The property of scrape-off layer(SOL) currents induced by a biased electrode is investigated by fully kinetic collisionless two-dimensional particle-in-cell(PIC) simulations. A reduced Vlasov–Darwin model is employed...The property of scrape-off layer(SOL) currents induced by a biased electrode is investigated by fully kinetic collisionless two-dimensional particle-in-cell(PIC) simulations. A reduced Vlasov–Darwin model is employed, which is capable of describing the low-frequency kinetic behavior without electromagnetic vacuum modes(w^2=w_(pe)~2+ c^2k^2). A linear decay distribution of electron currents parallel to the background magnetic field is exhibited. Simulation analyses indicate that the cross field ion current is a key factor in sheath formation and global current balance. The influences of electrode area, biasing voltage and plasma source on the SOL current profile are studied, respectively.Characteristic plasma parameters in the far SOL region of the EAST tokamak are used in simulations to assess the current driving ability of the electrode biasing method. Due to the limitations of computational power, the geometrical size of the simulation domain is significantly smaller than the realistic SOL, which may lead to an absence of the quasi-neutral region in the upstream plasma.At last, a heuristic method is proposed to calculate the upper bound of the total current strength.展开更多
The PARASOL code and the simulation by using PARASOL are introduced briefly. The PARASOL code with particle-in-cell （PIC） method and binary collision model was developed in JAERI and JAEA. Simulations using PARASOL ...The PARASOL code and the simulation by using PARASOL are introduced briefly. The PARASOL code with particle-in-cell （PIC） method and binary collision model was developed in JAERI and JAEA. Simulations using PARASOL code were carried out in order to investigate the power and particle control with diveror system in fusion reactors. The one-dimensional （1D） version of PARASOL was adopted to investigate the Bohm criterion, the supersonic flow, the SOL heat conduction, and so on. The heat propagation due to edge localized mode （ELM） was studied with the 1D-dynamic PARASOL. The two-dimensional version of PARASOL for the whole tokamak plasma including scrape-off-layer （SOL）-divertor region was useful for simulating the SOL flow pattern, the electric field formation etc. Based on PARASOL simulation results, improved physics modeling for the fluid simulation was built up.展开更多
Plasmas with vertically elongated cross-sections tend to be unstable to an axis-symmetric instability. This paper studies the magnetohydrodynamic equilibria in elongated plasmas after failure of vertical feedback cont...Plasmas with vertically elongated cross-sections tend to be unstable to an axis-symmetric instability. This paper studies the magnetohydrodynamic equilibria in elongated plasmas after failure of vertical feedback control by using magnetic data for EAST device. Vertical forces on the vessel due to the induced polodial and toroidal currents are evaluated. The maximum force of the Fzpol in vertical displacement events for EAST designed parameters is given.展开更多
The W7-X stellarator is optimized with respect to neoclassical transport.Therefore turbulent transport plays an important role.It is equipped with an inertial cooled graphite divertor which intersects the island chain...The W7-X stellarator is optimized with respect to neoclassical transport.Therefore turbulent transport plays an important role.It is equipped with an inertial cooled graphite divertor which intersects the island chain at the plasma edge depending on the magnetic configuration.Additional control coils and the plasma current modify the iota profile at the plasma edge and shift the position of the island chain.To monitor the effects on the poloidal propagation velocity in the scrape-off layer(SOL)and the plasma edge,an O-mode Poloidal Correlation Reflectometer(PCR)is used which simultaneously monitors the propagation of low-k turbulence.Operating in the density range of 0.6?×?1019 m-3 to2?×?1019 m-3 it covers a large part of the SOL and the plasma edge and allows for the experimental determination in the last closed flux surface(LCFS)and the associated shear layer in low to middensity discharges.In this paper it is shown that the propagation in the shear layer and its vicinity is determined best,when based on an elliptical model.Different magnetic configurations with magnetic edge topology of five independent islands forι?=?1 and six linked islands forι?=?0.81 are investigated.Also the effects of the plasma current and additional control coils on the edge magnetic topology are studied.The coherence spectra of antenna pairs for different poloidal separations is investigated.Using a decomposition method for the measured coherence spectra the characterization of turbulence spectra is possible with respect to e.g.broad band turbulence and quasi coherent modes.A strong reduction of the broad band turbulence is observed in the vicinity of the LCFS which is evidence for the suppression of low-k turbulence at the shear layer.展开更多
