The interaction between waves in the ion cyclotron range of frequencies and the plasma boundary

Noterdaeme, J.‐M.; Oost, G. Van

doi:10.1088/0741-3335/35/11/001

Cited by 109 publications

(154 citation statements)

References 102 publications

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“…A great deal of recent progress has been made in understanding and control of these interactions. An extensive summary of experimental and theoretical work in this area can be found in conference proceedings [1] and in recent review articles [2,3]. It was proposed that many of the deleterious ICRF-edge interactions are caused by the formation of radiofrequency (rf) sheaths [4][5][6][7][8][9].…”

Section: Introductionmentioning

confidence: 99%

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Analysis of RF sheath interactions in TFTR

D’Ippolito¹,

Myra²,

Rogers³

et al. 1998

Nucl. Fusion

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New theoretical and experimental tools are applied to the analysis of ICRF antenna-edge plasma interactions in the Tokamak Fusion Test Reactor (TFTR) tokamak. A new numerical method for computing the three-dimensional rf sheath voltage distribution is used, and the quantitative predictions of rf sheath theory are compared with measurements of the edge density profile obtained by microwave reflectometry and with titanium impurity concentration data. It is shown that the local density depletion at the antenna is consistent with density pump-out by strong E × B convection into the Faraday screen. Modeling of the Faraday screen impurity influx shows that the calculated Ti impurity concentration based on this direct influx agrees with the measured concentration for π phasing. It is also shown that screening of impurity neutrals by ionization in the SOL is a large effect and increases with rf power. At high power over many shots, a fraction of the metal impurities migrates around the machine and is deposited on the limiters, providing a secondary source of titanium. The data shows that the central Ti concentration is strongly dependent on antenna phasing. Possible explanations for this phasing dependence are discussed.

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Section: Introductionmentioning

confidence: 99%

“…This is discussed in more detail in Sec. 3. We refer to this mechanism as "near-field" sheath formation, and it is the dominant process during heating and current drive scenarios with good single pass absorption.…”

Section: Introductionmentioning

confidence: 99%

Analysis of RF sheath interactions in TFTR

D’Ippolito¹,

Myra²,

Rogers³

et al. 1998

Nucl. Fusion

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“…However, in addition to the desired heating in the core plasma, spurious nonlinear interactions with the plasma edge and with plasma limiting boundaries have been observed in magnetic fusion devices equipped with ICRF antennas [1], such as JET, ASDEX Upgrade (AUG), Tore Supra, Alcator C-Mod. These interactions often determine the operational limits of the radio-frequency systems.…”

Section: Introductionmentioning

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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“…There have been many previous measurements showing a correlation between ion loss (or fast ions in the edge) and the edge electric field [11][12][13][14], but it has been difficult to establish a causal connection between the two in the absence of electrode biasing. An interesting attempt was made at DIII-D to deliberately create beam ion loss using counter-neutral beam injection [15]; however, this did not significantly affect the H-mode threshold or change the edge electric field [16].…”

Section: Introductionmentioning

confidence: 99%

Edge Minority Heating Experiment in Alcator C-Mod

Zweben¹,

Terry²,

Bonoli³

et al. 2005

AIP Conference Proceedings

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An attempt was made to control global plasma confinement in the Alcator C-Mod tokamak by applying ICRH heating power to the plasma edge in order to deliberately create a minority ion tail loss. In theory, an edge fast ion loss could modify the edge electric field and so stabilize the edge turbulence, which might then reduce the H-mode power threshold or improve the H-mode barrier. However, the experimental result was that edge minority heating resulted in no improvement in the edge plasma parameters or global stored energy, at least at power levels of P RF ≤ 5.5 MW. A preliminary analysis of these results is presented and some ideas for improvement are discussed.

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The interaction between waves in the ion cyclotron range of frequencies and the plasma boundary

Cited by 109 publications

References 102 publications

Analysis of RF sheath interactions in TFTR

Analysis of RF sheath interactions in TFTR

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

Edge Minority Heating Experiment in Alcator C-Mod

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