Improved confinement in high l<sub>i</sub>lower hybrid driven steady state plasmas in TORE SUPRA

Hoang, G. T.; Gil, C.; Joffrin, E.; Moreau, D.; Bécoulet, A.; Bibet, P.; Bizarro, João P. S.; Budny, R.; Carrasco, J.; Coulon, J.-P.; Michelis, C. De; Wit, T. Dudok de; Monier‐Garbet, P.; Goniche, M.; Guirlet, R.; Hutter, T.; Kaye, S. M.; Lasalle, J.; Laurent, Louis; Lecoustey, P.; Litaudon, X.; Mattioli, M.; Peysson, Y.; Pecquet, A.‐L.; Rey, G.; Sabbagh, S. A.; Saoutic, B.; Tonon, G.; Vallet, J.C.

doi:10.1088/0029-5515/34/1/i05

Cited by 110 publications

(34 citation statements)

References 14 publications

(4 reference statements)

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“…Meanwhile, the level of turbulence decreases with I p. This could reflect the link between global confinement properties, the plasma current and SOL turtbulence. Consequently, for these discharges the confinement of the electrons (no ion heating) follows the general trend observed on Tore Supra for LHCD discharges [9]. At P LH =400 kW, the electron stored energy follows the Rebut-Lallia-Watkins scaling and at high power (P LH~4 .8MW), it is above the RLW scaling by a factor increasing when I p is decreasing.…”

Section: Level Of Fluctuations and Confinementsupporting

confidence: 54%

The Role of the Plasma Current in Turbulence Decrease with Lower Hybrid Waves

Antar

Goniche

2017

EPJ Web Conf.

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Abstract.We study the effect of lower hybrid waves on edge turbulence using a set of two Langmuir probes inserted in the scrape-off layer of the Tore Supra tokamak. We use the cross-correlation coefficient to assess the interplay between turbulence and the LH waves. We found that turbulence is affected at high plasma current even at relatively low LH powers. When the plasma current is below 1 MA, this effect disappears. Finally, we show that the level of fluctuations and the cross-correlation amplitude are correlated whereas the increase of the first leads to the increase of the second. The role of the plasma current could reflect that the exchange of the RF waves with edge turbulence is occurring in the closed field lines rather in the open field lines range.

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Section: Level Of Fluctuations and Confinementsupporting

confidence: 54%

The Role of the Plasma Current in Turbulence Decrease with Lower Hybrid Waves

Antar

Goniche

2017

EPJ Web Conf.

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“…Relatively small changes are observed in the electron heat conductivity. Similar behavior of the transport coefficients in reverse shear plasmas is seen on DIII-D as well, but both JT-60U and Tore Supra (Hoang et al, 1994) have reported significant decreases in &. Possible explanations for the apparent sub-neoclassical ion thermal diffusivity are the violation of the assumptions of standard neoclassical theory, the presence of anomalous electron-ion coupling, or a thermal pinch.…”

Section: Similar Improvements Inmentioning

confidence: 58%

Results from deuterium-tritium tokamak confinement experiments

Hawryluk

1998

Rev. Mod. Phys.

122

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Recent scientific and technical progress in magnetic fusion experiments has resulted in the achievement of plasma parameters (density and temperature) which enabled the production of significant bursts of fusion power from deuterium-tritium fuels and the first studies of the physics of burning plasmas. The key scientific issues in the reacting plasma core are plasma confinement, magnetohydrodynamic (MHD) stability, and the confinement and loss of energetic fusion products from the reacting fuel ions. Progress in the development of regimes of operation which have both good confinement and are MHD stable have enabled a broad study of burning plasma physics issues.

