In the last few years, long-pulse H-mode plasma discharges (with small edge-localized modes and normalized beta, β N ~ 1) have been realized at the Experimental Advanced Superconducting Tokamak (EAST). This paper reports on high-β N (>1.5) discharges in the 2015 EAST campaign. The characteristics of these H-mode plasmas have been presented in a database. Analysis of the experimental limit of β N has revealed several main features of typical discharges. Firstly, efficient, stable high heating power is required. Secondly, control of impurity radiation (partly due to interaction between the plasma and the in-vessel components) is also a critical issue for the maintenance of high-β N discharges. In addition an internal transport barrier (ITB) has recently been observed in EAST, introducing further improvement in confinement surpassing H-mode plasmas. ITB dynamics is another key issue for high-β N plasmas in EAST. Each of these features is discussed in this paper. Study and improvement of these issues could be considered as the key to achieving long-pulse high-β N operation with EAST.

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By installing an X-mode polarized Q-band (32-56 GHz) reflectometry at the low field side on EAST, the zero density cutoff layer was determined and the edge density profile was measured in normally operating plasmas. A Monte Carlo procedure has been developed to analyze the density profiles by considering the error of time delay measured by reflectometry. By combining this Q-band and previously developed V-and W-band reflectometries, the density profiles from edge to core can be measured in most EAST experiments. The line integrated densities deduced from density profiles measured by reflectometry are consistent with those directly measured by a horizontal interferometer. The density pedestal measured by reflectometry shows a clear crash during an ELM (edge localized mode) event, after which the pedestal gradually increases and recovers in 10 ms and then remains little changed up to the next ELM.

The excessive use of plastics has been accompanied by severe ecologically damaging effects. The recent discovery of a PETase from Ideonella sakaiensis that decomposes poly(ethylene terephthalate) (PET) under mild conditions provides an attractive avenue for the biodegradation of plastics. However, the inherent instability of the enzyme limits its practical 20 15 and the Biological Resources Program (KFJ-BRP-009) of the Chinese Academy of Sciences.

A microwave reflectometry system operating in the V-band frequency with extraordinary mode polarization has been developed on the EAST tokamak. The reflectometry system, using a voltage-controlled oscillator (VCO) source driven by an arbitrary waveform generator with high temporal resolution, can operate for the density profile measurement. The result of the bench test shows that the output frequency of the VCO has a linear dependence on time. The dispersion of reflectometry system is determined and reported in this paper. The evolution of a pedestal density profile during the L-H transition is observed by the reflectometry in H-mode discharges on EAST tokamak. A frequency synthesizer is used to replace the VCO as microwave source for density fluctuation measurements. The level of density fluctuation in the pedestal shows an abrupt decrease when the plasma enters into H-mode. A coherent mode with a frequency of about 100 kHz is observed and the mode frequency decreases gradually as the pedestal evolves.

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The (TOPography EXperiment) TOPEX/Poseidon (T/P) altimetry mission operated for 13 years before the satellite was decommissioned in January 2006, becoming a large space debris object at an altitude of 1,340 km. Since the end of the mission, the interaction of T/P with the space environment has driven the satellite's spin dynamics. Satellite laser ranging (SLR) measurements collected from June 2014 to October 2016 allow for the satellite spin axis orientation to be determined with an accuracy of 1.7°. The spin axis coincides with the platform yaw axis (formerly pointing in the nadir direction) about which the body rotates in a counterclockwise direction. The combined photometric and SLR data collected over the 11 year time span indicates that T/P has continuously gained rotational energy at an average rate of 2.87 J/d and spins with a period of 10.73 s as of 19 October 2016. The satellite attitude model shows a variation of the cross‐sectional area in the Sun direction between 8.2 m2 and 34 m2. The direct solar radiation pressure is the main factor responsible for the spin‐up of the body, and the exerted photon force varies from 65 μN to 228 μN around the mean value of 138.6 μN. Including realistic surface force modeling in orbit propagation algorithms will improve the prediction accuracy, giving better conjunction warnings for scenarios like the recent close approach reported by the ILRS Space Debris Study Group—an approximate 400 m flyby between T/P and Jason‐2 on 20 June 2017.

In this paper, a multiple diffuse coding metasurface (MDCM) of independent polarization is designed to control the propagation direction of diffuse reflections under different polarizations and to improve the monostatic and bistatic RCS (radar cross section) reduction effect. First, a method for controlling the distribution range and propagation direction of the diffuse field is studied, and the diffuse field distribution of the random phase metasurface is optimized by a genetic algorithm to improve the uniformity of the diffuse scattering distribution. Then, the random phase distribution is superimposed on the periodic gradient phase distributions of the linear and hedge types in the orthogonal direction so that the main propagation direction of the diffuse metasurface deviates from the specular reflection region under different polarizations, showing single and two diffuse beams. Finally, the anisotropic unit cell with a rectangle inside and an improved Jerusalem cross on the outside is employed as the basic coding element of the MDCM due to its independent polarization phase response. The numerical and experimental results show that the MDCM features multiple diffuse scattering, independent polarization and angle insensitivity and can efficiently improve the monostatic and bistatic RCS reduction effect simultaneously. Because the scattered energies are redirected away from the specular reflection direction, the specular scattering reduction effect is better than the isotropic diffuse metasurface. The proposed method increases the difficulty of detection by single or netted radar and has the potential for the applications of stealth techniques.