THE ROLE OF FIELD-EMISSION IN THE ELECTROSTATIC DISRUPTION OF COSMIC DUST

The role of field emission in mitigating the process of electrostatic disruption of charged cosmic dust grains is discussed. It is shown that this process prevents the disruption of even the smallest grains independent of the plasma environment if the tensile strength F(t) of such grains is greather than about 3.6 x 10(7) dynes cm-2. On the other hand, if such grains are very fragile (i.e., F(t) less-than-or-similar-to 10(6) dynes cm-2, as in 'cometary' grains) even field emission cannot always prevent their electrostatic disruption. In this case it is required that the magnitude of the potential of the grains is less-than-or-similar-to 0.15 V, which places stringent upper limits on the ambient plasma temperature T. For pure hydrogen and pure oxygen plasmas, T less-than-or-similar-to 700 K and T less-than-or-similar-to 460 K, respectively.