Shell structure of the neutron-rich isotopes Co

Lokotko, T.*; Leblond, S.*; Lee, J.*; Doornenbal, P.*; Obertelli, A.*; Poves, A.*; Nowacki, F.*; Ogata, Kazuyuki*; Yoshida, Kazuki; Authelet, G.*; et al.

Physical Review C, 101(3), p.034314_1 - 034314_7, 2020/03

https://doi.org/10.1103/PhysRevC.101.034314

The structures of the neutron-rich Co isotopes were investigated via () knockout reactions at the Radioactive Isotope Beam Factory, RIKEN. Level schemes were reconstructed using the coincidence technique, with tentative spin-parity assignments based on the measured inclusive and exclusive cross sections. Comparison with shell-model calculations suggests coexistence of spherical and deformed shapes at low excitation energies in the Co isotopes.

Shell evolution beyond =28 and =50; Spectroscopy of Zn

Shand, C. M.*; Podolyk, Zs.*; Grska, M.*; Doornenbal, P.*; Obertelli, A.*; Nowacki, F.*; Otsuka, T.*; Sieja, K.*; Tostevin, J. A.*; Tsunoda, T.*; et al.

Physics Letters B, 773, p.492 - 497, 2017/10

https://doi.org/10.1016/j.physletb.2017.09.001

decay of unbound neutron-hole states in Sn

Vaquero, V.*; Jungclaus, A.*; Doornenbal, P.*; Wimmer, K.*; Gargano, A.*; Tostevin, J. A.*; Chen, S.*; Ncher, E.*; Sahin, E.*; Shiga, Yoshiaki*; et al.

Physical Review Letters, 118(20), p.202502_1 - 202502_5, 2017/05

https://doi.org/10.1103/PhysRevLett.118.202502

decay of semi-magic Cd; Revision and extension of the level scheme of In

Jungclaus, A.*; Grawe, H.*; Nishimura, Shunji*; Doornenbal, P.*; Lorusso, G.*; Simpson, G. S.*; Sderstrm, P. A.*; Sumikama, Toshiyuki*; Taprogge, J.*; Xu, Z. Y.*; et al.

Physical Review C, 94(2), p.024303_1 - 024303_8, 2016/08

https://doi.org/10.1103/PhysRevC.94.024303

Dependence of pedestal structure on collisionality at fixed beta in JT-60U

Urano, Hajime; Aiba, Nobuyuki; Kamiya, Kensaku; Kamada, Yutaka; JT-60 Team

Nuclear Fusion, 56(1), p.016005_1 - 016005_8, 2016/01

https://doi.org/10.1088/0029-5515/56/1/016005

Dependence of pedestal structure on collisionality at fixed beta has been investigated in JT-60U. In the ITER-relevant low collisionality regime, the pedestal width does not change with edge collisionality. In the high collisionality regime, the pedestal width broadens with increased edge collisionality. The pedestal pressure gradient and width are not significantly changed when the pedestal is close to an intermediate peeling-ballooning mode boundary at low collisionality. The experimental result indicates that conventional pedestal models where the pedestal width is independent of collisionality and is determined by at the pedestal is not a bad assumption in the ITER-relevant low collisionality regime. On the other hand, the pressure gradient decreases and the pedestal width increases at high collisionality. The pedestal broadening becomes significant when the pedestal is marginal to be unstable at high ballooning mode in high collisionality regime.

Comparison of Ne and Ar seeded radiative divertor plasmas in JT-60U

Nakano, Tomohide; JT-60 Team

Journal of Nuclear Materials, 463, p.555 - 560, 2015/08

https://doi.org/10.1016/j.jnucmat.2014.11.127

In H-mode plasmas with Ne, Ar and a mixture of Ne and Ar injection, the divertor radiation power fraction amongst these impurities in addition to an intrinsic impurity, C, is investigated. In plasmas with the inner divertor plasma attached, carbon is the biggest radiator, whichever impurites, Ne, Ar or a mixture of Ar and Ne is injected. In contrast, in plasmas with the inner divertor plasma detached, Ne is the biggest radiator due to a significantly high recombination radiation from Ne VIII. Ar is always a minor contributor in plasmas with the innder divertor both attached and detached.

decay of Cd and excited states in In

Taprogge, J.*; Jungclaus, A.*; Grawe, H.*; Nishimura, Shunji*; Doornenbal, P.*; Lorusso, G.*; Simpson, G. S.*; Sderstrm, P.-A.*; Sumikama, Toshiyuki*; Xu, Z. Y.*; et al.

