Thermal analyses of the in-vessel frontends of the ITER plasma position reflectometry system

Nietiadi, Yohanes; Vidal, Catarina; Luís, R.; Varela, P.

doi:10.1016/j.fusengdes.2020.111599

Cited by 3 publications

(7 citation statements)

References 3 publications

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“…As shown, the maximum operating temperatures would be well above the limit of 450 °C for the selected material (ITER-grade stainless steel) under neutron irradiation. Thus, it was proposed that these components were manufactured from other materials, such as tungsten or a nickel-based superalloy [21]. The system of gap 4 had the antennas located in the low-field side (LFS) of sector 9, between the blanket modules (BMs) in rows #11 and #12.…”

Section: Thermal Loads and Materials Testingmentioning

confidence: 99%

“…As shown, the maximum operating temperatures would be well above the limit of 450 °C for the selected material (ITER-grade stainless steel) under neutron irradiation. Thus, it was proposed that these components were manufactured from other materials, such as tungsten or a nickel-based superalloy [21]. To minimise the EM forces induced during plasma disruptions, the in-vessel waveguides were made from ITER grade stainless steel (SS 316(LN)-IG), but coated inside with a thin (15-25 µm) Copper layer to keep ohmic losses at a minimum.…”

Section: Thermal Loads and Materials Testingmentioning

confidence: 99%

See 1 more Smart Citation

Advances, Challenges, and Future Perspectives of Microwave Reflectometry for Plasma Position and Shape Control on Future Nuclear Fusion Devices

Gonçalves

Varela

Silva

et al. 2023

Sensors

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Providing energy from fusion and finding ways to scale up the fusion process to commercial proportions in an efficient, economical, and environmentally benign way is one of the grand challenges for engineering. Controlling the burning plasma in real-time is one of the critical issues that need to be addressed. Plasma Position Reflectometry (PPR) is expected to have an important role in next-generation fusion machines, such as DEMO, as a diagnostic to monitor the position and shape of the plasma continuously, complementing magnetic diagnostics. The reflectometry diagnostic uses radar science methods in the microwave and millimetre wave frequency ranges and is envisaged to measure the radial edge density profile at several poloidal angles providing data for the feedback control of the plasma position and shape. While significant steps have already been given to accomplish that goal, with proof of concept tested first in ASDEX-Upgrade and afterward in COMPASS, important, ground-breaking work is still ongoing. The Divertor Test Tokamak (DTT) facility presents itself as the appropriate future fusion device to implement, develop, and test a PPR system, thus contributing to building a knowledge database in plasma position reflectometry required for its application in DEMO. At DEMO, the PPR diagnostic’s in-vessel antennas and waveguides, as well as the magnetic diagnostics, may be exposed to neutron irradiation fluences 5 to 50 times greater than those experienced by ITER. In the event of failure of either the magnetic or microwave diagnostics, the equilibrium control of the DEMO plasma may be jeopardized. It is, therefore, imperative to ensure that these systems are designed in such a way that they can be replaced if necessary. To perform reflectometry measurements at the 16 envisaged poloidal locations in DEMO, plasma-facing antennas and waveguides are needed to route the microwaves between the plasma through the DEMO upper ports (UPs) to the diagnostic hall. The main integration approach for this diagnostic is to incorporate these groups of antennas and waveguides into a diagnostics slim cassette (DSC), which is a dedicated complete poloidal segment specifically designed to be integrated with the water-cooled lithium lead (WCLL) breeding blanket system. This contribution presents the multiple engineering and physics challenges addressed while designing reflectometry diagnostics using radio science techniques. Namely, short-range dedicated radars for plasma position and shape control in future fusion experiments, the advances enabled by the designs for ITER and DEMO, and the future perspectives. One key development is in electronics, aiming at an advanced compact coherent fast frequency sweeping RF back-end [23–100 GHz in few μs] that is being developed at IPFN-IST using commercial Monolithic Microwave Integrated Circuits (MMIC). The compactness of this back-end design is crucial for the successful integration of many measurement channels in the reduced space available in future fusion machines. Prototype tests of these devices are foreseen to be performed in current nuclear fusion machines.

