Plasma control on high-β_N steady-state operation for JT-60 superconductingmodification is discussed. Accessibility to high-β_N exceeding the free-boundary limit isinvestigated with the stabilising wall of reduced-a...Plasma control on high-β_N steady-state operation for JT-60 superconductingmodification is discussed. Accessibility to high-β_N exceeding the free-boundary limit isinvestigated with the stabilising wall of reduced-activated ferritic steel and the active feedbackcontrol of the ill-vessel non-axisymmetric field coils. Taking the merit of superconducting magnet,advanced plasma control for steady-state high performance operation could be expected.展开更多
Recent progress in the physics and engineering design study for themodification programme of JT-60 is presented. In order to achieve a steady state high-βplasmaoperation, which is the dominant issue of this programme...Recent progress in the physics and engineering design study for themodification programme of JT-60 is presented. In order to achieve a steady state high-βplasmaoperation, which is the dominant issue of this programme, physics design for the MHD control and thestability analysis is investigated. Engineering design and the R & D for the superconducting coils,irradiation shield are performed well towards the mission of programme.展开更多
Present status of the JT-60SA （JT-60 Super Advanced） project, implemented jointly by Europe and Japan since 2007, is described. The design of the main tokamak components was completed in late 2008, and all the scien...Present status of the JT-60SA （JT-60 Super Advanced） project, implemented jointly by Europe and Japan since 2007, is described. The design of the main tokamak components was completed in late 2008, and all the scientific missions are preserved to contribute to ITER and DEMO reactors. The construction of the JT-60SA has begun with procurement activities for the superconducting magnet systems, vacuum vessel, in-vessel components and other components under the relevant procurement arrangements between the implementing agencies of JAEA （Japan Atomic Energy Agency） in Japan and Fusion for Energy in Europe. Designs and developments of the auxiliary heating systems for JT-60SA have been progressing at JAEA so as to provide the total injection power of 41 MW for 100 s.展开更多
A superconducting coil system is actually complicated by the distributed parameters, e.g. the distributed mutual inductance among turns and the distributed capacitance between adjacent conductors. In this paper, such ...A superconducting coil system is actually complicated by the distributed parameters, e.g. the distributed mutual inductance among turns and the distributed capacitance between adjacent conductors. In this paper, such a complicated system was modeled with a reasonably simplified circuit network with lumped parameters. Then, a detailed circuit analysis was conducted to evaluate the possible voltage transient in the coil circuit. As a result, an appropriate （minimum） snubber capacitance for the Switching Network Unit, which is a fast high voltage generation circuit in JT-60SA, was obtained.展开更多
This paper describes an asymmetric control method for the firing angle and a start/stop timing shift control of four thyristor converters called ＂Booster PS＂ to minimize the reactive power fluctuation during plasma ...This paper describes an asymmetric control method for the firing angle and a start/stop timing shift control of four thyristor converters called ＂Booster PS＂ to minimize the reactive power fluctuation during plasma initiation in JT-60SA. From the simulation using the ＂PSCAD/EMTDC＂ code, it is found that these control methods can drastically reduce the reac- tive power induced by the four units of the ＂Booster PS＂. In addition, the voltage fluctuation of the motor-generator connected to the ＂Booster PS＂ is expected to be suppressed. This can also contribute to achieve stable control of the JT-60SA magnet power supplies.展开更多
JT-60SA is a fully superconducting coil tokamak upgraded from the JT-60U. This paper focused on the integrity of the top lid of cryostat in JT-60SA. The design requirement for the cryostat in normal operations is to a...JT-60SA is a fully superconducting coil tokamak upgraded from the JT-60U. This paper focused on the integrity of the top lid of cryostat in JT-60SA. The design requirement for the cryostat in normal operations is to achieve vacuum insulation of 10-1 Pa, and the top flange of the top lid is lightly welded onto its body flange. The weld is tensile-loaded by bending deformation of the top lid due to vacuum pressure of external 0.1 MPa. This weld integrity is evaluated with tensile-load reduction, which results in clamp reinforcement. The structural integrity of the top lid is validated.展开更多
