Particle transport in the scrape-off layer and its relationship to discharge density limit in Alcator C-Mod

B. LaBombard; R. L. Boivin; M. Greenwald; J. Hughes; B. Lipschultz; D. Mossessian; C. S. Pitcher; J. L. Terry; S. J. Zweben;

doi:10.1063/1.1352596

Particle transport in the scrape-off layer and its relationship to discharge density limit in Alcator C-Mod

Physics of Plasmas ◽

10.1063/1.1352596 ◽

2001 ◽

Vol 8 (5) ◽

pp. 2107-2117 ◽

Cited By ~ 178

Author(s):

B. LaBombard ◽

R. L. Boivin ◽

M. Greenwald ◽

J. Hughes ◽

B. Lipschultz ◽

...

Keyword(s):

Particle Transport ◽

Density Limit ◽

Discharge Density

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Review and present status of the TEXTOR radiative improved (RI) mode

Journal of Plasma Physics ◽

10.1017/s0022377898006734 ◽

1998 ◽

Vol 59 (4) ◽

pp. 587-610 ◽

Cited By ~ 14

Author(s):

P. E. VANDENPLAS ◽

A. M. MESSIAEN ◽

J. P. H. E. ONGENA ◽

U. SAMM ◽

B. UNTERBERG

Keyword(s):

Density Profile ◽

High Power ◽

Present Status ◽

Particle Transport ◽

Density Limit ◽

Radiated Power ◽

Edge Radiation ◽

Intermediate Size ◽

Power Fraction ◽

Better Than

From 1990, the boronized TEXTOR tokamak was characterized by an improved confinement (coined the ‘I mode’) at high power that was substantially better than the L mode, but densities had to be limited to n[bar]e0/nGR[lsim ]0.5–0.6, where nGR is the Greenwald density limit. With the injection of Ne, Si or Ar in order to increase the edge radiation and provided that γ=Prad/Ptot[greater, similar]0.5, PNBI-co/Ptot[greater, similar]0.25 and n[bar]e0/nGR[greater, similar]0.75, a further improved confinement called the radiative improved mode (RI mode) was discovered in 1993 on TEXTOR, a tokamak of intermediate size, and confirmed on TEXTOR-94. The radiated power fraction γ can reach 0.9, and the radiation is nearly isotropically distributed over the torus wall. The RI mode is characterized by its ability to obtain simultaneously and stationarily high densities and high confinement. It is linked to a substantial lowering of edge ne, Te and Ti, a reduction in particle transport and a peaking of the density profile. The RI-mode confinement scales on TEXTOR as τE= (n[bar]e0/nGR)τITERH93-P and values up to n[bar]e0/nGR≈1.2 are obtained. There is no detrimental concentration of the seeded impurity at the centre of the plasma. Results of three different interpretative and modelling approaches are in agreement with the improved confinement features; the preliminary indications are that ITG turbulence is strongly reduced. The Z mode observed on ISX-B has a clear resemblance to the RI mode. The very favourable features of the RI mode justify efforts in trying to establish it on larger machines to verify if the present scaling then holds.

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