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TJ-II: Pellet induced Enhanced Confinement: the role of Er and turbulence: Difference between revisions
TJ-II: Pellet induced Enhanced Confinement: the role of Er and turbulence (view source)
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== Description of the activity == | == Description of the activity == | ||
Enter description here <ref>A. Einstein, Journal of Exceptional Results (2017)</ref>, including motivation/objectives and experience of the proponent (typically one-two pages) | Enter description here <ref>A. Einstein, Journal of Exceptional Results (2017)</ref>, including motivation/objectives and experience of the proponent (typically one-two pages) | ||
Pellet-induced Enhanced Confinement (PiEC) has been recently reported [I. Garcia-Cortes et al. submitted for publication in NF] in discharges made in the stellarator TJ-II after a cryogenic fuel pellet is injected into its neutral beam injection (NBI) heated phase. In addition to increased particle density in the plasma core after pellet injection (PI), these plasmas show diamagnetic energy content up to 40% higher to the reference shot without PI. Moreover, the energy confinement time, as determined using a diamagnetic loop, is enhanced when compared to predictions obtained using the International Stellarator Scaling law (H. Yamada et al., Nucl. Fusion 45 (2005) 1684). In general, the PiEC in TJ-II is characterized by increased density gradients, by enhanced negative radial electric fields that extend from the plasma edge region to the core, as observed by HIBP and Doppler reflectometer systems, as well as by reductions in density, plasma potential and magnetic fluctuations in the plasma core. | |||
However, the underlying physics that can induce this regime is still unclear in TJ-II. Taking into account that the Er and turbulence seems to play un key role in similar phenomena in W7-X (enhanced confinement after pellet injection), we propose series of shots with controlled density and with different NBI heating power (from low, only one NBI to high power, both NBI) in order to study at the same time the evolution of profiles like Er (by HIBP and DR) and density and its flucutations (HIBP and DR). | |||
== International or National funding project or entity == | == International or National funding project or entity == | ||