Effect of RF heating on edge parameters in the TCA tokamak

De.Chambrier, A.; Collins, George; Duperrex, P.A.; Heym, A.; Hofmann, F.; Hollenstein, Ch.; Joye, B.; Keller, R.; Lietti, A.; Lister, J.B.; Marcus, F.B.; Moret, J.M.; Nowak, S.; Pochelon, A.; Simm, W.; Vepřek, S.

doi:10.1016/0022-3115(84)90371-4

Cited by 20 publications

(4 citation statements)

References 6 publications

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“…During RF heating, regardless of which heating regime was studied, both Langmuir probes revealed a significant increase of T e (Fig. 10) (a similar effect was observed in Alfve"n wave heating experiments on TCA [8]). The fact that both probes detected an increase of T e indicates that the effect is not localized near the limiter.…”

Section: Effect Of Rf Heating On the Scrape-off Layersupporting

confidence: 69%

ICRF heating experiments in TFR using a low-field-side antenna

Sand

1985

Nucl. Fusion

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The paper describes the JET-TFR antenna designed for launching ICRF waves in TFR from the low magnetic field side of the torus, and the main experimental observations on plasma-wave interaction. Compared with a first design of a similar antenna, this antenna design includes new features, such as carbon lateral protections and a thick Faraday shield similar to the one which will be mounted on the JET antennas. Experiment shows that such a shield does not limit the coupling efficiency of the magnetosonic wave in the plasma, the loading resistance being comparable with the one predicted by theory assuming an ideal Faraday shield. With this system, the power coupled reached 600 kW. In the minority regime and for a central electron density around 10 14 cm~3, the ion central heating efficiency reaches 0.6-0.7 eV-kW" 1 for an RF power up to 350 kW and 0.5 eV'kW" 1 at 600 kW. As expected for a low-field-side antenna, no appreciable heating is observed in the mode conversion regime. Spectroscopic measurements show that, in all regimes, the RF pulse introduces a significant amount of both high-Z and low-Z impurities; at the end of a 300 kW/100 ms RF pulse, the total power radiated by the metallic impurities reaches 125-200 kW. The mechanisms responsible for such a generation of metal in the plasma remain unclear, but it can be said that a direct plasma-wave interaction in the scrape-off layer of the tokamak discharge is probably a determining factor.

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Section: Effect Of Rf Heating On the Scrape-off Layersupporting

confidence: 69%

ICRF heating experiments in TFR using a low-field-side antenna

Sand

1985

Nucl. Fusion

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show abstract

“…The observed decrease or Considerable attention has been paid to the conditions of the edge plasma during the RF pulse. We find that the electron temperature increases and the density decreases, with the density scale-length increasing [4]. We have also observed the formation of a non-Maxwellian electron distribution function during the RF pulse.…”

Section: High-power Heatingmentioning

confidence: 50%

“…The RF generator has delivered up to 400 kW of RF power with unshielded antennas. Figure 2 shows results obtained using an N = 2, M = 1 excitation in the n = 2, m = 0 continuum, with RF power roughly equal to the Ohmic power [3]. There was heating of both electrons and ions, with an increase of about 30% in each.…”

Section: High-power Heatingmentioning

confidence: 99%

“…The TCA tokamak was completed in 1980 and its aim was and remains the study of Alfven wave heating, at a frequency less than the ion cyclotron frequency, typically at 2 -5 MHz, with co/co ci = 0.1-0.3. It is a circular air-cored tokamak with the following parameters: R = 0.61 m, a = O.18m,B 0 < 1.5 T, I p < 170 kA, q a > 2.2, ff e < 10 20 m" 3 . Operation of TCA is extremely flexible, with the current plateau maintained for up to 180 ms in normal conditions and with an operational diagram limit corresponding to I/eN > 8.2 X 10 4 ms" 1 and rf 19 Ro/B^ < 4.4.…”

Section: Introductionmentioning

confidence: 99%

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