Self-consistent determination of the ion thermalization rate at the plasma boundary of TJ-II by the supersonic He beam diagnostic

Tabarés, F.L.; Tafalla, D.

doi:10.1088/0029-5515/55/1/013020

Cited by 2 publications

(4 citation statements)

References 25 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Aside from limiting the use of the LiLA-TOF diagnostic to ion temperatures above a few eV, a radial spreading of the Li + source can result in a blending of different flux tubes sampled by the detector, and hence, multiple TOF components. This could explain the presence of a low T i tail in the present experiments, indicating the presence of a T i gradient near the plasma boundary [7].…”

Section: Discussionsupporting

confidence: 50%

“…In some previous works made on the stellarator TJ-II [6,7], the He/He + line ratio method was successfully tested as a diagnostic for T i measurement in the plasma boundary region of this device. When combined with the traditional He lineratio technique and a suitable Collisional-Radiative model [8], it allows microscopic edge plasma parameter profiles to be obtained, i.e.…”

Section: Introductionmentioning

confidence: 99%

“…T i , T e , and n e . However, the presence of plasma rotation as a drift term for the locally generated He ions represented an important setback and complicated the interpretation of the diagnostic [7]. Although several methods for the measurement of T i at the edge of TJ-II have been tried (RFA, He beam, Doppler spectroscopy…) no systematic recording of this important parameter has been achieved so far.…”

Section: Introductionmentioning

confidence: 99%

“…In contrast, figure 1(b) shows the effect of toroidal rotation on the TOF trace for T i = 30 eV (see equation (7)). Here, a negative v rot corresponds to anti-clockwise rotation from the injection point in figure 2 to the monitoring point, while a positive v rot corresponds to a clockwise rotation in the same figure 3.…”

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

A lithium laser-ablation based time-of-flight (LILA-TOF) diagnostic for measuring plasma edge ion temperature and toroidal plasma rotation

López-Miranda¹,

Tabarés²,

McCarthy³

et al. 2021

Plasma Phys. Control. Fusion

View full text Add to dashboard Cite

A new method for studying the thermalization and transport of injected impurities at the edge of hot plasma, (considering the last closed magnetic surface, the free path is between 1 and 2 cm approx.) under no perturbative conditions, is presented. In the proposed technique, a Nd:YAG laser is used to ablate Li from the lithiated wall of the stellarator TJ-II. While the laser pulse allows for the analysis of the released species through laser induced breakdown spectroscopy (LIBS), its laser pulse also provides a time reference for the time-of-flight (TOF) measurements of the Li+ ions performed. This is done by positioning light detection systems sensitive to an intense Li II spectral line at different toroidal locations away from such a source. TOF times of tens to hundreds of microseconds are recorded. Then, by de-convolving the shape of the recorded light pulse, the velocity distribution of the lithium-ion during its thermalization with the background plasma can be extracted. From this velocity distribution, the ion temperature of the background ions and the toroidal rotation at the plasma periphery can be deduced. In contrast with conventional Doppler spectroscopy, this technique uses filter-scope detectors rather than high-spectral-resolution spectrometers thus a tradeoff between spectral and time or space resolution is required. Finally, preliminary results of the application of this novel technique are shown to validate this proof of principle.

show abstract

Section: Discussionsupporting

confidence: 50%