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| * Type B Past Week Summary * Mark and Hirata-san worked at Kamioka, with valuable help from Enzo (on loan from Type Bp team). * We got all the adapter cables for the BF made (Hirata-san did some work on Monday at Mitaka). * We installed the extension for the BF yaw pico on the IM pico adapter cable. * We got all the in-vacuum and in-air cabling for the IM OSEMs done. * We tried to install the stepper and LVDT adapter cables but realized we didn't have enough information on which wires was which. (We later tracked this info down but did not have time to do anything with it - we would have needed to do the rest of the in-vacuum and in-air cabling and set up the stepper motor and LVDT drivers, so we concentrated on the OSEMs.) * We plugged in the IM OSEMs, set gains and offsets, and did a noise test (analysis and klog pending). * We mounted the OSEMs on the IRM and routed the cabling neatly. * We released the suspension. * We adjusted the OSEM mounting plates to center the OSEMs on the flags. * We adjusted the OSEMs in/out to midrange. * The suspension is now ready for OSEM-OSEM TFs! |
=== Type B (Mark) === ==== Past week report ==== At Kamioka (Mark, Fabian, Enzo, Hirata-san): * Inspected LLB in tank - in a good position, but not very clean - apparent water spots and dirt. * Found the geophone adapter plates. * Retested SF FR stepper - still good. * Finally got SF LVDT working: * Found a short in the primary coil due to Al foil used for mechanical reinforcement at vacuum feedthrough connection. * Did a full calibration and found that linear range was too small (0.75 mm!) and did not cover nominal keystone height. * Decreased gain to increase linear range. * Adjusted the height of the yoke and secondary coil unit to center the linear region around the nominal keystone height. * Implemented velocity damping. * Found all parts for the LBB and damper rings. * Cu segments and some other parts were very dirty - wiped carefully for now, but should be properly cleaned before final install. * Outrigger parts for LBB have M16 thread cut directly into Al but should have had M16 helicoils. This is a galling risk with Ag-coated rod receptacles. Hirata-san organized rework. * Some special lock nuts are in short supply and are being borrowed from supply at ATC for next batch of BFs. * Made remaining two geophone in-air descrambler cables (total three). * Installed a thermometer supplied by Kokeyama-san on the tower around the BS tank. * Prepared the SF damper. * Designed a pattern of magnets for the two-segment arrangement of SF damper and laid it out on the magnet ring with the template. * Moved the Cu segments on SF cap by 30° (the cap had not been in the right position earlier). * Reinstalled PI: * Raised the PI with the crane and hooked the SF damper ring. Some of the rods did not fit the receptacles due to tolerance issue, but by going through a large number of rods and receptacles, we found three working sets. * Craned the PI onto the frame and suspended the SF/... section, this time with the hex cable clamp on the F0-SF rod. * Tensioned the PI yaw return spring, installed (but did not cable) the yaw stepper and adjusted the yaw of the SF/... section. We worry the return spring is not stiff enough. * Installed (but did not cable) the geophones. * Recentered the IP. The extra weight from the geophones (≈42 kg) and SF damper ring (≈17 kg) had brought the IP to near the point of instability, so we removed one arc weight (≈17 kg) and rearranged the other two in the top row to be symmetrical. * Added ballast to set the height of the F0 keystone. We now have about 6 kg in hand (due to removing one of the Cu segments for the SF damper). This should be enough margin for cables, temperature fluctuations etc. ==== Plan for coming weeks ==== For more detail, see [[KAGRA/Subgroups/VIS/TypeB/ToDo]]. Weeks of 5/22, 5/29: * Retest SF stepper every day, to see if problems recur. * Find/install geophone adapter plates or improvise replacement. * Reinstall PI, this time with rods and damper ring. * Reinstall PI-SF rod, this time with hex cable clamp. * Cable/test PI geophones LVDTs and steppers. * Reinstall LBB blade units. |
Scraps of text for incorporation in the VIS Meeting Minutes
KAGRA/Subgroups/VIS/MeetingNAOJ
Type B (Mark)
Past week report
At Kamioka (Mark, Fabian, Enzo, Hirata-san):
- Inspected LLB in tank - in a good position, but not very clean - apparent water spots and dirt.
- Found the geophone adapter plates.
- Retested SF FR stepper - still good.
- Finally got SF LVDT working:
- Found a short in the primary coil due to Al foil used for mechanical reinforcement at vacuum feedthrough connection.
- Did a full calibration and found that linear range was too small (0.75 mm!) and did not cover nominal keystone height.
- Decreased gain to increase linear range.
- Adjusted the height of the yoke and secondary coil unit to center the linear region around the nominal keystone height.
- Implemented velocity damping.
- Found all parts for the LBB and damper rings.
- Cu segments and some other parts were very dirty - wiped carefully for now, but should be properly cleaned before final install.
- Outrigger parts for LBB have M16 thread cut directly into Al but should have had M16 helicoils. This is a galling risk with Ag-coated rod receptacles. Hirata-san organized rework.
- Some special lock nuts are in short supply and are being borrowed from supply at ATC for next batch of BFs.
- Made remaining two geophone in-air descrambler cables (total three).
- Installed a thermometer supplied by Kokeyama-san on the tower around the BS tank.
- Prepared the SF damper.
- Designed a pattern of magnets for the two-segment arrangement of SF damper and laid it out on the magnet ring with the template.
- Moved the Cu segments on SF cap by 30° (the cap had not been in the right position earlier).
- Reinstalled PI:
- Raised the PI with the crane and hooked the SF damper ring. Some of the rods did not fit the receptacles due to tolerance issue, but by going through a large number of rods and receptacles, we found three working sets.
- Craned the PI onto the frame and suspended the SF/... section, this time with the hex cable clamp on the F0-SF rod.
- Tensioned the PI yaw return spring, installed (but did not cable) the yaw stepper and adjusted the yaw of the SF/... section. We worry the return spring is not stiff enough.
- Installed (but did not cable) the geophones.
- Recentered the IP. The extra weight from the geophones (≈42 kg) and SF damper ring (≈17 kg) had brought the IP to near the point of instability, so we removed one arc weight (≈17 kg) and rearranged the other two in the top row to be symmetrical.
- Added ballast to set the height of the F0 keystone. We now have about 6 kg in hand (due to removing one of the Cu segments for the SF damper). This should be enough margin for cables, temperature fluctuations etc.
Plan for coming weeks
For more detail, see KAGRA/Subgroups/VIS/TypeB/ToDo.
Weeks of 5/22, 5/29:
- Retest SF stepper every day, to see if problems recur.
- Find/install geophone adapter plates or improvise replacement.
- Reinstall PI, this time with rods and damper ring.
- Reinstall PI-SF rod, this time with hex cable clamp.
- Cable/test PI geophones LVDTs and steppers.
- Reinstall LBB blade units.