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[en] The determination of a ground fault current is described in the case where a ground fault occurs in JT-60 device. Specifically, a case in which six coils caused a simultaneous ground fault is investigated. It is found that when faults in vertical and toroidal magnetic field coils occur simultaneously, the resultant ground fault current is very large
[en] The JT-60SA device has been designed as a highly shaped large superconducting tokamak with a variety of plasma actuators (heating, current drive, momentum input, stability control coils, resonant magnetic perturbation coils, W-shaped divertor, fuelling, pumping, etc) in order to satisfy the central research needs for ITER and DEMO. In the ITER- and DEMO-relevant plasma parameter regimes and with DEMO-equivalent plasma shapes, JT-60SA quantifies the operation limits, plasma responses and operational margins in terms of MHD stability, plasma transport and confinement, high-energy particle behaviour, pedestal structures, scrape-off layer and divertor characteristics. By integrating advanced studies in these research fields, the project proceeds 'simultaneous and steady-state sustainment of the key performances required for DEMO' with integrated control scenario development applicable to the highly self-regulating burning high-β high bootstrap current fraction plasmas.
[en] The real vacuum vessel (VV) manufacturing of JT-60SA has started since November 2009 at Toshiba. Prior to starting manufacturing, fundamental welding R and Ds had been performed by three stages. In the first stage, primary tests for screening welding method were performed. In the second stage, the trial welding for 1 m-long straight and curved double shell samples were conducted. The dependences of welding quality and distortion on the welding conditions, such as arc voltage and current, setting accuracy, welding sequence, and the shape of grooves were studied. In addition, welding condition with low heat input was explored. In the last stage, fabrication sequence was confirmed and established by the trial manufacturing of the 20o upper half mock-up . This paper presents the R and D results obtained in the first and second stages.
[en] This paper describes the central control system of the JT-60 tokamak. This control system not only has to organize plasma operation, but also has to utilize devices under isolated operation. Therefore the control system has been designed in a special way. (orig.)
[en] JT-60 power supplies have been under operation from 1985 with some components of them being modified in shutdown period of JT-60 to satisfy the operational requirements in the plasma experiments. Especially, in 1987, to achieve the extended plasma current operations of 3.2MA in limiter and 2.7MA in magnetic separatrix configurations, the output current capabilities of JT-60 power supplies were enhanced by installing a booster thyristor convertor and so on. Here, such operational experiences, including relevant modifications, of JT-60 power supplies are described. And also, the present status of JT-60 power supplies for the operation in 1988 is mentioned. (author). 6 refs.; 4 figs
[en] Highlights: • We describe the status of the JT-60SA TF coils manufacture at Alstom. • The manufacturing workflow and related tooling are described. • Completion of qualification activities has allowed to start the coils production. • Production of the first winding up to its impregnation is described. • Winding of following coils is started. - Abstract: Within the framework of the Broader Approach, the French voluntary contributor represented by CEA awarded a contract for the production of 9 toroidal field coils for the JT-60SA project to Alstom, Belfort, France in mid-2011. A first preparatory phase was led to establish the team, produce the manufacture drawings, define the manufacturing process, procure the required tooling and prepare the quality documentation. In parallel, a qualification phase on the critical major processes has proved Alstom's ability to master the processes and reach the requirements. After reviewing of the qualification results and modification of the processes and tooling to overcome the encountered difficulties, a Production Readiness Review has authorized Alstom to start the production winding. A prototype double pancake was wound as the first of series. In addition to complying with the pancake width all around the D shape, the straightness of the centreline in the critical straight leg part was correct. The production of the successive double pancakes to constitute the first winding pack was then completed and the joints and terminals were manufactured. The paper describes the completion of the last qualifications and the status of the winding production.
[en] The objectives of JT-60 are to achieve and investigate hydrogen plasmas with equivalent Q=1 conditions and to make an integrated test of fusion technologies required for the next stage of advancement. JT-60 is composed of numerous components of the tokamak machine, the vacuum pumping system, the power supply system, the heating system, and the control system etc. JT-60 has been successfully in operation since April '85. It is owing to deliberate design, careful fabrication and maintenance and speedy trouble shooting. For instance, the bolted first wall is easily changeable and monitored during operation period in vacuum by the in-vessel inspection system, so as to shorten the period of shut down. Several kinds of criteria are settled for electrical insulation and vacuum control etc., and strictly applied for actual operation and maintenance. (author). 13 refs, 13 figs, 3 tabs