Realization of T_(e0)>10 keV long pulse operation over 100 s on EAST

In 2021,EAST realized a steady-state long pulse with a duration over 100 s and a core electron temperature over 10 keV.This is an integrated operation that resolves several key issues,including active control of wall conditioning,long-lasting fully noninductive current and divertor heat/particle flux.The fully noninductive current is driven by pure radio frequency(RF)waves with a lower hybrid current drive power of 2.5 MW and electron cyclotron resonance heating of 1.4 MW.This is an excellent experimental platform on the timescale of hundreds of seconds for studying multiscale instabilities,electron-dominant transport and particle recycling(plasma-wall interactions)under weak collisionality.

中国首个地基高分辨率傅里叶变换光谱观测站的大气成分长期观测研究

长期观测主要大气成分的体积混合比(VMR)廓线和柱总量对掌握中国气候变化和碳收支具有重要意义。本文对我国首个TCCON高分辨率傅里叶变换光谱(FTS)地基观测站——合肥观测站开展了系统性研究,该观测站可观测30多种大气成分的柱总量和VMR廓线。本文公布了2014年以来合肥观测站观测到的部分关键大气成分的时间序列,总结了迄今为止该站点取得的主要研究成果,包括光谱反演表征和归一化、关键大气成分的总体演变特征、排放估计、卫星和化学传输模式(CTM)校验以及对大气污染来源和传输的相关研究。同时,本文还对合肥观测站的观测、科学研究和未来研究计划进行了展望。中国明确提出2030年二氧化碳排放达到峰值,2060年实现碳中和。合肥观测站将为中国政府制定绿色经济政策、实现碳中和及《巴黎协定》目标提供科学支撑。

Realization of minute-long steady-state H-mode discharges on EAST

In the 2016 EAST experimental campaign,a steady-state long-pulse H-mode discharge with an ITER-like tungsten divertor lasting longer than one minute has been obtained using only RF heating and current drive,through an integrated control of the wall conditioning,plasma configuration,divertor heat flux,particle exhaust,impurity management,and effective coupling of multiple RF heating and current drive sources at high injected power.The plasma current（Ip - 0.45 MA） was fully-noninductively driven（Vloop 〈 0.0 V） by a combination of-2.5 MW LHW,-0.4 MW ECH and -0.8 MW ICRF.This result demonstrates the progress of physics and technology studies on EAST,and will benefit the physics basis for steady state operation of ITER and CFETR.

Magnetic field topology modeling under resonant magnetic perturbations on EAST

In order to understand the mechanism by which the resonant magnetic perturbation (RMP)mitigates or suppresses the edge-localized mode (ELM),the topological study of the edge magnetic field in ELM mitigation or suppression phase is a critical issue.To model the three-dimensional magnetic field topology superposed RMP on Experimental Advanced Superconducting Tokamak,a numerical model using the field line tracing method for both vacuum and ideal plasma response approximations is proposed.Using the numerical model,the topological change and the penetration depth of the stochastic field lines in the edge magnetic field are studied in an RMP experiment.Comparing profiles of minimum9 on edge stochastic field lines and the particle flux pattem,the ideal plasma response changes the field line penetration depth while remaining similar profile relative to vacuum approximation.To mitigate and suppress ELM strongly,the deep penetration of RMP fields and topological changes of the edge magnetic field is a key from our modeling.

Experimental study of density pump-out on EAST

In the experimental advanced superconducting tokamak,density pump-out phenomena were observed by using a multi-channel polarimeter-interferometer system under different heating schemes of ion cyclotron resonant heating,electron cyclotron resonance heating,and neutral beam injection.The density pump-out was also induced with application of resonant magnetic perturbation,accompanied with a degradation of particle confinement.For the comparison analysis in all heating schemes,the typical plasma parameters are plasma current 400 k A,toroidal field 2 T,and line average density 2×10^19m^-3.The experimental results show that the degree of pump-out is concerned with electron density and heating power.Low density deuterium low confinement（L-mode） plasmas（〈3.5×10^19m^-3） show strong pump-out effects.The density pump-out correlated with a significant drop of particle confinement.

Study on divertor heat flux under n=3 and n=4 resonant magnetic perturbations using infrared thermography diagnostic in EAST

Resonant magnetic perturbations(RMPs)with high toroidal mode number n are considered for controlling edge-localized modes(ELMs)and divertor heat flux in future ITER H-mode operations.In this paper,characteristics of divertor heat flux under high-nRMPs(n=3 and 4)in H-mode plasma are investigated using newly upgraded infrared thermography diagnostic in EAST.Additional splitting strike point(SSP)accompanying with ELM suppression is observed under both RMPs with n=3 and n=4,the SSP in heat flux profile agrees qualitatively with the modeled magnetic footprint.Although RMPs suppress ELMs,they increase the stationary heat flux during ELM suppression.The dependence of heat flux on q_(95)during ELM suppression is preliminarily investigated,and further splitting in the original strike point is observed at q 495=during ELM suppression.In terms of ELM pulses,the presence of RMPs shows little influence on transient heat flux distribution.

