KAGRA Logbook

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VAC (Valves & Pumps)

nobuhiro.kimura - 15:10 Tuesday 19 May 2026 (36915)

#39 Error message on the ion pump power supply

[Kimura, Yasui]

　On May 18, during a routine inspection, Masahiro Takahashi reported that the #39 ion pump power supply had stopped operating and was displaying “Error 20.”
The content of the displayed Error 20 is: “HV interlock not satisfied or HV switch is off. HV cannot run. See section on digital inputs for details.”
After confirming that there were no signs of arcing at the high-voltage cable connections and other parts of the ion pump power supply, the unit was restarted, and it was confirmed that it could operate without any issues.
As a precaution, a spare ion pump power supply and high-voltage cable were temporarily placed near the #39 ion pump power supply to serve as replacements in the event that the unit malfunctions again.

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nobuhiro.kimura - 19:13 Monday 22 June 2026 (37110)

[Kimura and Nakagaki]
On 22 June, M. Takahashi-san reported the #39 ion pump power supply of X-end had stopped again after displaying an error with "Eroor code 20".
(See Photos 1 and 2)
The pressure gauge shows “7.5×10⁻⁶ Pa,” leading us to conclude that the ion pump power supply did not shut down due to a pressure rise caused by a vacuum leak.
At around 2:30 p.m., we closed the gate valve between the vacuum duct and the vacuum pumping unit to replace the ion pump power supply.
We then replaced it with a spare power supply and high-voltage cable, and restarted the ion pump power supply.
After startup, the pressure inside the T-tube reached “2.7×10⁻⁶ Pa,” so we opened the previously closed gate valve to resume evacuation by the ion pump.
(See Photos 3 and 4)
The pressure after opening the gate valve was “5.5×10⁻⁶ Pa”.
(See Photos 5 and 6)

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