Lower hybrid wave coupling in TORE SUPRA through multijunction launchers

Litaudon, X.; Berger‐By, G.; Bibet, P.; Bizarro, João P. S.; Capitain, J.J.; Carrasco, J.; Goniche, M.; Hoang, G. T.; Küpfer, K.; Magne, R.; Moreau, D.; Peysson, Y.; Rax, Jean-Marcel; Rey, G.; Rigaud, D.; Tonon, G.

doi:10.1088/0029-5515/32/11/i01

Cited by 55 publications

(43 citation statements)

References 7 publications

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“…34,35 Preliminary studies indicate that LHW-plasma coupling and current drive efficiency are both affected by the plasma configuration. The best coupling is obtained in the limiter configuration, then the SN plasma, and the worst is the DN plasma.…”

Section: Discussionmentioning

confidence: 99%

Investigation of lower hybrid wave coupling and current drive experiments at different configurations in experimental advanced superconducting tokamak

Ding

Qin

et al. 2011

Physics of Plasmas

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Using a 2 MW 2.45 GHz lower hybrid wave (LHW) system installed in experimental advanced superconducting tokamak, we have systematically carried out LHW-plasma coupling and lower hybrid current drive experiments in both divertor (double null and lower single null) and limiter plasma configuration with plasma current (I p ) $ 250 kA and central line averaged density (n e ) $ 1.0-1.3 Â 10 19 m À3 recently. Results show that the reflection coefficient (RC) first is flat up to some distance between plasma and LHW grill, and then increases with the distance. Studies indicate that with the same plasma parameters, the best coupling is obtained in the limiter case (with plasma leaning on the inner wall), followed by the lower single null, and the one with the worst coupling is the double null configuration, explained by different magnetic connection length. The RCs in the different poloidal rows show that they have different coupling characteristics, possibly due to local magnetic connection length. Current drive efficiency has been investigated by a least squares fit with N peak == ¼ 2:1, where N peak == is the peak value of parallel refractive index of the launched wave. Results show that there is no obvious difference in the current drive efficiency between double null and lower single null cases, whereas the efficiency is somewhat small in the limiter configuration. This is in agreement with the ray tracing=Fokker-Planck code simulation by LUKE=C3PO and can be interpreted by the power spectrum up-shift factor in different plasma configurations. A transformer recharge is realized with $0.8 MW LHW power and the energy conversion efficiency from LHW to poloidal field energy is about 2%.

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Section: Discussionmentioning

confidence: 99%

Investigation of lower hybrid wave coupling and current drive experiments at different configurations in experimental advanced superconducting tokamak

Ding

Qin

et al. 2011

Physics of Plasmas

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“…Direct measurements of density in front of the grid are usually conveniently given by fixed Langmuir probes. 21 This diagnostic offers the advantage of having low cumbersome features; however, it provides a single radial point measurement. Moreover, due to the very low LH cut-off density, measurement in the private zone of the launcher is highly demanded.…”

Section: Reflectometry and Lhcd Launcher Arrangementmentioning

confidence: 99%

New signal processing technique for density profile reconstruction using reflectometry

Clairet

Ricaud

Briolle

et al. 2011

Review of Scientific Instruments

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Reflectometry profile measurement requires an accurate determination of the plasma reflected signal. Along with a good resolution and a high signal to noise ratio of the phase measurement, adequate data analysis is required. A new data processing based on time-frequency tomographic representation is used. It provides a clearer separation between multiple components and improves isolation of the relevant signals. In this paper, this data processing technique is applied to two sets of signals coming from two different reflectometer devices used on the Tore Supra tokamak. For the standard density profile reflectometry, it improves the initialization process and its reliability, providing a more accurate profile determination in the far scrape-off layer with density measurements as low as 10 16 m −1 . For a second reflectometer, which provides measurements in front of a lower hybrid launcher, this method improves the separation of the relevant plasma signal from multi-reflection processes due to the proximity of the plasma.

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“…Fig. 3 shows the power flux handling capabilities for various machines like Versator-II [7], JFT-2 [8], PLT [9], WT-2 [10], JT-60U [11], TRIAM-1M [12], JET [13], Tore Supra [14,15], Asdex [16], Alcator-C [17] and FTU [18] and its dependence on frequency and the width of the grill channel. The magnetic field for the machines is also shown in brackets in the same figure to show the growing trend with operating frequency and magnetic field.…”

Section: Design Criteria Of Lhcd Systemmentioning

confidence: 99%