Assessment of the ITER high-frequency magnetic diagnostic set

Testa, D.; Carfantan, Hervé; Toussaint, M.; Chavan, R.; Fournier, Yannick; Guterl, J.; Lister, J.B.; Maeder, Thomas; Moret, J.M.; Pérez, A.; Sánchez, F.; Schaller, Benoît; Slater, Conor; Stoeck, M.; Tonetti, G.

doi:10.1016/j.fusengdes.2011.03.118

Cited by 3 publications

(3 citation statements)

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“…The assembly of the winding pack is a difficult operation to perform when the reliability of the winding process and the geometrical reproducibility have to be guaranteed to a high degree, as is the case in ITER, where we will have between 170 and 500 HF magnetic sensors, depending on the chosen system implementation. 12 Hence, although each sensor will be individually tested, the reproducibility and the reliability of the assembly process must be as high as possible, if nothing else simply to facilitate the data analysis and the possible swapping of faulty sensors with unused sensors.…”

Section: Ivd Summary and Conclusion On The Mechanical Testingmentioning

confidence: 99%

“…For a more complete overview of these requirements, see the ITER Design Description Document DDD 5.5.A, ITER document reference N55DDD101-06-12W0.3. See also the various presentations made at the ITER diagnostics review meetings on July [9][10][11][12][13]2007. See also several presentations made at meetings of the International Tokamak Physics Activity~ITPA!…”

Section: Introductionmentioning

confidence: 99%

“…The latter has been discussed in detail elsewhere. 12 The previous development of the HF Mirnov-type pickup coil design was based on a sensor in use on ASDEX-Upgrade~Ref. 13 c !.…”

Section: Introductionmentioning

confidence: 99%

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Prototyping Conventionally Wound High-Frequency Magnetic Sensors for ITER

Testa

Toussaint

Chavan

et al. 2012

Fusion Science and Technology

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The high-frequency (HF) magnetic sensors for ITER are currently based on a conventional, Mirnov-type pickup coil, with an effective area in the range 0.03 Ͻ (NA) EFF (m 2) Ͻ 0.1; the sensor is required to provide measurements of magnetic instabilities with magnitude around |dB/B u | ;10 Ϫ4 in the 10-kHz to 2-MHz frequency range. The physical, mechanical, and electrical properties of one representative ITER HF pickup coil design have been analyzed with particular attention to the manufacturing and assembly process for the winding pack, as its integrity was found to be of concern when performing a coupled electromagnetic, structural, and thermal analysis of the sensor. Three different options for the guiding grooves in that design have been tested, using copper and tungsten for the winding pack, but none of them has been convincing enough due to the likelihood of breakages of the thin grooving and of the tungsten wire itself. Hence, alternative designs still based on a conventional Mirnovtype pickup coil have been explored, and a nonconventional Mirnov-type pickup coil was produced using direct laser cutting of a Type 316 stainless steel hollow tube, avoiding the difficulties encountered during the winding operations for conventional Mirnov-type sensors. This process of manufacturing appears to be acceptable for HF magnetic sensors of Mirnov-type design in ITER, and it is recommended for future prototyping studies, as the effective area of our first prototype, (NA) EFF ; 0.01 m 2 , was well below the ITER requirement. The electrical characteristics and the frequency response of all these prototypes were evaluated up to 8 MHz, with the results in good agreement with model calculations. The conventional Mirnov-type prototypes behave as expected in terms of their main electrical properties and should satisfy the present measurement performance requirements. Finally, a direct measurement of the effective area of these sensors has shown that the geometrical value is a sufficiently correct estimate of its actual value at low frequencies (Ͻ10 kHz) when the winding pack closely follows the nominal shape of the coil itself.

