Dust acoustic solitary waves in nonthermal plasmas consisting of negatively charged dust grains and isothermal electrons
Abstract
A Kortewegde Vries (KdV) equation is derived here, that describes the nonlinear behaviour of longwavelength weakly nonlinear dust acoustic waves propagating in an arbitrary direction in a plasma consisting of static negatively charged dust grains, nonthermal ions and isothermal electrons. It is found that the rarefactive or compressive nature of the dust acoustic solitary wave solution of the KdV equation does not depend on the dust temperature if σ_{d}^{c} < 0 or σ_{d}^{c} > σ_{d}*, where σ_{d}^{c} is a function of β_{1}, α and μ only, and σ_{d}*(<1) is the upper limit (upper bound) of σ_{d}. This β_{1} is the nonthermal parameter associated with the nonthermal velocity distribution of ions, α is the ratio of the average temperature of the nonthermal ions to that of the isothermal electrons, μ is the ratio of the unperturbed number density of isothermal electrons to that of the nonthermal ions, Z_{d}σ_{d} is the ratio of the average temperature of the dust particles to that of the ions and Z_{d} is the number of electrons residing on the dust grain surface. The KdV equation describes the rarefactive or the compressive dust acoustic solitary waves according to whether σ_{d}^{c} < 0 or σ_{d}^{c} > σ_{d}*. When 0 ≤ σ_{d}^{c} ≤ σ_{d}*, the KdV equation describes the rarefactive or the compressive dust acoustic solitary waves according to whether σ_{d} > σ_{d}^{c} or σ_{d} < σ_{d}^{c}. If σ_{d} takes the value σ_{d}^{c} with 0 ≤ σ_{d}^{c} ≤ σ_{d}*, the coefficient of the nonlinear term of the KdV equation vanishes and, for this case, the nonlinear evolution equation of the dust acoustic waves is derived, which is a modified KdV (MKdV) equation. A theoretical investigation of the nature (rarefactive or compressive) of the dust acoustic solitary wave solutions of the evolution equations (KdV and MKdV) is presented with respect to the nonthermal parameter β_{1}. For any given values of α and μ, it is found that the value of σ_{d}^{c} completely defines the nature of the dust acoustic solitary waves except for a small portion of the entire range of the nonthermal parameter β_{1}.
 Publication:

Journal of Plasma Physics
 Pub Date:
 August 2009
 DOI:
 10.1017/S0022377809008083
 Bibcode:
 2009JPlPh..75..455D