NIRSPEC is cooled continuously by use of Closed-Cycle Refrigeration (CCR). A compressor unit in the K2 machine room provides pressurized He gas to two cold heads on-board NIRSPEC. If this system is inoperable for more than about 90 minutes, then NIRSPEC may require a lengthy 16 day cooling cycle to become operable again.

Please do not skip sections in this page. I have designed it for you to read up through the section that corresponds to your power outage. For example, if NIRSPEC experiences a short power outage and is now on generator power, please follow sections A) and B).

  1. Power Glitch
  2. Short Power Outage (<30 minutes)
  3. Medium Term Power Outages (<6 hours)
  4. Long Term Power Outages and No Generator Power
  1. Momentary Power Glitch

    2. When NIRSPEC experiences a momentary power glitch, CCR cooling should continue uninterrupted; however, the keyword server may hang.

    1. Check the server by running the recover script from a waimea prompt.
    2. Monitor the cryotemps to ensure that cooling continues.
    3. If the temperatures begin to rise...
      1. Call the summit to verify that the CCRs are running
      2. Sometimes a stop and restart of the server helps

  2. Short Power Outage (<30 minutes)

    3. This section assumes that the UPS has kept the NIRSPEC host computer running during the power outage.

    Once power has been restored, there are 3 main checks to make:

    1. Check dewar temps and vacuum pressure
    2. Check facility glycol
    3. Check facility air (can be done without power)

    1. Check dewar temps and vacuum pressure
      Once the CCR cooling has stopped for more than a few minutes, the vacuum pressure inside the dewar must be monitored.

      1. Go up to NIRSPEC. Turn on and read the Edwards vacuum gauge display. Gauge 3 (termed Lo-Vac) should be displayed.
        Image of Edwards vacuum gauge display. N.B. If the pressure is below 1e-4 Torr, no pumping on the NIRSPEC dewar is necessary before restarting the CCR compressors and you may skip to step 5 in the Pumping and Cooling list below. If the pressure is above 1e-4, pumping on the dewar is recommended and may be necessary.
      2. Monitor the NIRSPEC cryotemperatures via any or all of the following methods:
        1. Run the cryotemps command from a waimea prompt
        2. View the plots in the Cryo Temp web page
        3. Have someone read the temperatures directly from the Lakeshore controller at the instrument
      3. As temperatures rise within the dewar, increase the setpoint for the ALADDIN chip via the change.detector.temp keyword so that the detector is not the coldest thing inside the dewar.
      4. While doing the above 3 steps, also run down the Pumping and Cooling list:
        1. Move the portable vacuum pump to NIRSPEC.
        2. Connect the pump to the NIRSPEC vacuum valve fitting.
        3. Start rough pumping the line. Open the NIRSPEC vacuum valve as soon as the line is a factor of 10 below the NIRSPEC vacuum reading.
        4. When the vacuum reaches 4e-2 (40 millitorr), start the turbo pump.
        5. Restarting the CCR compressor is dependent upon cooling for the compressor unit. Under HELCO power, this is done by the facility chiller. Under generator power, an icewagon is needed. Once an icewagon is connected to the 3 CCR compressors (OSIRIS, NIRC2, and NIRSPEC) via the "octopus", a series of glycol hoses, the CCR compressor can be restarted.
        6. Monitor the NIRSPEC vacuum. When it is less than 1e-4, valve off the pump. Verify that the vacuum continues to drop with the CCR running.

    2. Check facility glycol
      Determine whether instrument glycol is flowing. Without glycol, the electronics cabinets will overheat and shutdown the instrument.

      If there is no glycol flow,

      1. Remove the covers on the electronics cabinets.
      2. Disable the glycol flow meter at the instrument.

    3. Check facility air
      If facility air is not flowing, there is an increased chance to fog the dewar window.

      If the air is not flowing,

      1. Rig up a bottle of dry nitrogen to force air flow across the dewar window

  3. Medium Term Power Outages (<6 hours)

    4. In these cases, the vacuum pressure within the dewar likely will be too high to restart the CCR compressors straightaway. If the pressure is above 1e-1 Torr, the cold heads can be damaged if started without first pumping on the dewar. Please follow the Pumping and Cooling procedure presented above.

  4. Long Term Power Outages and No Generator Power

    5. Without electricity, there is nothing you can do but wait until power is restored.