Development and preliminary test of a space-resolved vacuum-ultraviolet spectroscopy in EAST.

The impurity radiation from the divertor region of the EAST tokamak is dominantly in the wavelength range of vacuum ultraviolet (VUV) due to the elevated edge electron temperature. A space-resolved VUV spectroscopy is developed to measure impurity radiation in the divertor region. An eagle-type VUV spectrometer with a focal length of 1 m is adopted in this system, equipped with a spherical grating and a charged-coupled device (CCD) detector. The performance of the VUV spectrometer is preliminarily tested on a synchrotron radiation facility. The wavelength calibration is conducted near 65 nm. It is found that the wavelength range observed by the CCD detector is about 11.07 nm around the central wavelength of about 65 nm. With a linear dispersion of 0.0053 nm/pixel, it is possible to measure the ion temperature lower than 20 eV at the edge region by analyzing the Doppler broadening of a carbon line. These test results show that the performance of the VUV spectrometer is capable of measuring divertor radiation and analyzing the ion temperature of edge impurity ions.

A compact electron beam ion trap in support of high-temperature plasma diagnostics based on conduction-cooled superconducting coils.

Spectroscopic diagnostics of future fusion reactor plasmas require information on impurity line emissions, especially for relevant high-Z metal elements (e.g., tungsten). These materials will be widely used as plasma facing components for their high heat tolerance and low sputtering yield. Based on an electron beam ion trap, a compact impurity spectra platform is developed to mimic the high-temperature environment of a fusion reactor. The proposed platform can deliver a focused e-beam at energies over 30 keV using a confining magnetic field of ∼1.0 T generated by two superconducting coils (NbTi). Cooled by a closed-loop cryocooler, the coils can avoid the usage of a complicated cryogenic system involving the handling of liquid helium. For spectroscopic studies of highly charged ions, a spherically curved crystal spectrometer is proposed to measure a wavelength range around 2-4 Å covering the typical wavelength range expected to be emitted by metal ions in a fusion plasma. This paper reports the design and development progress of the platform.

Upgrade of X-ray crystal spectrometer for high temperature measurement using neon-like xenon lines on EAST.

A two-crystal X-ray spectrometer system has been implemented in the EAST tokamak to simultaneously diagnose high- and low-temperature plasmas using He- and H-like argon spectra. But for future fusion devices like ITER and Chinese Fusion Engineering Test Reactor (CFETR), argon ions become fully stripped in the core and the intensity of the H-like lines will be significantly at high temperatures (Te > 5 keV). With increasing auxiliary heating power on EAST, the core plasma temperature could also reach 5 keV and higher. In such conditions, the use of a xenon puff becomes an appropriate choice for both ion-temperature and flow-velocity measurements. A new two-crystal system using a quartz 110 crystal (2d = 4.913 Å) to view He-like argon lines and a quartz 011 crystal (2d = 6.686 Å) to view Ne-like xenon spectra has been deployed on a poloidal X-ray crystal spectrometer. While the He-like argon spectra will be used to measure the plasma temperature in the edge plasma region, the Ne-like xenon spectra will be used for measurement in the hot core. The new crystal arrangement allows a wide temperature measurement ranging from 0.5 to 10 keV or even higher, being the first tests for burning plasmas like ITER and CFETR. The preliminary result of lab-tests, Ne-like xenon lines measurement will be presented.

Scalable synthesis of cubic Cu(1.4)S nanoparticles with long-term stability by laser ablation of salt powder.

Cubic Cu(1.4)S nanoparticles were synthesized on a large scale by laser ablation of salt powder dispersed in an organic solvent. A metastable Cu(1.4)S phase was formed at high temperature in a reductive solvent and was maintained at room temperature due to the quenching effect of the pulsed laser. The cubic Cu(1.4)S nanoparticles show good stability after being exposed to ambient atmosphere for as long as 1 month.

Laser-activated gold catalysts for liquid-phase growth of cadmium selenide nanowires.

A laser-activated-catalyst (LAC) technique was developed to grow CdSe nanowires in liquid medium at room temperature. The gold catalysts dispersed in the precursor solution were activated by a pulsed laser so as to decompose the precursor and catalyse the nanowire growth simultaneously. The LAC technique can achieve accurate positioning of nanowires, which is beneficial for device fabrication.

The icephobic performance of alkyl-grafted aluminum surfaces.