Physical Review C, 91(5), p.054324_1 - 054324_11, 2015/05

https://doi.org/10.1103/PhysRevC.91.054324

Roles of argon seeding in energy confinement and pedestal structure in JT-60U

Urano, Hajime; Nakata, Motoki; Aiba, Nobuyuki; Kubo, Hirotaka; Honda, Mitsuru; Hayashi, Nobuhiko; Yoshida, Maiko; Kamada, Yutaka; JT-60 Team

Nuclear Fusion, 55(3), p.033010_1 - 033010_9, 2015/03

https://doi.org/10.1088/0029-5515/55/3/033010

Physics picture of improving energy confinement with argon seeding at high density has been investigated in JT-60U. Better confinement is sustained at high density by argon seeding accompanied by higher core and pedestal temperatures. Peaked density profiles are kept with argon seeding. Density peaking and dilution effects lower the pedestal density at a given averaged density. The pedestal density in the argon seeded plasmas which is relatively lower than that in a single deuterium puff enables the pedestal temperature to be higher. The density peaking is a key factor of sustaining better confinement in argon seeded H-mode plasmas.

Boundary condition for toroidal plasma flow imposed at the separatrix in high confinement JT-60U plasmas with edge localized modes and the physics process in pedestal structure formation

Kamiya, Kensaku; Honda, Mitsuru; Urano, Hajime; Yoshida, Maiko; Kamada, Yutaka; Ito, Kimitaka*; JT-60 Team

Physics of Plasmas, 21(12), p.122517_1 - 122517_8, 2014/12

https://doi.org/10.1063/1.4904815

Modulation Charge eXchange Recombination Spectroscopy (MCXRS) measurements with high spatial and temporal resolution have made the evaluation of the toroidal plasma flow of fully stripped carbon impurity ions in the JT-60U tokamak peripheral region (including in particular separatrix) possible with a better signal-to-noise ratio. Boundary condition of Vt imposed at the separatrix in ELMy H-mode plasmas has been identified, comparing between co- and counter-NBI discharges. The Vt value at the separatrix is not held fixed at the zero, varying with momentum input direction, but being not strongly affected by the ELM event. A non-zero Vt value at the separatrix might be connected to fast ion losses due to toroidal field ripple that results in formation of a negative radial electric field (Er) layer having almost zero (or very weak positive) Er-shear value at the separatrix. Improved understanding of physics process in pedestal structure formation for the Vt and Er is also discussed.

Safe disassembly and storage of radioactive components of JT-60U torus

Ikeda, Yoshitaka; Okano, Fuminori; Hanada, Masaya; Sakasai, Akira; Kubo, Hirotaka; Akino, Noboru; Chiba, Shinichi; Ichige, Hisashi; Kaminaga, Atsushi; Kiyono, Kimihiro; et al.

Fusion Engineering and Design, 89(9-10), p.2018 - 2023, 2014/10

https://doi.org/10.1016/j.fusengdes.2013.12.017

Disassembly of the JT-60U torus was started in 2009 after 18-years D operations, and was completed in October 2012. The JT-60U torus was featured by the complicated and welded structure against the strong electromagnetic force, and by the radioactivation due to D-D reactions. Since this work is the first experience of disassembling a large radioactive fusion device in Japan, careful disassembly activities have been made. About 13,000 components cut into pieces with measuring the dose rates were removed from the torus hall and stored safely in storage facilities by using a total wokers of 41,000 person-days during 3 years. The total weight of the disassembly components reached up to 5,400 tons. Most of the disassembly components will be treated as non-radioactive ones after the clearance verification under the Japanese regulation in future. The assembly of JT-60SA has started in January 2013 after this disassembly of JT-60U torus.