Development of a quasi-direct temperature control system of modulated induction thermal plasmas for advanced materials processing

A new modulated induction thermal plasma system, called a feedback control type of modulated induction thermal plasma system, was developed for quasi-direct control of thermal plasma temperature for advanced materials processing. The system is based on the arbitrary-waveform modulation induction thermal plasma system developed previously in our work, and a real-time spectroscopic observation system. The Ar excitation temperature was measured in real time using a spectroscopic observation technique. Its time evolution was controlled to trace externally given waveform periodical signals between 6000 and 8000 K such as rectangular, triangular and sawtooth waveforms. In addition, the developed system was confirmed to adopt an automatic power injection control, synchronized with gas injection as a disturbance. (paper)