摘要 |
An apparatus and process are provided for controlling the heating and melting of a material that is non-electrically conductive in the solid state and is electrically conductive in the non-solid state. Power is selectively directed between coil sections surrounding different zones of the material in a susceptor vessel by changing the output frequency of the power supply to the coil sections. Coil sections comprise at least one active coil section, which is connected to the output of the power supply, and at least one passive coil section, which is not connected to the power supply, but is connected in parallel with a tuning capacitor so that the at least one passive coil section can be selectively operated at, or near, resonant frequency when the transition material in the vessel is molten. Depending upon the state of the transition material in the susceptor vessel, the frequency of the power applied to the active coil section can be changed to generate a magnetic field that selectively couples with the susceptor vessel, transition material in the vessel, and/or the passive coil section.
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