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Section: Thermal Loads and Materials Testingmentioning

confidence: 99%

“…As shown, the maximum operating temperatures would be well above the limit of 450 °C for the selected material (ITER-grade stainless steel) under neutron irradiation. Thus, it was proposed that these components were manufactured from other materials, such as tungsten or a nickel-based superalloy [21]. To minimise the EM forces induced during plasma disruptions, the in-vessel waveguides were made from ITER grade stainless steel (SS 316(LN)-IG), but coated inside with a thin (15-25 µm) Copper layer to keep ohmic losses at a minimum.…”

Section: Thermal Loads and Materials Testingmentioning

confidence: 99%

Advances, Challenges, and Future Perspectives of Microwave Reflectometry for Plasma Position and Shape Control on Future Nuclear Fusion Devices

Gonçalves

Varela

Silva

et al. 2023

Sensors

Self Cite

View full text Add to dashboard Cite

show abstract

“…Based on these results, there is no preferred value of . However, already for the currently 320 used = 120 mm the heat loads on the antennas could be problematic [37], so < 120 mm is not of reflectometers [38] and the asymmetry observed can be attributed to misalignment between the antenna and blanket structure, which can be introduced with each mechanical change done on the setup in between measurements. This explanation is supported by comparison of Figure 7b with Fig.…”

Section: −90° ( )Dmentioning

confidence: 99%

“…Based on these results, there is no preferred value of 𝐿. However, already for the currently used 𝐿 = 120 mm the heat loads on the antennas could be problematic [37], so 𝐿 < 120 mm is not advisable from a thermal point of view. In figure 7, multiple radiation patterns are asymmetrical.…”

Section: Jinst 16 P07040mentioning

confidence: 99%

“…Changing the antenna position relative to the blankets (corresponding to moving it closer to the plasma) did not result better frequency-independent radiation patterns. Multiple measurements show that small misalignment of the antenna in the blanket environment causes strong asymmetry in the radiation patterns, indicating the need of 361 careful mounting and a further study on possible thermal expansion [37], which could introduce asymmetry in the setup during tokamak operation. Additional PROFUSION simulations with the optimally-shaped antenna showed that also small fractions of higher-order modes at the antenna feed result in asymmetry in the radiation pattern.…”

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confidence: 99%

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On frequency-independent horn antenna design for plasma positioning reflectometers, from simulation to prototype testing

Lips¹,

Heuraux²,

Lechte³

et al. 2021

J. Inst.

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Using a new framework for horn antenna optimization, a first frequency-independent horn antenna for a plasma positioning reflectometer (PPR) is designed. This hardware optimization is a new approach aiming on lowering the computational complexity of PPR interpretative models able to extract profiles and fluctuations of electron density and temperature from reflectometry measurements. PPR measurements are a strong candidate to provide real-time feedback for plasma position control in long-discharge fusion tokamaks such as ITER and DEMO, which requires fast interpretative models. Reducing the computational complexity of these models is therefore critical. In this paper, ray tracing simulations in the poloidal plane are used to compare different radiation patterns and evaluate them on multiple performance criteria. An antenna shape leading to a frequency-independent far-field radiation diagram is found with the PROFUSION optimizer and a prototype of this antenna is tested against an unoptimized conical reference antenna. The ray tracing performance criteria indicate that fundamental Gaussian frequency-independent antennas perform well, albeit in general worse than same-sized frequency-dependent antennas. Furthermore, it is seen that the pyramidal ITER gap 6 antenna performs well given the spatial constraints and that more performant antennas could be used, when more space was available. The prototype testing reveals challenges in obtaining frequencyindependent characteristics within a tokamak blanket environment, which is additionally complicated by misalignment risks.

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Design and performance analysis of a High Field Side antenna for Plasma Position Reflectometry control on DTT

Santos,

Silva,

da Silva

et al. 2024

Fusion Engineering and Design

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Thermal analyses of the in-vessel frontends of the ITER plasma position reflectometry system

Cited by 3 publications

References 3 publications

Advances, Challenges, and Future Perspectives of Microwave Reflectometry for Plasma Position and Shape Control on Future Nuclear Fusion Devices

Advances, Challenges, and Future Perspectives of Microwave Reflectometry for Plasma Position and Shape Control on Future Nuclear Fusion Devices

On frequency-independent horn antenna design for plasma positioning reflectometers, from simulation to prototype testing

Design and performance analysis of a High Field Side antenna for Plasma Position Reflectometry control on DTT

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