Ion-beam-excited electrostatic ion cyclotron waves

Self-excited electrostatic ion cyclotron waves were observed in an ion-beam-plasma system produced in a DP-operated Q-machine. The frequency of the waves showed the theoretically predicted variation with the magnetic field.     

Dust-acoustic solitary waves in an adiabatic hot dusty plasma

An adiabatic hot dusty plasma (containing non-inertial adiabatic electron and ion fluids, and negatively charged inertial adiabatic dust fluid) is considered. The basic properties of arbitrary amplitude dust-acoustic (DA) solitary waves, which exist in such an adiabatic hot dusty plasma, are explicitly examined by the pseudo-potential approach. To compare the basic properties (critical Mach number, amplitude and width) of the DA solitary waves observed in a dusty plasma containing adiabatic electron, ion and dust fluids with those observed in a dusty plasma containing isothermal electron and ion fluids and adiabatic dust fluid, it has been found that the adiabatic effect of inertia-less electron and ion fluids has significantly modified the basic properties of the DA solitary waves, and that on the basic properties of the DA solitary waves, the adiabatic effect of electron and ion fluids is much more significant than that of the dust fluid.     

无碰撞等离子体电流片中的低频波

采用两种无碰撞二维三分量不可压缩磁流体力学（MHD）模型，计入电子扰动压力张量效应，研究了电流片等离子体的色散性质和波.由于得到的一般色散关系较为复杂，只解析讨论了电流片的中心区和电子β*e=0两种特殊情况.主要结果如下：(1)在短波区（kdi＞1），存在快磁声 动理学Alfven波和斜Alfven 哨声模，电子磁流体力学模型是足够精确的MHD模型；在长波区（kdi＜1＝，存在Alfven波和离子声波，理想的MHD模型是适用的.（2）电子β*e＝0情况下的结果，显然遗漏了一些波模（如离子声波和快磁声动理 关键词： 电流片 磁流体力学 电子压力张量 色散关系     

Nonlinear development of drift waves

This note presents a model equation which describes nonlinear evolution of finite amplitude drift waves in a non-uniform plasma. Significant nonlinearities originate from the ion polarization drift and the electron temperature gradient. Modulational instability and possible final state of unstable drift waves are investigated.     

Laser-generated waves and wakes in rotating ion crystals

Locally excited plasma waves are generated in a Coulomb crystal by "pushing" with radiation pressure on a rotating cloud of laser-cooled 9Be+ ions. The waves form a stationary wake that is directly imaged through the dependence of the ion fluorescence on Doppler shifts, and theoretical calculations in a slab geometry are shown to accurately reproduce these images. The technique demonstrates a new method of exciting and studying waves in cold ion clouds.     

Exact nonlinear alfvén waves

Exact localized nonlinear Alfvén waves are investigated by retaining the complete ion nonlinearity and the finite-β effects. Solitary waves with a density hump and a density dip are found to exist.     

心脏中的螺旋波和时空混沌的抑制研究

以Luo-Rudy相I心脏模型为基础,研究心脏中螺旋波和时空混沌的控制,提出了两种控制方法: (Ⅰ)通过交替改变细胞外钾离子浓度来产生平面波,再利用弱外电场辅助平面波抑制螺旋波和时空混沌; (Ⅱ)先提高细胞外钾离子浓度,然后利用外电场激发波的方式产生平面波,再用平面波去抑制螺旋波和时空混沌. 研究结果表明,只要适当选择控制参数,这两种方法都能够有效抑制螺旋波和时空混沌. 当心肌出现局部缺血时,在心肌缺血处就会出现高的细胞外钾离子浓度,在这种情况下, 可以采用电场发射波的方法来抑制心脏中的螺旋波和时空混沌.对这些控制方法的优点和控制机制做了解释.     

Scattering of electromagnetic waves by drift modes

It is shown that high-frequency electromagnetic waves can parametrically excite the convection and ion drift waves in a slightly inhomogeneous magnetized plasma. The growth rates of the nonlinear decay instabilities are obtained analytically.     

Ion-acoustic shock waves in multi-electron temperature collisional plasma

The nonlinear propagation of ion-acoustic waves in a collision-dominated double electron temperature plasma is considered. Accounting for the ion viscosity and the ion heat conductivity, it is shown by means of two-warm fluid equations that the nonlinear evolution of the ion-acoustic waves is governed by the Korteweg—de Vries—Burgers equation. Stationary shock solution of the KdV—Burgers equation is presented.     

Behaviors of electrostatic ion cyclotron waves excited in ion beam-plasma systems

Experimental results are presented for a behavior of the electrostatic ion cyclotron waves excited in an ion beam-plasma system. This wave appears as forward and backward waves with respect to the propagating component along the magnetic field.     

