Study of MARFE Phenomena on HT-7 Tokamak

Gao, Xiang; team, the HT-7

doi:10.1088/1009-0630/1/1/004

Cited by 5 publications

(1 citation statement)

References 12 publications

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“…It is very difficult to obtain good current drive effects above the density limit. During the past few years, LHCD experiments have been carried out in HT-7 for various purposes, and good confinement has been obtained at a low density level [10]. Very good LHCD results have been obtained on the FTU tokamak in high density conditions [11].…”

Section: High Density Operation With Lhcdmentioning

confidence: 99%

High performance discharges near the operational limit in HT-7

Wan

Luo

et al. 2001

Nucl. Fusion

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Efforts have been made on the HT-7 tokamak to extend the stable operation boundaries. Extensive RF boronization and siliconization have been used and a wider operational Hugill diagram has been obtained. The transit density reached 1.3 times the Greenwald density limit in ohmic discharges. A stationary high performance discharge with qa = 2.1 has been obtained after siliconization. Confinement improvement was obtained as a result of the significant reduction of electron thermal diffusivity χe in the outer region of the plasma. An improved confinement phase was also observed with LHCD in the density range of 70-120% of the Greenwald density limit. Off-axis LH wave power deposition was attributed to the weak hollow current density profile. Code simulations and measurements showed good agreement with the off-axis LH wave deposition. Supersonic molecular beam injection has been successfully used to achieve stable high density operation in the region of the Greenwald density limit.

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Section: High Density Operation With Lhcdmentioning

confidence: 99%

High performance discharges near the operational limit in HT-7

Wan

Luo

et al. 2001

Nucl. Fusion

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Runaway electron dynamics during impurity gas puffing on HT-7 tokamak

et al. 2010

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Runaway electrons have been studied by injection/gas puffing of argon and neon gases during low-density, current ramp-down deuterium discharges in the HT-7 tokamak [X. Gao, Plasma Sci. Technol. 1, 25 (1999)]. The argon and neon gases have been injected/puffed separately during runaway Ohmic discharges, and the effects of these gases on runaway electron dynamics have been observed with different gas pulse widths and varied injection times. It has been found that the injection of a noble gas such as argon or neon can terminate the already generated runaway currents in the discharge before the runaway electrons hit the limiter or vessel structures. It has also been observed that runaway electrons cannot gain high energies in the presence of noble gas, and thereby are cooled down to their thermal velocities. During puffing of argon gas, a time delay has been observed before triggering the secondary emission of runaway electrons with a gas pulse width of 10–20 ms, whereas the same effect has also been observed with neon gas with a gas pulse width of 40–50 ms. For a 60–100 ms gas pulse width the runaway electrons have been partially suppressed, and earlier termination of the discharges was observed due to sawtooth collapse of heat energy in the center of the discharge, characterized by hard x-ray and γ ray emissions. The maximum energy of runaway electrons (12 MeV) inferred from gamma spectra is in agreement with the runaway limiting energy predicted by a test particle description of the runaway dynamics [J. R. Martín-Solís et al., Phys. Plasmas 5, 2370 (1998)].

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Plasma density behavior in the Hefei tokamak-7

et al. 2000

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The density profiles were measured in the Hefei tokamak-7 (HT-7) [World Survey of Activities in Controlled Fusion Research, Nuclear Fusion Special Supplement (International Atomic Energy Agency, Vienna, 1997), p. 61] ohmic discharges by means of a new multichannel far-infrared (FIR) laser interferometer. The progress on the extension of the HT-7 ohmic discharge operation region was introduced. The experiment results at the density limit, the multifaceted asymmetric radiation from the edge (MARFE) phenomena, the rf (radio frequency) boronization experiments, and the fueling efficiency studies were reported. The plasma physics in the molecular beam injection (MBI), the pellet injection (PI), and the gas puffing (GP) fueling experiments was studied and discussed.

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Study of MARFE Phenomena on HT-7 Tokamak

Cited by 5 publications

References 12 publications

High performance discharges near the operational limit in HT-7

High performance discharges near the operational limit in HT-7

Runaway electron dynamics during impurity gas puffing on HT-7 tokamak

Plasma density behavior in the Hefei tokamak-7

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