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Pedestal width and ELM size identity studies in JET and DIII-D: implications for ITER

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Abstract
The dependence of the H-mode edge transport barrier width on normalized ion gyroradius (rho* = rho/a) in discharges with type I ELMs was examined in experiments combining data for the JET and DIII-D tokamaks. The plasma configuration as well as the local normalized pressure (beta), collisionality (nu*), Mach number and the ratio of ion and electron temperature at the pedestal top were kept constant, while rho* was varied by a factor of four. The width of the steep gradient region of the electron temperature (T-e) and density (n(e)) pedestals normalized to machine size showed no or only a weak trend with rho*. A rho(1/2) or rho(1) dependence of the pedestal width, given by some theoretical predictions, is not supported by the current experiments. This is encouraging for the pedestal scaling towards ITER as it operates at lower rho* than existing devices. Some differences in pedestal structure and ELM behaviour were, however, found between the devices; in the DIII-D discharges, the n(e) and T-e pedestal were aligned at high rho* but the ne pedestal shifted outwards in radius relative to T-e as rho* decreases, while on JET the profiles remained aligned while rho* was scanned by a factor of two. The energy loss at an ELM normalized to the pedestal energy increased from 10% to 40% as rho* increased by a factor of two in the DIII-D discharges but no such variation was observed in the case of JET. The measured pedestal pressures and widths were found to be consistent with the predictions from modelling based on peeling-ballooning stability theory, and are used to make projections towards ITER
Keywords
ASDEX UPGRADE, H-MODE PEDESTAL, EDGE, PLASMAS, STABILITY, ENERGY, INSTABILITIES, TRANSPORT, PHYSICS, JT-60U, nuclear fusion, H-mode, pedestal

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MLA
Beurskens, MNA et al. “Pedestal Width and ELM Size Identity Studies in JET and DIII-D: Implications for ITER.” PLASMA PHYSICS AND CONTROLLED FUSION 51.12 (2009): n. pag. Print.
APA
Beurskens, M., Osborne , T., Horton, L., Frassinetti, L., Groebner, R., Leonard, A., Lomas, P., et al. (2009). Pedestal width and ELM size identity studies in JET and DIII-D: implications for ITER. PLASMA PHYSICS AND CONTROLLED FUSION, 51(12). Presented at the 36th European-Physical-Society Conference on Plasma Physics.
Chicago author-date
Beurskens, MNA , TH Osborne , LD Horton, L Frassinetti, R Groebner, A Leonard, P Lomas, et al. 2009. “Pedestal Width and ELM Size Identity Studies in JET and DIII-D: Implications for ITER.” Plasma Physics and Controlled Fusion 51 (12).
Chicago author-date (all authors)
Beurskens, MNA , TH Osborne , LD Horton, L Frassinetti, R Groebner, A Leonard, P Lomas, I Nunes, S Saarelma, PB Snyder, I Balboa, B Bray, Kristel Crombé, J Flanagan, C Giroud, E Giovannozzi, M Kempenaars, N Kohen, A Loarte, J Lonnroth, E de la Luna, G Maddison, C Maggi, D McDonald, G McKee, R Pasqualotto, G Saibene, R Sartori, E Solano, W Suttrop, E Wolfrum, M Walsh, Z Yan, L Zabeo, and D Zarzoso. 2009. “Pedestal Width and ELM Size Identity Studies in JET and DIII-D: Implications for ITER.” Plasma Physics and Controlled Fusion 51 (12).
Vancouver
1.
Beurskens M, Osborne T, Horton L, Frassinetti L, Groebner R, Leonard A, et al. Pedestal width and ELM size identity studies in JET and DIII-D: implications for ITER. PLASMA PHYSICS AND CONTROLLED FUSION. 2009;51(12).
IEEE
[1]
M. Beurskens et al., “Pedestal width and ELM size identity studies in JET and DIII-D: implications for ITER,” PLASMA PHYSICS AND CONTROLLED FUSION, vol. 51, no. 12, 2009.
@article{810261,
  abstract     = {The dependence of the H-mode edge transport barrier width on normalized ion gyroradius (rho* = rho/a) in discharges with type I ELMs was examined in experiments combining data for the JET and DIII-D tokamaks. The plasma configuration as well as the local normalized pressure (beta), collisionality (nu*), Mach number and the ratio of ion and electron temperature at the pedestal top were kept constant, while rho* was varied by a factor of four. The width of the steep gradient region of the electron temperature (T-e) and density (n(e)) pedestals normalized to machine size showed no or only a weak trend with rho*. A rho(1/2) or rho(1) dependence of the pedestal width, given by some theoretical predictions, is not supported by the current experiments. This is encouraging for the pedestal scaling towards ITER as it operates at lower rho* than existing devices. Some differences in pedestal structure and ELM behaviour were, however, found between the devices; in the DIII-D discharges, the n(e) and T-e pedestal were aligned at high rho* but the ne pedestal shifted outwards in radius relative to T-e as rho* decreases, while on JET the profiles remained aligned while rho* was scanned by a factor of two. The energy loss at an ELM normalized to the pedestal energy increased from 10% to 40% as rho* increased by a factor of two in the DIII-D discharges but no such variation was observed in the case of JET. The measured pedestal pressures and widths were found to be consistent with the predictions from modelling based on peeling-ballooning stability theory, and are used to make projections towards ITER},
  author       = {Beurskens, MNA  and Osborne , TH and Horton, LD  and Frassinetti, L and Groebner, R and Leonard, A and Lomas, P and Nunes, I and Saarelma, S and Snyder, PB and Balboa, I and Bray, B and Crombé, Kristel and Flanagan, J and Giroud, C and Giovannozzi, E and Kempenaars, M and Kohen, N and Loarte, A and Lonnroth, J and de la Luna, E and Maddison, G and Maggi, C and McDonald, D and McKee, G and Pasqualotto, R and Saibene, G and Sartori, R and Solano, E and Suttrop, W and Wolfrum, E and Walsh, M and Yan, Z and Zabeo, L and Zarzoso, D},
  issn         = {0741-3335},
  journal      = {PLASMA PHYSICS AND CONTROLLED FUSION},
  keywords     = {ASDEX UPGRADE,H-MODE PEDESTAL,EDGE,PLASMAS,STABILITY,ENERGY,INSTABILITIES,TRANSPORT,PHYSICS,JT-60U,nuclear fusion,H-mode,pedestal},
  language     = {eng},
  location     = {Sofia, Bulgaria},
  number       = {12},
  title        = {Pedestal width and ELM size identity studies in JET and DIII-D: implications for ITER},
  url          = {http://dx.doi.org/10.1088/0741-3335/51/12/124051},
  volume       = {51},
  year         = {2009},
}

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