Dual shaft stepper
motor with electromechanical brake (clutch plate and rotor at right).
Assembled, this system is used to position the camera block, through
the THK screw rail, and lock it in place.
Motor and brake/clutch
Closing up Mimir
cryostat for second cooldown. Note temperature units and vacuum
unit mounted in electronics rack.
The cold shield
/ light cover that surrounds the cold space inside the cryostat
has been attached to the cold bulkhead. A temperature sensing diode
is attached to the back of the cold shield to measure temperature
gradients along the cold shield from the cold bulkhead.
Front view of
cryostat being closed up for the second cold test. Just beyond the
cold shield, the green G10 shell supporting the 120 layers of MLI
inside the cryostat shell can be seen. This G10 shell rests on the
cold shield and against the warm bulkhead, forming a thermal barrier
to warm IR radiation from the cryostat shell.
Side view of
front, showing temperature sensor cabling. Also note that the LN2
precool loop stainless steel baffle hoses have been MLI wrapped to
reduce LN2 boiling before entry to the cold bulkhead.
A new, thin G10
layer surrounds the central G10 collar and many layers of MLI have
been attached to the new G10 layer to act as a radiation shield to
prevent warm IR photons from the backside of the warm bulkhead from
hitting the cold bulkhead.
Zoom detail of
temperature sensor placement on back of cold shield.
of same placement.
and Kris Makrides puzzling over one of the electronics unit manuals.
reading N2 flowmeter during cooldown
LN2 storage dewar
connected to Mimir LN2 inlet. Notice the much shortened line and the
increased thickness of insulation applied.
during the second cold test. Electronics units in electronics rack,
new sensor location cartoon above them. Cryostat shell still wrapped
in heater tape and surrounded by aluminum foil.
Top detail showing
turbo pump connected to mech (oil) pump located outside the clean
continuing to read manuals as Mimir cools.
Side view from
outside clean room during cooldown.
cooldown. Vacuum gauge reads about 6x10^-6 torr. A sensor of temperature
controller (at right) shows 83K at the LN2 inlet and 262K at the outlet.
temperature sensors locations on LN2 baffled hose inside cryostat.