Overview of TOMAS plasma diagnostics

Kovtun, Yu. V.; Goriaev, A.; Lopez-Rodriguez, D.; Dittrich, Laura; Petersson, P.; Moon, S.; Wauters, T.; Crombé, Kristel; Möller, S.; Buermans, J.; Verstraeten, M.; Brezinsek, S.

doi:10.1088/1748-0221/18/02/c02034

Cited by 4 publications

(2 citation statements)

References 6 publications

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“…The electron density and temperature are readily obtained by triple Langmuir probe (TLP) measurements [15,16]. Figure 2 shows the evolution of the forwarded and reflected power.…”

Section: Methodsmentioning

confidence: 99%

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Study of the Electron cyclotron power deposition in TOMAS

Buermans,

Adriaens,

Brezinsek

et al. 2024

Phys. Scr.

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Efficient Electron Cyclotron Resonance Heating (ECRH) breakdown and pre-ionization can be achieved with fundamental X-mode, while higher harmonics can introduce excessive stray radiation. Fundamental heating however is characterized by a low cut-off density, introducing additional power absorption mechanisms in the plasma. A good knowledge of these mechanisms is necessary to use fundamental X-mode as an efficient pre-ionization method. Numerous experiments were performed on the TOroidally MAgnetized System (TOMAS) to study the power deposition for ECRH in helium. It is a facility designed to study plasma production, wall conditioning and plasma–surface interactions and is operated by LPP-ERM/KMS at the FZ-J¨ulich. The influence of the injected power $P_{EC}$ and the magnetic field $B_0$ on the absorption mechanisms is examined, in order to reduce stray radiation and improve the absorption efficiency. This will allow to determine the best scenarios for plasma start-up and pre-ionization.

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“…The electron density and temperature are readily obtained by triple Langmuir probe (TLP) measurements [15,16]. Figure 2 shows the evolution of the forwarded and reflected power.…”

Section: Methodsmentioning

confidence: 99%

“…Various plasma diagnostics are available [15]. The Langmuir probe system consists of two triple movable probes and one single probe.…”

Section: The Tomas Devicementioning

confidence: 99%

Study of the Electron cyclotron power deposition in TOMAS

Buermans,

Adriaens,

Brezinsek

et al. 2024

Phys. Scr.

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Triple Langmuir probe calibration in TOMAS ECRH plasma

et al. 2023

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In the TOMAS device, a triple Langmuir probe is used to measure the electron temperature and density. The accuracy of this measurement depends on correct determination of the effective collecting area of the probe, which depends on complex plasma transport processes. The probe can be calibrated by electron cyclotron resonance heating experiments using the cut-off density of the ordinary wave (O-wave). This threshold only depends on the frequency of the injected wave, and the occurrence of this phenomenon is clearly visible in the temperature evolution. The value of density is consequently known at this point and can be used to calibrate the density measurements of the triple Langmuir probe.

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Characterization of ECRH plasmas in TOMAS

Buermans,

Adriaens,

Brezinsek

et al. 2024

Physics of Plasmas

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To improve the plasma performance and control the density and plasma quality during the flat top phase, wall conditioning techniques are used in large fusion devices like W7-X and in JT60-SA. To study the performance of electron cyclotron wall conditioning, numerous experiments were performed on the TOroidally MAgnetized System, which is operated by LPP-ERM/KMS at the FZ-Jülich. It is a facility designed to study plasma production, wall conditioning, and plasma–surface interactions. The produced electron cyclotron resonance heating plasmas are characterized in various conditions by density and temperature measurements using a movable triple Langmuir probe in the horizontal and the vertical direction, complemented by video and spectroscopic data, to obtain a 2D extrapolation of the plasma parameters in the machine. A way to calibrate the triple Langmuir probe measurements is also investigated. These data can be used to determine the direction of the plasma drift in the vessel and identify the power absorption mechanisms. This will give more insight in the plasma behavior and improve the efficiency of wall conditioning and sample exposure experiments.

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Overview of TOMAS plasma diagnostics

Cited by 4 publications

References 6 publications

Study of the Electron cyclotron power deposition in TOMAS

Study of the Electron cyclotron power deposition in TOMAS

Triple Langmuir probe calibration in TOMAS ECRH plasma

Characterization of ECRH plasmas in TOMAS

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