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TJ-II:Role of isotope effect on biasing induced transitions in the TJ-II stellarator: Difference between revisions
TJ-II:Role of isotope effect on biasing induced transitions in the TJ-II stellarator (view source)
Revision as of 15:13, 26 January 2017
, 26 January 2017→Description of the activity, including motivation/objectives and experience of the proponent (typically one-two pages)
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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 <ref>F. Ryter et al., Nuclear Fusion 53 (2013) 113003</ref>. The influence of isotope mass on spontaneous L-H transition has been recently investigated 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>. | 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 investigated 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 | # Study the influence of ion mass to reach biasing improved confinement regimes | ||
# Study the influence of magnetic configuration (ripple / iota) on biasing induced transitions | # Study the influence of magnetic configuration (ripple / iota) on biasing induced transitions | ||
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: <math>\rho \simeq 0.8</math>/ Biasing ramp up/down up to 350 V | 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 (<math>H_\alpha</math>) | 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 == | ||