Impurity transport studies in ASDEX by means of neon-seeded pellets
Neon-seeded deuterium pellets with a content of 1% neon have been successfully produced and injected into ASDEX divertor discharges. The behaviour of the deposited neon ions has been studied by VUV spectroscopy using a special version of the ASDEX/JET impurity transport code for interpretation. The neutral neon source has been modelled to resemble theoretical ablation curves. Estimates of time scales for ionisation and toroidal spreading of neon ions show that toroidal symmetry is established before ionisation to NeX, while the NeVIII burn-through must be treated with caution in a 1-d model. Some ionisation and recombination rate coefficients have been verified experimentally by investigation of the time delays between pellet entry and maximum intensities, and of the low remaining level of NeVIII radiation after its ionisation peak. The anomalous neon diffusion coefficient has been derived from the final decay of the NeX line intensity, which was observed to be exponential down to the 5% level.
Bibliographic Reference: Report: IPP1/246 EN (1988)
Availability: Available from Max-Planck-Institut für Plasmaphysik, 8046 Garching bei München (DE)
Record Number: 198910225 / Last updated on: 1994-12-01
Original language: en
Available languages: en