Suppression and mitigation of inter-ELM high-frequency Alfvén-like mode by resonant magnetic perturbation in EAST

Suppression and mitigation of a high-frequency Alfvén-like mode(HFAM)between type-I edge localized modes(ELMs)during ELM mitigation by resonant magnetic perturbation(RMP)is observed for the first time in the EAST tokamak.This mode is located near the edge pedestal region.The modeling result of the Alfvén continuum shows that the HFAM is located near the elipical Alfvén eigenmode(EAE)gap.During the application of n=1 RMP for ELM mitigation,the HFAM can be fully suppressed when the RMP amplitude exceeds a threshold,below which the HFAM is mitigated.The suppression is caused by a reduction of pedestal height induced by RMP.In the case using n=3 RMP,the mode is localized toroidally at specific phase depending on the phase of applied RMP,i.e.locked in the three-dimensional equilibrium formed by RMP.The dominant toroidal mode number of HFAM is around n=-6 and it reduces to-3 during the application of n=3 RMP,which indicates the existence of possible nonlinear coupling between the HFAM and RMP.Here the negative mode number denotes that the mode rotates in electron diamagnetic drift direction.The observation reported here improves the understanding of pedestal dynamics and its stability in RMP ELM control.

Physical design of a new set of high poloidal mode number coils in the EAST tokamak

An external resonant magnetic perturbation(RMP)field,which is an effective method to mitigate or suppress the edge localized mode(ELM),has been planned to be applied on the ELM control issue in ITER.A new set of magnetic perturbation coils,named as high m coils,has been developed for the EAST tokamak.The magnetic perturbation field of the high m coils is localized in the midplane of the low field side,with the spectral characteristic of high m and wide n,where m and n are the poloidal and toroidal mode numbers,respectively.The high m coils generate a strong localized perturbation field.Edge magnetic topology under the application of high m coils should have either a small or no stochastic region.With the combination of the high m coils and the current RMP coils in the EAST,flexible working scenarios of the magnetic perturbation field are available,which is beneficial for ELM control exploration on EAST.Numerical simulations have been carried out to characterize the high m coil system,including the magnetic spectrum and magnetic topology,which shows a great flexibility of magnetic perturbation variation as a tool to investigate the interaction between ELM and external magnetic perturbation.

FEQ:a new flux coordinates based equilibrium solver including both magnetic axis and separatrix

Accurate tokamak plasma equilibrium solution in flux coordinates is crucial for many stability and transport studies.Different approaches for dealing with singularities in solving the nonlinear Grad-Shafranov(GS)equation in flux coordinates or also known as straight field line coordinates are proposed in this paper.The GS equation is solved by iterating the position of grids directly in flux coordinates,and hence,no additional errors are introduced due to mapping process for a convergent solution.The singularity at magnetic axis in flux coordinates is removed by using a novel coordinate transform technique.Different from other techniques previously developed,no assumption in boundary condition at magnetic axis is used.This is consistent with the fact that there is no physical boundary at the magnetic axis.A flux coordinate system with poloidal coordinate chosen as the geometric poloidal angle is proposed.It conquers the difficulty in no definition of poloidal coordinate in flux coordinates at separatrix because of the singularity at x-point(s)in a divertor configuration.It also simplifies the process for computing poloidal flux coordinate during the iteration for solving the nonlinear GS equation.Non-uniform grids can be applied in both radial and poloidal coordinates,which allows it to increase the spacial resolution near x-point(s)in a divertor configuration.Based on the model proposed in this paper,a new Flux coordinates based EQuilibrium solver(FEQ)in tokamaks is developed.The numerical solutions from this code agree well with both the analytic Solov’ev solution and the numerical one from the EFIT code for a divertor configuration in the EAST tokamak.This code can be applied for simulating different equilibria with prescribed shape,pressure and current profiles,i.e.including both limiter and divertor configurations,positive triangularity and negative triangularity,differentβ,arbitrary magnetic shear profile etc.It provides a powerful and convenient fixed-boundary inverse equilibrium solver including both magnetic axis and separatrix in the solution for tokamak researches.

