Atomic beam diagnostics for characterization of edge plasma in TJ-II stellarator

Brañas, B.; Tafalla, D.; Tabarés, F.L.; Ortiz, P.

doi:10.1063/1.1319868

Cited by 40 publications

(29 citation statements)

References 7 publications

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“…6. So far, n e and T e measurements based on the CR model using the line intensity ratios have been applied in TEXTOR ͑To-kamak Experiment for Technology Oriented Research, Julich, Germany͒, 6 JET ͑Joint European Torus, Abingdon, UK͒, 7,8 JT-60U ͑Japan Atomic Energy Research Institute Tokamak-60 Upgrade, Naka, Japan͒, 9 RFX ͑Reversed Field experiment, Padova, Italy͒, 10 TJ-II stellarator ͑Madrid, Spain͒, 11,12 and LHD ͑Large Helical Device, Toki, Japan͒. 5 Although the spectroscopic method deduced consistent value with other measurement method in some literatures, it has been recently reported from the results in linear divertor simulators that the effects of radiation trapping on the population distribution of helium atoms are considerable.…”

Section: Introductionmentioning

confidence: 99%

Comparison of He I line intensity ratio method and electrostatic probe for electron density and temperature measurements in NAGDIS-II

et al. 2006

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The electron density and temperature obtained from the line intensity ratio method of HeI (λ=667.8, 706.5, and 728.1nm) are compared to the probe method in a divertor simulator. When a collisional radiative model that does not include the effect of the radiation transport was used for the analysis, ne obtained from the spectroscopic method was significantly higher than that from the electrostatic probe method. The discrepancy between the two methods increases with the gas pressure; in other words, it increases with the optical thickness. In the case that the effect of the radiation trapping is taken into consideration using optical escape factor, the discrepancy becomes moderate. And then, the parameters obtained from the line intensity ratio method agree with the probe method within a factor of 2 in the case that the radiation trapping was introduced with R=0.05m, which corresponds to the column radius of the spatial profile of the excited population density. In recombining plasmas, however, it was shown that the line intensity ratios might not be appropriate because the recombining component broke the monotonic increase/decrease dependences of the line intensity ratios on ne and Te. A measurement of another HeI line intensity of 447.1nm (2P3←4D3) is proposed for solving the problem.

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Section: Introductionmentioning

confidence: 99%

Comparison of He I line intensity ratio method and electrostatic probe for electron density and temperature measurements in NAGDIS-II

et al. 2006

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“…After the pioneering work in the TJ-IU torsatron, 5 the technique has been applied in other devices for edge characterization and its use for the determination of electric fields at the plasma edge has also been proposed. [6][7][8] In its former version 5,6 only one He pulse, of duration less than 2 ms, was produced, thus precluding the measurement of the evolution of the plasma edge parameters profiles evolution in a single shot scheme. In this article, the development of a multipulse supersonic He beam able to produce spatial profiles of the relevant emission lines at repetition frequencies of F up to 200 Hz is presented.…”

Section: Introductionmentioning

confidence: 99%

Multipulse supersonic helium beam diagnostic in the TJ-II stellarator

Hidalgo

Tafalla

Brañas

et al. 2004

Review of Scientific Instruments

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The well known He beam diagnostic, able to provide profiles of the electronic plasma edge parameters, has undergone a significant improvement by the application of supersonic expansion techniques in the last years. The use of pulsed fast piezoelectric valves was initiated in the TJ-IU and implemented in the TJ-II stellarators. In its former configuration the repetition rate of the beam was ultimately limited in the expansion chamber by the pressure buildup. In the actual upgraded version, however, a repetition rate up to 200 Hz can be achieved, and the recording of the electron temperature and density profiles with millisecond resolution is possible. In the present work, the technical development of the diagnostic required for optimized performance is described. In addition, the validation of the collisional-radiative model needed for the reconstruction of the edge profiles and the analysis of the complementary information given by the beam attenuation is also addressed.

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“…The properties of the resulting beam depend on the source pressure, the nozzle-skimmer distance and the volume and pumping capacity of the chamber between the nozzle and the [8]. Optimized designs for particular diagnostic requirements have been published [9][10][11][12][13].…”

Section: Introductionmentioning

confidence: 99%

A short-pulsed compact supersonic helium beam source for plasma diagnostics

Andruczyk

Namba

James

et al. 2006

Plasma Devices and Operations

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A short-pulsed (less than 1 ms) compact supersonic helium beam source has been developed for plasma diagnostics purposes. The beam has been characterized experimentally and the results compared with calculations from a simple model that takes into account interaction between the supersonic beam and gas in the region between the nozzle and the skimmer. For a 200 µs driving pulse, a beam of density N > 1 × 10 18 m −3 on the axis, a width of D ≈ 1 cm at a distance of 30 cm from the nozzle and a velocity v ≈ 1.8 × 10 3 m s −1 has been achieved.

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Atomic beam diagnostics for characterization of edge plasma in TJ-II stellarator

Cited by 40 publications

References 7 publications

Comparison of He I line intensity ratio method and electrostatic probe for electron density and temperature measurements in NAGDIS-II

Comparison of He I line intensity ratio method and electrostatic probe for electron density and temperature measurements in NAGDIS-II

Multipulse supersonic helium beam diagnostic in the TJ-II stellarator

A short-pulsed compact supersonic helium beam source for plasma diagnostics

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