Ion cyclotron wave coupling in the magnetized plasma edge of tokamaks: impact of a finite, inhomogeneous density inside the antenna box

Lu, Lihe; Crombé, Kristel; Eester, D. Van; Colas, L.; Jacquot, J.; Heuraux, S.

doi:10.1088/0741-3335/58/5/055001

Cited by 17 publications

(21 citation statements)

References 26 publications

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“…In a real tokamak, this propagative FW heats the plasma core outside our simulation domain, via non-collisional processes that cannot easily be described within the cold plasma theory. To emulate full wave damping without reflection, a Perfectly Matched Layer (PML) technique is used: an equation similar to (1) is solved in a specific artificial dielectric and magnetic lossy medium introduced in [24] and generalized to tilted B 0 in [21]. The PML properties have been tuned to damp efficie ntly plane FWs with the main n// radiated by the antenna.…”

Section: Figure 3 Tilted Magnetic Configuration In 2d Sswich-full Wamentioning

confidence: 99%

Modelling of radio frequency sheath and fast wave coupling on the realistic ion cyclotron resonant antenna surroundings and the outer wall

Lu¹,

Colas²,

Jacquot³

et al. 2018

Plasma Phys. Control. Fusion

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In order to model the sheath rectification in a realistic geometry over the size of Ion Cyclotron Resonant Heating (ICRH) antennas, the Self-consistent Sheaths and Waves for ICH (SSWICH) code couples self-consistently the RF wave propagation and the DC SOL biasing via non-linear RF and DC sheath boundary conditions (SBCs) applied at plasma/wall interfaces. A first version of SSWICH had 2D (toroidal and radial) geometry, rectangular walls either normal or parallel to the confinement magnetic field B0 and only included the evanescent slow wave (SW) excited parasitically by the ICRH antenna. The main wave for plasma heating, the fast wave (FW) plays no role on the sheath excitation in this version. A new version of the code, 2D SSWICH-Full Wave, was developed based on the COMSOL software, to accommodate full RF field polarization and shaped walls tilted with respect to B0. SSWICH-Full Wave simulations have shown the mode conversion of FW into SW occurring at the sharp corners where the boundary shape varies rapidly. It has also evidenced "far-field" sheath oscillations appearing at the shaped walls with a relatively long magnetic connection length to the antenna, that are only accessible to the propagating FW. Joint simulation, conducted by SSWICH-Full Wave within a multi-2D approach excited using the 3D wave coupling code (RAPLICASOL), has recovered the double-hump poloidal structure measured in the experimental temperature and potential maps when only the SW is modelled. The FW contribution on the potential poloidal structure seems to be affected by the 3D effects, which was ignored in the current stage. Finally, SSWICH-Full Wave simulation revealed the left-right asymmetry that has been observed extensively in the unbalanced strap feeding experiment s , suggesting that the spatial proximity effects in RF sheath excitation, studied for SW only previously, is st ill important in the vicinity of the wave launcher under full wave polarizations.

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Section: Figure 3 Tilted Magnetic Configuration In 2d Sswich-full Wamentioning

confidence: 99%

Modelling of radio frequency sheath and fast wave coupling on the realistic ion cyclotron resonant antenna surroundings and the outer wall

Lu¹,

Colas²,

Jacquot³

et al. 2018

Plasma Phys. Control. Fusion

Self Cite

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“…To avoid numerical resolution issues in the private region of the antenna and in particular near the LH resonance [12], the density is assumed to be 0 up to the leading edge of the antenna.…”

Section: Raplicasolmentioning

confidence: 99%

Sequential modelling of ICRF wave near RF fields and asymptotic RF sheaths description for AUG ICRF antennas

et al. 2017

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Abstract. A sequence of simulations is performed with RAPLICASOL and SSWICH to compare two AUG ICRF antennas. RAPLICASOL outputs have been used as input to SSWICH-SW for the AUG ICRF antennas. Using parallel electric field maps and the scattering matrix produced by RAPLICASOL, SSWICH-SW, reduced to its asymptotic part, is able to produce a 2D radial/poloidal map of the DC plasma potential accounting for the antenna input settings (total power, power balance, phasing). Two models of antennas are compared: 2-strap antenna vs 3-strap antenna. The 2D DC potential structures are correlated to structures of the parallel electric field map for different phasing and power balance. The overall DC plasma potential on the 3-strap antenna is lower due to better global RF currents compensation. Spatial proximity between regions of high RF electric field and regions where high DC plasma potentials are observed is an important factor for sheath rectification.

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“…Numerically, the LH resonance is particularly hard to simulate (Lu et al. 2016; Nicolopoulos, Campos-Pinto & Després 2019; Usoltceva et al. 2019; Otin et al.…”

Section: Introductionmentioning

confidence: 99%

Analytical edge power loss at the lower hybrid resonance: ANTITER IV validation and application to ion cyclotron resonance heating systems

Maquet

Druart²,

Messiaen³

2021

J. Plasma Phys.

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In the ion cyclotron range of frequency (ICRF), the presence of a lower hybrid (LH) resonance can appear in the edge of a tokamak plasma and lead to deleterious edge power depositions. An analytic formula for these losses is derived in the cold plasma approximation and for a slab geometry using an asymptotic approach and an analytical continuation near the LH resonance. The way to minimize these losses in a large machine like ITER is discussed. An internal verification between the power loss computed with the semi-analytical code ANTITER IV for ion cyclotron resonance heating (ICRH) and the analytic result is performed. This allows us to check the precision of the numerical integration of the singular set of cold plasma wave differential equations. The set of cold plasma equations used is general and can be applied in other parameters domain.

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Ion cyclotron wave coupling in the magnetized plasma edge of tokamaks: impact of a finite, inhomogeneous density inside the antenna box

Cited by 17 publications

References 26 publications

Modelling of radio frequency sheath and fast wave coupling on the realistic ion cyclotron resonant antenna surroundings and the outer wall

Modelling of radio frequency sheath and fast wave coupling on the realistic ion cyclotron resonant antenna surroundings and the outer wall

Sequential modelling of ICRF wave near RF fields and asymptotic RF sheaths description for AUG ICRF antennas

Analytical edge power loss at the lower hybrid resonance: ANTITER IV validation and application to ion cyclotron resonance heating systems

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