To minimize heat dissipation loss at the terminal part of a tube by a method wherein a driving plate is attached to a graphite pipe indirectly while a flexible atmosphere seal assembly, a heating chamber and a heating body are provided on the periphery and the inside of the graphite tube.

In order to transfer a rotating torque from a motor power source to a graphite tube 2 through a driving plate 14 while allowing the difference of thermal expansion, the driving plate 14 is attached to the graphite tube 2 indirectly through a key, a spline or a similar interlocking unit 15. In this case, one set or more of flexible bellows 19 or another load spring type seal assembly, a heat insulating heating chamber 11 surrounding a heating area 4, an electric heating body in the heating chamber for sealing a selected atmosphere around and inside of the graphite tube 2 during rotating are equipped. According to this method, heat dissipation loss at the terminal part of the tube can be minimized.