Parametric instability of dust lattice waves in a turbulent plasma sheath

It is shown that dust lattice waves (DLWs) become parametrically unstable in a turbulent dusty plasma sheath that contains random-phase ion plasma waves. Physically, the parametric instability arises because of the nonlinear coupling between ion plasma waves and DLWs. The parametric instability is identified as the possible reason for the observed "sublimation" transition of the plasma crystal from a solid to a gaslike state.     

弱相对论等离子体横向扰动下的离子声孤波

在低阶近似下，得到了描述无磁场相对论热离子等离子体的KP(Kadomtsev-Petviashvilli) 方程.研究表明，相对论热离子等离子中的非线性离子声孤波在高阶横向拢动下是稳定的， 且在相对论热离子等离子体中仅存在压缩型孤波. 关键词： 离子等离子体 孤波 声波 约化摄动法     

Thomson-scattering study of the subharmonic decay of ion-acoustic waves driven by the Brillouin instability

Thomson scattering (TS) has been used to investigate the two-ion decay instability of ion acoustic waves generated by stimulated Brillouin scattering in an underdense CH plasma. Two complementary TS diagnostics, spectrally and spatially resolved, demonstrate the occurrence of the subharmonic decay of the primary ion acoustic wave into two secondary waves. The study of the laser intensity dependence shows that the secondary ion acoustic waves are correlated with the SBS reflectivity saturation, at a level of a few percent.     

Nonlinear amplitude osçillations of absolutely unstable electrostatic ion cyclotron waves in an ion beam-plasma system

We have observed experimentally the amplitude oscillations of absolutely unstable electrostatic ion cyclotron waves in an ion beam-plasma system due to nonlinear interaction between the beam ions and electrostatic ion cyclotron waves.     

Electrostatic ion-cyclotron waves in a two-ion component plasma

The excitation of electrostatic ion cyclotron (EIC) waves is studied in a single-ended Q machine in a two-ion component plasma (Ca⁺ and K⁺). Over a large range of relative concentrations of Ca⁺ and K⁺ ions, two modes are excited with frequencies greater than the respective cyclotron frequencies of the ions. The results are discussed in terms of a fluid theory of electrostatic ion cyclotron waves in a two-ion component plasma     

Ion surface cyclotron waves at plasma-metal interfaces

The dispersion properties of slow electromagnetic surface waves propagating across a constant external magnetic field and along a plane plasma-metal interface at harmonics of the ion cyclotron frequency are studied. The motion of the plasma particles is described by a Vlasov-Boltzmann kinetic equation. The effects of the plasma size, the dielectric permittivity of the transition region between the plasma and metal, and the magnitude of the constant external magnetic field on the dispersion characteristics of ion surface cyclotron waves are studied. Zh. Tekh. Fiz. 69, 83–89 (October 1999)     

Ion waves in a partially ionized gas in an external electric field

The propagation of longitudinal acoustic waves in the ion gas in an external electric field is studied theoretically. The results are compared with properties of waves in space without the external field. The phase velocities, damping factors and the influence of parameters of the gas on the properties of ion waves is discussed.In conclusion, the author would like to express his thanks to Prof. J. Kracík DrSc., for valuable advice and suggestions.     

Obliquely propagating dust-density plasma waves in the presence of an ion beam

Self-excited dust-density waves are experimentally studied in a dusty plasma under microgravity. Two types of waves are observed: a mode inside the dust volume propagating in the direction of the ion flow and a new mode propagating obliquely at the boundary between the dusty plasma and the space-charge sheath. A model for dust-density waves propagating at an arbitrary angle with respect to the ion-flow direction is presented, which explains the preference for oblique or parallel modes as a function of ion velocity.     

Stability of electrostatic ion cyclotron waves in a multi-ion plasma

We have studied the stability of the electrostatic ion cyclotron wave in a plasma consisting of isotropic hydrogen ions (H⁺) and temperature-anisotropic positively (O⁺) and negatively (O⁻) charged oxygen ions, with the electrons drifting parallel to the magnetic field. Analytical expressions have been derived for the frequency and growth/damping rate of ion cyclotron waves around the first harmonic of both hydrogen and oxygen ion gyrofrequencies. We find that the frequencies and growth/damping rates are dependent on the densities and temperatures of all species of ions. A detailed numerical study, for parameters relevant to comet Halley, shows that the growth rate is dependent on the magnitude of the frequency. The ion cyclotron waves are driven by the electron drift parallel to the magnetic field; the temperature anisotropy of the oxygen ions only slightly enhance the growth rates for small values of temperature anisotropies. A simple explanation, in terms of wave exponentiation times, is offered for the absence of electrostatic ion cyclotron waves in the multi-ion plasma of comet Halley.