Evaluation of NBI absorption and fast ion stored energy to improve thermal energy confinement time calculation in EAST

The absorption of neutral beam power and the fast ion stored energy in EAST plasmas with neutral beam injection(NBI)is analyzed to improve the calculation of thermal energy confinement time.The neutral beam power absorption and fast ion stored energy are systematically calculated using the TRANSP code,through the investigation of global parameters including plasma current,line averaged density and beam energy.Results have shown that scaling laws for the NBI absorption coefficient and fast ion energy rate are obtained through statistical analysis.A comparison of the confinement improvement factor H98y2 with these new scaling laws against those assuming fixed coefficients is given.

Expression of connexin43 and its correlation with the expressions of Bcl-2 and Bax proteins in transitional cell carcinoma of the bladder

Objective: To study the expression of connexin43 (Cx43) gene and its correlation with the apoptosis related genes Bcl-2 and Bax in transitional cell carcinoma of the bladder (BTCC), and to investigate the role of Cx43 in the BTCC. Methods: Reverse transcription polymerase chain reaction was used to detect the expression of Cx43 mRNA and immunocytochemistry technique was used to detect the expressions of Bcl-2 and Bax proteins in 60 cases of BTCC tissues, and compared with that of 15 cases of pericancerous tissues and 15 cases of normal bladder tissues. Results: The positive expression rate of Cx43 mRNA in 60 cases of BTCC tissues was 43.33% which was significantly lower than that in pericancerous tissues (73.33%) and normal tissues (100%) (χ2 = 17.58, P < 0.01). The expression of Cx43 had significant negative correlation with the pathological degree and lymph node metastasis of BTCC (χ2 = 9.33 and 9.74, respectively, P < 0.01). However, no correlation was found between the expression and patient sex, age, clinical staging and diameter and growth pattern of BTCC (P > 0.05). Expression of Cx43 negatively correlated with Bcl-2 protein (r = -0.63, P < 0.01) and positively correlated with Bax protein (r = 0.52, P < 0.01). Conclusion: The down-regulated expression of Cx43 gene was closely associated with the development, invasion and metastasis of BTCC. It could be used as a prognostic indicator for BTCC. Cx43 gene may have antagonistic effects with Bcl-2 gene and synergic with Bax gene in the initiation and progression of BTCC.

Atmospheric environment monitoring technology and equipment in China:A review and outlook

Accurate monitoring of the atmospheric environment and its evolution are important for understanding the sources,chemical mechanisms,and transport processes of air pollution and carbon emissions in China,and for regulatory and control purposes.This study gives an overview of atmospheric environment monitoring technology and equipment in China and summarizes the major achievements obtained in recent years.China has made great progress in the development of atmospheric environment monitoring technology and equipment with decades of effort.The manufacturing level of atmospheric environment monitoring equipment and the quality of products have steadily improved,and a technical&production system that can meet the requirements of routine monitoring activities has been initiated.It is expected that domestic atmospheric environment monitoring technology and equipment will be able to meet future demands for routine monitoring activities in China and provide scientific assistance for addressing air pollution problems.

Advances in coastal ocean boundary layer detection technology and equipment in China

Accurate and comprehensive knowledge of the atmospheric environment and its evolution within the coastal ocean boundary layer are necessary for understanding the sources,chemical mechanisms,and transport processes of air pollution in land,sea,and atmosphere.We present an overview of coastal ocean boundary layer detection technology and equipment in China and summarize the progress and main achievements in recent years.China has developed a series of coastal ocean boundary layer detection technologies,including Light Detection and Ranging(LIDAR),turbulent exchange analyzer,air-sea flux analyzer,stereoscopic remote sensing of air pollutants,and oceanic aerosol detection equipment to address the technical bottleneck caused by harsh environmental conditions in coastal ocean regions.Advances in these technologies and equipment have provided scientific assistance for addressing air pollution issues and understanding land-sea-atmosphere interactions over coastal ocean regions in China.In the future,routine atmospheric observations should cover the coastal ocean boundary layer of China.

Vertical aerosol data assimilation technology and application based on satellite and ground lidar:A review and outlook

Observations and numerical models are mainly used to investigate the spatiotemporal distribution and vertical structure characteristics of aerosols to understand aerosol pollution and its effects.However,the limitations of observations and the uncertainties of numerical models bias aerosol calculations and predictions.Data assimilation combines observations and numerical models to improve the accuracy of the initial,analytical fields of models and promote the development of atmospheric aerosol pollution research.Numerous studies have been conducted to integrate multi-source data,such as aerosol optical depth and aerosol extinction coefficient profile,into various chemical transport models using various data assimilation algorithms and have achieved good assimilation results.The definition of data assimilation and the main algorithms will be briefly presented,and the progress of aerosol assimilation according to two types of aerosol data,namely,aerosol optical depth and extinction coefficient,will be presented.The application of vertical aerosol data assimilation,as well as the future trends and challenges of aerosol data assimilation,will be further analysed.

