Design of the ITER In-Vessel Coils

Neumeyer, C.; Brooks, A.; Bryant, L.T.; Chrzanowski, J.; Feder, R.; Gomez, M.F.; Heitzenroeder, P.; Kalish, M.; Lipski, A.; Mardenfeld, M.; Simmons, R.T.; Titus, P.; Zatz, I.; Daly, Edward; Martín, A.; Nakahira, Masataka; Pillsbury, R.D.; Feng, Jun; Bohm, Tim D.; Sawan, M.E.; Griffiths, Ian M.; Schaffer, M. J.

doi:10.13182/fst11-a12333

Cited by 29 publications

(13 citation statements)

References 2 publications

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“…For ITER D-T operation, reliable ELM control is one of the biggest challenges. Therefore, it is equipped with various, well suited actuators including 27 individually powered MP coils, a variety of gas valves and pellet injectors [14,15]. MP ELM suppression is one of the main strategies to avoid ELMs and for this reason it is important to demonstrate the sustainment of such conditions in long plasma discharges as ITER will have.…”

Section: Prospects Towards Iter Controlmentioning

confidence: 99%

“…MP ELM suppression was achieved in various machines like DIII-D [5], KSTAR [6], EAST [7] and AUG [8]. While understanding the underlying mechanisms leading to MP ELM suppression is a field of ongoing research [9][10][11][12], it was decided to equip ITER with a set of MP coils for ELM control [13][14][15]. ELM suppression usually comes together with a density 'pump-out' [16], i.e.…”

Section: Introductionmentioning

confidence: 99%

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Real-time pedestal optimization and ELM control with 3D fields and gas flows on DIII-D

et al. 2020

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The capabilities of the DIII-D tokamak's plasma control system (PCS) were expanded to allow for pedestal optimization and edge localized mode (ELM) control. Three proof of principle control schemes are presented that were successfully implemented and tested. These use multiple inputs from real-time (RT) diagnostics like a D α based ELM monitor and edge profile measurements from Thomson scattering (TS) as well as 3D, i.e. non-axisymmetric, magnetic fields and gas puffs as actuators to regulate the density pedestal.The first scheme targets to optimize the access of ELM suppression induced by non-axisymmetric magnetic perturbations (MPs). The conducted set of experiments identifies a path dependence of plasma confinement on the applied MP amplitude. The controller aims to transition into ELM suppression at the minimum 3D field amplitude and reduces it further afterwards, allowing for partial confinement recovery. Another pedestal control scheme is deployed to compensate the density 'pump-out' in MP ELM suppression by regulating the gas puff. This uses RT TS diagnostic data, extracting the pedestal height from the electron density (n e ) profiles and enables studies of the transition into and out of MP ELM suppression at constant density. A limit cycle behavior of edge rotation and MP amplitude persists under these conditions. The third control scheme combines MPs and gas puffs as actuators to perform pedestal density trajectory control to access Super high confinement mode (H-mode) and furthermore, allowing the integration of a radiative divertor in this regime. While MPs mainly impact the pedestal top density, the control scheme allows to loosen the tight coupling of pedestal top and separatrix density evolution.With respect to ITER, the achieved results emphasize the need for an advanced control system to keep MP amplitude close to but above the ELM suppression threshold at all times, enabling high confinement and, respectively, at high fusion energy gain factor (Q). Furthermore, pedestal control enables detailed physics studies in present-day tokamaks and allows the exploration of core-edge integrated plasma scenarios.

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Section: Prospects Towards Iter Controlmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Real-time pedestal optimization and ELM control with 3D fields and gas flows on DIII-D

et al. 2020

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“…The predictive model for mode dynamics was adapted to ITER to estimate the entrainment capabilities for 2/1 islands. In its present design, ITER will have two sets of 3D coils: the internal three rows of nine ELM control coils [40] and the external three rows of six correction coils [41]. Continuing the phasor representation used by Olofsson [21], each set of coils was modeled by an amplitude and phase appropriate for the applied RMP, optimized for maximum coupling (in vacuum) to the 2/1 island.…”

