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[en] Lower hybrid (LH) wave current drive efficiency on our HT-7 tokamak has been investigated based on the hot electrical conductivity theory. The interaction of the residual toroidal electric field with fast electrons has been included in the determination of current drive efficiency. The LH wave power scan was performed in the plasma parameter ranges of Ip=50-156 kA (anti ne)=0.5 x 1019-1.6 x 1019 m-3, PLH=50-350 kW. The current drive efficiency is derived to be about 0.1 x 1019-0.4 x 1019 Am-2W-1 on the HT-7 tokamak, which depends on the electron density and the LH wave phase velocity. At the electron density of about 1.5 x 1019 m-3, with the LH wave parallel refraction index peaked at 1.8, the highest current drive efficiency was obtained. A more generally normalized method is introduced to analyse the experimental data, which combines all the data in one curve. The normalized parameters are independent of the plasma parameters. (author)
[en] In the Ion Cyclotron Range of Frequency (ICRF) heating experiment, impedance matching is of great practical significance, because wide variations in antenna loading are observed within the discharge, in tokamaks operating in H-mode. A sudden decrease in antenna loading accompanying the L-mode to H-mode transition typically occurs on a timescale of a few milliseconds, as does the increase in loading at the H- to L-mode transition. Therefore, it is necessary to match dynamically in the transmission line between the generator output and the antenna input connections. A new type of stub tuner being developed utilizes the difference in radio-frequency wavelengths between gas and liquid due to different relative dielectric constants. The impedance matching can be adjusted in realtime in an attempt to track the variations in the antenna loading. Since there are no mechanically moving parts in the short ends of stub, the change can be more convenient and safe, moreover, it can withstand higher voltage without breakdown. This system device will be applied in the HT-7 superconductor Tokamak ICRF experiment
[en] Highlights: • SiO2@LaPO4:Eu3+ phosphors were synthesized by a wet-chemical method. • The pH value plays an important role in the formation of core shell-structured particles. • The SiO2@LaPO4:Eu3+ phosphors show strong orange–red luminescence. • This synthesis route can lower the cost of precious phosphors. - Abstract: SiO2@LaPO4:Eu3+ core–shell phosphors have been successfully synthesized by a one-step and economical wet-chemical route at low temperature. The as-obtained products were characterized by means of photoluminescence spectroscopy (PL), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), selected area electron diffraction (SAED), scanning electron microscopy (SEM), X-ray diffraction (XRD), energy-dispersive spectrometer (EDS) and X-ray photoelectron spectroscopy (XPS). The SEM, EDS and XPS analysis indicate that SiO2@LaPO4:Eu3+ core–shell phosphors can only be synthesized in a pH range of 8–11 and the possible mechanism has been proposed. The XRD results demonstrate that the structure of LaPO4:Eu3+ layers is transferred into monoclinic phase from hexagonal phase after annealing at 800 °C for 2 h. The SiO2@LaPO4:Eu3+ phosphors show strong orange–red luminescence under ultraviolet excitation. The relative emission intensity of Eu3+ increases with increasing the annealing temperature and the number of coating cycles, and the optimum concentration for Eu3+ was determined to be 5 mol% of La3+ in SiO2@LaPO4 phosphors.
[en] 1.5 MW Ion Cyclotron Wave Heating system was developed, the transmitter and the antenna both have their ground loops, which will severely perturb the system's normal operation. To avoid perturbation, a DC break was designed. The S parameter and the VSWR (voltage standing wave ratio) of incident port were calculated; the thermal effect caused by conductor loss and dielectric loss was analyzed. (authors)
[en] Taking into account the turn off time of the Q-switch, the coupled equations for a mid-infrared KTiOAsO4 optical parametric oscillator (OPO) are given. These rate equations are solved numerically and some key parameters for designing the laser system are determined. The key parameters include the optimal coupling and nonlinear crystal length which maximize the output power and OPO conversion efficiency. We found that a low-loss singly resonant OPO cavity not only enhances the mid-infrared output but also decreases the optimal OPO crystal length. (paper)
[en] There is an intimate connection between mitochondrial DNA (mtDNA) methylation and some diseases, such as cancer. MtDNA is almost strictly maternally inherited. However, whether the aberrant mtDNA methylation involved in breast cancer progression and whether mtDNA methylation can be transmitted through maternal line are poorly understood. Here we applied bisulfite sequencing to global mitochondrial DNA and whole genomic DNA methylation array from fifteen members of five three-female-generation families with one breast cancer patient in each family. We found that mtDNA methylation was maternally inherited in D-loop region and eight aberrant mtDNA methylation sites were correlated with breast cancer. Furthermore, conjoint analysis showed that mtDNA methylation sites could be potential biomarkers combined with nuclear DNA methylation sites for breast cancer risk prediction. - Highlights: • MtDNA methylation was modestly maternally inherited, especially in D-loop region. • Eight aberrant mtDNA methylation sites were correlated with breast cancer. • Nine nDNA methylation sites were identified as potential breast cancer-related sites. • MtDNA-nDNA methylation sites could be potential biomarkers for breast cancer. • A hypothetical model of mtDNA methylation maternal inheritance was proposed.