Preface

The serious air pollution problems in China have significantly affected the development of China’s economy and society,especially in key areas such as Beijing-Tianjin-Hebei,Yangtze River Delta,and Pearl River Delta,which has aroused widespread concern throughout society.With the launch of the MOST(Ministry Of Science and Technology)key project for Air Pollution Formation Mechanism and Control Technology during the 13thFive-Year Plan.

Palladium-Catalyzed Formal [4＋2] Cycloaddition of Benzoic and Acrylic Acids with 1,3-Dienes via C-H Bond Activation： Efficient Access to 3,4-Dihydroisocoumarin and 5,6-Dihydrocoumalins

We report a palladium-catalyzed formal intermolecular [4＋2] cycloaddition of benzoic and acrylic acids with 1,3-dienes including the stock chemicals 1,3-butadiene and isoprene leading to synthetically useful 3,4-dihydroisocoumarins and 5,6-dihydrocoumalins. Stepwise C-H bond cleavage and annulation are likely involved in the reaction pathway. The synthetic potential of the methodology was demonstrated by two short derivatizations and total synthesis of natural product Clausamine B.

Spatiotemporal variation and source analysis of air pollutants in the Harbin-Changchun (HC) region of China during 2014e2020

This study analyzed the characteristics of air pollution and specific pollution periods within the HarbinChangchun(HC)metropolitan area during 2014e2020.Regarding annual,seasonal,and monthly variations of the six pollutants,the change trend in 11 cities of HC showed strong consistency in spatial distribution.The western cities(Songyuan,Daqing,and Siping)were vulnerable to dust storms from Inner Mongolia.The concentrations of all air pollutants,except O3-8h,showed downward fluctuation trends from 2014 to 2018 and remained stable from 2018 to 2020 in terms of annual variations.The interannual trend of significant reductions in SO2 and SO2/PM2.5 during the heating period indicated that strict emission reduction measures posed by the government were highly successful.The ratio of PM2.5/SO2 was used to identify open biomass burning(OBB),which showed a double peak(OctobereNovember(OcteNov),MarcheApril(MareApr)).The burning prohibition shifted the OBB from OcteNov to Mar eApr.

Plasma-tungsten interactions in experimental advanced superconducting tokamak(EAST)

Tungsten(W)is used as the armor material of the International Thermonuclear Experimental Reactor(ITER)divertor and is regarded as the potential first wall material of future fusion reactors.One of the key challenges for the successful application of W in fusion devices is effective control of W at an extremely low concentration in plasma.Understanding and control of W erosion are not only a prerequisite for W impurity control,but also vital concerns to plasma-facing component(PFC)lifetime.Since the application of ITER-like water-cooled full W divertor in EAST in 2014,great efforts were made to inves-tigate W erosion by experiment and simulation.A spectroscopic system was developed to provide a real-time measurement of W sputtering source.Both experiment and simulation results indicate that carbon(C)is the dominant impurity causing W sputtering in L-mode plasmas,which comes from the erosion of C plasma-facing material(PFM)in the lower divertor and the main chamber limiters.The mixture layer on the surface of W PFCs formed through redeposition or the wall coating can effectively suppress W erosion.Increasing the plasma density and radiation can reduce incident ion energy,thus alleviating W sputtering.In H-mode plasmas,control of edge localized mode(ELM)via resonant magnetic perturbation(RMP)proves to be capable of suppressing intra-ELM W erosion.The experiences and lessons from the EAST W divertor are beneficial to the design,manufacturing and operation of ITER and beyond.

Formation of secondary inorganic aerosol in a frigid urban atmosphere

Formation of secondary inorganic aerosol(SIA)was investigated during a six-month long heating season in Harbin,China.Enhanced sulfate formation was observed at high relative humidity(RH),with the same threshold RH(80%)for both colder and warmer measurement periods.Compared to wintertime results from Beijing,the threshold RH was considerably higher in Harbin,whereas the RH-dependent enhancement of sulfur oxidation ratio(SOR)was less significant.In addition,the high RH events were rarely encountered,and for other periods,the SOR were typically as low as~0.1.Therefore,the sulfate formation was considered inefficient in this study.After excluding the several cases with high RH,both SOR and the nitrogen oxidation ratio(NOR)exhibited increasing trends as the temperature increased,with the increase of NOR being sharper.The nitrate to sulfate ratio tended to increase with increasing temperature as well.Based on a semi-quantitative approach,this trend was attributed primarily to the temperature-dependent variations of precursors including SO_(2) and NO_(2).The influence of biomass burning emissions on SIA formation was also evident.With stronger impact of biomass burning,an enhancement in NOR was observed whereas SOR was largely unchanged.The different patterns were identified as the dominant driver of the larger nitrate to sulfate ratios measured at higher concentrations of fine particulate matter.