Cryopump, cryopump controller, and cryopump control method

A cryopump comprising:

• a first stage cryopanel configured to be cooled to a first-stage cryopanel temperature;
• a second stage cryopanel configured to be cooled to a second-stage cryopanel temperature, the second-stage cryopanel temperature being lower than the first-stage cryopanel temperature;
• a data storage configured to store a first-stage target-temperature table, the first-stage target-temperature table comprising:
• a normal target temperature for a normal mode of maintaining the first stage cryopanel within a cryogenic temperature region, and
• a cool-down target temperature for a cool-down mode of cooling the first stage cryopanel from room temperature to the cryogenic temperature region, the cool-down target temperature being lower than the normal target temperature,
• and
• a cryocooler controller communicably connected to the data storage, the cryocooler controller is configured to:
• select, as a current operation mode, one of the normal mode and the cool-down mode,
• select, in accordance with the first-stage target temperature table and the selected current operation mode, one of the normal target temperature and the cool-down target temperature as a first-stage target temperature,
• control, according to the selected first-stage target temperature, the first-stage cryopanel temperature,
• determine a current phase in the cool-down mode, based on at least one of an elapsed time from a start of the cool-down mode and a second stage cryopanel temperature, and
• select the first-stage target temperature according to the at least one of the elapsed time from the start of the cool-down mode and the second stage cryopanel temperature.

A cryopump controller comprising:

• a data storage configured to store a first-stage target-temperature table, the first-stage target-temperature table comprising:
• a normal target temperature for a normal mode of maintaining a first stage cryopanel within a cryogenic temperature region, and
• a cool-down target temperature for a cool-down mode of cooling the first stage cryopanel from room temperature to the cryogenic temperature region, the cool-down target temperature being lower than the normal target temperature;
• and
• a cryocooler controller communicably connected to the data storage, the cryocooler controller is configured to:
• select, as a current operation mode, one of the normal mode and the cool-down mode,
• select, in accordance with the first-stage target temperature table and the selected current operation mode, one of the normal target temperature and the cool-down target temperature as a first-stage target temperature,
• control, according to the selected first-stage target temperature, a first-stage cryopanel temperature, and
• switch, when a second-stage cryopanel temperature reaches a second target temperature during the cool-down mode, the current operation mode from the cool-down mode to the normal mode and change the first-stage target temperature from the cool-down target temperature to the normal target temperature to control the first-stage cryopanel temperature to the normal target temperature.

A cryopump control method comprising:

• selecting, by a cryocooler controller as a current operation mode one of:
• a normal mode of maintaining a first stage cryopanel within a cryogenic temperature region, and
• a cool-down mode of cooling the first stage cryopanel from room temperature to the cryogenic temperature region,
• selecting, by the cryocooler controller as a first-stage target temperature one of:
• a normal target temperature, and
• a cooldown target temperature according to the current operation mode, the cool-down target temperature being lower than the normal target temperature;
• controlling, by the cryocooler controller, a first-stage cryopanel temperature according to the selected first stage target temperature;
• and
• switching, when a second-stage cryopanel temperature reaches a second target temperature during the cool-down mode, the current operation mode from the cool-down mode to the normal mode and changing the first-stage target temperature from the cool-down target temperature to the normal target temperature to control the first-stage cryopanel temperature to the normal target temperature.