Casimir energy of a dilute dielectric ball with uniform velocity of   light at finite temperature
  The Casimir energy, free energy and Casimir force are evaluated, at arbitrary finite temperature, for a dilute dielectric ball with uniform velocity of light inside the ball and in the surrounding medium. In particular, we investigate the classical limit at high temperature. The Casimir force found is repulsive, as in previous calculations. 
I. Klich, J. Feinberg, A. Mann and M. Revzen