Design and control of coaxial switching system for ion cyclotron wave resonance heating system of EAST

Ion cyclotron wave resonance heating system(ICRH)which is one of the most important auxiliary system in EAST provides conditions for heating the plasma.In order to make the whole transmission network of ICRH form the required state,the coaxial switching system was developed,which mainly consists of 11 same coaxial switches.Each coaxial switch has a controller with an RS485 communication interface and is able to switch between two states.All controllers are integrated to an RS485 hub which connects to the computer.A master computer software is developed to control the coaxial switching system so as to achieve the state needs of ICRH.Moreover,several rounds of experiments show that the coaxial switching system operates reliably.The coaxial switching system has already been applied to normal use currently.

Tunable biasing magnetic field design of ferrite tuner for ICRF heating system in EAST

Ion cyclotron range of frequency（ICRF） heating has been used in tokamaks as one of the most successful auxiliary heating tools and has been adopted in the EAST. However, the antenna load will fluctuate with the change of plasma parameters in the ICRF heating process. To ensure the steady operation of the ICRF heating system in the EAST, fast ferrite tuner（FFT） has been carried out to achieve real-time impedance matching. For the requirements of the FFT impedance matching system, the magnet system of the ferrite tuner（FT） was designed by numerical simulations and experimental analysis, where the biasing magnetic circuit and alternating magnetic circuit were the key researched parts of the ferrite magnet. The integral design goal of the FT magnetic circuit is that DC bias magnetic field is 2000 Gs and alternating magnetic field is±400 Gs. In the FTT, E-type magnetic circuit was adopted. Ferrite material is Nd Fe B with a thickness of 30 mm by setting the working point of Nd Fe B, and the ampere turn of excitation coil is 25 through the theoretical calculation and simulation analysis. The coil inductance to generate alternating magnetic field is about 7 m H. Eddy-current effect has been analyzed, while the magnetic field distribution has been measured by a Hall probe in the medium plane of the biasing magnet. Finally, the test results show the good performance of the biasing magnet satisfying the design and operating requirements of the FFT.

Design of a multi-voltage probe system for ICRF antenna coupling resistance measurement on EAST

A multi-voltage probe array system is designed to measure the coupling resistance of an ion cyclotron resonance frequency antenna. In the process of the antenna coupling resistance data extraction, the minimization algorithm, the original Levenberg–Marquardt algorithm, is replaced by the Broyden–Fletcher–Goldfarb–Shanno algorithm to achieve more stable and accurate results. Moreover, a simple model of the multi-voltage probe array was applied to simulate the performance of the Kalman filter, and to optimize the distance and position of the probes and probe number to mitigate the influence of the system noise on the rebuilt results. During the EAST experiment in 2019, a four-voltage probe array was applied to measure the coupling resistance of line 6 during high confined mode discharge. The measurement results by the multivoltage probe array system and the voltage/current probe pair show a good agreement.

Design of improved compact decoupler based on adjustable capacitor for EAST-ICRF antenna

The Ion Cyclotron Radio Frequency(ICRF)heating antenna on EAST adopts a decoupling device to constrain power coupling among the radiation straps,which was discovered shortcomings such as long size,poor contact,and etc.In order to improve these weak points,a new type decoupler with terminal-loaded tunable capacitor is designed to replace the previous design.Besides the capability of the tunable admittance parameters of decoupler,the withstand voltage of the capacitor is the most significant consideration for working under high power.Therefore,the theoretical analysis carefully elaborates the capacitor withstand voltage,and the detailed analytical equations and criteria for design are given.After the comparative analysis of theoretical calculation and 3D simulation results,the decoupler design scheme is finalized.The capacitor-loaded decoupler has been successfully adopted for ICRF antenna at port N on EAST,and achieved the optimization of adjacent port isolation from-22 to-58 dB at 37 MHz without plasma to restrict mutual coupling.The new design of the decoupler has greatly improved its compactness and automatic adjustment performance,and could be good solution for the decoupling network of ICRF antennas.

Influence of Heavy Metals on Seed Germination and Early Seedling Growth in <i>Eruca sativa</i>Mill.

Heavy metals present in soil and water naturally or as contaminants from human activities can cause bioaccumulation affecting the entire ecosystem and pose harmful health consequences in all life forms. Some famous non-food hyperaccumulators such as Thlaspi caerulescens, Sedum alfredii, Pteris vittata, Arabidopsis halleri and Athyrium yokoscense are of very little economic value, making it difficult for them to be used for phytoremediation. In this paper, the influence of heavy metals Cu, Ni, Zn, Hg, Cr, Pb and Cd on seed germination and early seedling growth in oil crop Eruca sativa was evaluated under laboratory conditions. Our results indicated that among the 7 heavy metals tested, only Ni at higher concentrations (1 mM and above) significantly decreased the Eruca seed germination in a dose-dependent manner. All heavy metals except Zn and Ni decreased the root length first, then the shoot length or the fresh seedling weight, and seed germination was always the last to be influenced. With Ni, the root length, shoot length and fresh seedling weight were stimulated when Ni concentrations were under 1 mM;with Zn, the root length, shoot length and fresh seedling weight were increased by all concentrations tested (0.20 - 5.0 mM). Our results indicated that Eruca is tolerant or moderately tolerant to Cu, Hg, Cr, and Cd and highly tolerant to Pb, Ni and Zn, and can be developed as an industrial oil crop for phytoremediation of soils contaminated by heavy metals.

