TJ-II:Role of isotope effect on biasing induced transitions in the TJ-II stellarator
Experimental campaign
2017 Spring
Proposal title
Role of isotope effect on biasing induced transitions in the TJ-II stellarator
Name and affiliation of proponent
S. Ohshima, Institute of Advanced Energy, Kyoto University, Kyoto, Japan
Details of contact person at LNF (if applicable)
Enter contact person here or N/A
Description of the activity, including motivation/objectives and experience of the proponent (typically one-two pages)
Motivation Experimental studies have shown a reduction of the L-H power threshold by about 50% when using Deuterium instead of Hydrogen in tokamaks [1]. 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 [2].
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:
- Study the influence of ion mass to reach biasing improved confinement regimes
- Study the influence of magnetic configuration (ripple / iota) on biasing induced transitions
Experimental set-up 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). Electrode position: / 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 ( )
If applicable, International or National funding project or entity
Enter funding here or N/A
Description of required resources
Required resources:
- Number of plasma discharges or days of operation:
- Essential diagnostic systems:
- Type of plasmas (heating configuration):
- Specific requirements on wall conditioning if any:
- External users: need a local computer account for data access: yes/no
- Any external equipment to be integrated? Provide description and integration needs:
Preferred dates and degree of flexibility
Preferred dates: (format dd-mm-yyyy)