Large acoustic solitons and double layers in plasmas with two positive ion species

Verheest, Frank; Hellberg, M. A.; Saini, N. S.; Kourakis, Ioannis

doi:10.1063/1.3579397

Cited by 31 publications

(20 citation statements)

References 51 publications

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“…Clearly, the plasma composition parameter values that give rise to the switch are critical [10,24,29], and in this model one is led to critical values of the nonthermality parameter, β c , and dust charge fraction, denoted by f c . It is possible with this technique to find numerous realistic plasma models in which, for some fixed plasma parameter values, both polarities are supported [4,10,14,17,24,28,31,32], a phenomenon sometimes referred to as "coexistence" [24,[28][29][30][32][33][34]. Even though positive and negative solitons can occur for the same parameter values in the Sagdeev pseudopotential, only one possibility can be realized at a time, depending on the initial perturbations.…”

Section: Basic Formalismmentioning

confidence: 99%

Dust-ion-acoustic supersolitons in dusty plasmas with nonthermal electrons

2013

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Supersolitons are a recent addition to the literature on large-amplitude solitary waves in multispecies plasmas. They are distinguished from the usual solitons by their associated electric field profiles which are inherently distinct from traditional bipolar structures. In this paper, dust-ion-acoustic modes in a dusty plasma with stationary negative dust, cold fluid protons, and nonthermal electrons are investigated through a Sagdeev pseudopotential approach to see where supersolitons fit between ranges of ordinary solitons and double layers, as supersolitons always have finite amplitudes. They therefore cannot be described by reductive perturbation treatments, which rely on a weak amplitude assumption. A systematic methodology and discussion is given to distinguish the existence domains in solitary wave speed and amplitude for the different solitons, supersolitons and double layers, in terms of compositional parameters for the plasma model under consideration.

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Section: Basic Formalismmentioning

confidence: 99%

Dust-ion-acoustic supersolitons in dusty plasmas with nonthermal electrons

2013

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“…49,54,56 As mentioned above, KdV theory can only yield solitons of one polarity for a given composition, and its polarity coincides with the sign of the coefficient of the nonlinear KdV term. 43,49,56 Further, it was shown that the sign of the latter KdV coefficient can be found from the Sagdeev potential through that of S 000 ð0; M s Þ. 43,49 On the other hand, the "other" soliton was found to have finite amplitude at the acoustic speed, i.e., it was clearly "nonKdV-like" in behavior.…”

Section: Introductionmentioning

confidence: 90%

“…40 The true acoustic speed, M s , is found from the Sagdeev potential through S 00 ð0; M s Þ ¼ 0, where primes denote differentiation with respect to u. 49,54,56 As mentioned above, KdV theory can only yield solitons of one polarity for a given composition, and its polarity coincides with the sign of the coefficient of the nonlinear KdV term. 43,49,56 Further, it was shown that the sign of the latter KdV coefficient can be found from the Sagdeev potential through that of S 000 ð0; M s Þ.…”

Section: Introductionmentioning

confidence: 99%

Arbitrary amplitude ion-acoustic soliton coexistence and polarity in a plasma with two ion species

2012

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Using a Sagdeev pseudopotential formalism, large ion-acoustic waves are investigated in a multispecies plasma model consisting of two cold positive ion species in the presence of nonthermal Cairns electrons. Positive solitons are limited in amplitude by infinite compression of the lighter ion species. Negative solitons become possible at a sufficient degree of electron nonthermality, and their amplitudes are limited by the occurrence of double layers. What determines coexistence is the possibility of having parameter ranges for which there are solitons at the acoustic speed, which is a necessary and sufficient condition but unfortunately not an easy criterion to check analytically. For the first time a parameter range has been found where both negative and positive polarity solutions coexist, with the solitons at the acoustic speed always having a positive polarity, contrary to earlier results which seemed to indicate that polarity switches and coexistence ranges were linked. Finally, some useful proofs are presented in an Appendix, concerning the Sagdeev pseudopotential behavior at the acoustic speed, results of which are generic to a range of physical plasma models. V C 2012 American Institute of Physics. [http://dx.

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“…The converse, however, is certainly not true: one can have polarity changes and double layers without coexistence. 61,62 However, all possible ramifications of a precise link between polarity changes and coexistence domains have not been exhaustively investigated yet.…”

Section: Polarity Switches and Coexistence Domainsmentioning

confidence: 99%

Dust-acoustic solitary modes in plasmas with isothermal and nonthermal ions: Polarity switches and coexistence domains

Verheest¹

2011

Physics of Plasmas

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Large dust-acoustic waves are investigated in a multispecies plasma model consisting of cold negative dust in the presence of cooler Boltzmann and hotter nonthermal Cairns positive ions, in a Sagdeev pseudopotential formalism. Use of the pseudopotential at the acoustic speed itself yields in a systematic way compositional parameter values where negative=positive solitons interchange polarities and also where both polarities coexist. The latter requires that solitons at the acoustic speed exist, with finite amplitudes, compared to superacoustic solitons of the opposite polarity. The coexistence region starts when the pseudopotential at the acoustic speed has a negative root at the limit of infinite dust compression and ends when a positive double root is encountered. Outside the coexistence domain, only negative or positive superacoustic solitons can exist. Thus, the discussion and numerical evaluations are guided by precise physical and analytic arguments rather than mere numerical experimentation. Graphs of relevant Sagdeev pseudopotentials illustrate the link with the analytical constraints.

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Large acoustic solitons and double layers in plasmas with two positive ion species

Cited by 31 publications

References 51 publications

Dust-ion-acoustic supersolitons in dusty plasmas with nonthermal electrons

Dust-ion-acoustic supersolitons in dusty plasmas with nonthermal electrons

Arbitrary amplitude ion-acoustic soliton coexistence and polarity in a plasma with two ion species

Dust-acoustic solitary modes in plasmas with isothermal and nonthermal ions: Polarity switches and coexistence domains

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