Transport and confinement physics Chapter 2 of the special issue: on the path to tokamak burning plasma operation

Yoshida, M.*; McDermott, R. M.*; Angioni, C.*; Camenen, Y.*; Citrin, J.*; Jakubowski, M.*; Hughes, J. W.*; Idomura, Yasuhiro; Mantica, P.*; Mariani, A.*; et al.

Nuclear Fusion, 65(3), p.033001_1 - 033001_132, 2025/02

https://doi.org/10.1088/1741-4326/ad8ced

Progress in physics understanding and theoretical model development of plasma transport and confinement in the ITPA Transport and Confinement Topical Group since the publication of the ITER Physics Basis was summarized focusing on the contributions to ITER and burning plasma prediction and control. This paper provides a general and streamlined overview on the advances that were mainly led by the ITPA TC joint experiments and joint activities for the last 15 years. This paper starts with the scientific strategy and scope of the ITPA TC Topical group and overall picture of the major progress, followed by the progress of each research field: particle transport, impurity transport, ion and electron thermal turbulent transport, momentum transport, impact of 3D magnetic fields on transport, confinement mode transitions, global confinement, and reduced transport modeling.

Remnants of spherical shell structures in deformed nuclei; The Impact of an = 64 neutron subshell closure on the structure of 90 gadolinium nuclei

Ross, T. J.*; Hughes, R. O.*; Beausang, C. W.*; Allmond, J. M.*; Angell, C.; Basunia, M. S.*; Bleuel, D. L.*; Burke, J. T.*; Casperson, R. J.*; Escher, J. E.*; et al.

Physical Review C, 88(3), p.031301_1 - 031301_4, 2013/09

AA2013-0388.pdf:0.32MB

https://doi.org/10.1103/PhysRevC.88.031301

Measurement of the entry-spin distribution imparted to the high excitation continuum region of gadolinium nuclei via (,) and (,) reactions

Ross, T. J.*; Beausang, C. W.*; Hughes, R. O.*; Allmond, J. M.*; Angell, C.; Basunia, M. S.*; Bleuel, D. L.*; Burke, J. T.*; Casperson, R. J.*; Escher, J. E.*; et al.

Physical Review C, 85(5), p.051304_1 - 051304_5, 2012/05

AA2012-0155.pdf:0.62MB

https://doi.org/10.1103/PhysRevC.85.051304

The surrogate reaction technique has been employed to cross sections in the actinide region to a precision of 20%, but in the rare earth region a factor of 2-3 discrepancy exists between the directly measured and extracted surrogate cross sections. A possible origin of this discrepancy lies in differences between the initial spin/parity population distribution. To investigate this, the angular momentum transfer of the surrogate reaction in Gd nuclei has been measured.

Pedestal stability comparison and ITER pedestal prediction

Snyder, P. B.*; Aiba, Nobuyuki; Beurskens, M.*; Groebner, R. J.*; Horton, L. D.*; Hubbard, A. E.*; Hughes, J. W.*; Huysmans, G. T. A.*; Kamada, Yutaka; Kirk, A.*; et al.

Proceedings of 22nd IAEA Fusion Energy Conference (FEC 2008) (CD-ROM), 8 Pages, 2008/10

Investigation of intermediate wavelength MHD modes has led to improved understanding of important constraints on the pedestal height and the mechanism for ELMs. The combination of high resolution pedestal diagnostics and a suite of highly efficient stability codes, has made edge stability analysis routine on several major tokamaks, contributing both to understanding, and to experimental planning and performance optimization. Here we present extensive comparisons of observations to predicted edge stability boundaries on several tokamaks, both for the standard ELM regime, and for small ELM and ELM-free regimes. We further use the stability constraint on pedestal height to test models of the pedestal width, and self-consistently combine a simple width model with MHD stability calculations to develop a new predictive model (EPED1) for the pedestal height and width. This model is tested against experimental measurements, and used in initial predictions of the pedestal height for ITER.

Comparisons of small ELM H-mode regimes on the Alcator C-Mod and JFT-2M tokamaks

Hubbard, A. E.*; Kamiya, Kensaku; Oyama, Naoyuki; Basse, N.*; Biewer, T.*; Edlund, E.*; Hughes, J. W.*; Lin, L.*; Porkolab, M.*; Rowan, W.*; et al.

Plasma Physics and Controlled Fusion, 48(5A), p.A121 - A129, 2006/05

https://doi.org/10.1088/0741-3335/48/5A/S11

Dedicated experiments were carried out to compare the properties, fluctuation behaviour and access conditions of these regimes. A common shape was developed which scaled the plasma boundary except for aspect ratio. Scans of density and input power were carried out at several values of q95, so as to achieve ranges of dimensionless parameters. A striking similarity of access conditions was seen. These results suggest common physical mechanisms for the H-mode regimes, which do not depend critically on aspect ratio over this range. On the other hand, several differences in the details of the edge fluctuations were found, and will be reported. The effect of wall conditioning via boronization on the H-mode regimes will also be discussed.