| 摘要 |
PROBLEM TO BE SOLVED: To settle output power (progressive wave power) of a high frequency power source at target power even in the case where a load state is changed faster than a speed of feedback control.SOLUTION: An RF power control part 15 generates a control signal S'[k] by performing predetermined calculation on the basis of differential power ΔP[k] between progressive wave power P[k] that is outputted in a predetermined cycle from the high frequency power source, and preset target power P. The RF power control part 15 calculates a rate of change of progressive wave power Pand a rate of change of a reflection coefficient Γ in an output terminal of the high frequency power source and determines a coefficient K(0≤K≤1) on the basis of the rates of change. The RF power control part 15 generates a control signal S[k] for feedback control of the progressive wave power Pby performing arithmetic processing of S[k]=S'[k]-K×(S'[k]-S[k-1]). When fast changing the load state, the coefficient K is made closer to 1, and an update amount of the control signal S[k] with respect to the control signal S'[k] is reduced, thereby suppressing a rapid change of a control gain.SELECTED DRAWING: Figure 3 |
