Condensation, by homogeneous nucleation, of UF6 carried in a mixture o
f argon and methane was studied experimentally in a continuously opera
ting supersonic Laval nozzle. The onset of condensation was detected b
y Rayleigh light scattering. Measurements of static pressure in the no
zzle, together with the equations of isentropic flow, permitted the de
termination of the relation between the pressure of UF6, P-k, and the
temperature, T-c, at the observed onset of condensation. The experimen
ts addressed conditions of condensation onset in the range 80 < T-c <
160 K and 0.1 P-k < 3.0 Torr. We found that there was no influence of
the pressure of the carrier gas argon, which ranged from 3.5 to 68 Tor
r at onset points, on the onset of condensation. The dependence of the
supersaturation ratio on temperature at the onset could be expressed
by a straight line as deduced by P.P. Wegener and B.J.C. Wu from the c
lassical theory of homogeneous nucleation [Adv. Colloid Interface Sci.
7, 325 (1977)]. These results indicate that supersonic expansion in t
he nozzle formed single-component droplets of UF6 in a mixture of UF6,
CH4, and Ar under the experimental conditions studied herein.