Cryo-Torr Cryopump Description
1-12
P/N 8040613
C
HELIX TECHNOLOGY CORPORATION
-
TI
CRYOGENICS
Theory of Operation
Your Cryo-Torr Cryopump consists of a cold head and a vacuum vessel. An
80K condensing array, a 15K array, cold head station heaters, and an 80K
radiation shield are located in the vacuum vessel. The cold station heaters
and 15K array are secured to the cold head, which is welded to the vacuum
vessel. The cold head provides cooling to the three arrays. Gases are
removed from your vacuum chamber, thereby creating a vacuum when
they are condensed or adsorbed on the cryogenically-cooled arrays.
Cold Head
The cold head consists of a two-stage cold head cylinder (part of the
vacuum vessel) and drive unit displacer assembly, that together produce
closed-cycle refrigeration at temperatures that range from 60 to 120K for
the first-stage cold station to 10 to 20K for the second-stage cold station,
depending on operating conditions. Within the drive unit displacer
assembly, the drive unit actuates the displacer-regenerator assembly
located in the cold head cylinder and thereby controls the flow of helium
into the cold head. Within the drive unit are located the crankcase and drive
motor, which is a direct-drive constant-speed motor, operating at 72 rpm on
60Hz power and 60 rpm on 50 Hz power.
During operation, high pressure helium from the compressor enters the
cold head at the helium supply connector, and flows through the displacer-
regenerator assembly, crankcase, and motor housing before exiting through
the helium gas return connector and returning to the compressor. Helium
expansion in the displacer-regenerator assembly provides cooling at the
first and second stage cold stations.
Vacuum Vessel and Arrays
The 80K condensing array, as shown in Figure 1-3, condenses water and
hydrocarbon vapors. The 15K array condenses nitrogen, oxygen, and argon
while the specially processed charcoal of this array traps helium, hydrogen,
and neon.