This paper describes a conceptual design study for the circuit configuration of the Error Field Correction Coil （EFCC） power supply （PS） to maximize the expected performance with reasonable cost in JT-60SA. The EF...This paper describes a conceptual design study for the circuit configuration of the Error Field Correction Coil （EFCC） power supply （PS） to maximize the expected performance with reasonable cost in JT-60SA. The EFCC consists of eighteen sector coils installed inside the vacuum vessel, six in the toroidal direction and three in the poloidal direction, each one rated for 30 kA-turn. As a result, star point connection is proposed for each group of six EFCC coils installed cyclically in the toroidal direction for decoupling with poloidal field coils. In addition~ a six phase inverter which is capable of controlling each phase current was chosen as PS topology to ensure higher flexibility of operation with reasonable cost.展开更多
Recent results of JT-60U towards establishment of physics basis for ITER andadvanced tokamak operation are presented. Progress in high integrated performance is achieved withimprovement of N-NB and ECRF heating system...Recent results of JT-60U towards establishment of physics basis for ITER andadvanced tokamak operation are presented. Progress in high integrated performance is achieved withimprovement of N-NB and ECRF heating systems. In the next experimental campaign 2003～2004,discharge duration with 17 MW heating will be extended up to 30s for sustaining high-beta plasmalonger than the current diffusion time. Superconducting modification of JT-60 is planned todemonstrate high-beta plasma sustainment exceeding ideal MHD instability limit without wallstabilization.展开更多
The edge transport code SOLPS5.0 is used to model edge plasmas in the experi- mental shots on JT-60U and the profiles of the transverse particle and heat transport coefficients D, Xe and Xi along the outer midplane ar...The edge transport code SOLPS5.0 is used to model edge plasmas in the experi- mental shots on JT-60U and the profiles of the transverse particle and heat transport coefficients D, Xe and Xi along the outer midplane are obtained by fitting the simulational results to the experimental data in L-mode shot 39090 and H-mode shots 37851, 37856. The modelling and fitting results show that within the pedestal region in H-mode shots 37851 and 37856 the radial particle transport coefficient D exhibits a significant drop, but, for L-mode shot 39090, the obvious drop in both D and Xe was not found.展开更多
A transport simulation has been done by using a i.5D time dependent transportcode to reproduce a formation of the ITB on electron temperature Profile during the long pu1seLHCD in JT-60U tokamak. The transport coeffici...A transport simulation has been done by using a i.5D time dependent transportcode to reproduce a formation of the ITB on electron temperature Profile during the long pu1seLHCD in JT-60U tokamak. The transport coefficients were assumed to reduce with a reversedmagnetic shear and the LH driven current profile was evaluated by fitting dynamic change inthe measured current profile. The gradual increase in the central electron temperature could beexplained by the change in the current profile during LHCD in the present simulation model. Theestimated LH-driven current profile by the transport code analysis shows a finite current densityat the plasma center. Analysis of transport simulation suggests some mechanisms for broadeningthe LH-driven current profile at the central region of the plasma.展开更多
文摘Plasma control on high-β_N steady-state operation for JT-60 superconductingmodification is discussed. Accessibility to high-β_N exceeding the free-boundary limit isinvestigated with the stabilising wall of reduced-activated ferritic steel and the active feedbackcontrol of the ill-vessel non-axisymmetric field coils. Taking the merit of superconducting magnet,advanced plasma control for steady-state high performance operation could be expected.
文摘Recent progress in the physics and engineering design study for themodification programme of JT-60 is presented. In order to achieve a steady state high-βplasmaoperation, which is the dominant issue of this programme, physics design for the MHD control and thestability analysis is investigated. Engineering design and the R & D for the superconducting coils,irradiation shield are performed well towards the mission of programme.
文摘Present status of the JT-60SA （JT-60 Super Advanced） project, implemented jointly by Europe and Japan since 2007, is described. The design of the main tokamak components was completed in late 2008, and all the scientific missions are preserved to contribute to ITER and DEMO reactors. The construction of the JT-60SA has begun with procurement activities for the superconducting magnet systems, vacuum vessel, in-vessel components and other components under the relevant procurement arrangements between the implementing agencies of JAEA （Japan Atomic Energy Agency） in Japan and Fusion for Energy in Europe. Designs and developments of the auxiliary heating systems for JT-60SA have been progressing at JAEA so as to provide the total injection power of 41 MW for 100 s.
