Dynamical Casimir effect at finite temperature

The dynamics of the Maxwell field in a cavity with movable perfectly reflecting boundaries is investigated at nonzero temperature, applying the techniques of the thermo field dynamics (TFD). For a resonantly vibrating cavity, the thermal effect on the creation of photons and the temperature correction to the mechanic response of the intervening vacuum are all derived, based on the previous work at zero temperature by Dodonov and Klimov [Phys. Rev. A 53 (1996) 2664]. The strong amplification of the Casimir effect due to finite temperature, which was first predicted by Plunien et al. [Phys. Rev. Lett. 84 (2000) 1882] in response theory, is also observed. The squeezing effect at finite temperature is probed too.