Speaker
Antonio Frattolillo
(ENEA C.R. Frascati)
Description
Core fuelling of DEMO fusion reactor is under investigation within the EUROfusion Work Package "Tritium, Fuelling and Vacuum". An extensive analysis of fuelling requirements and technologies, suggests that pellet injection still represents, to date, the most realistic option. Modelling of both pellet penetration and fuel deposition profiles for different injection locations, assuming a specific plasma reference scenario and the ITER reference pellet mass (6×1021 21 atoms), indicates that:
1. Low Field Side (LFS) injection is inadequate, even at speeds ≥ 10 km/s;
2. Vertical injection may be effective only provided that pellets are injected at ≈10 km/s from a radial position ≤8 m, so this injection scheme is not presently considered as a practical option, unless such high injection speeds will become available;
3. Effective core fuelling can be achieved launching pellets from the High Field Side (HFS) at ≈1 km/s. Guiding tracks with a bend radius ≥6 m are envisaged to deliver intact pellets at 1 km/s.
HFS injection was therefore selected as the reference scheme, though scenarios featuring less steep density and temperature gradients at the plasma edge could induce to reconsider vertical injection at speeds in the range of 4 to 5 km/s.
The results of above simulations rely, of course, on the hypothesis that pellets are delivered at the plasma edge with the desired mass and speed. However, mass erosion and fracturing of pellets inside the track, severely limiting the transfer speed, as well as pressure build up and speed losses at relevant injection rates, might hamper the use of curved guide tubes.
An additional innovative approach, aimed at individuating inboard straight "free flight" injection paths, to inject pellets from the HFS at significantly higher speeds, is proposed and discussed as a backup solution. Outboard high-speed injection is still being considered, instead, for JT-60SA.
Co-authors
Antonio Frattolillo
(ENEA C.R. Frascati, via Enrico Fermi, 45 Frascati (Rome), Italy)
Bernard Pegourie
(CEA-IRFM, 13108 Saint-Paul-lez-Durance, France)
Christian Day
(Karlsruhe Institute of Technology, 76021 Karlsruhe, Germany)
Francesca Bombarda
(ENEA C.R. Frascati, via Enrico Fermi, 45 Frascati (Rome), Italy)
Peter T. Lang
(Max Planck Institute for Plasma Physics, EURATOM Association, 85748 Garching, Germany)
Silvio Migliori
(ENEA C.R. Frascati, via Enrico Fermi, 45 Frascati (Rome), Italy)
