Sawtooth induced q-profile evolution at ASDEX Upgrade. (26th March 2019)
- Record Type:
- Journal Article
- Title:
- Sawtooth induced q-profile evolution at ASDEX Upgrade. (26th March 2019)
- Main Title:
- Sawtooth induced q-profile evolution at ASDEX Upgrade
- Authors:
- Fischer, R.
Bock, A.
Burckhart, A.
Ford, O.P.
Giannone, L.
Igochine, V.
Weiland, M.
Willensdorfer, M. - Other Names:
- collab.
- Abstract:
- Abstract: The sawtooth induced q -profile evolution was modelled at ASDEX Upgrade and validated with imaging motional Stark effect (IMSE) measurements. The equilibrium current distribution was estimated by the coupling of a Grad–Shafranov solver and the current diffusion equation. At ASDEX Upgrade an extensive diagnostic suite allows for a reliable modelling of the current density profile and its temporal evolution as long as neo-classical current diffusion can be assumed. The sawtooth-induced central q change, , was estimated from equilibrium reconstruction between the sawtooth events without using IMSE measurements. The sawtooth-induced current relaxation is modelled with two different reconnection models, a Kadomtsev full reconnection and a newly developed fully stochastic flat-current model. Both models result in about the same sawtooth-induced 0.10–0.12 but with a small difference in the absolute q 0 values. The sawtooth-induced evolution of the forward modelled MSE angles agrees well with the IMSE measurements. This confirms the assumption of neo-classical current diffusion between the sawtooth events. A sensitivity study reveals two major ingredients for a reliable interpretation of MSE measurements. Firstly, the sawtooth-induced redistribution of fast ions has to be taken into account for a reliable estimation of the Shafranov shift. The fast-ion redistribution is modelled with a particle-conserving homogeneous fast-ion pressure profile in the plasma core and aAbstract: The sawtooth induced q -profile evolution was modelled at ASDEX Upgrade and validated with imaging motional Stark effect (IMSE) measurements. The equilibrium current distribution was estimated by the coupling of a Grad–Shafranov solver and the current diffusion equation. At ASDEX Upgrade an extensive diagnostic suite allows for a reliable modelling of the current density profile and its temporal evolution as long as neo-classical current diffusion can be assumed. The sawtooth-induced central q change, , was estimated from equilibrium reconstruction between the sawtooth events without using IMSE measurements. The sawtooth-induced current relaxation is modelled with two different reconnection models, a Kadomtsev full reconnection and a newly developed fully stochastic flat-current model. Both models result in about the same sawtooth-induced 0.10–0.12 but with a small difference in the absolute q 0 values. The sawtooth-induced evolution of the forward modelled MSE angles agrees well with the IMSE measurements. This confirms the assumption of neo-classical current diffusion between the sawtooth events. A sensitivity study reveals two major ingredients for a reliable interpretation of MSE measurements. Firstly, the sawtooth-induced redistribution of fast ions has to be taken into account for a reliable estimation of the Shafranov shift. The fast-ion redistribution is modelled with a particle-conserving homogeneous fast-ion pressure profile in the plasma core and a subsequent recovery time of 50 ms. Secondly, a reliable estimation of the electric field is necessary for a credible interpretation of the MSE angles. … (more)
- Is Part Of:
- Nuclear fusion. Volume 59:Number 5(2019:May)
- Journal:
- Nuclear fusion
- Issue:
- Volume 59:Number 5(2019:May)
- Issue Display:
- Volume 59, Issue 5 (2019)
- Year:
- 2019
- Volume:
- 59
- Issue:
- 5
- Issue Sort Value:
- 2019-0059-0005-0000
- Page Start:
- Page End:
- Publication Date:
- 2019-03-26
- Subjects:
- equilibrium reconstruction -- sawtooth instability -- reconnection models -- imaging motional Stark effect -- fast-ion redistribution -- electric fields -- ASDEX Upgrade
Nuclear fusion -- Periodicals
621.48405 - Journal URLs:
- http://www.iop.org/EJ/journal/0029-5515 ↗
http://iopscience.iop.org/0029-5515/ ↗
http://ioppublishing.org/ ↗ - DOI:
- 10.1088/1741-4326/ab0b65 ↗
- Languages:
- English
- ISSNs:
- 0029-5515
- Deposit Type:
- Legaldeposit
- View Content:
- Available online (eLD content is only available in our Reading Rooms) ↗
- Physical Locations:
- British Library DSC - BLDSS-3PM
British Library STI - ELD Digital store - Ingest File:
- 10122.xml