Section: Modeling Of Feedback Control On Itermentioning

confidence: 99%

Feedforward and feedback control of locked mode phase and rotation in DIII-D with application to modulated ECCD experiments

et al. 2018

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Abstract. The toroidal phase and rotation of otherwise locked magnetic islands of toroidal mode number n=1 are controlled in the DIII-D tokamak by means of applied magnetic perturbations of n=1. Pre-emptive perturbations were applied in feedforward to "catch" the mode as it slowed down and entrain it to the rotating field before complete locking, thus avoiding the associated major confinement degradation. Additionally, for the first time, the phase of the perturbation was optimized in real-time, in feedback with magnetic measurements, in order for the mode's phase to closely match a prescribed phase, as a function of time. Experimental results confirm the capability to hold the mode in a given fixed-phase or to rotate it at up to 20 Hz with good uniformity. The controlcoil currents utilized in the experiments agree with the requirements estimated by an electromechanical model. Moreover, controlled rotation at 20 Hz was combined with Electron Cyclotron Current Drive (ECCD) modulated at the same frequency. This is simpler than regulating the ECCD modulation in feedback with spontaneous mode rotation, and enables repetitive, reproducible ECCD deposition at or near the island O-point, X-point and locations in between, for careful studies of how this affects the island stability. Current drive was found to be radially misaligned relative to the island, and resulting growth and shrinkage of islands matched expectations of the Modified Rutherford Equation for some discharges presented here. Finally, simulations predict the as designed ITER 3D coils can entrain a small island at sub-10 Hz frequencies.Page 1 of 15 AUTHOR SUBMITTED MANUSCRIPT -NF-102117. R2 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 Control of locked mode phase and rotation with application to modulated ECCD 2 Figure 1. Perturbed current pattern, sinusoidal in helical angle mθ − nφ, of a m/n = 2/1 magnetic island mapped onto a thin surface. Also depicted are the internal I-coils (green) and external C-coils (red) used to generate 3D fields on DIII-D.

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“…where I, ρ, l, A, a, n are the effective value of total current (36 kAt), copper resistivity (2.21e-8 Ω•m), conductor length, cross-section area of all turns, crosssection area per turn (8.84e-4 m 2 ) and the number of remaining turns, respectively. To cool down the conductors and attachments, the hollow copper pipe is designed to force the water flow with velocity of 3 m/s and inlet temperature of 100 o C [1] . The film coefficient of convection relating to the water properties, flow rate and the hydraulic diameter of the pipe can be calculated as follows.…”

Section: Load Descriptionmentioning

confidence: 99%

“…The "Stainless Steel Jacketed Mineral Insulated Conductor (SSMIC)" is the key feature of the design. The C10200 copper is used to deliver currents, magnesium oxide is used as insulation, and AISI 316LN is used in the jacket and other attachments in the structures of the coil [1] . The coil is very axisymmetric and in a circular structure with no bends until the 120 degree joints, break-outs and leads are encountered ( Fig.…”

Section: Introductionmentioning

confidence: 99%

Thermal and Hydraulic Analysis of the ITER Upper Vertical Stabilization Coil

Yang¹,

Song²,

Wang³

2014

Plasma Sci. Technol.

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The ITER upper vertical stabilization (VS) coil is a part of the ITER in-vessel coil (IVC) system, which has the abilities of restraining edge localized modes (ELMs) and maintaining plasma vertical stability. Preliminary structural analysis of the coil has revealed serious thermal stress problems. Due to the very restricted geometry space, it is necessary to perform detailed analysis on thermal and hydraulic characteristics to help optimal design of the coil. It will focus on the temperature distribution and energy balance, as well as some key factors, such as the coolant flow state and surface emissivity, which have influences on the coil performance. The APDL code and some hand calculations are employed in the analysis. The results show that the coolant convection can effectively take away the heat deposited in the coil. But improving the coolant flow state can hardly mitigate the peak temperature occurring at the edges of coil attachments, which are located far away from the coolant. Thermal radiation was expected to be a good method of cooling down these parts. But the reality is not so optimistic since it usually contributes little in the whole energy balance. However, the effect of thermal radiation will become remarkable when bad scenarios or accidents take place. Poor radiation performance of the coil will result in a potential safety hazard.

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Design of the ITER In-Vessel Coils

Cited by 29 publications

References 2 publications

Real-time pedestal optimization and ELM control with 3D fields and gas flows on DIII-D

Real-time pedestal optimization and ELM control with 3D fields and gas flows on DIII-D

Feedforward and feedback control of locked mode phase and rotation in DIII-D with application to modulated ECCD experiments

Thermal and Hydraulic Analysis of the ITER Upper Vertical Stabilization Coil

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