Plasma processing apparatus and plasma processing method

A plasma processing apparatus including a processing chamber that is arranged in a vacuum container and allows plasma to be formed therein, a sample stage on which a sample, which is an object to be processed by the plasma, is mounted, the sample stage including a plurality of refrigerant channels that are concentrically arranged and allow a refrigerant to flow inside and functioning as a first evaporator, a refrigerant inlet and a refrigerant outlet arranged in each of the plurality of refrigerant channels, and an exhaust unit that exhausts an inside of the processing chamber for pressure reduction, the apparatus comprising:

• a plurality of upstream-side expansion valves and a plurality of downstream-side expansion valves that are connected to the respective refrigerant inlets and the respective refrigerant outlets and adjust a flow rate or a pressure of a refrigerant flowing into the respective refrigerant inlets and a flow rate or a pressure of a refrigerant flowing out from the respective refrigerant outlets;
• and a refrigeration cycle including a compressor, a condenser, the plurality of upstream-side expansion valves, the plurality of refrigerant channels, the plurality of downstream-side expansion valves and a second evaporator connected in this order via a refrigerant duct, and allowing the refrigerant to flow in the order, wherein openings of the plurality of upstream-side expansion valves and openings of the plurality of downstream-side expansion valves are adjusted so that no change in flow rate of the refrigerant occurs in a plurality of refrigerant paths between the plurality of upstream-side expansion valves and the plurality of downstream-side expansion valves via the plurality of refrigerant channels.