Dusty Plasma Dynamics During a Void Instability: Heartbeat Instability (original) (raw)
Related papers
New Journal of Physics, 2007
When a three-dimensional dust cloud is present in a plasma, a dust-free region, called void, is usually observed in the plasma centre. Forces involved in the void existence are an inward electrostatic force and an outward ion drag one. Under certain conditions, this force balance can be disturbed and this region exhibits a self-excited unstable behaviour consisting in successive contractions and expansions of its size. This low frequency instability (few Hz), called "heartbeat", is here characterised by various diagnostics: electrical and optical measurements, high-speed video imaging. The results brought to the fore the main features of this instability. Correlations between physical processes in the plasma volume and the dust cloud motion are investigated through experimental results.
On the heterogeneous character of the heartbeat instability in complex (dusty) plasmas
Physics of Plasmas, 2012
A hypothesis on the physical mechanism generating the heartbeat instability in complex (dusty) plasmas is presented. It is suggested that the instability occurs due to the periodically repeated critical transformation on the boundary between the microparticle-free area (void) and the complex plasma. The critical transformation is supposed to be analogous to the formation of the sheath in the vicinity of an electrode. The origin of the transformation is the loss of the electrons and ions on microparticles surrounding the void. We have shown that this hypothesis is consistent with the experimentally measured stability parameter range, with the evolution of the plasma glow intensity and microparticle dynamics during the instability, as well as with the observed excitation of the heartbeat instability by an intensity-modulated laser beam (inducing the modulation of plasma density).
Self-excited void instability during dust particle growth in a dusty plasma
Physics of Plasmas, 2010
A new kind of void instability in a complex plasma is described. This instability is directly linked to the growth of a new generation of dust particles inside the void. It consists of slow contraction and expansion sequences of the void size which frequency and amplitude evolve while the new dust particles are growing.
Experimental investigations of void dynamics in a dusty discharge
Physics of Plasmas, 2004
We report on first electrical and spectroscopic characterizations of an instability, usually called "heartbeat" instability, occurring in a laboratory dusty plasma. It consists of successive contractions and expansions of the central dust free region observed in a dense cloud of dust particles. This cloud is formed in a radio-frequency plasma by sputtering polymer material deposited on the electrodes. The evolution of the discharge current reveals the relatively complex shape of the instability and allows to measure its evolution as a function of gas pressure and radio-frequency power.
Low frequency instabilities during dust particle growth in a radio-frequency plasma
Physics of Plasmas, 2006
In this paper, instabilities appearing in a dusty plasma are experimentally investigated. These low frequency self-excited instabilities appear during dust particle growth and are characterized by a frequency spectrum evolving during this process. Beginning, time evolution and main characteristics of these instabilities are investigated thanks to electrical and optical measurements. Both signals show a clear evolution scheme with a well-defined succession of phases. From the beginning to the end of this scheme, regular oscillations and/or chaotic regimes are observed. Finally, instabilities stop when the dust particle size reaches few hundreds of nanometers and a stable three-dimensional dust cloud is obtained. A dust free region called void is then usually observed in the plasma center.
Dust-lower-hybrid instability in a streaming magnetized dusty plasma
Physica Scripta, 2006
Instabilities for the excitation of the dusty plasma modes, namely the dust-acoustic and dust-lower-hybrid waves, due to the free streaming of ion/dust particles in uniformly magnetized dusty plasmas have been examined analytically. Expressions for growth rates and threshold have been presented for different conditions of free streaming beams of either ions, dust grains, or two contrastreaming dust particle beams. The relevance of the present investigation has been pointed out for laboratory as well as space dusty plasmas.
Oscillations in a Dusty Plasma Medium
2002
Novel properties introduced by charged particulates in a plasma medium and how they influence excitation and propagation of waves are discussed. Such a medium, commonly known as dusty plasma, is generated in the near Earth environment by dust and other debris of meteoric origin and exhausts and effluents from space platforms. A novel feature of dusty plasma is that the charge to mass ratio can become a dynamical variable and represent an additional degree of freedom unavailable to a classical plasma. Charged dust particles in a plasma introduce unique potential structures and significantly alter the short and long range forces which can affect the short and long range ordering of the dust grains.
Threshold Phenomena in a Throbbing Complex Plasma
Physical Review Letters, 2010
In complex plasmas, the trapped dust particle cloud is often characterized by a central dustfree region ("void"). The void induces a spatial inhomogeneity of the dust particle distribution and is at the origin of many intricate unstable phenomena. One of this behavior is the so-called heartbeat instability consisting of successive contractions and expansions of the void. This instability is characterized by a strong nonlinear dynamics which can reveal the occurrence of incomplete sequences corresponding to failed contractions. Experimental results based on high-speed imaging are presented for the first time and underline this threshold effect in both the dust cloud motion and the evolution of the plasma light emission. PACS numbers: 52.27.Lw
Magnetosonic wave instability in a streaming dusty plasma
Physica Scripta, 2006
General dispersion relation of plasma waves in a finite temperature flowing dusty plasma in the presence of an external magnetic field has been examined using the Vlasov-Maxwell system of equations. In the frequency regime between ion and dust cyclotron frequencies, the transverse electromagnetic dust-ion magnetosonic wave mode is found to propagate nearly perpendicular to the external magnetic field, which reduces to the usual magnetosonic wave in the absence of dust. The electrostatic dust-lower-hybrid mode is also recovered propagating nearly perpendicular to the external magnetic field in a finite ion temperature and cold dust plasma, which for the strong ion-Larmor radius effect reduces to the usual dust-acoustic wave driven by the ion pressure.