"A hydrogen pellet injector for the TJ-II stellarator: Testing, modelling and first experiments"
Event details
| Date | 05.12.2014 |
| Hour | 10:30 › 11:30 |
| Speaker | I. Arapoglou (CIEMAT, Spain) |
| Location |
PPB 019
|
| Category | Conferences - Seminars |
The new compact four-barrel pellet injection system that has been recently installed on the TJ-II stellarator, is equipped with a cryogenic refrigerator for in situ hydrogen pellet formation and will be used as a fuelling and diagnostic tool. This system has been modelled and tested in order to predict and study particle ablation and deposition along the pellet path through the plasma, together with the resulting evolution of the background plasma. A pellet ablation model, based on the NGS model, has been developed and adjusted to the pellet path inside the standard magnetic configuration of TJ-II. After verifying the validity of the model, it was implemented into a transport code as a subroutine adapted to provide a pellet source term in the equations. The obtained results showed relatively good agreement with the subsequent first experiments. Injecting pellets into TJ-II plasmas, besides verifying the successful installation and operation of the system, confirmed pellet injection to be a useful central fuelling tool and also the wide range of applications of the system was apparent. Better particle and plasma energy confinement was observed due to the injected pellet. Furthermore, the presence of plasma current, that can modify the topology of the magnetic surfaces and shift the filaments of very fast electrons in the plasma, which cause the sudden, almost instantaneous, ablation of the pellet. Thus, it was found that pellet injection could also be used to explore magnetic configurations, and identify and locate these populations of fast electrons inside the plasma.
Practical information
- Informed public
- Free
Organizer
- Prof. P. Ricci
Contact
- Prof. P. Ricci