Eigenmode analysis of the ITER ICRF antenna plug and electrical solution to the grounding of the antenna

Louche, F.; Messiaen, A.; Dumortier, P.; Durodié, F.; Koch, R.; Lamalle, P.

doi:10.1088/0029-5515/49/6/065025

Cited by 13 publications

(15 citation statements)

References 9 publications

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“…Theoretical and experimental [24,25] efforts were spent to understand the aspects of the grounding of the PP to the VV to avoid spurious resonances in the 24x24 strap impedance matrix [26] as well as the presence of high electric fields in the nominal 20mm gap between the PP and VV [27]. The effectiveness of the proposed grounding to reduce electric fields in these areas is discussed in [28] which shows that without the additional grounding towards the front of the PP the fields can even exceed these on the high power components of the launcher.…”

Section: Groundingmentioning

confidence: 99%

Performance assessment of the ITER ICRF antenna

Durodié¹,

Vrancken²,

Bamber

et al. 2014

AIP Conference Proceedings

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ITER's Ion Cyclotron Range of Frequencies (ICRF) system [1] comprises two antenna launchers designed by CYCLE (a consortium of European associations listed in the author affiliations above) on behalf F4E for the ITER Organisation (IO), each inserted as a Port Plug (PP) into one of ITER's Vacuum Vessel (VV) ports. Each launcher is an array of 4 toroidal by 6 poloidal RF current straps specified to couple up to 20 MW in total to the plasma in the frequency range of 40 to 55 MHz but limited to a maximum system voltage of 45 kV and limits on RF electric fields depending on their location and direction with respect to respectively the torus vacuum and the toroidal magnetic field. A crucial aspect of coupling ICRF power to plasmas is the knowledge of the plasma density profiles in the Scrape-Off Layer (SOL) and the location of the RF current straps with respect to the SOL. The launcher layout and details were optimized and its performance estimated for a worst case SOL provided by the IO. The paper summarizes the estimated performance obtained within the operational parameter space specified by IO. Aspects of the RF grounding of the whole antenna PP to the VV port and the effect of the voids between the PP and the Blanket Shielding Modules (BSM) surrounding the antenna front are discussed.

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Section: Groundingmentioning

confidence: 99%

Performance assessment of the ITER ICRF antenna

Durodié¹,

Vrancken²,

Bamber

et al. 2014

AIP Conference Proceedings

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“…if Isc is sufficiently small. To further assess the performance of the grounding solution, we have computed the maximum currents on the blanket connectors [4]: the proposed solution (#1) keeps the currents on the connectors below 5 % of the strap currents. In real operation of the antenna the modes which can be excited and can propagate on the plug are dependent on the generator frequency as well as on the phasing of the currents on the straps.…”

Section: Modeling Of the Iter Icrh Antenna Plugmentioning

confidence: 99%

“…It is designed to deliver 20 MW to the plasma with low strap voltages and a well controlled distribution of RF current among the straps. The results summarized here are extensively developed in [4]. The former are mostly dependent on the geometry of the array and therefore the usage of modern commercial electromagnetic solvers like CST Microwave Studio®(MWS) [2] is strongly helpful.…”

Section: Introductionmentioning

confidence: 99%

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Eigenmode analysis of the ITER ICRF antenna plug and electrical solution to the grounding of the antenna

Louche¹,

Messiaen²,

Dumortier³

et al. 2009

AIP Conference Proceedings

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The excitation of resonant modes in the gap between the ITER ICRH antenna plug and the vessel can considerably increase the level of RF currents and voltages on the ITER plug and disturb the radiation characteristic of the array. We report on a study of these modes and a solution to avoid them in the ITER ion cyclotron range of frequencies. From a transmission Une approach we show that resonances can be avoided if the distance between the mouth of the Une and an added short-circuit is sufficiently small. We therefore propose to position short-circuits at about Im from the antenna mouth, constituted by rows of closely spaced contacts all around the plug. These conclusions are further validated with Microwave Studio simulations. A simplified model of the ITER ICRF array is used for comparing various grounding solutions and it is proved that the solution already inferred from transmission line approximation suppresses the resonances from the frequency domain relevant for ICRH in ITER. The MWS calculations predict that the proposed solution also avoids large RF currents in the blanket modules and in their connectors. Their amplitude barely exceeds 5 % of the strap RF currents. This solution avoids perturbation of the antenna array impedance matrix by the coaxial gap.

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“…RF calculations have established that in the ports containing an ICRH antenna, parasitic electrical resonances in this gap at ICRH frequencies can be excited which have an adverse effect on the performance of the antenna and induce large voltages on surrounding components. Further calculation has shown that these resonances can be effectively mitigated by a series of electrically conducting contacts between the port and plug, recessed 1m from the first wall [1]. In order to be able to install and remove the antenna from the port, these contacts must not interfere with the surrounding components while still being able to make reliable electrical contact once the antenna is in operation.…”

Section: Introductionmentioning

confidence: 99%

Design of a mechanically actuated RF grounding system for the ITER ICRH antenna

Hancock

Shannon

Beaumont

et al. 2013

Fusion Engineering and Design

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In the ITER equatorial ports containing ICRH antennas, parasitic electrical resonances can be excited in the nominal 20 mm clearance gap between the port walls and the plug contained within it. RF calculations have established that these resonances can be effectively mitigated by a series of suitably located electrically conducting contacts between the port and plug. These contacts must allow installation and removal of the antenna but must also make reliable electrical contact during antenna operation. In addition, the contacts must be compliant enough to survive deflection of the port during seismic and disruption events without transmitting large forces to the vacuum vessel. The distance to be spanned is subject to significant uncertainty, due to the large manufacturing tolerances of the surrounding components, and this also must be considered during the design process. This paper outlines progress made in the design of the grounding system, as well as detailing a number of concepts which have been investigated and abandoned, leading up to the current reference design. The current reference design is a simple and robust mechanical solution consisting of sprung Copper-plated Inconel flaps which use part of the range of the shimming system included in the antenna design as the actuation mechanism. This paper also details practical testing of a number of aspects of the design, including building and testing a prototype to validate mechanical and thermal analyses.

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Eigenmode analysis of the ITER ICRF antenna plug and electrical solution to the grounding of the antenna

Cited by 13 publications

References 9 publications

Performance assessment of the ITER ICRF antenna

Performance assessment of the ITER ICRF antenna

Eigenmode analysis of the ITER ICRF antenna plug and electrical solution to the grounding of the antenna

Design of a mechanically actuated RF grounding system for the ITER ICRH antenna

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