A two-point model is used to investigate the characteristics of scrape-off layer(SOL)plasma with the field line tracing method in the experimental advanced superconducting tokamak.The profiles of plasma density,temper...A two-point model is used to investigate the characteristics of scrape-off layer(SOL)plasma with the field line tracing method in the experimental advanced superconducting tokamak.The profiles of plasma density,temperature and particle flux on the divertor target calculated by the model are in reasonable agreement with experimental observation.Moreover,the profiles of plasma parameters on the divertor target strongly depend on the SOL magnetic topology or the equilibrium configuration from the modeling.展开更多
Several results based on the Langmuir probes’data on the HL-2A tokamak are presented.The blob structures’radial and poloidal drift velocities,estimated by the gradient of floating potential and by time delay evaluat...Several results based on the Langmuir probes’data on the HL-2A tokamak are presented.The blob structures’radial and poloidal drift velocities,estimated by the gradient of floating potential and by time delay evaluation,are compared in different line-averaged density and electron cyclotron resonance heating conditions.A positive correlation is observed in the comparison between blobs’radial velocity estimated by the two methods mentioned above,regardless of the situation differences mentioned above.Correlation is also observed in the comparison between the blobs’poloidal velocity estimated by the two methods in different situations,while a shift due to the different line-averaged density is observed.These results imply that the radial gradient of floating potential may have some value as a reference during data analysis in low-parameter discharge.展开更多
介绍了一种可以对等离子体进行快速扫描的新型气动式静电探针诊断系统 ,该系统由气动传送杆和一组四探针阵列组成。结合相应的数据采集和分析手段 ,能够在一次放电中得到边缘等离子体的电子温度 Te、电子密度ne 以及它们的涨落 Te Te、...介绍了一种可以对等离子体进行快速扫描的新型气动式静电探针诊断系统 ,该系统由气动传送杆和一组四探针阵列组成。结合相应的数据采集和分析手段 ,能够在一次放电中得到边缘等离子体的电子温度 Te、电子密度ne 以及它们的涨落 Te Te、 ne ne展开更多
基于C++撰写测试程序,研究SIMPLE(Semi-Implicit Method for Pressure Linked Equations)、SIMPLEC(SIMPLE Consistent)、SIMPLER(SIMPLE Revised)、SIMPLEX(SIMPLE Extrapolation)以及PISO(Pressure-Implicit with Splitting of Operat...基于C++撰写测试程序,研究SIMPLE(Semi-Implicit Method for Pressure Linked Equations)、SIMPLEC(SIMPLE Consistent)、SIMPLER(SIMPLE Revised)、SIMPLEX(SIMPLE Extrapolation)以及PISO(Pressure-Implicit with Splitting of Operators)等压力修正算法对刮削层等离子体Braginskii输运方程数值求解性能的影响。测试程序采用SOLPS(Scrape-Off Layer Plasma Simulation)的等离子体模型方程,数值计算针对简化平板模型开展。结果表明:5种压力修正算法均能使程序收敛至正确的结果,其中PISO算法的收敛速度最快,SIMPLE、SIMPLEC、SIMPLER、SIMPLEX的收敛速度无明显差异。展开更多
基金supported by National Natural Science Foundation of China (Nos. 51828101 and No.11875294)the National Key R&D Program of China (No. 2017YFE0301100)。
文摘The property of scrape-off layer(SOL) currents induced by a biased electrode is investigated by fully kinetic collisionless two-dimensional particle-in-cell(PIC) simulations. A reduced Vlasov–Darwin model is employed, which is capable of describing the low-frequency kinetic behavior without electromagnetic vacuum modes(w^2=w_(pe)~2+ c^2k^2). A linear decay distribution of electron currents parallel to the background magnetic field is exhibited. Simulation analyses indicate that the cross field ion current is a key factor in sheath formation and global current balance. The influences of electrode area, biasing voltage and plasma source on the SOL current profile are studied, respectively.Characteristic plasma parameters in the far SOL region of the EAST tokamak are used in simulations to assess the current driving ability of the electrode biasing method. Due to the limitations of computational power, the geometrical size of the simulation domain is significantly smaller than the realistic SOL, which may lead to an absence of the quasi-neutral region in the upstream plasma.At last, a heuristic method is proposed to calculate the upper bound of the total current strength.
