Microwave output device and plasma processing apparatus

A microwave output device comprising:

• a microwave generation unit configured to generate a microwave having a center frequency and a bandwidth respectively corresponding to a setting frequency and a setting bandwidth instructed by a controller, the microwave having power pulse-modulated such that a pulse frequency, a duty ratio, a high level and a low level respectively corresponding to a pulse frequency, a setting duty ratio, high level setting power and low level setting power instructed by the controller;
• an output unit configured to output the microwave propagating from the microwave generation unit;
• a first directional coupler configured to output parts of travelling waves propagating from the microwave generation unit to the output unit;
• and
• a measurement unit configured to determine a first high measured value and a first low measured value respectively indicating a high level and a low level of power of the travelling waves in the output unit on the basis of the parts of the travelling waves output from the first directional coupler,
• wherein the microwave generation unit
• averages the first high measured value and the first low measured value with a predetermined movement average time and a predetermined sampling interval,
• controls high level power of the pulse-modulated microwave on the basis of the averaged first high measured value and the high level setting power, and
• controls low level power of the pulse-modulated microwave on the basis of the averaged first low measured value and the low level setting power.