Documentation

System Operation

4

This chapter details the “Cool down” and “Warm up” procedures for the cryogenic components of the Opus One nanowire system.

WARNING

If either the compressor or Opus One unit operate in a seemingly erratic or unsafe manner, turn off and disconnect power to the compressor and the electronics unit and contact Quantum Opus for assistance.

Cool Down Procedure

4.1

For Opus One Integrated and Opus One Portable Units

4.1.1
NOTE

For a portable system, there may be a front cover attached. See Section 2.1 on how to safely remove it.

For systems with one-button cooldown, the Opus One is able to autonomously handle normal operating conditions and has built-in safeguards for equipment or power failure. To begin system cooldown, follow the steps below.

  1. Switch the electronics on. The cooldown button will turn green.

  2. Press the button and the system will begin cooling. The button will turn from green to magenta, and the vacuum pump will turn on after a 1 minute delay.

    NOTE

    The hum of the compressor and the 1 cycle-per-second "hiss" of the Opus One unit should begin immediately. If the 1 cycle-per-second sound from the Opus One is not heard, turn off the compressor and confirm that the helium line and electrical connections between the Opus One unit and the compressor are correct, as per Section 2.2.3.

  3. Once sufficient time has elapsed, the button will turn to cyan when the vacuum pump relay is switched off, and will turn to dark blue when the system is fully cold. You may confirm that the temperature reading of the Stage 1 thermometer indicates the temperature has started to decrease via the Opus One controller software.

For Opus One Standard Units

4.1.2

The procedures in this section should be accomplished for first-time operation and repeated any time that the system has been warmed such that both stages are above 50 Kelvin, for example in case of power failure, cooling water loss, or intentional system shutdown.

NOTE

The system should be in its warm state before starting this procedure to ensure proper cool down. A fully "warm" state is defined as both thermometers (Stage 1 and Stage 2) read above 280 K. This state is commonly achieved within 12 hours after the system has been powered off. For the system warm-up procedure, see Section 4.2.

NOTE

A vacuum pump that reaches a pressure below approximately 0.1 mbar (100 mTorr) is required for the cool down procedure, but is not required for continuous operation. A dry, or oil-free, pump is preferred to prevent the possibility of oil backstreaming that could contaminate the cryogenic system.

WARNING

For Opus One standard systems, when closing the green vacuum valve (labeled "Valve") on the rear of the system, do not overtighten. This valve should be closed only until finger tight. Never use pliers or tools to close the valve. Using excessive force to close the valve can permanently damage the valve mechanism.

The cool down procedure steps should be completed in the following order when the system is fully warm:

The cool down procedure steps should be completed in the following order when the system is fully warm:

  1. Evacuate the Opus One unit according to the following procedure.
    1. Ensure the green vacuum valve (labeled "Valve") on the rear of the Opus One unit is closed by gently applying clockwise torque. The valve should not open under light counter-clockwise torque. Do not overtighten.
    2. Remove the NW25 cap and o-ring from the vacuum port (labeled "Pump/Vent") by loosening the clamp screw and removing the clamp.
    3. Inspect the o-ring to ensure it is dust-free and has no cracks or flaws. If so, replace the o-ring before proceeding.
    4. Using the o-ring and clamp, connect the vacuum pump via an appropriate NW25 vacuum tube (not provided) to the vacuum port and hand tighten the clamp securely.
    5. Follow the vacuum pump manufacturer's recommended procedure for starting the pump.
    6. Slowly open the vacuum valve on the Opus One unit. The valve is fully open once rotated counterclockwise approximately two (2) full turns. The valve should remain open and the pump on until the system has reached 50 K.
  2. Ensure the compressor is ready for use, including turning on any required cooling water or electrical breakers.
  3. Turn on the electrical power to the compressor. The hum of the compressor and the 1 cycle-per-second "hiss" of the Opus One unit should begin immediately. If the 1 cycle-per-second sound from the Opus One is not heard, turn off the compressor and confirm that the helium line and electrical connections between the Opus One unit and the compressor are correct, as per Section 2.2.3.
  4. Confirm that the temperature reading of the Stage 1 thermometer indicates the temperature has started to decrease.
  5. After the temperature of the Stage 1 thermometer drops below approximately 50 K, close the vent valve by turning the green valve knob clockwise until (gently) finger tight. Do not overtighten.

  2. Ensure the compressor is ready for use, including turning on any required cooling water or electrical breakers.

  3. Turn on the electrical power to the compressor. The hum of the compressor and the 1 cycle-per-second "hiss" of the Opus One unit should begin immediately. If the 1 cycle-per-second sound from the Opus One is not heard, turn off the compressor and confirm that the helium line and electrical connections between the Opus One unit and the compressor are correct, as per Section 2.2.3.

  4. Confirm that the temperature reading of the Stage 1 thermometer indicates the temperature has started to decrease.

  5. After the temperature of the Stage 1 thermometer drops below approximately 50 K, close the vent valve by turning the green valve knob clockwise until (gently) finger tight. Do not overtighten.

    WARNING

    For Opus One standard systems, if using a dry pump with strong pumping capabilities such as a turbomolecular drag pump (i.e., "turbo" pump), you may choose to wait until the system is fully cold to close the green vacuum valve as there is little risk of backstreaming contaminants such as air or pump oil into the cryogenic space of the Opus One unit.

  6. Once the vacuum valve is closed you may disconnect the pumping line from the Opus One and turn off the pump, according to the process recommended by the pump manufacturer.

  7. Seal the NW25 Pump/Vent port using the NW25 o-ring, cap, and clamp.

  8. Wait until the temperature of the Stage 2 thermometer indicates the system is at its "base" temperature (typically below 2.5 K). The cool-down takes approximately three to four (3-4) hours from the time the compressor is turned on.

  9. The Opus One devices are now ready to be used. Refer to Section 5.1.

Warm Up Procedure

4.2

For Opus One Integrated and Opus One Portable Units

4.2.1

To warm the system, press the lit button on the front of the Opus One. The light will turn from its current status color to green, the compressor will turn off, and the system will begin warming.

For Opus One Standard Units

4.2.2
WARNING

Ensure the system has been turned off for a minimum of 12 hours before opening the vent valve or making changes to any of the high-pressure helium line connections. Unsafe conditions can be created if the system is vented or the helium lines are disconnected from the compressor or Opus One unit while either internal temperature is much below room temperature.

To warm the system, turn off the compressor. If using a water-cooled compressor, the water cooling can be turned off at this time as well.

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