This work analyzes the anti-icing performance of flat aluminum surfaces coated with widely used alkyl-group based layers of octadecyltrimethoxysilane, fluorinated alkylsilane and stearic acid as they are subjected to repeated icing/deicing cycles. The wetting properties of the samples upon long-term immersion in water are also evaluated. The results demonstrate that smooth aluminum surfaces grafted with alkyl groups are prone to gradual degradation of their hydrophobic and icephobic properties, which is caused by interactions and reactions with both ice and liquid water. This implies that alkyl-group based monolayers on aluminum surfaces are not likely to be durable icephobic coatings unless their durability in contact with ice and/or water is significantly improved.

Development of the charge exchange recombination spectroscopy and the beam emission spectroscopy on the EAST tokamak.

Charge eXchange Recombination Spectroscopy (CXRS) and Beam Emission Spectroscopy (BES) diagnostics based on a heating neutral beam have recently been installed on EAST to provide local measurements of ion temperature, velocity, and density. The system design features common light collection optics for CXRS and BES, background channels for the toroidal views, multi-chord viewing sightlines, and high throughput lens-based spectrometers with good signal to noise ratio for high time resolution measurements. Additionally, two spectrometers each has a tunable grating to observe any wavelength of interest are used for the CXRS and one utilizes a fixed-wavelength grating to achieve higher diffraction efficiency for the BES system. A real-time wavelength correction is implemented to achieve a high-accuracy wavelength calibration. Alignment and calibration are performed. Initial performance test results are presented.

Superhydrophobic surfaces: are they really ice-repellent?

This work investigates the anti-ice performance of various superhydrophobic surfaces under different conditions. The adhesion strength of glaze ice (similar to that deposited during "freezing rain") is used as a measure of ice-releasing properties. The results show that the ice-repellent properties of the materials deteriorate during icing/deicing cycles, as surface asperities appear to be gradually damaged. It is also shown that the anti-icing efficiency of superhydrophobic surfaces is significantly lower in a humid atmosphere, as water condensation both on top of and between surface asperities takes place, leading to significantly larger values of ice adhesion strength. This work thus shows that superhydrophobic surfaces are not always ice-repellent and their use as anti-ice materials may therefore be limited.

Hollow nanoparticles of metal oxides and sulfides: fast preparation via laser ablation in liquid.

In this work, diverse hollow nanoparticles of metal oxides and sulfides were prepared by simply laser ablating metal targets in properly chosen liquids. The Kirkendall voiding and the selective heating with an infrared laser were shown to work as two independent mechanisms for the formation of such hollow nanoparticles in only one- or two-step synthesis approaches. One of the prepared materials, ZnS hollow nanoparticles, showed high performance in gas sensing. The simple, fast, inexpensive technique that is proposed demonstrates very promising perspectives.

Morphology control of nanostructures via surface reaction of metal nanodroplets.

We report on the controllable synthesis of diverse nanostructures using laser ablation of a metal target in a liquid medium. The nanodroplets generated by laser ablation react with the liquid and produce various nanostructures, such as hollow nanoparticles, core-shell nanoparticles, heterostructures, nanocubes, and ordered arrays. A millisecond laser with low power density is essential for obtaining such metal nanodroplets, while the target material, the reactivity of liquid medium, and the laser frequency are decisive for controlling the morphology and size of the nanostructures produced. This green and powerful technique can be extended to different material systems for obtaining various nanostructures.

Analyses of microbial consortia in the starter of Fen Liquor.

AIMS: This study aimed to determine the microbial diversity in the starter of Fen Liquor. METHODS AND RESULTS: The plate method was used to enumerate the micro-organisms; meanwhile, the 16S rDNA of bacteria and the internal transcribed spacer of fungi were used to determine microbial diversity. Several genera were accordingly identified. Among the bacteria, Lactobacillales and Actinomycetales were detected only on the surface of the starter, whereas Bacillales was dominant within the starter. Among the fungi, Saccharomycopsis and Issatchenkia were the main genera in surface and interior starter, respectively; in addition, Thermomyces was found in interior starter, while other species of fungi were detected on the surface. CONCLUSIONS: The culture-dependent and polymerase chain reaction-based methods revealed the significant microbial diversity in different locations in the starter of Fen Liquor. SIGNIFICANCE AND IMPACT OF THE STUDY: This study is the first to identify the bacterial and fungal communities associated with the starter of Fen Liquor using both traditional and molecular methods; it is also the first to compare the microbial diversity on the surface of starter with that in the interior. The results enrich our knowledge on liquor-related micro-organisms, and can be used to promote the development of the traditional fermentation technology.