Crombé, Kristel

D'Inca, R.

Faudot, E.

Heureux, S.

Jacquot, J.

Noterdaeme, Jean-Marie

Ochoukov, R.

Usoltceva, Mariia

Ghent University Academic Bibliography

Numerical Simulations of Ion Cyclotron Range ofFrequency (ICRF) Wave Fields in a Linear Plasma DeviceM. Usoltceva1, K. Crombé2, E. Faudot3, S. Heuraux3, R. D’Inca4, J. Jacquot4, J-M.Noterdaeme5, R. Ochoukov41Department of Applied Physics, Ghent University, Ghent, Belgium; Max-Planck-Institut fürPlasmaphysik, Garching, Germany; Université de Lorraine, Nancy, France2Department of Applied Physics, Ghent University, Ghent, Belgium; LPP-ERM-KMS, TECpartner, Brussels, Belgium3Université de Lorraine, Nancy, France4Max-Planck-Institut für Plasmaphysik, Garching, Germany5Department of Applied Physics, Ghent University, Ghent, Belgium; Max-Planck-Institut fürPlasmaphysik, Garching, GermanyAbstractFusion devices (tokamaks, stellarators) require hundreds of millions degree Celsiustemperature to reach the plasma state when the fusion reactions start to occur. Ioncyclotron resonance heating (ICRH) is a method of energy transfer to the ions in theplasma from electromagnetic radiation with a frequency equal to the cyclotron motionfrequency of ions in the presence of magnetic field, which is in the range of 30-120 MHz.Main components of an ICRH system are a generator, transmission lines and an antennaplaced inside the vacuum vessel of a fusion device. An impedance matching system is alsonecessary in order to enable the process of power transmission from antenna to plasma.Studies of interactions between ion cyclotron range of frequency (ICRF) radiation andplasma in a configuration representative of a tokamak edge region are carried out on aspecialized linear device IShTAR (Ion cyclotron Sheath Test ARrangement). The device isequipped with: 1) a helicon plasma source and magnetic coils to produce a high density,homogeneous, magnetized plasma, 2) an antenna similar to tokamak ICRH antennas, 3) aradially movable manipulator with diagnostic tools: Langmuir probes for electrontemperature and plasma density measurements and B-dot probes for radio-frequency(RF) wave magnetic field measurements. Typical operating conditions on IShTAR are:magnetic field of up to 0.2 T in the main chamber and 0.1 T near the helicon source, 10E-4mbar neutral gas (Argon or Helium) pressure, helicon source power of 3 kW withfrequency of 11.76 MHz, ICRF antenna power of 1 kW with 5 MHz frequency. Typicalmeasured parameters are: density of the order 1E16 m^-3 - 1E18 m^-3, electrontemperature of few eV and RF B-fields power around 100 mW.Presented simulation work is intended to support the experimental studies of RF sheathsin front of the ICRF antenna performed on IShTAR. The RF Module of COMSOLMultiphysics® software is used to model the electromagnetic field distribution inside thevessel. Different tasks are addressed, including power losses through the use of aperfectly matched layer (PML), diagnostics calibration, impedance matching tests, andachievement of coupling conditions equal to experimental and studying the effect of ametallic probe presence inside the plasma. Evanescent nature of the wave inside the main vacuum vessel (f = 5 MHz, λ = 60 m,characteristic size of vacuum chamber is 1 m) and little wave absorption in plasmadetermine special conditions for simulations. Instead of the standard PML a new one wascreated with manually prescribed characteristics. Different tests were performed insimplified geometries first (and in vacuum, without plasma), with further adjustments tothe real IShTAR geometry.

Numerical Simulations of Ion Cyclotron Range of Frequency (ICRF) Wave Fields in a Linear Plasma Device

https://biblio.ugent.be/publication/8555888/file/8555892

Numerical Simulations of Ion Cyclotron Range of Frequency (ICRF) Wave Fields in a Linear Plasma Device

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