TY - GEN
T1 - The influence of toroidal field ripple on H-mode transitions on JET
AU - Andrew, Y.
AU - Biewer, T. M.
AU - Crombe, K.
AU - Giroud, C.
AU - Hawkes, N. C.
AU - Keeling, D.
AU - Korotkov, A.
AU - De La Luna, E.
AU - Naulin, V.
AU - Parail, V.
AU - Saibene, G.
AU - Salmi, A.
AU - Sartori, R.
AU - De Vries, P.
PY - 2007
Y1 - 2007
N2 - A series of shots have been run on JET to document the effect of TF ripple on the L-H, Hmode and H-L phases. An increased level of ripple was found to have no significant effect on the power required for H-mode access, T iped, Teped or on νθ over a range of edge n̄e. The values of edge νφ, measured at the locations of Ti ped and ρ = 0.85, were measured to change direction from co- to counter-current rotation and to decrease in gradient on application of enhanced TF ripple. For the ELMy H-mode phase of the shots, time-slices with matched values of both PCORR and edge n̄e had very similar values of Tiped and νθ. Further analysis is required to understand the observed lowering of Te ped by ∼ 200 eV with increased ripple amplitude at the lower end of the n̄e scan. Increased ripple amplitude during the higher power, ELMy phase results in even stronger reversal of the edge νφ rotation from co- to counter-current direction. This change in edge rotation direction with ripple is also accompanied by a ∼ 65 % decrease in νφ gradient. Finally, a 20 % decrease in H 89 and lowered energy confinement times are measured for the shots with enhanced TF ripple, despite closely matched values of PCORR, edge n̄e and Tped. The braking and reversal of edge νφ and its gradient appears to have a strong association with reduced confinement in the ELMy H-mode phase. Therefore, the level TF ripple on ITER should be minimised in order to reduce any detrimental effects of confinement.
AB - A series of shots have been run on JET to document the effect of TF ripple on the L-H, Hmode and H-L phases. An increased level of ripple was found to have no significant effect on the power required for H-mode access, T iped, Teped or on νθ over a range of edge n̄e. The values of edge νφ, measured at the locations of Ti ped and ρ = 0.85, were measured to change direction from co- to counter-current rotation and to decrease in gradient on application of enhanced TF ripple. For the ELMy H-mode phase of the shots, time-slices with matched values of both PCORR and edge n̄e had very similar values of Tiped and νθ. Further analysis is required to understand the observed lowering of Te ped by ∼ 200 eV with increased ripple amplitude at the lower end of the n̄e scan. Increased ripple amplitude during the higher power, ELMy phase results in even stronger reversal of the edge νφ rotation from co- to counter-current direction. This change in edge rotation direction with ripple is also accompanied by a ∼ 65 % decrease in νφ gradient. Finally, a 20 % decrease in H 89 and lowered energy confinement times are measured for the shots with enhanced TF ripple, despite closely matched values of PCORR, edge n̄e and Tped. The braking and reversal of edge νφ and its gradient appears to have a strong association with reduced confinement in the ELMy H-mode phase. Therefore, the level TF ripple on ITER should be minimised in order to reduce any detrimental effects of confinement.
UR - http://www.scopus.com/inward/record.url?scp=84873862497&partnerID=8YFLogxK
M3 - Conference contribution
AN - SCOPUS:84873862497
SN - 9781622763344
T3 - 34th EPS Conference on Plasma Physics 2007, EPS 2007 - Europhysics Conference Abstracts
SP - 828
EP - 831
BT - 34th EPS Conference on Plasma Physics 2007, EPS 2007 - Europhysics Conference Abstracts
T2 - 34th European Physical Society Conference on Plasma Physics 2007, EPS 2007
Y2 - 2 July 2007 through 6 July 2007
ER -
