ICRF-edge and surface interactions

D’Ippolito, D. A.; Myra, J. R.

doi:10.1016/j.jnucmat.2010.08.039

Cited by 24 publications

(19 citation statements)

References 26 publications

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“…Although it does not pose a particular problem for the present 1D treatment which requires modest CPU time whatsoever, it both points to the fact there is a need for improvement of the numerical scheme when the wave-plasma interaction is to be modeled in more than a single dimension, and underlines the fact that the linearisation locally breaks down and the physics model needs to be upgraded to properly describe regions where that happens. The difficulty of solving the nonlinear set of equations relevant for high amplitude waves in low density regions close to metallic walls has already been noticed when adopting simpler models: Van Compernolle et al 34 experimented with implementing the sheath boundary condition due to Myra and D'Ippolito [35][36][37][38][39][40][41][42][43] and was confronted with nonconvergence when the RF power density was too high.…”

Section: -15mentioning

confidence: 99%

A crude model to study radio frequency induced density modification close to launchers

Eester¹,

Crombé

2015

Physics of Plasmas

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Articles you may be interested inA crude model to study radio frequency induced density modification close to launchers The interplay between radio frequency (RF) waves and the density is discussed by adopting the general framework of a 2-time-scale multi-fluid treatment, allowing to separate the dynamics on the RF time scale from that on the time scale on which macroscopic density and flows vary as a result of the presence of electromagnetic and/or electrostatic fields. The focus is on regions close to launchers where charge neutrality is incomplete and waves are commonly evanescent. The fast time scale dynamics influences the slow time scale behavior via quasilinear terms (the Ponderomotive force for the case of the equation of motion). Electrons and ions are treated on the same footing. Also, both fast and slow waves are retained in the wave description. Although this work is meant as a subtopic of a large study-the wave induced "convective cell" physics at hand is of a 2-or 3-dimensional nature while this paper limits itself to a single dimension-a few tentative examples are presented.[http://dx

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Section: -15mentioning

confidence: 99%

A crude model to study radio frequency induced density modification close to launchers

Eester¹,

Crombé

2015

Physics of Plasmas

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“…This approach is used rather than a reduction of the integrated E || on a family of magnetic field lines, because of the known complexity of the antenna-plasma-wall interactions [5,6]. Recently, the popular criterion of reduction of the integrated E || on the "long" field lines (the open field lines which pass in front of an antenna) has been questioned by the experimental observations in Tore Supra and in Alcator C-Mod.…”

Section: Introductionmentioning

confidence: 99%

ICRF operation with improved antennas in ASDEX Upgrade with W wall

et al. 2013

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Abstract. Experiments with boron-coated side limiters of two antennas operated together in 2012 showed that the side limiters are responsible to more than half of the increased W content in the plasma. Together with the contribution from the other limiter tiles, not replaced in 2012, the limiters accounts for at least 2/3rds of the W content. A modified test two-strap ICRF antenna in ASDEX Upgrade with broad limiters and narrow straps has shown an improved operation with full W-wall in 2011/2012 campaigns with up to a 40% lower rise of W concentration allowing more stable operation at low deuterium gas injection rate. Limiter spectroscopy measurements indicate up to a 40% reduction of the rise of the W sputtering yield during ICRF power, measured under the assumption of negligible influence of geometry variations and reflections on the measurements. The boron limiters on two antennas together with the improved broad-limiter antenna allowed a successful ICRF operation in 2012. As a part of long-term strategy of antenna design development, two threestrap antennas with phase and power balance control for reduction of E || are planned for installation in the future.

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“…On the other hand, the impurity content is affected by changes of transport plasma properties in the core, due to the heating and effects on the fast particle population [8], or in the scrape-off layer (SOL) by enhanced density convection driven mainly by the RF sheaths [9]. Impurity sources can be driven by 3 main mechanisms: a) sputtering by ions; b) thermal (evaporation, melting); c) sputtering by fast particles including charge exchange (CX) neutrals.…”

Section: Introductionmentioning

confidence: 99%

“…Impurity sources can be driven by 3 main mechanisms: a) sputtering by ions; b) thermal (evaporation, melting); c) sputtering by fast particles including charge exchange (CX) neutrals. The sheath effects [9] are the most likely contributors to (a) and (b). In this respect, a special attention should be paid to the magnetic field line connections going from active ICRF antennas to high-Z PFCs, where the RF sheaths are driven by high antenna near fields, in particular parallel electric field E || .…”

Section: Introductionmentioning

confidence: 99%

ICRF specific plasma wall interactions in JET with the ITER-like wall

Bobkov

Arnoux

Brezinsek³

et al. 2013

Journal of Nuclear Materials

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Abstract.A variety of plasma wall interactions (PWIs) during operation of the so-called A2 ICRF antennas is observed in JET with the ITER-like wall. Amongst effects of the PWIs, the W content increase is the most significant, especially at low plasma densities. No increase of W source from the main divertor and entrance of the outer divertor during ICRF compared to NBI phases was found by means of spectroscopic and W I (400.9 nm) imaging diagnostics. In contrary, the W flux there is higher during NBI. Charge exchange neutrals could be excluded as considerable contributors to the W source. The high W content in ICRF heated limiter discharges suggests the possibility of other W sources than the divertor alone. Dependencies of PWIs to individual ICRF antennas during q 95 -scans, and intensification of those for the -90 o phasing, indicate a link between the PWIs and the antenna near-fields. The PWIs include heat loads and Be sputtering pattern on antenna limiters. Indications of some PWIs at the outer divertor entrance are observed which do not result in higher W flux compared to the NBI phases, but are characterized by small antenna-specific (up to 25% with respect to ohmic phases) bipolar variations of W I emission. The first TOPICA calculations show a particularity of the A2 antennas compared to the ITER antenna, due to the presence of long antenna limiters in the RF image current loop and thus high near-fields across the most part of the JET outer wall.

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ICRF-edge and surface interactions

Cited by 24 publications

References 26 publications

A crude model to study radio frequency induced density modification close to launchers

A crude model to study radio frequency induced density modification close to launchers

ICRF operation with improved antennas in ASDEX Upgrade with W wall

ICRF specific plasma wall interactions in JET with the ITER-like wall

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