No abstract

The slowing-down process of suprathermal alpha particles in a rippled toroidal field is investigated by means of an orbit-following Monte-Carlo code. It is found that numerical results on the collisionless ripple loss agree fairly well with the theoretical predictions. The collisional diffusion coefficient for non-ergodic banana particles in a field ripple is derived. The ripple-enhanced power loss of alpha particles during slowing-down amounts to 10% of their total power in a reactor-grade tokamak with a toroidal-field ripple of 𝛅 ∼ 1%. The fraction of particle loss is 1.5 to 1.8 times as large as that of power loss. The ripple-enhanced banana drift dominates the alpha-particle loss process.

The Japanese large tokamak JT-60 has been focusing its research emphasis on the development of high performance plasmas, with high confinement, high temperature and high density and non-inductive sustainment for a long time with possible minimization of external power input. The first demonstration of high bootstrap current discharges up to 80% of the total plasma current in a high-poloidal-beta (high-β p ) mode and the concept development of a steady-state tokamak reactor (SSTR) based on this experimental achievement initiated the so-called 'advanced tokamak research'. The internal transport barriers (ITBs), discovered in the JT-60 high-β p mode, have been followed by worldwide explorations of reversed shear discharges associated with ITBs. The highest DT equivalent energy gain of Q eq DT = 1.25 was achieved in the JT-60 reversed shear H-mode discharges. The highest ion temperature of T i = 45 keV and the highest fusion triple product of n i (0)τ E T i (0) = 1.5 × 10 21 m −3 s keV were obtained in high-β p discharges. Advanced tokamak research is now the major trend of the current tokamak development. A new concept of compact ITER has been developed and proposed in the context of this advanced tokamak approach pursued on JT-60. Prospects for burning plasma physics have been investigated along the progress made in these modern tokamak experiments on JT-60 and related computer simulation analyses.

Using STM, we have directly confirmed the incommensurate stacking of double atomic layers of graphene and monolayer h-BN on Ni(111). The formation of a graphene layer weakens the interfacial interaction between monolayer h-BN and Ni(111), resulting in insulating h-BN layers, while a pristine monolayer h-BN on Ni(111) is metallic. The STS spectra of the double atomic layers showed a tunneling character with a band gap of 0.5 eV.

The atomic-scale processes of benzene adsorption and desorption on an Si(111)-7×7 surface have been investigated with scanning tunnelling microscopy. Analysis of the atomic-scale images obtained during the adsorption and desorption processes yielded the following results: benzene molecules adsorbed on Si(111)-7 × 7 with the di-s bonds between molecules and two Si atoms, an adatom and a rest atom; and benzene molecules chemisorb and desorb through physisorption states.