are connected via a graphite bolt 34 to position the graphite heater 2 a positioning member 35 is disposed at a position corresponding to the heating pin 33 on the connecting base 3 in order to improve the current carrying capacity between the heating pin 33 and the connecting base 3 the positioning member 35 comprises a contact surface 351 in a vertical direction and the contact surface 351 is attached to a lateral side of the heating pin 33 the lateral side of the heating pin 33 and the contact surface 351 are bonded by a high temperature conductive filler therefore the contact area between the lateral side of the heating pipe and the contact surface are increased thereby increasing the current carrying capacity and decreasing the contact resistance 3 as shown in fig1 the graphite heater 2 is connected to the electrode 4 via the connecting base 3 the electrode 4 both functions in supporting the connecting base 3 and the graphite heater 2 when using the graphite heater having a high power easily a very high temperature of the electrode is easily resulted thus the electrode herein is cooled by water cooling method a liquid cooling cavity 36 is disposed inside the electrode 4 a liquid inlet 37 and a.