The Effects Of Lennard-Jones Potential On Dust-acoustic Wave And Jeans Instability

Dusty plasma has become an important branch of plasma physics due to its abundant physical phenomena and being easily investigated at kinetic level in experimental scenarios. Lots of studies on dusty plasma take Debye potential as the shielding potential of dust particulate. However, it is unable being used to interpret some special phenomena, such as the cutoff of dust-acoustic waves(DAWs) and double sheer structure of a cathode. Hence, how to modify the present theory for explaining these particular physical phenomena has become a hot topic to scientists.The discovery of Lennard-Jones potential(L-J potential) provides a significant clue for elucidating above problems. L-J potential is a mathematically approximate model and was proposed by Lennard-Jones for describing the interaction between a pair of neutral atoms or molecules. The study of L-J potential in dusty plasma should be improved, even though it has been probed very well in solid physics. In the context above, using kinetic theory and numerical method, the effects of Lennard-Jones potential on dust acoustic wave and Jeans instability were investigated in dusty plasma. The principal results are given as follows:(1). Comparing with self-gravitating potential, the effects of L-J potential on DAWs and Jeans instability was studied and the results presented that the L-J potential contains the properties of Debye and self-gravitating potential;(2). A cutoff effect was induced for DAWs owning to the presence of L-J potential in dusty plasma and it matched the experimental results of Morfill's team very well;(3). Due to the L-J potential being introduced into dusty plasma, a purely growing instability, which was similar with the Jeans instability in self-gravitating system, was caused. Its formation also has the similar physical mechanism with Jeans instability, i.e. the balance between attractive and repulsive interactions among dust particulates was broken;(4). The existence of particulates which has higher free energy was the root reason for the occurrences of cutoff effect on DAWs and purely growing instability by comparing L-J potential with super thermal particulates.