Observation of Plasma Hole in an ECR Ar Plasma

The first experimental observation of a plasma hole structure in an ECR argon plasma is reported. The plasma hole is a cylindrical density cavity, which is formed spontaneously in the center of the plasma. The steep density gradient between the hole plasma and the ambient plasma is sustained by a thin interfacial layer, the width of which is a few ion Larmor radii. Supersonic rotation is found over the large cross-sectional area of Ar plasma hole. The axial flow can also exceed ion sound speed. Spectral measurements revealed that the neutral density profile exhibits a hole structure as well as that in ion density, the diameter of which is much shorter than the mean free path of neutral particles

Application of tensor network method to two dimensional lattice N=1\mathcal{N}=1 Wess-Zumino model

We study a tensor network formulation of the two dimensional lattice $\mathcal{N}=1$ Wess-Zumino model with Wilson derivatives for both fermions and bosons. The tensor renormalization group allows us to compute the partition function without the sign problem, and basic ideas to obtain a tensor network for both fermion and scalar boson systems were already given in previous works. In addition to improving the methods, we have constructed a tensor network representation of the model including the Yukawa-type interaction of Majorana fermions and real scalar bosons. We present some numerical results.Comment: 8 pages, 4 figures, talk presented at the 35th International Symposium on Lattice Field Theory (Lattice 2017), 18-24 June 2017, Granada, Spai

負イオンプラズマ中におけるイオン波の伝播特性に関する研究

1 緒言 2 理論的背景 3 負イオンプラズマ中のイオン波の分散関係 4 負イオンプラズマ中のバーストの観測 5 負イオンプラズマ中のfast modeとslow modeの同時励起および伝播 6 総括Made available in DSpace on 2012-09-06T02:19:49Z (GMT). No. of bitstreams: 2 yoshimura1.pdf: 11328366 bytes, checksum: 13628089f200cf6a871bd305dfb882d5 (MD5) yoshimura2.pdf: 5624306 bytes, checksum: 0c2e731bf132feff5febacdcad58331f (MD5) Previous issue date: 1998-03-2

Plasma–neutral coupling allows electrostatic ion cyclotron waves to propagate below ion cyclotron frequency

The effect of ion–neutral collisions on the propagation characteristics of electrostatic ion cyclotron (EIC) waves in a partially ionized plasma is investigated. The dispersion relation of EIC waves is derived using a fluid model taking neutral dynamics into account. The propagation properties of EIC modes, including the damping factor, are examined for various ionization degrees and collision frequencies, which determine the momentum transferred from ions to neutral particles. It is found that the motion of neutral particles driven by plasma–neutral coupling leads to an increase in the effective ion mass, and consequently, EIC waves can propagate even below the ion cyclotron frequency. In a hot neutral gas, the gas-thermal mode can also propagate as well as the EIC mode. The possibility of observing in the laboratory and the Earth\u27s ionosphere is discussed

Application of optical vortex to laser-induced fluorescence velocimetry of ions in a plasma

Atoms moving in an optical vortex beam are subjected to the azimuthal Doppler effect in addition to the usual longitudinal Doppler effect. This fact extends the capabilities of plasma flow measurement using laser-induced fluorescence to the direction perpendicular to the laser path by employing optical vortex beams. Furthermore, by assuming a uniform flow traversing the beam, the LIF spectrum undergoes deformation due to the spatial dependence of the resonant absorption condition. Preliminary experiments were performed for metastable argon ions in the vicinity of a negatively biased electrode immersed in a plasma. An increase in the standard deviation of the spectrum was observed when a negative voltage was applied to the electrode, which qualitatively agrees with our previous numerical study