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TJ-II:Role of isotope effect on biasing induced transitions in the TJ-II stellarator: Difference between revisions
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== Name and affiliation of proponent == | == Name and affiliation of proponent == | ||
S. Ohshima, Institute of Advanced Energy, Kyoto University, Kyoto, Japan | S. Ohshima, Institute of Advanced Energy, Kyoto University, Kyoto, Japan | ||
H. Takahashi, NIFS, Japan | |||
Ulises Losada Ciemat, Spain | |||
== Details of contact person at LNF (if applicable) == | == Details of contact person at LNF (if applicable) == | ||
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== Description of the activity, including motivation/objectives and experience of the proponent (typically one-two pages)== | == Description of the activity, including motivation/objectives and experience of the proponent (typically one-two pages)== | ||
Motivation | '''Motivation''': | ||
Experimental studies have shown a reduction of the L-H power threshold by about 50% when using Deuterium instead of Hydrogen in tokamaks | Experimental studies have shown a reduction of the L-H power threshold by about 50% when using Deuterium instead of Hydrogen in tokamaks <ref>F. Ryter et al., Nuclear Fusion 53 (2013) 113003</ref>. The influence of isotope mass on spontaneous L-H transition has been recently reported in DIII-D <ref>L. Schmitz, EX/P3-11, IAEA2016</ref> and in the TJ-II stellarator, concluding that Zonal Flows are instrumental both in H and D dominated plasmas to trigger the L-H transition <ref>U. Losada et al., CWGM/Madrid January 2017</ref>. | ||
Goals and planning | '''Goals and planning''': | ||
We propose to investigate the influence of isotope mass (H vs D) on TJ-II electrode biasing induced transitions with to goals: | We propose to investigate the influence of isotope mass (H vs D) on TJ-II electrode biasing induced transitions with to goals: | ||
# Study the influence of ion mass to reach biasing improved confinement regimes. If possible, biasing induced Limit cycle oscillation will be investigated to explore the dynamics of L-H transition and the difference between H vs D plasmas. This phenomenon was observed in Heliotron J biasing plasma. | |||
# Study the influence of magnetic configuration (ripple / iota) on biasing induced transitions and turbulence-induced transport. | |||
Experimental set-up | '''Experimental set-up''': | ||
Target plasma: ECRH and NBI plasmas | Target plasma: ECRH and NBI plasmas | ||
Configuration: comparative studies in standard configuration (e.g. 100_42) and configuration with reduced volume (e.g. 100_30). | Configuration: comparative studies in standard configuration (e.g. 100_42) and configuration with reduced volume (e.g. 100_30). | ||
Electrode position: | Electrode position: <math>\rho \simeq 0.8</math> / Biasing ramp up/down up to 350 V | ||
Key diagnostics:
Dual Langmuir probe system (density, potential and LRC), HIBP (space potential, Er profiles fluctuation), Thomson scattering (Te, ne profiles), Doppler reflectometer (poloidal flow velocity, Er, fluctuations), ECE (Te profile), spectroscopy ( | Key diagnostics:
Dual Langmuir probe system (density, potential and LRC), HIBP (space potential, Er profiles fluctuation), Thomson scattering (Te, ne profiles), Doppler reflectometer (poloidal flow velocity, Er, fluctuations), ECE (Te profile), spectroscopy (<math>H_\alpha</math>) | ||
== If applicable, International or National funding project or entity == | == If applicable, International or National funding project or entity == | ||
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[[Category:TJ-II internal documents]] | [[Category:TJ-II internal documents]] | ||
[[Category:TJ-II experimental proposals]] | [[Category:TJ-II experimental proposals 2017]] | ||