Monte Carlo Calculations of the Sputtering of Grains: Enhanced Sputtering of Small Grains
S. Jurac, R. E. Johnson, B. Donn;
ApJ, 1998, 503, 247
ABSTRACT:The sputtering of a small grain embedded in a plasma or hot gas in the interstellar medium (ISM) is calculated using a Monte Carlo binary collision
code.
This technique is used to describe the transport of the atoms set in motion in
the solid by an incident ion or atom and the sputtering from the surface of a
grain induced by collisional cascades.
The calculations, calibrated to
laboratory data, describe the enhancement in the yield due to erosion from the
edges and back surfaces by the incident particle and the energetic
recoils.
The angular dependence of the sputtering yield typically used, Y ~ (cos
theta )-1, is shown not to be valid.
The grain size effect manifests itself
even when the grain radius is only ~3 times larger than the mean penetration
depth of the incident particle.
Sputtering of a grain in a single-fluid
shock is used as an example to test the effect of grain size on the erosion
rate.
The enhancement in the sputtering rate due to grain size exacerbates the
problem of small grain destruction, placing more severe constraints on grain
growth in the ISM.
The results presented are also relevant to the erosion of
circumstellar and circumplanetary grains by energetic ions.
KEYWORDS: ism: dust, extinction, ism: general
PERSOKEY:dust, size distribution, ,
CODE: jurac98