Tohru Hada | Kyushu University (original) (raw)

Papers by Tohru Hada

Research paper thumbnail of The simulation of helicon plasma discharge

Research paper thumbnail of Self-consistent discharge growing model of helicon plasma

Bulletin of the American Physical Society, Nov 16, 2015

Research paper thumbnail of Spatio-temporal behavior of density jumps and the effect of neutral depletion in high-density helicon plasma

Physics of Plasmas, May 1, 2019

Research paper thumbnail of One Dimensional Modeling of Radio Frequency Electric Field Penetration into Magnetized Plasmas

Japanese Journal of Applied Physics, Sep 1, 2012

Research paper thumbnail of Underlying competition mechanisms in the dynamic profile formation of high-density helicon plasma

Physics of Plasmas, Feb 1, 2019

Research paper thumbnail of Is the bulk mode conversion important in high density helicon plasma?

Physics of Plasmas, Jun 1, 2016

Research paper thumbnail of Ion acceleration and its effect in shock-shock interaction

Research paper thumbnail of Modeling of Particle Acceleration in Shock-Shock Interaction

Japan Geoscience Union, May 1, 2015

Research paper thumbnail of Upstream wave evolution, particle diffusion and acceleration in the earth's foreshock: One-dimensional PIC simulation

Japan Geoscience Union, Mar 10, 2017

Research paper thumbnail of Landau resonance between electrons and lower-hybrid waves in the inner magnetosphere

Japan Geoscience Union, Mar 10, 2017

Research paper thumbnail of Kinetic effects on the parametric decays of Alfvwaves in relativistic pair plasmas

Research paper thumbnail of Solar wind parameter and seasonal variation effects on the South Atlantic Anomaly using Tsyganenko Models

Earth, Planets and Space, Jul 13, 2020

Research paper thumbnail of Parametric instabilities of circularly polarized Alfvén waves in plasmas with beam protons

Journal of Geophysical Research, Jul 1, 2009

The proton velocity distribution functions (VDFs) observed in the solar wind often show beam comp... more The proton velocity distribution functions (VDFs) observed in the solar wind often show beam components. In this study, by means of one-dimensional hybrid simulation, parametric instabilities of circularly polarized Alfvén waves in core proton-electron-beam proton plasmas are discussed. Numerical results show that nonlinear evolution of parametric instabilities in core proton-electron-beam proton plasmas are different from those in core proton-electron plasmas. Furthermore, numerical solutions of the linear dispersion relations suggest the importance of the proton kinetic effects, which agrees with the past studies. In the case that the beams are stable, according to the excitation of the broadband Alfvén waves by the parametric instabilities, protons are diffused in the velocity space, resulting in the scattering and broadening of the beam components. Such time evolution of the proton VDFs changes the wave dispersion relation and affects the properties of the parametric instabilities, in agreement with the past theoretical studies. As a result, even if a decay instability is dominant at the linear stage, the parent wave can mainly be dissipated by the modulational instability at the nonlinear stage. Phase coherent turbulence is generated corresponding to the occurrence of the modulational instability. Parametric instabilities are also observed in plasmas with unstable beams. When left-hand polarized (LH-) Alfvén wave is initially given, both backward propagating right-hand polarized (RH-) and LH- Alfvén waves are excited by the decay instabilities in our runs. As time elapses, phase coherent turbulence is generated by the modulational instabilities, as in the case of stable beams. Some of the beam protons are perpendicularly accelerated by cyclotron resonance with the primary wave.

Research paper thumbnail of Space Plasma Environment

Research paper thumbnail of Large-amplitude electromagnetic waves in magnetized relativistic plasmas with temperature

Nonlinear Processes in Geophysics, Feb 14, 2014

Research paper thumbnail of Broadband electrostatic noise in the magnetotail: Its relation to plasma sheet dynamics

Journal of Geophysical Research, 1985

Research paper thumbnail of Decay instability of finite-amplitude circularly polarized Alfven waves: A numerical simulation of stimulated Brillouin scattering

