Measurement of lower hybrid hot spots using a retarding field analyzer in Tore Supra

Gunn, J.; Petržı́lka, V.; Ekedahl, A.; Fuchs, V.; Gauthier, E.; Goniche, M.; Kočan, M.; Pascal, J. Y.; Saint‐Laurent, F.

doi:10.1016/j.jnucmat.2009.01.232

Cited by 26 publications

(43 citation statements)

References 9 publications

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“…By varying the launcher position, (retracting it away from a starting position close to the plasma, (see Fig.6e)), such that the radial distance between the field lines (generating the hot spots on the dump plates) and the launcher was increased from 0 to 3.5cm, it was possible to diagnose the radial width of the absorption layer in front of the launcher. This is in agreement with recent observations on Tore Supra [22], but not with the standard modelling of the linear damping of LH waves in the SOL that predicts a dissipation layer of a few mm. This is in agreement with recent observations on Tore Supra [22], but not with the standard modelling of the linear damping of LH waves in the SOL that predicts a dissipation layer of a few mm.…”

Section: Characterisation Of Lh Power Losses In Front Of the Launchersupporting

confidence: 89%

Overview of Recent Results on Heating and Current Drive in the JET tokamak

Mayoral¹,

Ongena²,

Argouarch³

et al. 2009

AIP Conference Proceedings

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Section: Characterisation Of Lh Power Losses In Front Of the Launchersupporting

confidence: 89%

Overview of Recent Results on Heating and Current Drive in the JET tokamak

Mayoral¹,

Ongena²,

Argouarch³

et al. 2009

AIP Conference Proceedings

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“…This result is consistent with the low diffusion coefficient for fast electrons from the core to the SOL [12]. It appears that the enhancement of  P at lower n // is due to heating of thermal electrons by collisional damping of the LH waves, however, the effect of fast electrons generated locally in the SOL cannot be discarded [13,14].…”

Section: Resultssupporting

confidence: 72%

Experimental Investigation of RF Sheath Rectification in ICRF and LH Heated Plasmas on Alcator C-Mod

Ochoukov¹,

Whyte²,

Faust³

et al. 2011

AIP Conference Proceedings

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Radio frequency (RF) rectification of the plasma sheath is being actively studied on C-Mod as a likely mechanism that leads to prohibitively high molybdenum levels in the plasma core of ion cyclotron RF (ICRF) heated discharges. We installed emissive, ion sensitive, Langmuir, and 3-D B-dot probes to quantify the plasma potentials ( P) in ICRF and lower hybrid (LH) heated discharges. Two probe sets were mounted on fixed limiter surfaces and one set of probes was mounted on a reciprocating (along the major radius) probe. Initial results showed that RF rectification is strongly dependent on the local plasma density and not on the local RF fields. The RF sheaths had a threshold-like appearance at the local density of ~10 16 m-3. Radial probe scans revealed that the RF sheaths peaked in the vicinity of the ICRF limiter surface, agreeing with a recent theory [1]. The highest  P 's were observed on magnetic field lines directly mapped to the active ICRF antenna. Measurements in LH heated plasmas showed a strong  P dependence on the parallel index of refraction n // of the launched LH waves:  P is greater at lower n //. Little dependence was observed on the local plasma density.

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“…Hotspots on a PFC magnetically connected to the LH launcher were observed before on JET [37], [38], [39] and on other machines [40], [41], [42], [43]. In our study we refer to all areas seen on the IR cameras which are brighter than normal as hotspots.…”

Section: Observation Of Arcs Via a Dedicated Visible Cameramentioning

confidence: 95%

Operation and coupling of LH waves with the ITER-like wall at JET

Kirov¹,

Mailloux²,

Petržı́lka³

et al. 2013

Plasma Phys. Control. Fusion

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In this paper important aspects of Lower Hybrid (LH) operation with the ITER Like Wall (ILW) [1] at JET are reported. Impurity release during LH operation was investigated and it was found that there is no significant Be increase with LH power. Concentration of W was analysed in more detail and it was concluded that LH contributes negligibly to its increase. No cases of W accumulation in LH-only heating experiments were observed so far. LH wave coupling was studied and optimised to achieve the level of system performance similar to before ILW installation. Measurements by Li-beam were used to study systematic dependencies of the SOL density on the gas injection rate from a dedicated gas introduction module and the LH power and launcher position. Experimental results are supported by SOL transport modelling. Observations of arcs in front of the LH launcher and hotspots on magnetically connected sections of the vessel are reported. Overall, a relatively troublefree operation of the LH system up to 2.5MW of coupled Radio Frequency (RF) power in L-mode plasma was achieved with no indication that the power cannot be increased further.

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Measurement of lower hybrid hot spots using a retarding field analyzer in Tore Supra

Cited by 26 publications

References 9 publications

Overview of Recent Results on Heating and Current Drive in the JET tokamak

Overview of Recent Results on Heating and Current Drive in the JET tokamak

Experimental Investigation of RF Sheath Rectification in ICRF and LH Heated Plasmas on Alcator C-Mod

Operation and coupling of LH waves with the ITER-like wall at JET

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