AI Article Synopsis

  • The new laser blow-off system at Wendelstein 7-X enables controlled impurity transport studies by injecting tracer ions into the plasma edge using a Nd:YAG laser to ablate metal films.
  • The system operates at up to 20 Hz and features adjustable laser spot size and positioning, allowing for precise targeting of non-ablated areas.
  • Initial experiments showed detectable spectral lines from tracer ions, and the measurements suggest impurity transport times around 100 ms without significantly altering global plasma parameters.

Article Abstract

We present a detailed overview and first results of the new laser blow-off system on the stellarator Wendelstein 7-X. The system allows impurity transport studies by the repetitive and controlled injection of different tracer ions into the plasma edge. A Nd:YAG laser is used to ablate a thin metal film, coated on a glass plate, with a repetition rate of up to 20 Hz. A remote-controlled adjustable optical system allows the variation of the laser spot diameter and enables the spot positioning to non-ablated areas on the target between laser pulses. During first experiments, clear spectral lines from higher ionization stages of the tracer ions have been observed in the X-ray to the extreme ultraviolet spectral range. The temporal behavior of the measured emission allows the estimate of transport properties, e.g., impurity transport times in the order of 100 ms. Although the strong injection of impurities is well detectable, the global plasma parameters are barely changed.

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Source
http://dx.doi.org/10.1063/1.5037543DOI Listing

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