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“…In DIII-D we have shown that the current density near the edge plays a role in achieving high confinement in certain operating regimes (Ferron 1994) and is in general unfavorable for achieving high beta (Strait 1993, Taylor 1991. A region near the axis with negative central shear allowing access to the second stability regime was identified in DIII-D experiments as favorable for high beta and very high central beta, and improved transport with a central negative shear has been shown in several experiments (Hugon 1992, Tubbing 1991. Hoang 1994.…”

Section: Plasma Rotation and Sheared Exbflowmentioning

confidence: 93%

“…These characteristics will figure 0.0 strongly in defining a stable high performance scenario. The negative central shear also has a posi--OS (Tubbing 1991, Hugon 1992 and Tore Supra (Hoang 1994) have observed reduced core transport in dis--1.5…”

Section: Plasma Rotation and Sheared Exbflowmentioning

confidence: 98%

Optimized profiles for improved confinement and stability in the DIII-D tokamak

Taylor¹,

John²,

Turnbull³

et al. 1994

Plasma Phys. Control. Fusion

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Simultaneous achievement of high energy confinement, 'ZE, and high plasma beta, P. leads to an economically attractive compact tokamak fusion reactor. High confinement enhancement, H = 'CF/'ZE.ITER~~P = 4, and high normalized beta PN = P/(UaB) = 6%-m-T/MA. have been obtained in DIU-D experimental discharges.These improved confinement and/or improved stability limis are observed in several Dll-D high performance operational regimes: VH-mode, high 4 H-mode, second stable core, and high beta poloidal. We have identified several important features of the improved performance in these discharges: details of the plasma shape, toroidal rotation or ErB flow profile, q profile and current density profile, and pressure profile. From our improved physics understanding of these enhanced performance regimes, we have developed operational scenarios which maintain the essential features of the improved confinement and which increase the stability limits using localized current profile control. The stability limit is increased by modifying the interior safety factor profile to be nonmonotonic with high central q. while maintaining the edge current density consistent with the improved transport regimes and the high edge bootstrap current. We have calculated high beta equilibria with BN = 6.5, stable to ideal n=l kinks and stable to ideal ballooning modes.The safety factor at the 95% flux surface is 6. the central q value is 3.9 and the minimum in q is 2.6. The current density profile is maintained by the natural profile of the bootstrap current, and a modest amount of electron cyclotmn current drive. ' T E R ~R -S ~~)are observed in several operational regimes; VH-mode (Jackson 1991), high internal inductance (&) H-mode (Lao 1993a). and high poloidal @ (Politzer 1994). The performance in the high confinenent regimes observed in the JET, JT4OU, TFTR, and DIU-D tokamaks is no longer limited by transport or heating power, but instead are limited by stability limits at~high @T ( E T Team 1993. Mauel 1993, Zamstorff 1993. Taylor 1993. Strait 1993. Perfomance in present day tokamaks can be improved if the @-limit can be increased while maintaining the observed high confinement. Our ssategy for identifying 3 self-consistent high confinement high beta steady-state discharge scenario is to identify and maintain those features that are favorable for the high confinement and then modify the profiles to increase the stability limit, without adversely affecting the confinement. The features that we have identified that are favorable for high confinement are: (1) strong plasma shaping, high triangularity (6) and high elongation (K):(2) high plasma rotation. large shear in the ExB flow;(3) finite current density near the edge; (4) negative central shear; and (5) high q(0). We intend to show are compatible with steady-state high p.In the next section, we review a number of high performance regimes that have been identified in DlI-D experimental discharges, and discuss the features that we believe are important for achieving the high

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Improved confinement in high l_ilower hybrid driven steady state plasmas in TORE SUPRA

Cited by 110 publications

References 14 publications

The Role of the Plasma Current in Turbulence Decrease with Lower Hybrid Waves

The Role of the Plasma Current in Turbulence Decrease with Lower Hybrid Waves

Results from deuterium-tritium tokamak confinement experiments

Optimized profiles for improved confinement and stability in the DIII-D tokamak

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Improved confinement in high lilower hybrid driven steady state plasmas in TORE SUPRA

Cited by 110 publications

References 14 publications

The Role of the Plasma Current in Turbulence Decrease with Lower Hybrid Waves

The Role of the Plasma Current in Turbulence Decrease with Lower Hybrid Waves

Results from deuterium-tritium tokamak confinement experiments

Optimized profiles for improved confinement and stability in the DIII-D tokamak

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Improved confinement in high l_ilower hybrid driven steady state plasmas in TORE SUPRA