基金supported within the framework of the "Broader Approach Internationals Agreement"
文摘A superconducting coil system is actually complicated by the distributed parameters, e.g. the distributed mutual inductance among turns and the distributed capacitance between adjacent conductors. In this paper, such a complicated system was modeled with a reasonably simplified circuit network with lumped parameters. Then, a detailed circuit analysis was conducted to evaluate the possible voltage transient in the coil circuit. As a result, an appropriate （minimum） snubber capacitance for the Switching Network Unit, which is a fast high voltage generation circuit in JT-60SA, was obtained.
基金supported within the framework of the "Broader Approach Internationals Agreement"
文摘This paper describes an asymmetric control method for the firing angle and a start/stop timing shift control of four thyristor converters called ＂Booster PS＂ to minimize the reactive power fluctuation during plasma initiation in JT-60SA. From the simulation using the ＂PSCAD/EMTDC＂ code, it is found that these control methods can drastically reduce the reac- tive power induced by the four units of the ＂Booster PS＂. In addition, the voltage fluctuation of the motor-generator connected to the ＂Booster PS＂ is expected to be suppressed. This can also contribute to achieve stable control of the JT-60SA magnet power supplies.
文摘JT-60SA is a fully superconducting coil tokamak upgraded from the JT-60U. This paper focused on the integrity of the top lid of cryostat in JT-60SA. The design requirement for the cryostat in normal operations is to achieve vacuum insulation of 10-1 Pa, and the top flange of the top lid is lightly welded onto its body flange. The weld is tensile-loaded by bending deformation of the top lid due to vacuum pressure of external 0.1 MPa. This weld integrity is evaluated with tensile-load reduction, which results in clamp reinforcement. The structural integrity of the top lid is validated.
基金supported within the framework of the "Broader Approach Internationals Agreement"
文摘This paper describes a conceptual design study for the circuit configuration of the Error Field Correction Coil （EFCC） power supply （PS） to maximize the expected performance with reasonable cost in JT-60SA. The EFCC consists of eighteen sector coils installed inside the vacuum vessel, six in the toroidal direction and three in the poloidal direction, each one rated for 30 kA-turn. As a result, star point connection is proposed for each group of six EFCC coils installed cyclically in the toroidal direction for decoupling with poloidal field coils. In addition~ a six phase inverter which is capable of controlling each phase current was chosen as PS topology to ensure higher flexibility of operation with reasonable cost.
文摘Recent results of JT-60U towards establishment of physics basis for ITER andadvanced tokamak operation are presented. Progress in high integrated performance is achieved withimprovement of N-NB and ECRF heating systems. In the next experimental campaign 2003～2004,discharge duration with 17 MW heating will be extended up to 30s for sustaining high-beta plasmalonger than the current diffusion time. Superconducting modification of JT-60 is planned todemonstrate high-beta plasma sustainment exceeding ideal MHD instability limit without wallstabilization.
基金supported by National Natural Science Foundation of China （No. 10975158）, the National Magnetic Confinenmnt Fusion Research Program of China （Nos. 2009GB106002, 2010GB104005） and in part by the JSPS-CAS Core University program in the field of ＇Plasma and Nuclear Fusion＇
文摘The edge transport code SOLPS5.0 is used to model edge plasmas in the experi- mental shots on JT-60U and the profiles of the transverse particle and heat transport coefficients D, Xe and Xi along the outer midplane are obtained by fitting the simulational results to the experimental data in L-mode shot 39090 and H-mode shots 37851, 37856. The modelling and fitting results show that within the pedestal region in H-mode shots 37851 and 37856 the radial particle transport coefficient D exhibits a significant drop, but, for L-mode shot 39090, the obvious drop in both D and Xe was not found.
文摘A transport simulation has been done by using a i.5D time dependent transportcode to reproduce a formation of the ITB on electron temperature Profile during the long pu1seLHCD in JT-60U tokamak. The transport coefficients were assumed to reduce with a reversedmagnetic shear and the LH driven current profile was evaluated by fitting dynamic change inthe measured current profile. The gradual increase in the central electron temperature could beexplained by the change in the current profile during LHCD in the present simulation model. Theestimated LH-driven current profile by the transport code analysis shows a finite current densityat the plasma center. Analysis of transport simulation suggests some mechanisms for broadeningthe LH-driven current profile at the central region of the plasma.
