Search

Silicone rubber (SR) is widely used in external insulation. However, the utilization of either high-temperature vulcanized (HTV) SR or liquid SR (LSR) remains controversial in China because of their differences in tracking and erosion resistance and aging resistance due to various amounts of nonreinforcing fillers. Here, the tracking and erosion behaviors of HTV and LSR during the inclined plane test (IPT) are captured and compared for a detailed comprehension of the difference between the two materials. The results revealed that LSR was easily carbonized and formed electrical tracks initially. Then, the carbonization slowed because of developing a protective ceramic layer. The relatively stable ceramic layer resulted in less frequent rapid erosion but increased the average arc burning time. An energy balance model of dry-band arcing (DBA) was established to evaluate DBA’s energy dissipation and absorption. Then, the emission spectra of DBA were collected to analyze the arc temperature and resistance more accurately. The energy input from the system is dissipated primarily through heating and evaporation of the liquid film, with radiant energy only accounting for a minuscule fraction. In different erosion states, the power absorbed by the surface of samples is different. LSR shows an average absorption power of 19.9 W in the initial carbonization state, which is higher than that of HTV (16.5 W). The average absorption power in the fast erosion state is the same for both samples at about 30 W. The absorption power at 20–25 W is considered the threshold range of relatively stable erosion. [ABSTRACT FROM AUTHOR]

Recent studies have shown that helicon waves may be an attractive option for driving an efficient off-axis current drive in order to supplement bootstrap current for steady state operation in fusion reactors. Based on the China fusion engineering test reactor parameters, the helicon wave trajectories, profiles of driven current and current driven efficiency are calculated with the ray-tracing code GENRAY. Both the peak position and the peak value of driven current profiles are dependent on the wave frequency. In the frequency range of 1.6 GHz–2.0 GHz, the peak value increases with the increase of frequency, and the peak position has a slight change (concentrate around ρ= 0.75). High electron temperature and low electron density seem to be favorable for the helicon wave absorption. A driving current of I/P > 70 kA MW−1 at the off-axis position of ρ < 0.7 can be obtained with the electron temperature at the plasma center, T e(0) < 25.4 keV and the electron density at the plasma center, n e(0) ∼ 0.7 × 7.8 × 1019m−3–0.8 × 7.8 × 1019m−3. The current drive efficiency decreases with the increase of the electron density. Peak positon of the driven current profile is insensitive to the parallel refractive index n ∥. It is found that the poloidal launch angle has some effect on the peak positon and its value. [ABSTRACT FROM AUTHOR]

The Chinese Fusion Engineering and Testing Reactor (CFETR) has been performed and is in its engineering design stage. Presently, there are two options allowed for the divertors; the helium-cooled stage and water-cooled stage. The water-cooled one has been focused in this article. The configuration of CFETR divertor module was designed. The cassette design scheme and cassette box inner and outer locking systems were introduced, and the locking system was designed to compliant with the remote-handling (RH) requirements. Two divertor RH design options were provided: one is removed through lower port; the other is targets and baffles removed through upper port; supports and cassette were not removed. The other major research was the water cooling channels’ design and its pressure drop calculation. In addition, the fluid, thermal, and mechanical analyses on the outer target were done. Within 10-MW/m2 heat flux, outer target design can ensure that the temperature for all the components works within their temperature limit, and all the components meet the stress design criteria except the copper alloy pipe. The maximum primary stress induced by pressure on the copper alloy pipe appears in the local position between the two monoblocks, which exceeds the design limit. Protection components are need to be added at the gap of the future design optimization to reduce the local stress. After the thermal-hydraulic analysis on water-cooled divertor cassette, the maximum temperature and the maximum stress of cassette meet the requirements. The results of electromagnetic force analysis shows that the deformation on first wall and transition support is less than 0.5 mm, and the maximum stress is also below its tensile strength values. This article summarized the latest achievements in the design and research of CFETR water-cooled diverter in China. All the results will be of great reference for the CFETR divertor optimal design. [ABSTRACT FROM AUTHOR]

Electron-ion recombination rate coefficients for fluorine-like nickel ions have been measured by employing the merged-beam technique at the cooler storage ring CSRm at the Institute of Modern Physics in Lanzhou, China. The measured spectrum covers the energy range of 0–160 eV, including all the dielectronic recombination (DR) resonances associated with ΔN = 0 core excitations. The DR cross sections in this energy range were calculated by a relativistic configuration interaction method using the flexible atomic code (FAC). Radiative recombination (RR) cross sections were obtained from a modified version of the semi-classical Bethe & Salpeter (1957, Quantum Mechanics of One- and Two-Electron 56 Systems (Springer)) formula for hydrogenic ions. The comparison between the measurement and the calculation shows that the present theoretical model still needs to be improved at low collision energies. Temperature dependent plasma recombination rate coefficients were derived from the measured DR rate coefficients in the temperature range of 103–108 K and compared with the presently calculated result as well as previous available data in the literature. The experimentally derived data agree well with the theoretical calculations for temperatures where Ni19+ ions form in collisionally ionized plasmas. At lower temperatures typical for photo-ionized plasmas, discrepancies are found beyond the experimental uncertainty, which can be attributed to the disagreement between the measurement and the calculation of the low-lying DR resonances. The present experimental result benchmarks the plasma DR rate coefficients, in particular for temperatures below 105 K where the ΔN = 0 DR resonances dominate. [ABSTRACT FROM AUTHOR]

According to the four spectra of a cloud-to-ground lightning discharge, channels have been captured by a slitless spectrograph in Qinghai and Tibet plateau, the electrical conductivities are calculated, and, for the first time, the electron thermal conductivities and the electron thermal diffusivities are calculated by applying the transport theory of air plasma to the lightning channels. The results are compared with existing values, and in general, they are in satisfactory agreement. These transport characteristic parameters have added important value for further research on the transport characteristic of the current and energy of the lightning discharge channel. [ABSTRACT FROM AUTHOR]

Sanghuangporous sanghuang is a rare medicinal fungus which contains polysaccharide as the main active substance and was used to treat gynecological diseases in ancient China. The intracellular polysaccharide yield of S. sanghuang was enhanced by the strain A130 which was screened from mutant strains via atmospheric and room temperature plasma (ARTP) mutagenesis. The objective of this research was to investigate the effects of ARTP mutagenesis on structural characteristics and biological activities of intracellular polysaccharides from S. sanghuang. Six intracellular polysaccharide components were obtained from S. sanghuang mycelia cultivated by the mutagenic strain (A130) and original strain (SH1), respectively. The results revealed that the yields of polysaccharide fractions A130-20, A130-50 and A130-70 isolated from the mutagenic strain fermentation mycelia were significantly higher than those of the original ones by 1.5-, 1.3- and 1.2-fold, and the clear physicochemical differences were found in polysaccharide fractions precipitated by 20% ethanol. A130-20 showed a relatively expanded branching chain with higher molecular weight and better in vitro macrophage activation activities and the IL-6, IL-1, and TNF-α production activities of macrophages were improved by stimulation of A130-20 from the mutagenic strain. This study demonstrates that ARTP is a novel and powerful tool to breed a high polysaccharide yield strain of S. sanghuang and may, therefore, contribute to the large-scale utilization of rare medicinal fungi. [ABSTRACT FROM AUTHOR]