Wendelstein 7-X Trim Coils—Component Safety Aspects and Commissioning Strategy

Riße, K.; Füllenbach, F.; Rummel, Thomas; Mardenfeld, M.; Zhao, Xin

doi:10.1109/tps.2013.2294341

Cited by 6 publications

(5 citation statements)

References 4 publications

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“…In fig. 6 a comparison is shown between flux surfaces without error field, and with an error field with a 1/1 component of B 11 /B 0 = 1 • 10 −4 T. The error field in this simulation is generated by operating the five trim coils [32,33] with different currents (following a sine function around the torus). The direction of the shift of the axis is uniquely related to the phase of the 1/1 field error and the magnitude of the shift allows a direct measurement of the 1/1 field error amplitude (see fig.…”

Section: Flux Surface Measurementsmentioning

confidence: 99%

“…Although this would result in an asymmetric distribution of the heat load to the different divertor modules, it may prove difficult to detect it by flux surface mapping. Instead, the high -ι reference configuration which has ι just above 1 on the magnetic axis will be chosen, such that the axis itself will shift measurably for a resonant 1/1 field error as low as 4 T. The error field in this simulation is generated by operating the five trim coils [32,33] with different currents (following a sine function around the torus). The direction of the shift of the axis is uniquely related to the phase of the 1/1 field error and the magnitude of the shift allows a direct measurement of the 1/1 field error amplitude (see figure 7).…”

Section: Flux Surface Measurementsmentioning

confidence: 99%

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Plans for the first plasma operation of Wendelstein 7-X

et al. 2015

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Wendelstein 7-X (W7-X) is currently under commissioning in preparation for its initial plasma operation phase, operation phase 1.1 (OP1.1). This first phase serves primarily to provide an integral commissioning of all major systems needed for plasma operation, as well as systems, such as diagnostics, that need plasma operation to verify their foreseen functions. In OP1.1, W7-X will have a reduced set of in-vessel components. In particular five graphite limiter stripes replace the later foreseen divertor. This paper describes the expected machine capabilities in OP1.1, as well as a selection of physics topics that can be addressed in OP1.1, despite the simplified configuration and the reduced machine capabilities. Physics topics include verification and adjustment of the magnetic topology, testing of the foreseen plasma start-up scenarios and feed-forward control of plasma density and temperature evolution, as well as more advanced topics such as scrape-off layer (SOL) studies at short connection lengths, and transport studies. Plasma operation in OP1.1 will primarily be performed in helium, with a hydrogen plasma phase at the end.

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Section: Flux Surface Measurementsmentioning

confidence: 99%

Section: Flux Surface Measurementsmentioning

confidence: 99%

Plans for the first plasma operation of Wendelstein 7-X

et al. 2015

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“…Equation (1) shows the general relation between strain (ε) and corresponding equivalent temperature (#Þ.…”

Section: Ivc2 Temperature Compensationmentioning

confidence: 99%

“…In addition to the superconducting coils a set of 5 normal conducting trim coils could be in operation to allow a fine tuning of the main magnetic field in order to influence field errors disturbing the toroidal periodicity. 1 The ramp up and down rate of the trim coil currents is up to 2000 A/s (Ref. 2).…”

Section: Introductionmentioning

confidence: 99%

Engineering Challenges of W7-X: Improvement of Numerical Modeling and Mechanical Monitoring After Commissioning and First Phase of Operation

Bykov

Zhu

Carls

et al. 2017

Fusion Science and Technology

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The largest modular stellarator Wendelstein 7-X (W7-X) has successfully passed commissioning and first phase of operation in Greifswald, Germany. The limiter configurations of plasma with 2.5 T of magnetic induction on the plasma axis produce already considerable loads (MN) in the W7-X systems. The sophisticated W7-X superconducting magnet system with its non-linear support system is instrumented with an extensive set of mechanical and temperature sensors. Measurement results showed that magnet system behavior is in good correspondence with original predictions from numerical models. However, several areas require modeling improvements and/or proper adjustment of parameters to reflect "as-built" situation. Moreover, high temperature dependence of strain gauge signal accuracy in the range below 10 K requires its compensation in order to avoid fault alarms during monitoring. The work is considered as benchmarking of numerical models and as a preparation for upcoming more demanding phases with longer plasma pulses to guarantee safe and reliable W7-X operation with different divertor configurations. Both results of W7-X measurements and implemented improvements as well as lessons learned so far are also given.

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“…Wendelstein 7-X Presently the focus of activities is shifted to in-vessel components, diagnostics and periphery [18,30], as well as to fast analyses of non-conformities (NCR) reported by manufacturers and the assembly team. Error field analyses are to be completed in order to specify the initial current configuration of the trim coils [26][27][28][29].…”

Section: Further Activitiesmentioning

confidence: 99%

Numerical modelling in the construction of Wendelstein 7-X

Bykov

Fellinger

Schauer

et al. 2013

2013 IEEE 25th Symposium on Fusion Engineering (SOFE)

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The Wendelstein 7-X modular stellarator is in the final assembly phase at the Max Planck Institute for Plasma Physics in Greifswald, Germany. The design and assembly of the "basic machine", i.e. without in-vessel components, diagnostics and periphery, is completed. Structural parameters such as bolt preload, initial gap widths for contacts between structure elements, final magnet module positions, etc., were specified on the basis of detail numerical modeling and are now implemented. The focus of the numerical analysis has been shifted towards fast consideration of nonconformities and changes in assembly procedures, to preparation of commissioning, assessment of possible field disturbances, and exploration of operational limits. In parallel the analyses of in-vessel components, diagnostics and periphery are being continued.The paper focuses on the development, evolution and realization of analysis strategies, implemented numerical approaches and most remarkable results, and on a few specific issues like parameterization and complex finite element model structuring. Further subjects are reasonable safety margins in relation to expected tolerances and uncertainties, and the confirmation of analysis results by tests as well as their benchmarking with alternative models in different codes. Finally, some lessons learned so far which might be relevant for other large fusion machines are highlighted, and a brief outlook on future work is given.

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Wendelstein 7-X Trim Coils—Component Safety Aspects and Commissioning Strategy

Cited by 6 publications

References 4 publications

Plans for the first plasma operation of Wendelstein 7-X

Plans for the first plasma operation of Wendelstein 7-X

Engineering Challenges of W7-X: Improvement of Numerical Modeling and Mechanical Monitoring After Commissioning and First Phase of Operation

Numerical modelling in the construction of Wendelstein 7-X

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