TJ-II:Influence of positive and negative density gradients in turbulent transport using the HIBP system
Experimental campaign
2018 Autumn
Proposal title
Influence of positive and negative density gradients in turbulent transport using the HIBP system
Ph. Khabanov and the HIBP team
Enter name and affiliation here
Details of contact person at LNF (if applicable)
Enter contact person here or N/A
An important factor contributing to the particle transport is the density gradient localization which is closely connected to the refuelling for next step tokamaks (like ITER) and stellarators devices (W7-X). Refuelling of core plasma particles is foreseen by pellets that injects particles at high speed deep into the plasma. However, at reactor relevant plasma densities and temperatures, pellets are unable to reach the core plasma region. In fact, pellet ablation will take place in the plasma edge region [[1]; P. Vincenzi et al., Nuclear Fusion 55 (2015)113028], causing plasma bumps with positive and negative density gradient regions where eventually particles could be transported radially inwards by turbulence. Fluid and GK simulations have investigated the level of inward turbulent particle transport in the inverted density gradient region [L. Garzotti et al Plasma Phys. Control. Fusion 56 (2014) 035004; C. Angioni et al., Nucl. Fusion 57 (2017) 116053, but comparisons of GK with experimental fluctuation levels and fluxes are missing. Stellarators are well suited to investigate the influence of such positive and negative density gradients on plasmas fluctuations and transport because of its capabilities to control plasma scenarios and magnetic configuration. Recent experiments in TJ-II have shown that density fluctuations appear both at the positive and negative gradient regions in electron root ECRH plasmas, with the minimum amplitude in the zero density gradient regions [R. Sharma et al., EPS 2018]. The goal is to systematically investigate the influence of on-axis / off-axis ECRH heating on fluctuations and turbulent ExB transport in positive and negative density gradient regions. == Enter description here [2]
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)