Particle source impact on fusion plasma density profile in JET experiments

Show simple item record

dc.contributor Helsingin yliopisto, Matemaattis-luonnontieteellinen tiedekunta fi
dc.contributor University of Helsinki, Faculty of Science en
dc.contributor Helsingfors universitet, Matematisk-naturvetenskapliga fakulteten sv
dc.contributor.author Kirjasuo, Anu
dc.date.issued 2021
dc.identifier.uri URN:NBN:fi:hulib-202104071828
dc.identifier.uri http://hdl.handle.net/10138/328798
dc.description.abstract Despite a vast body of knowledge that has already been accumulated on particle transport at both theoretical and experimental level, a simple method for estimating particle source impact on plasma density profile peaking has been lacking. Fable et al. presented a parameter for calculating the source strength (Sstr, the S parameter) in [1]. The parameter is derived from particle flux continuity equation, and after approximations takes as input parameters only the information on neutral beam injection (NBI) power, beam ions injection energy, effective core heat transport diffusivity and plasma density, radius, and volume together with a fitted coefficient from an ASDEX Upgrade experiment. The formula was applied to a database of 165 pulses in both high and low confinement mode, mostly with neutral beam heating, in JET, Joint European Torus, fusion experiment. The results appear reasonable considering the fitted parameter and the approximations in the formula. In addition to the S parameter values, also normalised density gradient dependence on neutral beam heating power and collisionality were investigated, to compare the results with those obtained at ASDEX Upgrade in [1]. Detailed studies of six gas puff modulation shots [2, 3, 4] at JET are used as reference. In [2] the source contribution for the H-mode shots was 50-60% and low confinement mode shots 10-20%. This is further validated in [3] and the high confinement mode shots are compared to similar shots DIII-D fusion experiment in [4], where the source impact on density peaking was negligible. Observed differences are attributed to different dominant turbulent environments. The average calculated level of S parameter values suggest mostly non-negligible source contribution to density peaking, and the values differ for high and low confinement mode plasmas, in line with [2, 3, 4]. However, the results imply that the coefficient 2000 is not constant across the database, and while a scalar correction to fit the coefficient to JET may be possible for low confinement mode plasmas, the high confinement mode plasmas require further research. en
dc.language.iso eng
dc.publisher Helsingin yliopisto fi
dc.publisher University of Helsinki en
dc.publisher Helsingfors universitet sv
dc.subject fusion en
dc.subject fusion energy en
dc.subject tokamak en
dc.subject neutral beam heating en
dc.subject plasma density peaking en
dc.subject particle transport en
dc.title Particle source impact on fusion plasma density profile in JET experiments en
dc.type.ontasot pro gradu -tutkielmat fi
dc.type.ontasot master's thesis en
dc.type.ontasot pro gradu-avhandlingar sv
dct.identifier.urn URN:NBN:fi:hulib-202104071828
dc.subject.specialization Kokeellinen materiaalifysiikka fi
dc.subject.specialization Experimental Material Physics en
dc.subject.specialization Experimentell materialfysik sv
dc.subject.degreeprogram Materiaalitutkimuksen maisteriohjelma fi
dc.subject.degreeprogram Master's Programme in Materials Research en
dc.subject.degreeprogram Magisterprogrammet i materialforskning sv

Files in this item

Files Size Format View
Kirjasuo_Anu_tutkielma_2021.pdf 6.231Mb application/pdf View/Open

This item appears in the following Collection(s)

Show simple item record