Sister-city Ties and Chinese Outward Foreign Direct Investment:A Spatial Econometric Analysis

This paper employs dynamic spatial econometric methods to analyze the impact of the sister-city relationship on Chinese outward foreign direct investment(OFDI)using a linked country-level dataset from 2003 to 2016.The results show strong and robust evidence that the sister-city relationship has been a crucial OFDI location determinant in host countries and their neighbors.Specifically,the sister-city tie between China and the host country has stimulated Chinese OFDI in host countries.Moreover,Chinese OFDI in host countries would be reduced if China concluded sister-city ties with their neighbors to which we refer as the neighboring effect.Further mechanism tests show that sister cities have promoted OFDI in host countries via four channels:reducing political risk,decreasing information asymmetry,narrowing institutional distance,and mitigating cultural differences.This tendency for sister-city links to promote OFDI has varied substantially depending on OFDI entry modes(i.e.,greenfield or cross-border mergers and acquisitions),motivation(i.e.,resource-,market-,technology-,or efficiency-oriented OFDI),and Sino–foreign geographical relationships(i.e.,Belt and Road Initiative countries or other countries).

Capital flows, economic growth and the real effective exchange rate: Evidence from China

This paper examines the Granger causal relationship between capital flows and economic growth in China over the period 1998Q1–2019Q2,allowing for real effective exchange rate(REER)effects.As parameter instability tests indicate structural changes,we use bootstrap rolling window causality tests,which suggest that the causal nexus between capital flows and GDP growth is time-varying.We find that the causal links between foreign direct investments(FDIs)and GDP growth are hardly affected by the REER,whereas the REER plays a more important role in affecting the causal connections between portfolio investments and other investments and GDP growth.Our results suggest that cumulative portfolio inflows and cumulative other investment inflows harm GDP growth,whereas cumulative portfolio outflows and cumula-tive other investment outflows positively affect GDP growth.

Exploration and practice of general practitioner responsibility system in an urban community of Shanghai

Objective:The Minhang district of Shanghai was selected as the subject and its public health management model was investigated.Methods:Minhang became a pilot location for the implementation of the general practitioner responsibility system(GPRS)in 2011.Since then,the management model of public health services in the district has gradually merged with the GPRS through a series of actions:the adjustment of organizations and the coordination mechanism in community public health services,the integration of basic public health services and clinic practice,the establishment of an informationized Internet service platform,comprehensive budgeting management of public health service programs,and performance assessment management of health workers.Results:By the end of 2014,the number of residents who had a contractual relationship with a general practitioner(GP)in Minhang had reached 1.4367 million and all of them had family health records.Compared with 2010,both the rate of maternal management and the rate of children management stayed at high level(≥96%),the rate of hypertension management increased(40.73%vs.28.70%),the rate of blood pressure control increased(82.13%vs.77.51%),the incidence of diabetes decreased(21.93%vs.37.85%),the rate of effective control of blood glucose for dia-betic patients increased(82.43%vs.62.77%),and the rate of child health management increased(99.79%vs.91.54%).Conclusion:The GPRS has helped to create a better community health environment.How-ever,the development of this system is limited by several factors,including the following:the shortage of GPs,most GPs do not have good public health service skills and a correct public health concept,unclear division of different services,and imperfect department coordination.

Edge localized modes suppression via edge E × B velocity shear induced by RF sheath of ion cyclotron resonance heating in EAST

The control of large edge localized modes(ELMs) is a critical issue for the successful operation of future burning plasma devices,such as the international thermonuclear experimental reactor(ITER) and China fusion engineering test reactor(CFETR). In this paper, we present a new active and effective means of ELM suppression using ion cyclotron resonant heating(ICRH) on the experimental advanced superconducting tokamak(EAST). We obtained the key role of the external E × B velocity shear near the pedestal top and the scrape-off-layer(SOL) induced by the RF sheath potential of ICRH in ELM suppression. The experimental results showed a positive correlation between the RF sheath and the E × B shear rate in SOL. BOUT++ simulations indicate that increased E × B velocity shear rates in the pedestal and SOL regions promote ELM suppression;thereby, supporting the experimental observations on EAST. These findings suggest a new simple approach to access the ELM suppressed regimes in plasma with low torque input as ITER baseline discharges.