A Glance on the Physics of Dusty Plasmas

Professor Enzo Lazzaro, Institute for Plasma Physics, CNR-Milan, Italy

Monday 08 November 2010, 1500-1700
Marcus Merriman Lecture Theatre

SPEARS Seminar - All welcome.

A brief survey and an introduction to the physics of dusty plasmas is presented. Dust particles are an ubiquitous presence in space and laboratory plasmas and a "dusty plasma" is a non-trivial extension of the plasma concept and a source of new phenomena, applications and challenging problems. The traditional definition of a classical plasma is that of a physical medium, consisting of a large number of positive ions and negative electrons and neutral species with total net charge balancing to zero, and exhibiting a collective behaviour, associated with the long range electrostatic interaction. The physics of the response of a plasma to e.m. fields is all contained in the dielectric function that in principle is derived from the self consistent distribution function of the charged species. Actually this definition is easily and naturally generalized just by considering the presence of neutral mesoscopic particles that necessarily become variably charged by influx of electrons and ions, while keeping the whole mixture globally neutral. The inclusion of a third kind of minority particles with variable charge in a plasma alters significantly the dielectric function of the new system, that now can appropriately be called "dusty plasma"

if the particles are of macrosopic size . This fact introduces a wealth of new phenomena and new properties, that sets a new paradigm of generalized classical plasma physics. Of particular interest are also new ideas for diagnosing the presence of submicron sized dust based on the modifications of the electrostatic fluctuation spectra. Information is given on some recent studies in this field carried out in Italy sponsored by a PRIN grant.