Influence of gas injection location and magnetic perturbations on ICRF antenna performance in ASDEX Upgrade

Bobkov, V.; Stepanov, I.; Jacquet, P.; Monakhov, I.; Bilato, R.; Colas, L.; Czarnecka, A.; Dux, R.; Faugel, H.; Kallenbach, A.; Müller, H. W.; Noterdaeme, J.‐M.; Potzel, S.; Pütterich, T.; Suttrop, W.

doi:10.1063/1.4864540

Cited by 24 publications

(8 citation statements)

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“…References [41,97] reported larger W erosion on AUG antenna limiters in N 2 -seeded discharges aimed at enhancing the divertor radiation, as compared to similar pure D 2 -fuelled plasmas. Depending on the fraction of extrinsic impurities injected, the enhancement of effective sputtering yield could reach 1 order of magnitude in the limiters of a passive antenna [41].…”

Section: Antenna Limiter Erosion In Light Impurity Seeding Experimentsmentioning

confidence: 99%

“…Local gas injection was applied successfully to restore good LH wave coupling in ICRF-disturbed convective cells [65] and to enhance ICRF wave coupling without disturbing the plasma core in H mode [1]. Local D 2 injection also lowered the W production at the AUG antenna limiters [5,97]. Reference [5] showed that the reduction is all the more pronounced as the gas is injected close to the antennas toroidally.…”

Section: Control Of Local Density With Localized Gas Injectionmentioning

confidence: 99%

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The geometry of the ICRF-induced wave–SOL interaction. A multi-machine experimental review in view of the ITER operation

Colas¹,

Urbanczyk²,

Goniche³

et al. 2021

Nucl. Fusion

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As part of ITPA-Integrated Operational Scenario activities, this contribution reviews recent experimental characterizations of radio-frequency (RF)-induced scrape-off layer (SOL) modifications of various tokamaks worldwide and of the LArge Plasma Device at UCLA. The phenomenology, as observed using a large variety of measurement techniques, is consistent with expectations from RF sheath rectification. Emphasis is then put on the complex three-dimensional (3D) spatial patterns of the RF–SOL interaction, in relation to the magnetic topology and the spatial distribution of RF currents over the metallic structures surrounding the RF wave launchers. Dependence on the local plasma parameters in the antenna vicinity is also briefly addressed. The final part discusses implications for future devices.

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Section: Antenna Limiter Erosion In Light Impurity Seeding Experimentsmentioning

confidence: 99%

Section: Control Of Local Density With Localized Gas Injectionmentioning

confidence: 99%

The geometry of the ICRF-induced wave–SOL interaction. A multi-machine experimental review in view of the ITER operation

Colas¹,

Urbanczyk²,

Goniche³

et al. 2021

Nucl. Fusion

Self Cite

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“…However not every design of the midplane valve is suitable. As shown in [15], valves with the orifices close to the antenna mouth can lead to enhancement of non-linear effects and extremely local density increase. It is therefore preferable to place the orifices with a significant radial retraction, so that neutral can spread poloidally and toroidally before getting ionized.…”

Section: Improvements With Local Gas Injectionmentioning

confidence: 99%

Progress in controlling ICRF-edge interactions in ASDEX upgrade

Bobkov¹

2015

AIP Conference Proceedings

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RF measurements during variation of the strap voltage balance of the original 2-strap ICRF antenna in ASDEX Upgrade at constant power are consistent with electromagnetic calculations by HFSS and TOPICA, more so for the latter. RF image current compensation is observed at the antenna limiters in the experiment at a local strap voltage of about half of the value of the remote strap, albeit with a non-negligible uncertainty in phasing. The RF-specific tungsten (W) source at the broad-limiter 2-strap antenna correlates strongly with the RF voltage at the local strap at the locations not connected to opposite side of the antenna along magnetic field lines. The trends of the observed increase of the RF loading with injection of local gas are well described by a combined EMC3-Eirene-FELICE calculations, with the most efficient improvement confirmed for the outer-midplane valves, but underestimated by about 1/3. The corresponding deuterium density tailoring is also likely responsible for the decrease of local W sources observed in the experiment.

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“…Previous experiments on ASDEX Upgrade (AUG) [1,2], JET [3,4] and DIII-D [5,6] show that the edge density could indeed be increased with top or mid-plane deuterium gas puffing. A factor 2 increase of antenna loading in these tokamaks was reported for the antennas close to the mid-plane valves in [7].…”

Section: Simulations Of Gas Puff Effects On Edge Density and Icrf Coumentioning

confidence: 99%

Simulations of gas puff effects on edge density and ICRF coupling in ASDEX upgrade using EMC3-Eirene

2015

AIP Conference Proceedings

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Simulations were carried out with the 3D plasma transport code EMC3-EIRENE, to study the deuterium gas (D 2) puff effects on edge density and the coupling of Ion Cyclotron Range of Frequency (ICRF) power in ASDEX Upgrade. Firstly we simulated an inter-ELM phase of an H-mode discharge with a moderate (1.2 × 10 22 electrons/s) lower divertor gas puff. Then we changed the gas source positions to the mid-plane or top of machine while keeping other conditions the same. Cases with different mid-plane or top gas valves are investigated. Our simulations indicate that compared to lower divertor gas puffing, the mid-plane gas puff can enhance the local density in front of the antennas most effectively, while a rather global (toroidally uniform) but significantly smaller enhancement is found for top gas puffing. Our results show quantitative agreement with the experiments.

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Influence of gas injection location and magnetic perturbations on ICRF antenna performance in ASDEX Upgrade

Cited by 24 publications

References 0 publications

The geometry of the ICRF-induced wave–SOL interaction. A multi-machine experimental review in view of the ITER operation

The geometry of the ICRF-induced wave–SOL interaction. A multi-machine experimental review in view of the ITER operation

Progress in controlling ICRF-edge interactions in ASDEX upgrade

Simulations of gas puff effects on edge density and ICRF coupling in ASDEX upgrade using EMC3-Eirene

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