Plasma surface interaction during rf heating on JFT-2 tokamak

Suzuki, Norio; Ohtsuka, Hokuto; Sugie, Toshiharu; Ogiwara, Norio; Kasai, S.; Fujisawa, N.; Maeno, Masaki; Yamamoto, T.; Nagashima, Takashi; Imai, T.; Uehara, K.; Yoshida, Hiroshi; Funahashi, A.; Takeuchi, Hiroshi; Shoji, T.; Kumagai, K.; Kawakami, T.; Yamauchi, Toshihiko

doi:10.1016/0022-3115(80)90335-9

Cited by 7 publications

(8 citation statements)

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“…On ISX-B it was noticed that the rate of density rise was strongly reduced during heating experiments with neutral beam injection [1,2], an effect described as a density 'clamp'. Similar results have been obtained on other tokamaks with neutral injection [3,4,5] and other heating methods [3,6,7,8]. There has been some debate on whether this effect is principally due to a decrease in the recycling of particles from the vacuum vessel and limiters [2,4,8] or an increase in the particle flux from the discharge [1,5] equivalent to a decrease in particle confinement time, r p .…”

supporting

confidence: 66%

Boundary layer measurements during density clamp in DITE

Erents¹,

Fielding²,

Hugill³

et al. 1983

Nucl. Fusion

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supporting

confidence: 66%

Boundary layer measurements during density clamp in DITE

Erents¹,

Fielding²,

Hugill³

et al. 1983

Nucl. Fusion

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“…Xe -electron thermal diffusivity deduced from TRANSPTFR1, TFR2, TFR3 -Girard [84] for q>l, 1 <q<2, q <2, respectively. 20 30 RADIUS (cm) FIG. 34.…”

Section: Discussionmentioning

confidence: 99%

“…30. Xe ~ electron thermal diffusivity deduced from TRANSP, Bohm -ckTJ16eB, Intor -5X10 ll /n e cm 2 -s~l, 1/nT -4X10 20 /n e T e (eV) cm 2 -s~\ scaling laws. The scalings are listed in the figure captions, either through references or explicit expressions.…”

Section: Discussionmentioning

confidence: 99%

“…Neutral-beam heating experiments with limiter plasmas have been carried out in a variety of tokamaks (ASDEX [7,8], DITE [9,10], D-III [11][12][13], ISX-B [14][15][16][17][18], JFT-2 [19,20], PLT [2,[21][22][23][24][25], TFR [26,27] and T-l 1 [28]). Since reviews of transport and energy confinement scaling have recently appeared in the literature [29,30], only the gross features of the studies on the above-mentioned machines will be discussed here.…”

Section: Survey Of Tokamak Confinement During Neutral-beam Heatingmentioning

confidence: 99%

See 1 more Smart Citation

Thermal energy confinement scaling in PDX limiter discharges

et al. 1984

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Experiments were performed on the PDX tokamak to study plasma heating and beta scaling with high-power, near-perpendicular neutral-beam injection. The data taken during these experiments were analysed, using a time-dependent data interpretation code (TRANSP), to study the transport and thermal confinement scaling over a wide range of plasma parameters. This study focuses on results from experiments with D° injection into H* plasmas using graphite rail limiters, a = 40-44 cm, R = 143 cm, I p = 200-480 kA, B T = 0.7-2.2 T, and, typically, n e = (2.5-4.2) X 10 13 cm" 3 . The results of this study indicate that for both Ohmic and neutral-beam-heated discharges the energy flow out of the plasma is dominated by anomalous electron losses which are attributed to electron thermal conduction. The ion conduction losses are not inconsistent with neoclassical theory; however, the total ion loss influences the power balance significantly only at high toroidal fields and high plasma currents. Therefore, except for these cases, the total thermal energy confinement time for the neutral-beam-heated discharges follows the scaling of electron energy confinement. While the confinement is found to have little dependence on toroidal field, it is a strong function of plasma current, increasing with increasing I p . In contrast, Ohmic confinement times are found to scale as n e q 1/2 . Because of the dominant effect of the electrons, the total confinement is found to depend heavily on the variation of the electron thermal diffusivity, Xe, in t n e outer region of the plasma (a/2 < r < 7a/8). The values of Xe m this region of the plasma show an approximately inverse dependence on the local value of the poloidal magnetic field.

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“…In 1980, a high-beta experiment was performed with a 2 MW NBI heating system [2]. The volume-averaged thermal beta values deduced from the profile measurements of plasma temperature and density ranged over 2.5-3%, at that time record values which were also reached in ISX-B and T-l 1.…”

Section: Jft-2 Experimentsmentioning

confidence: 99%