文摘The PARASOL code and the simulation by using PARASOL are introduced briefly. The PARASOL code with particle-in-cell （PIC） method and binary collision model was developed in JAERI and JAEA. Simulations using PARASOL code were carried out in order to investigate the power and particle control with diveror system in fusion reactors. The one-dimensional （1D） version of PARASOL was adopted to investigate the Bohm criterion, the supersonic flow, the SOL heat conduction, and so on. The heat propagation due to edge localized mode （ELM） was studied with the 1D-dynamic PARASOL. The two-dimensional version of PARASOL for the whole tokamak plasma including scrape-off-layer （SOL）-divertor region was useful for simulating the SOL flow pattern, the electric field formation etc. Based on PARASOL simulation results, improved physics modeling for the fluid simulation was built up.
基金supported by the National Natural Science Foundation of China (Grant No 10725523)the Ministry of Science and Technology of China (Grant No 2007DFA11290)
文摘Plasmas with vertically elongated cross-sections tend to be unstable to an axis-symmetric instability. This paper studies the magnetohydrodynamic equilibria in elongated plasmas after failure of vertical feedback control by using magnetic data for EAST device. Vertical forces on the vessel due to the induced polodial and toroidal currents are evaluated. The maximum force of the Fzpol in vertical displacement events for EAST designed parameters is given.
基金funding from the Euratom research and training program 2014-2018 and2019-2020 under grant agreement no.633053。
文摘The W7-X stellarator is optimized with respect to neoclassical transport.Therefore turbulent transport plays an important role.It is equipped with an inertial cooled graphite divertor which intersects the island chain at the plasma edge depending on the magnetic configuration.Additional control coils and the plasma current modify the iota profile at the plasma edge and shift the position of the island chain.To monitor the effects on the poloidal propagation velocity in the scrape-off layer(SOL)and the plasma edge,an O-mode Poloidal Correlation Reflectometer(PCR)is used which simultaneously monitors the propagation of low-k turbulence.Operating in the density range of 0.6?×?1019 m-3 to2?×?1019 m-3 it covers a large part of the SOL and the plasma edge and allows for the experimental determination in the last closed flux surface(LCFS)and the associated shear layer in low to middensity discharges.In this paper it is shown that the propagation in the shear layer and its vicinity is determined best,when based on an elliptical model.Different magnetic configurations with magnetic edge topology of five independent islands forι?=?1 and six linked islands forι?=?0.81 are investigated.Also the effects of the plasma current and additional control coils on the edge magnetic topology are studied.The coherence spectra of antenna pairs for different poloidal separations is investigated.Using a decomposition method for the measured coherence spectra the characterization of turbulence spectra is possible with respect to e.g.broad band turbulence and quasi coherent modes.A strong reduction of the broad band turbulence is observed in the vicinity of the LCFS which is evidence for the suppression of low-k turbulence at the shear layer.
基金JSPS-CAS Bilateral Joint Research Projects,‘Control of wall recycling on metallic plasma facing materials in fusion reactor’supported by the NIFS Collaboration Research Program (Nos.NIFS18KNST130 and NIFS20KNST171)supported by ‘PLADy S’,JSPS Core-to-Core Program,A. Advanced Research Networks
文摘A two-point model is used to investigate the characteristics of scrape-off layer(SOL)plasma with the field line tracing method in the experimental advanced superconducting tokamak.The profiles of plasma density,temperature and particle flux on the divertor target calculated by the model are in reasonable agreement with experimental observation.Moreover,the profiles of plasma parameters on the divertor target strongly depend on the SOL magnetic topology or the equilibrium configuration from the modeling.
基金supported by the National Key Research and Development Program of China(Nos.2017YFE0300500,2017YFE0300501)No.2018YFE0309100National Natural Science Foundation of China(Nos.11705052,11875124,11905050,11875020 and U1867222)。
文摘Several results based on the Langmuir probes’data on the HL-2A tokamak are presented.The blob structures’radial and poloidal drift velocities,estimated by the gradient of floating potential and by time delay evaluation,are compared in different line-averaged density and electron cyclotron resonance heating conditions.A positive correlation is observed in the comparison between blobs’radial velocity estimated by the two methods mentioned above,regardless of the situation differences mentioned above.Correlation is also observed in the comparison between the blobs’poloidal velocity estimated by the two methods in different situations,while a shift due to the different line-averaged density is observed.These results imply that the radial gradient of floating potential may have some value as a reference during data analysis in low-parameter discharge.
