Disk device

A disk device comprising:

• a rotatable disk-shaped recording medium with a magnetic recording layer;
• a magnetic head comprising a recording head including a main magnetic pole configured to generate a recording magnetic field, a write shield magnetic pole opposed to the main magnetic pole with a write gap, and a coil configured to excite a magnetic flux, an assist element, and a heater configured to heat the recording head;
• and
• a controller including a heater voltage supply circuit configured to supply heater power to the heater, a drive voltage supply circuit configured to supply a drive voltage to the assist element, and a contact detection circuit configured to detect contact between the magnetic head and the recording medium, wherein the controller adjusts a set value of the drive voltage based on an amount of protrusion of the assist element when contact is detected by the contact detection circuit;
• and
• the controller is configured to perform an operation to increase the heater power supplied from the heater voltage supply circuit to the heater with the drive voltage of the assist element turned off, an operation to stop increasing the heater power when contact between the magnetic head and the recording medium is detected for the first time by the contact detection circuit, an operation to decrease a power value of the heater power by a desired amount of element protrusion from the power value of the heater power when the contact between the magnetic head and the recording medium is detected for the first time, an operation to increase the drive voltage supplied to the assist element from the drive voltage supply circuit, and an operation to stop increasing of the drive voltage when the contact detection circuit detects the contact between the magnetic head and the recording medium for the first time while setting the drive voltage value at that time to the set value.