transferred to the temperature controller 242 t when the temperature indicated by the temperature sensor 236 reaches a desired level the electromagnet controller 242 m interrupts the transfer of electrical energy this process repeats when the temperature sensor 236 detects a change in temperature of about 1 3 u00b0 c placing the first temperature sensor 236 in the vicinity of the first heating element 234 and controlling the energy provided to the first heating element 234 based on feedback provided by at least the first temperature sensor 236 can achieve good control of the temperature of the base plate 228 if the temperature were detected by a temperature sensor positioned away from the first heating element 234 then the temperature of the base plate 228 and the magnetic section 220 could be more difficult to maintain due to heat transfer hysterisis in an alternative embodiment only the temperature controller 242 t is used to control the magnetic flux in the magnetic gap 220 e in another embodiment the electromagnet controller 242 m operates in conjunction with temperature controller 242 t to control the magnetic flux because controlling the temperature of the base plate 228 takes time the current in the coil 220 g can be adjusted during this lag time if needed during the period of temperature transition any tendency for the magnetic flux to change can be controlled by the electromagnet controller 242 m the magnetic sensor 120 f induces the electromagnet controller 242 m to provide current to the coil 220 g in an appropriate amount and direction so that the magnetic flux remains within the desired range.