6. If a leak detector is accessible, use it to leak check the sample housing, cryostat, vacuum hose,
vacuum connections to find the source of the leak.
If the leak persists, please contact an authorized service representative.
There is enough charcoal in the system to freeze particles that may be introduced from a small leak. If
there has been a large leak, or if a small leak persists over a period of time, the charcoal adsorbers will
need to be recharged. To do this, run a COOLDOWN or PULL VACUUM operation with PLATFORM BAKEOUT
(350 K for 60+ mins) and DRY NITROGEN PURGE (3+ times) enabled.
7.3.4 Helium Check
The helium pressure in the system can be checked when the compressor is idle.
1. Warm the system to room temperature and leave unattended for at least one hour. Do not start
a cooldown.
2. Ensure the power on the back of the unit is ON ( | ) and the ENABLE switch on the front panel is
ON ( | ).
3. In the UI, navigate to the OVERVIEW display screen, then press the CRYOCOOLER reading to show
compressor details.
a. Or, on the front panel of the compressor, toggle the DISPLAY button until it shows the
supply and return values.
4. The values should be between 1.55 – 1.80 MPa on both the supply and return. If the supply or
return values are <1.55 MPa, helium will need to be recharged. See Helium Recharge Process on
page 65 for details.
Helium Hose Fittings
Improper attachment or missing O-rings on the helium hose fittings can cause a loss in helium pressure
and hinder cooling performance.
To inspect fittings on the back of the compressor and cryostat:
• Ensure the fittings are straight.
• Ensure there is a single O-ring at each end of the hose and at each connection point. The O-
rings have a tendency to dislodge from the hose and stay on the fitting (or vice versa).
o If this happens, the errant O-ring must be carefully removed and replaced in the correct
location before reconnecting, otherwise it will not seat properly.
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