Detects small traces of impurities in a vacuum environment down
to parts per million resolution.
Operates in vacuums down to the 10-12 torr range.
Used to identify which elements and compounds are still
present.
Gives data about partial pressures as a function of atomic
masses.
Useful for leak detection using helium or isopropyl alcohol.
Thermal Vacuum Testing Sequence
Turbo Pump System
Turbo Pump Sequence of Operation
Cryo Pump System
Cryo Pump Sequence of Operation
Types of T-VAC Tests
Bakeout
Cleaning hardware by raising its temperature
Thermal Cycling
Subjecting hardware to multiple temperature swings
Thermal Balances
Setting the vacuum chamber to a fixed temperature and allowing the hardware to reach thermal
equilibrium
Turbo Pump Sequence of Operation
Please refer to the video above for a visual representation of the turbo pump operation
sequence:
The thermal vacuum system is off.
The roughing pump is started and begins to evacuate the
plumbing
up to the roughing and foreline valves.
The ballast valve is opened to purge the roughing pump with
nitrogen to keep it dry.
The roughing valve is opened which connects the vacuum
chamber to the roughing pump. The chamber pressure starts to drop rapidly.
The roughing valve is closed once the pressure in the
chamber reaches equilibrium
The vent valve is opened to "backfill" the chamber with
nitrogen, usually 300-600 torr. This makes it easier to pump the chamber to lower
pressure on subsequent cycles.
The vent valve is closed once the nitrogen levels in the
chamber are between 300-600 torr.
The roughing/venting cycles (steps 4-7) are repeated until
the final chamber pressure is low enough to switch to the high vacuum pump (turbo).
The foreline valve is opened to evacuate the plumbing
connected to the turbo pump.
The turbo pump is then turned on. It takes a few minutes
for it to speed up to its maximum speed.
The high-vac valve is opened which connects the vacuum
chamber to the turbo pump. The chamber pressure will rapidly decrease as molecules
travel through the turbo pump and are then pumped out with the roughing pump.
Cryo Pump Sequence of Operation
Please refer to the video above for a visual representation of the cryo pump operation
sequence:
The thermal vacuum system is off.
The roughing pump is started and begins to evacuate the
plumbing up to the roughing and regeneration valves.
The ballast valve is opened to purge the roughing pump
with nitrogen to keep it dry.
The purge valve is opened to fill the cryo pump with
nitrogen to push out any contaminants that were collected on the previous test.
The purge valve is closed once the cryo pump has been
flushed with nitrogen for sufficient time.
The regeneration valve is opened which connects the cryopump
to the roughing pump. This will pump the recently purged nitrogen out of the cryo
pump.
The regeneration valve is closed once sufficient pressure is
reached in the cryo pump.
The purge/regeneration cycles (steps 4-7) are repeated until
the cryo pump pressure does not rise more than 10 milli-torr per minute when the
regeneration valve is closed.
The cryo pump is turned on and it begins to cool. It
takes around two hours
for it to reach its final temperature.
The roughing valve is opened which connects the vacuum
chamber to the roughing pump. The chamber pressure starts to drop rapidly.
The roughing valve is closed once the pressure in the
chamber reaches equilibrium.
The vent valve is opened to "backfill" the chamber
with nitrogen, usually 300-600 torr. This makes it easier to pump the chamber to lower
pressure on subsequent cycles.
The vent valve is closed once the nitrogen levels in
the chamber are between 300-600 torr.
The roughing/venting cycles (steps 10-13) are repeated
until the final chamber pressure is low enough to switch to the high vacuum pump
(cryo).
The high-vac valve is opened which connects the vacuum
chamber to the cryo pump. The chamber pressure will rapidly decrease as molecules
are trapped and frozen inside the cryo pump.
The roughing pump is turned off as it will not be
needed for the remainder of the test.
The ballast valve is closed as it will not be
needed since the roughing pump is off.
