Starting method for cryocooler and cryocooler

A cryocooler comprising:

• a compressor;
• a cold head;
• a high pressure line through which a refrigerant gas is supplied from the compressor to the cold head;
• a low pressure line through which the refrigerant gas is collected from the cold head to the compressor;
• a pressure sensor that measures a pressure of the high pressure line or a differential pressure between the high pressure line and the low pressure line;
• a compressor controller that controls an operation frequency of the compressor based on the pressure measured by the pressure sensor;
• and
• a buffer volume configured to be connected to the high pressure line when the cold head is cooled from a room temperature to a cryogenic temperature, and the buffer volume is configured to be disconnected from the high pressure line when the cold head is maintained at the cryogenic temperature.

A cryocooler comprising:

• a compressor;
• a cold head;
• a high pressure line through which a refrigerant gas is supplied from the compressor to the cold head;
• a low pressure line through which the refrigerant gas is collected from the cold head to the compressor;
• a pressure sensor that measures a pressure of the high pressure line or a differential pressure between the high pressure line and the low pressure line;
• and
• a compressor controller that controls an operation frequency of the compressor based on the pressure measured by the pressure sensor,
• wherein a volume of the high pressure line is larger than a volume of the low pressure line.

A starting method for a cryocooler, the cryocooler including a compressor, a cold head, a high pressure line through which a refrigerant gas is supplied from the compressor to the cold head, and a low pressure line through which the refrigerant gas is collected from the cold head to the compressor, the method comprising:

• increasing a volume of the high pressure line when the cold head is at a room temperature;
• and
• cooling the cold head from the room temperature to a cryogenic temperature after the volume of the high pressure line has been increased,
• wherein the cooling of the cold head from the room temperature to the cryogenic temperature comprises:
• measuring a temperature of the cold head,
• comparing the measured temperature of the cold head to a temperature threshold value, and
• when the measured temperature of the cold head exceeds the temperature threshold value, controlling the operation frequency of the compressor such that the pressure of the high pressure line follows a pressure target value.