Pui-Wai Ma W. C. Liu C. H. Woo S. L. Dudarev
We perform large-scale molecular dynamics simulations to study the magnetic properties of amorphous iron under pressure. Simulations, exceeding by at least two orders of magnitude those accessible to density functional calculations, use the recently developed magnetic interatomic potential for iron. The distributions of the size of atomic magnetic …
PublishedD. Dickinson C. M. Roach S. Saarelma R. Scannell A. Kirk H. R. Wilson
Plasma equilibria reconstructed from the Mega-Amp Spherical Tokamak have sufficient resolution to capture plasma evolution during the short period between edge-localized modes (ELMs). Immediately after the ELM, steep gradients in pressure, P , and density, n e , form pedestals close to the separatrix, and they then expand into the core. Local gyrok…
PublishedM.R. Gilbert S.L. Dudarev S. Zheng L.W. Packer J.-Ch. Sublet
The high-energy, high-intensity neutron fluxes produced by the fusion plasma will have a significant life-limiting impact on reactor components in both experimental and commercial fusion devices. As well as producing defects, the neutrons bombarding the materials initiate nuclear reactions, leading to transmutation of the elemental atoms. Products …
PublishedAnthony J. Webster
This paper reconsiders the problem of calculating the expected set of probabilities hpii, given the observed set of items {mi}, that are distributed among n bins with an (unknown) set of probabilities {pi} for being placed in the ith bin. The problem is often formulated using Bayes theorem and the multinomial distribution, that with a constant prio…
PublishedPui-Wai Ma S. L. Dudarev C. H. Woo
We develop an atomistic spin-lattice-dynamics model for simulating energy relaxation in magnetic materials. The model explicitly solves equations of motion for the atoms and spins, and includes interaction with electron excitations. We apply the model to simulate the dynamics of propagation of a compressive elastic wave in iron. We find that coupli…
PublishedJ. H. E. Proll P. Helander J.W. Connor G. G. Plunk
It is shown that in perfectly quasi-isodynamic stellarators, trapped particles with a bounce frequency much higher than the frequency of the instability are stabilizing in the electrostatic and collisionless limit. The collisionless trapped-particle instability is therefore stable as well as the ordinary electron-densitygradient- driven trapped-ele…
PublishedD. Nguyen-Manh M.Yu. Lavrentiev M. Muzyk S.L. Dudarev
Generic materials-related problems foreseen in connection with the operation of a fusion power plant present a major challenge for the development of magnetically confined fusion as a commercial power generation option. In this review, we focus on the predictive capabilities of first-principles-based atomistic models for radiation defects and phase…
PublishedD. Alves R. Felton S. Jachmich P. Lomas P. Mccullen A. Neto D. F. Valcárcel G. Arnoux P. Card S. Devaux A. Goodyear D. Kinna A. Stephen K.-D. Zastrow
The installation of international thermonuclear experimental reactor-relevant materials for the plasma facing components (PFCs) in the Joint European Torus (JET) is expected to have a strong impact on the operation and protection of the experiment. In particular, the use of all-beryllium tiles, which deteriorate at a substantially lower temperature…
PublishedPui-Wai Ma S. L. Dudarev
We develop a dynamic spin-lattice-electron model for simulating the time-dependent evolution of coupled spin, atomic, and electronic degrees of freedom in a magnetic material. Using the model, we relate the dissipative parameters entering the Langevin equations for the lattice and spin degrees of freedom to the heat transfer coefficients of a pheno…
PublishedA. Kirk J. Harrison Yueqiang Liu E. Nardon I. T. Chapman P. Denner The Mast Team
The application of nonaxisymmetric resonant magnetic perturbations (RMPs) with a toroidal mode number n . 6 in the MAST tokamak produces a significant reduction in plasma energy loss associated with type-I edge localized modes (ELMs), the first such observation with n>3 . During the ELM mitigated stage clear lobe structures are observed in visible-…
Published