Simple dispersion relations for Coulomb and Yukawa fluids

Very simple explicit analytical expressions, which are able to describe the dispersion relations of collective modes in strongly coupled plasma fluids, are summarized. The accuracy of these expressions is demonstrated using the comparison with available results from benchmark numerical simulations.Comment: To be published in a special issue of IEEE Trans. Plasma Sci. devoted to ICPDP 2017 in Pragu

Influence of a charge-gradient force on dust acoustic waves

The influence of a charge-gradient force, associated with variations of the particle charge in response to external perturbations, on the propagation of low-frequency waves in weakly coupled complex (dusty) plasmas is investigated. The magnitude of the effect is compared with that due to polarization force, studied previously in the literature. Numerical estimates are presented for the regime, where the orbital motion limited approach to particle charging is relevant.Comment: To appear in Phys. Plasma

炭化水素液体中のイオンの移動度と構造に関する考察

The mobility of ions in liquid hydrocarbons is discussed within the framework of Stokes'formula. In the Stokes model, the ions are considered as submicroscopic spheres, consisting of the ionic core (the ionized parent molecule) surrounded by a more or less solid shell of neutral molecules, which are bound by the polarization force to the ionic core. Under the influence of an applied electric field these charged particles (clusters) move with a velocity given by the Stokes'mobility formula and the applied electric field strength. The retarding effect of the liquid is assumed to be friction and the motion proceeds in a laminar regime. One result is Walden's rule. Sometimes Walden's rule is not fulfilled. Taking into account the temperature dependence of the cluster radius in Stokes'formula allows modification of Walden's rule. A discussion of the ionic drift velocity at the high field strengths on the basis of Reynold's number or Newtons law of friction leads to the conclusion that the mobility of these ionic clusters at temperatures near the melting point will be independent of the applied electric field strength up to very high values. The measured data reported in the literature support this finding. In another set of experiments, the radius of positive ions was increased by pre-irradiation with y -rays. Formation of dimers led to ions with larger radii.ストークスの法則の観点から炭化水素液体中のイオン移動度について考察している。ストークスモデルでは、イオンは電離した母体分子が多少とも中性分子からなる固体シェルで囲まれたイオンコアからなるサブマイクロスコピックな球体と考えられる。中性分子はイオンコアに分極の力で束縛されている。電界印加下ではこれらの電荷を帯びた粒子（クラスター）はストークス移動度の法則と印加電界強度によって決まる速度で動く。抵抗力効果は液体の摩擦と層流の中での動きで決まる。その結果ワルデン則が成立する。しかし、ときにはワルデン則に従わない場合がある。ストークスの法則の中でクラスター径の温度依存性を考慮に入れるとワルデン則の変歪を示すことができる。レイノルズ数、摩擦のニュートン則を元に高電界強度でのイオンドリフト速度を考察すると、融点付近のこれらイオンクラスターの移動度は非常に高い電界まで電界依存性がないことが導かれる。文献に見られる測定結果はこの考え方を支持するものである。他の一連の実験で、正イオンの径が前もってガンマ線を照射することによって大きくなることが見出された。これはダイマーが形成された結果、イオン径が大きくなったためである

On the lower bound of the internal energy of the one-component-plasma

A new simple yet accurate analytical estimate for the internal energy of the classical onecomponent- plasma is proposed. In the limit of weak coupling, it reduces to the Debye-Hueckel result. In the opposite limit of strong coupling, the ion sphere approximation is recovered. The agreement with the accurate numerical results in the intermediate coupling regime is fairly good

Simple thermodynamics of strongly coupled one-component-plasma in two and three dimensions

Simple analytical approximations for the internal energy of the strongly coupled one-componentplasma in two and three dimensions are discussed. As a result, new practical expressions for the internal energy in the fluid phase are proposed. Their accuracy is checked by evaluating the location of the fluid-solid phase transition from the free energy consideration. Possible applications to other related systems are briefly discussed

Ion sphere model for Yukawa systems (dusty plasmas)

Application of the ion sphere model (ISM), well known in the context of the one-componentplasma, to estimate thermodynamic properties of model Yukawa systems is discussed. It is shown that the ISM approximation provides fairly good estimate of the internal energy of the strongly coupled Yukawa systems, in both fluid and solid phases. Simple expressions for the excess pressure and isothermal compressibility are derived, which can be particularly useful in connection to wave phenomena in strongly coupled dusty plasmas. It is also shown that in the regime of strong screening a simple consideration of neighboring particles interactions can be sufficient to obtain quite accurate estimates of thermodynamic properties of Yukawa systems