PURPOSE: To enhance the evaporation capacity and to solve the problem of leakage of vacuum from a vacuum seal at a driving part and damage and wear of the seal by performing a desired revolving motion with a nonsealed rotary body inside a closed container.

CONSTITUTION: Permanent magnets 5, 6 are fixed to the stainless steel rotary body 5 in a glass-made closed container 1. An AC current is impressed on electromagnets 7, 8 to generate a rotary magnetic field, and the permanent magnets 5, 6 are driven by the magnetism of this rotary magnetic field to rotate the rotary body.