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High-performance plasmas after pellet injections in Wendelstein 7-X
- Source :
- Nuclear Fusion, Nuclear Fusion, 60(6):066011. Institute of Physics
- Publication Year :
- 2020
-
Abstract
- A significant improvement of plasma parameters in the optimized stellarator W7-X is found after injections of frozen hydrogen pellets. The ion temperature in the post-pellet phase exceeds 3 keV with 5 MW of electron heating and the global energy confinement time surpasses the empirical ISS04-scaling. The plasma parameters realized in such experiments are significantly above those in comparable gas-fuelled discharges. In this paper, we present details of these pellet experiments and discuss the main plasma properties during the enhanced confinement phases. Local power balance is applied to show that the heat transport in post-pellet phases is close to the neoclassical level for the ion channel and is about a factor of two above that level for the combined losses. In comparable gas-fuelled discharges, the heat transport is by about ten times larger than the neoclassical level, and thus is largely anomalous. It is further observed that the improvement in the transport is related to the peaked density profiles that lead to a stabilization of the ion-scale turbulence.
- Subjects :
- Nuclear and High Energy Physics
Materials science
Hydrogen
Plasma parameters
Pellets
chemistry.chemical_element
01 natural sciences
7. Clean energy
010305 fluids & plasmas
law.invention
stellarator
law
Physics::Plasma Physics
Phase (matter)
0103 physical sciences
Wendelstein 7-X
010306 general physics
Plasma
Condensed Matter Physics
chemistry
Heat transfer
Atomic physics
improved confinement
pellet injection
heat transport
Stellarator
Subjects
Details
- ISSN :
- 00295515, 07413335, 00344885, and 17480221
- Database :
- OpenAIRE
- Journal :
- Nuclear Fusion
- Accession number :
- edsair.doi.dedup.....e202b022faac6197b030ddbc87bb6573
- Full Text :
- https://doi.org/10.1088/1741-4326/ab7867