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Section: Ivd Summary and Conclusion On The Mechanical Testingmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Prototyping Conventionally Wound High-Frequency Magnetic Sensors for ITER

Testa

Toussaint

Chavan

et al. 2012

Fusion Science and Technology

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LTCC and Thick-film Ceramic Magnetic Sensors for Tokamak Nuclear Fusion

Maeder

Jacq

Testa

et al. 2016

Procedia Engineering

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Manufacturing, installation, commissioning, and first results with the 3D low-temperature co-fired ceramic high-frequency magnetic sensors on the Tokamak à Configuration Variable

Testa

Team²,

Team³

2020

Review of Scientific Instruments

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Innovative high-frequency magnetic sensors have been designed and manufactured in-house for installation on the Tokamak à Configuration Variable (TCV), which are now routinely operational during the TCV experimental campaigns. These sensors combine the Low Temperature Co-fired Ceramic (LTCC) and the classical thick-film technologies and are in various aspects similar to the majority of the in-vessel inductive magnetic sensors foreseen for ITER (around 450 out of the 505 currently being procured are of the LTCC-1D type). The TCV LTCC-3D magnetic sensors provide measurements in the frequency range up to 1 MHz of the perturbations to the wall-aligned toroidal (δBTOR), vertical (δBVER), and radial (δBRAD) magnetic field components. Knowledge of the equilibrium at the last closed flux-surface allows us to then obtain the field-aligned parallel (δBPAR ∼ δBTOR), poloidal (δBPOL), and normal (δBNOR) components, the latter being in most cases rather different from the vertical and radial components, respectively. The main design principles were aimed at increasing the effective area and reducing the self-inductance of the sensor in each of the three measurement axes, which are centered at the same position on each sensor, while reducing the mutual and parasitic coupling between them by optimizing the on-board wiring. The physics requirements are set by the installation of two high-power/high-energy neutral beam injection systems on TCV, i.e., studying fast ions physics, coherent instabilities, and turbulence in the (super-)Alfvénic frequency range. In this paper, we report the manufacturing, installation, and commissioning work for these high-frequency LTCC-3D magnetic sensors and conclude with an overview of illustrative experimental results obtained with this system. The LTCC-3D data provide new insights into the δBPOL coherent (eigenmodes, up to ∼400 kHz) and in-coherent background turbulent fluctuations in the higher frequency range up to ∼1 MHz, which were not previously available with the TCV Mirnov sensors. Furthermore, the LTCC-3D δBPOL measurements allow us to cross-check the data obtained with the standard Mirnov coils and have led to the identification of largeelectromagnetic (EM) noise pick-up for the Mirnov data acquisition (DAQ). When the sources of EM noise pick-up on the Mirnov DAQ are removed, the LTCC-3D data for δBPOL are in good overall agreement, i.e., within the expected measurement uncertainties, with those obtained with the standard Mirnov sensors located at the same poloidal position in the frequency range where the respective data acquisition overlap, routinely up to 125 kHz and up to 250 kHz in some discharges. The LTCC-3D δBPAR measurements (not previously available in TCV or elsewhere) provide evidence that certain instabilities have a finite parallel δB at the wall, hence at the LCFS, consistent with the recent theoretical results for pressure-driven modes. The LTCC-3D δBNOR measurements improve significantly on the corresponding measurements with the saddle loops, which are mounted onto the wall and have a bandwidth of ∼3 kHz (due to the wall penetration time). A detailed end-to-end system modeling tool has been developed and applied to test on the simulated data the actual measurement capabilities of this new diagnostic system and obtain the ensuing estimates of the intrinsic measurement uncertainties. A detailed error analysis is then performed so that, finally, fully calibrated, absolute measurements of the frequency-dependent amplitude and spectral breaks of coherent eigenmodes and in-coherent broadband magnetic fluctuations are provided for the first time in physical units with quantitative uncertainties.

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Assessment of the ITER high-frequency magnetic diagnostic set

Cited by 3 publications

References 13 publications

Prototyping Conventionally Wound High-Frequency Magnetic Sensors for ITER

Prototyping Conventionally Wound High-Frequency Magnetic Sensors for ITER

LTCC and Thick-film Ceramic Magnetic Sensors for Tokamak Nuclear Fusion

Manufacturing, installation, commissioning, and first results with the 3D low-temperature co-fired ceramic high-frequency magnetic sensors on the Tokamak à Configuration Variable

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