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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 == | ||
A Pellet-induced Enhanced Confinement (PiEC) regime has been recently reported <ref>I. García-Cortés et al. submitted for publication in NF</ref> in discharges made in the 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 in reference shots 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 <ref>H. Yamada et al., Nucl. Fusion 45 (2005) 1684</ref>. 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. | A Pellet-induced Enhanced Confinement (PiEC) regime has been recently reported <ref>I. García-Cortés et al. submitted for publication in NF</ref> in discharges made in the 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 in reference shots 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 <ref>H. Yamada et al., Nucl. Fusion 45 (2005) 1684</ref>. 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 Er and turbulence seems to play a key role in similar phenomena observed in the W7-X (enhanced confinement after pellet injection)<ref>T. Estrada et al., Nucl. Fusion 61 (2021) 046008</ref>, we propose series of PIs into plasmas with controlled density and different NBI heating powers (from low power, with 1 NBI working, to high power, with both NBI working) in order to study simultaneously the evolution of plasma potential and Er profiles (HIBPs and DR) as well as of the plasma density and its | However, the underlying physics that can induce this regime is still unclear in TJ-II. Taking into account that Er and turbulence seems to play a key role in similar phenomena observed in the W7-X (enhanced confinement after pellet injection)<ref>T. Estrada et al., Nucl. Fusion 61 (2021) 046008</ref>, we propose series of PIs into plasmas with controlled density and different NBI heating powers (from low power, with 1 NBI working, to high power, with both NBI working) in order to study simultaneously the evolution of plasma potential and Er profiles (HIBPs and DR) as well as of the plasma density and its fluctations (HIBPs and DR). | ||
== International or National funding project or entity == | == International or National funding project or entity == | ||