Description
Cryopump Components (See Figure 3)
Cold Head: Provides the refrigeration necessary to cool the cryopanels.
Cold Head Cylinder: This part of the cold head includes the heat station flanges onto which the
cryopanels are mounted.
First-Stage Cryopanel: Shields the second-stage cryopanel from radiant heat:
Louver: A series of concentric rings that captures water vapor and shields the second-stage
panel from radiant heat.
Mounting Flange: ISO 200 mm, mates the cryopump assembly to the operator's vacuum
chamber.
Nitrogen Purge Port: Nitrogen supply connection for regeneration purge and hazardous gas
dilution.
Pressure Relief Devices: Two types of pressure relief devices, a pressure relief valve or a
rupture disc, are available.
A pressure-relief valve is attached to the vacuum enclosure. The valve is
designed to open and vent gases if the pressure rises to 7 kPa (1 psig).
A rupture disc, instead of a relief valve, is used in an ultra-high vacuum
(UHV) system. The disc will burst if the internal pressure of the cryopump
exceeds 124 kPa (18 psia).
Pumpout Port: Allows the operator to connect a roughing pump to the cryopump for evacuating
the cryopump vacuum enclosure. Close the vacuum valve after the initial evacuation.
Second-Stage Cryopanel: Captures nitrogen, oxygen and argon by solidification on copper
surfaces and captures hydrogen and helium by adsorption in charcoal.
Temperature Sensors: Two types of sensors, encapsulated silicon diode or hydrogen vapor
bulb, are available to measure second-stage temperature. For a cryopump connected to a
Marathon
®
Cryopump Controller, an alternate dual diode is furnished to measure first-stage and
second-stage temperatures.
The silicon diode is encapsulated in a cartridge and the diode wires are
covered with tubing to prevent the diode from becoming an ignition source.
Sensor lead wires exit the vacuum enclosure through a hermetically-sealed
connector so the sensor can be monitored remotely.
The vapor-bulb sensor is filled with hydrogen gas. The pressure gauge,
calibrated in degrees K, monitors the vapor pressure of the gas. The
gauge is mounted locally on the vacuum enclosure. The sensor has
a useful temperature range indication of 14 K to 24 K.
Vacuum Enclosure: Forms the vacuum boundary around the cryopanels.
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