effective measure to stop the dispersion of dust to the outside. In this study, a reliable numerical model was developed to calculate the impact range of dust dispersion using the concentration–velocity distribution of pollutants based on the DPM-CFD simulation, and validated by field measurement data. Then, the hazard distance was defined as the basis for determining the boundary of the closed shed. Finally, we determined the dimensions of the boundaries by a comprehensive analysis of the structure and materials of the closed shed. Our results demonstrated that the most unfavorable wind speed determines the maximum concentration of dust at a height of 1.5 m. As a result, hazard distance thresholds are obtained to be 63.5 m and then the shed boundary dimensions are calculated to be 127 m. Our studies can provide some theoretical basis for the construction of closed sheds in field yards

A new model for calculating the adsorption equilibrium constant of water vapor in micropores of activated carbon

A new model for calculating the adsorption equilibrium constant of water vapor in the micropores of activated carbon was established, the mechanism of which is based on the penetration of water clusters into micropores. Two kinds of carbon materials with significantly different pore and surface structures were prepared for water vapor adsorption, and the adsorption experiments were conducted in different conditions to test the accuracy of the new model. The new model was also applicable to water adsorption on bituminous-based activated carbon. Furthermore, being able to calculate the values for enthalpy of activation and entropy of activation, the new model can provide universal thermodynamic criteria for the water adsorption on activated carbon

Synthesis and Gas Sensing Properties of Single La-Doped SnO2 Nanobelts

Single crystal SnO2 nanobelts (SnO2 NBs) and La-SnO2 nanobelts (La-SnO2 NBs) were synthesized by thermal evaporation. Both a single SnO2 NB sensor and a single La-SnO2 NB sensor were developed and their sensing properties were investigated. It is found that the single La-SnO2 NB sensor had a high sensitivity of 8.76 to ethanediol at a concentration of 100 ppm at 230 °C, which is the highest sensitivity of a single SnO2 NB to ethanediol among three kinds of volatile organic (VOC) liquids studied, including ethanediol, ethanol, and acetone. The La-SnO2 NBs sensor also exhibits a high sensitivity, good selectivity and long-term stability with prompt response time to ethanediol. The mechanism behind the enhanced sensing performance of La-doped SnO2 nanobelts is discussed

Evaluation and optimization of heat extraction in enhanced geothermal system via failure area percentage

It is quite difficult to quantitatively measure heat extraction in a fractured enhanced geothermal system (EGS) reservoir and its impacting factors. This study thus aims to define a characteristic parameter that is failure area percentage for evaluating and optimizing geothermal extraction. Through establishing a thermal-fluid-solid coupling model, the operation lifecycle and economy of an EGS case was evaluated by the proposed parameter. A sensitivity indicator was developed to measure the quantitatively effection of various factors on heat extraction. The results show that heat extraction increases with the three growing-up factors: fracture network complexity, pressure difference, and rock permeability. However, too large value of these factors are adverse to geothermal system smooth operation. Based on the sensitivity indicator analysis, heat extraction is the most sensitive to the variation of fracture network complexity. This study would provide a guidance for optimization of EGS designing