4 System Operation
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 the power to the compressor and the electronics unit and contact
Quantum Opus for additional help.
B
WARNING
Whenever using a vacuum pump to evacuate a system, ensure there is adequate “slack”
in the pumping line to allow for line contraction (sometimes very significant) during
pumping. Inadequate line length can cause unsafe forces on the pump, pumping lines,
or Opus One unit and can cause equipment to be damaged or to move in undesired
ways (e.g., tip over, fall off of shelving).
B
4.1 Cool Down Procedure
The procedures in this chapter should be accomplished for first-time operation and repeated any
time that the system has been allowed to warm to a point at which both stages are above 50
Kelvin, for example in case of accidental 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 should be achieved within 12 hours after the system
has been powered off. For the system warm-up procedure, see Section
i
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.
i
WARNING
When closing the green vacuum valve (labeled “Valve”) on the rear of the Opus One
unit, do not overtighten. This valve should be closed only until finger tight. Never use
B
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