Japan Atomic Energy Agency, Naka Fusion Institute H モード周辺プラズマの無次元量解析 Japan Atomic Energy Agency 浦野 創 原子力機構 那珂核融合研究所

Japan Atomic Energy Agency, Naka Fusion Institute H-mode is considered as the standard operation mode in ITER. 1.Steady state with the existence of ELM accompanied by pulsating expulsion of heat and particle. 2.Favorable confinement due to edge transport barrier Pedestal characteristics can strongly be linked to 1.Boundary condition determining the core energy confinement 2.Characterization of ELM losses Introduction width

Japan Atomic Energy Agency, Naka Fusion Institute Dimensionless analysis on spatial width of H-mode pedestal Optimizing pedestal width  ped and height is a crucial issue to control the overall H-mode confinement. Dimensionless analysis is urgent issue for extrapolation to ITER. This is because a strong co-linearity between  and  is hard to separate out at the plasma edge.  ped expressed by non-dimensional parameters are not consistent among several devices.      F( , q, , , , …) =  ped  Examine the scaling of pedestal width by conducting the non-dimensional transport experiment introducing hydrogen discharges.

Japan Atomic Energy Agency, Naka Fusion Institute Co-linearity between  and  at the plasma edge in the H-modes Dependence of p ped on I p yields  and  * as a function of I p at * = const. This co-linearity is hard to separate in the H-mode plasmas only with a single species. ITn  I p Tn 

Japan Atomic Energy Agency, Naka Fusion Institute JT-60U Tokamak: p. 5 Examine dependence on  introducing hydrogen plasmas CONDITION: IP~1MA, BT~2, DELTA~0.3 Examine the dependence of  ped on  or  while keeping total  pol fixed in hydrogen and deuterium H-modes. (1) If  PED  , spatial profiles would deviate by m 0.5. (2) If  PED  , spatial profiles would be similar. Similar profiles are obtained in H/D plasmas. This result implies  * dependence is weak. (H. Urano, et al., NF 48 (2008) )

Japan Atomic Energy Agency, Naka Fusion Institute Power scan of satisfying  = const. in H/D plasmas reveals the  (  m 0.5 ) dependence of  ped at fixed density. Experiments on  dependence of  ped I p = 1.08 MA, B T = 2.4T  = 0.35 Power required to sustain the same  in H-plasma is ~2 times larger than that in D-plasma. Higher ELM frequency is observed in H-plasma.

Japan Atomic Energy Agency, Naka Fusion Institute Similar profiles of n e, T e, T i were obtained in H/D plasmas. Thus, mass effect clearly appeared in the  profiles (  m 0.5 ) while the profiles of  and  were similar. *

Japan Atomic Energy Agency, Naka Fusion Institute Despite of different  at the pedestal by mass ratio (~ 1.4), the similar edge profile are obtained in H/D plasmas. In a series of experiments, change of  ped is small in the variation of  pol  at fixed  pol (  ped  a p  0.2 ).  = 0.2

Japan Atomic Energy Agency, Naka Fusion Institute Experiments on  pol dependence of  ped Power scan of satisfying  pol  I p 4 at the pedestal with controlling n  I p 4 gives the variation of  pol at fixed  pol . Compare profiles at time slices when  pol * remains constant at the pedestal.

Japan Atomic Energy Agency, Naka Fusion Institute In the peripheral region,  is varied while keeping  and  fixed. *

Japan Atomic Energy Agency, Naka Fusion Institute When  (  T 0.5 /I p ) remains constant at the pedestal,  ped becomes wider at higher  pol plasma. Appropriate power scan gives a data set with the variation of . Then, the relation of  ped  a p  0.5 is obtained  pol  ped /a p  = 0.5

Japan Atomic Energy Agency, Naka Fusion Institute Scaling of pedestal width  pol  0.2  pol 0.5  ped / a p D H Based on the non-dimensional transport experiments using H/D plasmas, the scaling on H-mode pedestal width is obtained Rho dependence of the pedestal width is weak while it depends strongly on beta.  ped  a p  0.2  0.5  ped  a p 

Japan Atomic Energy Agency, Naka Fusion Institute Summary Conducting the H-mode experiments using hydrogen (H) and deuterium (D) discharges, dependence of pedestal width on non-dimensional parameters were examined. Similar pedestal profiles were obtained at H/D plasmas. When  is raised, pedestal width increased with a relation expressed as  ped  a p  0.2  0.5.