Journal of Geophysical Research, 1986

By means of a numerical simulation, nonlinear evolution of large amplitude dispersive Alfven wave... more By means of a numerical simulation, nonlinear evolution of large amplitude dispersive Alfven waves is studied. An energy transfer from the parent wave to two daughter Alfven‐like waves and a soundlike wave is observed (a stimulated Brillouin scattering process). The observed growth rates and propagation characteristics of these daughter waves agree with the analytical results, which we obtain by extending the previous treatments by Goldstein, Derby, Sakai, and Sonnerup. Ions are first trapped by the electrostatic potential of the daughter soundlike waves. Along with the eventual decay (ion Landau damping) of the soundlike waves, ions are phase‐mixed and left heated in the parallel direction. The increased parallel energy of ions is transferred to the perpendicular thermal energy through the nonresonant scattering process in the colliding Alfven waves (parent and daughter waves). We further observe that the daughter Alfven waves, which still have a large amplitude, are also unstable for further decay, and that the wave energy is continuously transferred to the longer wavelength regime (inverse cascading process).

Research paper thumbnail of Radial structure of heliospheric boundary region

Japan Geoscience Union, Mar 14, 2019

Research paper thumbnail of Alfvén waves, magnetic decreases, and discontinuities in interplanetary space

Advances in Space Research, 2001

Research paper thumbnail of Chaos in driven Alfvén systems

Physics of fluids. B, Plasma physics, Nov 1, 1990

The chaos in a one-dimensional system, which would be nonlinear stationary Alfvén waves in the ab... more The chaos in a one-dimensional system, which would be nonlinear stationary Alfvén waves in the absence of an external driver, is characterized. The evolution equations are numerically integrated for the transverse wave magnetic field amplitude and phase using the derivative nonlinear Schrödinger equation (DNLS), including resistive wave damping and a long-wavelength monochromatic, circularly polarized driver. A Poincaré map analysis shows that, for the nondissipative (Hamiltonian) case, the solutions near the phase space (soliton) separatrices of this system become chaotic as the driver amplitude increases, and ‘‘strong’’ chaos appears when the driver amplitude is large. The dissipative system exhibits a wealth of dynamical behavior, including quasiperiodic orbits, period-doubling bifurcations leading to chaos, sudden transitions to chaos, and several types of strange attractors.

Research paper thumbnail of The simulation of helicon plasma discharge

Research paper thumbnail of Self-consistent discharge growing model of helicon plasma

Bulletin of the American Physical Society, Nov 16, 2015

Research paper thumbnail of Spatio-temporal behavior of density jumps and the effect of neutral depletion in high-density helicon plasma

Physics of Plasmas, May 1, 2019

Research paper thumbnail of One Dimensional Modeling of Radio Frequency Electric Field Penetration into Magnetized Plasmas

Japanese Journal of Applied Physics, Sep 1, 2012

Research paper thumbnail of Underlying competition mechanisms in the dynamic profile formation of high-density helicon plasma

Physics of Plasmas, Feb 1, 2019

Research paper thumbnail of Is the bulk mode conversion important in high density helicon plasma?

Physics of Plasmas, Jun 1, 2016

Research paper thumbnail of Ion acceleration and its effect in shock-shock interaction

Research paper thumbnail of Modeling of Particle Acceleration in Shock-Shock Interaction

Japan Geoscience Union, May 1, 2015

Research paper thumbnail of Upstream wave evolution, particle diffusion and acceleration in the earth's foreshock: One-dimensional PIC simulation

Japan Geoscience Union, Mar 10, 2017

Research paper thumbnail of Landau resonance between electrons and lower-hybrid waves in the inner magnetosphere

Japan Geoscience Union, Mar 10, 2017

Research paper thumbnail of Kinetic effects on the parametric decays of Alfvwaves in relativistic pair plasmas

Research paper thumbnail of Solar wind parameter and seasonal variation effects on the South Atlantic Anomaly using Tsyganenko Models

Earth, Planets and Space, Jul 13, 2020

Research paper thumbnail of Parametric instabilities of circularly polarized Alfvén waves in plasmas with beam protons

