Syota Nunomura

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The Fourier spectra of longitudinal and transverse waves corresponding to random particle motion were measured in a two-dimensional plasma crystal. The crystal was composed of negatively charged microspheres immersed in a plasma at a low gas pressure. The phonons were found to obey a dispersion relation that assumes a Yukawa interparticle potential. The(More)
Dispersion relations of longitudinal and transverse waves in two-dimensional (2D) screened-Coulomb crystals were investigated. The waves were excited in 2D crystals made from complex plasmas, i.e., dusty plasmas, by applying radiation pressure of laser light. The dependencies of the dispersion relation on the shielding parameter, the damping rate, and the(More)
Self-diffusion has been experimentally studied in a two-dimensional underdamped liquid complex (dusty) plasma. It was found that the self-diffusion coefficient D increases linearly with the temperature T: D/omega(E)a2 = (0.019 +/- 0.007)(T/T(m) - 1), where T(m), omega(E), and a are the melting temperature, the Einstein frequency, and the mean particle(More)
Spectra of longitudinal and transverse waves were obtained experimentally in liquid and solid two-dimensional complex (dusty) plasmas at different kinetic temperatures. As the temperature increased and the phase state of the plasma changed from solid to liquid, the phonon spectra of both longitudinal and transverse modes broadened (especially at high wave(More)
Compressional pulses were launched in a two-dimensional Yukawa lattice, a hexagonal monolayer of polymer microspheres suspended in a plasma. The pulsed wave was excited by a laser beam, and nonlinear effects were observed for Mach numbers M>0.07 and for variation of particle number density delta(n)/n>0.1, but no steepening of the pulse was detected. The(More)
Wave spectra corresponding to the random particle motion in a monolayer Yukawa crystal were studied for various directions of propagation. It was found that there are two wave modes with a polarization alternating between the longitudinal and transverse. In the long-wavelength regime, the modes became purely longitudinal and transverse as was known before.(More)
A fracture mechanics approach has been adopted in the present study to investigate the fracture toughness behavior of three commercial composite resins for dental use named Clearfil photo posterior, P-50 and Occlusin. The resins have been cast in to ring-shaped specimens for the determination of individual fracture toughness values. The experimentally(More)
Experimental studies of the formation and structure of Mach cones in a plasma crystal are presented. Plasma crystals are ordered structures of charged microspheres trapped in the sheath of an rf discharge plasma. Using a monolayer crystal with a hexagonal lattice, Mach cones were excited by the radiation pressure of a focused laser beam. The beam was swept(More)
Transverse shear waves were observed experimentally in a two-dimensional screened Coulomb crystal. They were excited by applying a chopped laser beam to a 2D dusty plasma, i.e., a monolayer of charged microspheres levitated in a plasma. Measurements of the dispersion relation reveal an acoustic, i.e., nondispersive, character over the entire range of wave(More)
We have observed transport of nano-particles having, on average, a fractional elementary charge in single pulse and double pulse capacitively-coupled rf discharges both without and with an Amplitude Modulation (AM) of the discharge voltage, using a two-dimensional laser-light scattering method. Rapid transport of nano-particles towards the grounded(More)