Self-diffusion properties of neutral monatomic alkali–metal plasmas

Using the Chapman–Enskog method, the calculations of the coefficients of self-diffusion D of neutral alkali–metal atoms in their respective parent gas as a function of the temperature T have been performed. These calculations are more accurate, since they have been carried out by using recent interatomic potentials constructed from Rydberg–Klein–Rees data, and by taking into consideration the symmetry effects caused by the identity of the atoms undergoing the collisions and the nuclear spins. When compared to the present results, the published data of D(T) show they are overestimated. The variation law of D with T has also been investigated. For temperatures ranging from about 100 K to 3000 K, it is found that the results can be reproduced by the relation D=aT b ( m 2 s −1 ), where a=3.911×10 −8 and b=0.692 for Li, a=1.774×10 −8 and b=0.681 for Na, and a=7.443×10 −9 and b=0.700 for K.