Journal of Geophysical Research, Jul 1, 2009

The proton velocity distribution functions (VDFs) observed in the solar wind often show beam comp... more The proton velocity distribution functions (VDFs) observed in the solar wind often show beam components. In this study, by means of one-dimensional hybrid simulation, parametric instabilities of circularly polarized Alfvén waves in core proton-electron-beam proton plasmas are discussed. Numerical results show that nonlinear evolution of parametric instabilities in core proton-electron-beam proton plasmas are different from those in core proton-electron plasmas. Furthermore, numerical solutions of the linear dispersion relations suggest the importance of the proton kinetic effects, which agrees with the past studies. In the case that the beams are stable, according to the excitation of the broadband Alfvén waves by the parametric instabilities, protons are diffused in the velocity space, resulting in the scattering and broadening of the beam components. Such time evolution of the proton VDFs changes the wave dispersion relation and affects the properties of the parametric instabilities, in agreement with the past theoretical studies. As a result, even if a decay instability is dominant at the linear stage, the parent wave can mainly be dissipated by the modulational instability at the nonlinear stage. Phase coherent turbulence is generated corresponding to the occurrence of the modulational instability. Parametric instabilities are also observed in plasmas with unstable beams. When left-hand polarized (LH-) Alfvén wave is initially given, both backward propagating right-hand polarized (RH-) and LH- Alfvén waves are excited by the decay instabilities in our runs. As time elapses, phase coherent turbulence is generated by the modulational instabilities, as in the case of stable beams. Some of the beam protons are perpendicularly accelerated by cyclotron resonance with the primary wave.

Research paper thumbnail of Space Plasma Environment

Research paper thumbnail of Large-amplitude electromagnetic waves in magnetized relativistic plasmas with temperature

Nonlinear Processes in Geophysics, Feb 14, 2014

Research paper thumbnail of Broadband electrostatic noise in the magnetotail: Its relation to plasma sheet dynamics

Journal of Geophysical Research, 1985

Research paper thumbnail of Decay instability of finite-amplitude circularly polarized Alfven waves: A numerical simulation of stimulated Brillouin scattering

Journal of Geophysical Research, 1986

By means of a numerical simulation, nonlinear evolution of large amplitude dispersive Alfven wave... more By means of a numerical simulation, nonlinear evolution of large amplitude dispersive Alfven waves is studied. An energy transfer from the parent wave to two daughter Alfven‐like waves and a soundlike wave is observed (a stimulated Brillouin scattering process). The observed growth rates and propagation characteristics of these daughter waves agree with the analytical results, which we obtain by extending the previous treatments by Goldstein, Derby, Sakai, and Sonnerup. Ions are first trapped by the electrostatic potential of the daughter soundlike waves. Along with the eventual decay (ion Landau damping) of the soundlike waves, ions are phase‐mixed and left heated in the parallel direction. The increased parallel energy of ions is transferred to the perpendicular thermal energy through the nonresonant scattering process in the colliding Alfven waves (parent and daughter waves). We further observe that the daughter Alfven waves, which still have a large amplitude, are also unstable for further decay, and that the wave energy is continuously transferred to the longer wavelength regime (inverse cascading process).

Research paper thumbnail of Radial structure of heliospheric boundary region

Japan Geoscience Union, Mar 14, 2019

Research paper thumbnail of Alfvén waves, magnetic decreases, and discontinuities in interplanetary space

Advances in Space Research, 2001

Research paper thumbnail of Chaos in driven Alfvén systems

Physics of fluids. B, Plasma physics, Nov 1, 1990

The chaos in a one-dimensional system, which would be nonlinear stationary Alfvén waves in the ab... more The chaos in a one-dimensional system, which would be nonlinear stationary Alfvén waves in the absence of an external driver, is characterized. The evolution equations are numerically integrated for the transverse wave magnetic field amplitude and phase using the derivative nonlinear Schrödinger equation (DNLS), including resistive wave damping and a long-wavelength monochromatic, circularly polarized driver. A Poincaré map analysis shows that, for the nondissipative (Hamiltonian) case, the solutions near the phase space (soliton) separatrices of this system become chaotic as the driver amplitude increases, and ‘‘strong’’ chaos appears when the driver amplitude is large. The dissipative system exhibits a wealth of dynamical behavior, including quasiperiodic orbits, period-doubling bifurcations leading to chaos, sudden transitions to chaos, and several types of strange attractors.