Camera Maintenance and Access Martin Nordby, Kevin Reil August, 2017 R2

Introduction Goals of the session Review camera maintenance access use cases Agree on access regions and use cases for camera operations and maintenance Develop first-cut list of access and recovery processes based on designs of TMA, GIS, and dome access control—with a goal of using these to set durations for maintenance tasks The camera is somewhat unique in that maintaining almost any part of the camera likely affects other parts of the system and may prevent other operations from taking place Defining these incompatibilities is important for understanding commissioning and operations time available for various maintenance activities However, this will be much easier once we have a better idea of the steps needed to perform the various maintenance activities For this exercise, I’ve defined a “use case” as: A grouping of activities that all require the same access, contamination control, and general personnel support Sets of activities that can all be accomplished by way of the same access, contamination control, and general personnel support Camera Systems Integration

Camera assembly and access regions Back flange bay covers Access to: -Carousel power and control electronics -Filter loader connect point -Auto changer and shutter interconnects -Purge ducting Camera has been designed with servicing plans in mind Portholes for access into camera volume Access to: -Carousel clamps -Cryostat housing -Carousel rotating assy Utility Trunk Filter loader mount and access hatch Access to: -Auto changer rails Shroud panels allow for access into camera front flange Access to: -Auto changer -Shutter -L2-S2 and L3-S1 -Purge ducting UT sliding doors in accessible region through hexapod Access to: -Cam electronics -Cam Vol Purge cabinet Back flange L1-L2 Assembly Camera housing Shroud Camera Systems Integration

Partially assembled camera with panels removed Open region to allow for removal of auto changer unit while on the telescope Parts of carousel visible through open porthole Shroud panels removed, showing longerons and L1-L2 interface rings Camera Systems Integration

On-camera maintenance use cases These are described in LCA-282, Camera Operations Concept Document Access/Secure Camera Body Stage equipment on platforms on for maintenance work Mount clean tent, remove shroud panels Prepare for accessing front flange mechanisms and optics inside camera Maintain Mechanisms Troubleshoot and service shutter: check belt tension, H-E switches, E-box and controls, etc. Troubleshoot and service auto changer: check clamps, motors, lubricate ball screws, etc Remove porthole covers to service carousel clamps Remove/Replace Mechanisms Replace auto changer unit Replace shutter Inspect Components in Camera Body Inspect and align L1-L2 struts Inspect and clean L2-S2 and L3-S1 Access Front of Camera Inspect, clean L1-S1 Mount/de-mount L1 lens cover Mount/de-mount SMRs Camera Systems Integration

On-camera maintenance use cases (cont.) Swap Out Filter Install empty filter loader to remove filter Install loaded filter loader to install new filter Access Back Flange Remove bay covers Access carousel components, cabling, purge lines Lubricate carousel ring gear, replace motor, brakes, unclamp motors, electronics components Check torque on camera—rotator mounting screws Access/Secure Utility Trunk Prepare to open UT: install auxiliary blower unit, clean UT outside Open UT doors Replace Component in Utility Trunk Replace auxiliary electronics components Replace Camera Volume Purge cabinet filters Service, Leak Check Vacuum Systems Crane in pump cart and equipment Pump cryostat, Heat-X vacuums Leak check cryostat seals Camera Systems Integration

Refrigeration use cases Access and service compressor cabinets Evacuate, purge, charge refrigeration circuit Check and service compressor units: oil levels, refrigerant charge, etc. Service refrigeration lines from top end isolation valves at CCW Evacuate refrigeration circuit Purge circuit during disconnect Service refrigeration lines at bulkhead plate Mate/de-mate refrigeration connections Leak check refrigeration connections Camera Systems Integration

Questions and issues to address and consider What capabilities do we have for staging equipment on the floor and sub-floor for later maintenance? What are expected times for crane lifts from TMA floor and lower enclosure to camera? How can we access relief valves outside of CCW on the top end? How do we access the bulkhead plate; is this considered a confined space? Some of these use cases require exclusive control of certain resources—crane, azimuth and azimuth drives, rotator/hexapod drives, L1/M1 region As we further define use cases, this needs to be captured, since it will affect our ability to do maintenance in the dome Camera Systems Integration

Regions needing access for camera maintenance Dome floor Sub-floor for refrig compressor cabinet servicing Camera maintenance platforms (for UT maintenance and filter loading) Camera platforms and scaffolding (for in-camera maintenance) Isolation valves near CCW on TEA Bulkhead plate inside TEA Questions What needs to happen to provide safe access to these regions, starting from when the operator takes the last image of the night? What are expected procedures and rough timing for dome search and close-up after an access? What are expected procedures and rough timing for sub-floor search and close-up after an access? What needs to happen to recover from in-camera maintenance? Camera Systems Integration

Installing and removing the camera and integrating structure The camera is largely a self-contained system that will be tested and verified prior to mounting to the telescope However, some key systems need further assembly and testing during and after the process of integrating to the telescope Refrigeration system interconnection and commissioning Dynalene system interconnection and commissioning DAQ connectivity and throughput testing For the refrigeration system, in particular, this is expected to take some time—estimates based on the most recent prototyping and process control demonstrations: 15 additional shifts needed for refrigeration system activities during Camera/IS assembly and installation on the telescope 3 additional shifts needed for refrigeration system activities when removing the Camera/IS, if the system does not need to be operated on the ground Likely applicable for M2 mirror re-coating 8 additional shifts needed for refrigeration system activities when removing the Camera/IS, if the system will be operated on the ground These dates need further scrubbing, and include the following caveats: This assumes that the refrig pathfinder has already proved out performance of the compressor chasses and allowed for cleaning and drying of the lines running up the TMA Much of this work requires exclusive access to the TMA and sub-floor regions, with the TMA locked out Camera Systems Integration

Refrigeration integration and testing during Camera/IS install Mount camera to Integrating Structure (on the ground) Interconnect camera and CCW refrig lines at bulkhead plate – 3 days Assumes camera refrig system parts have already been pressure/leak checked and cleaned Purge during installation from isolation valves Leak check connections from isolation valves Mount Integrating Structure/Camera assembly on TMA Interconnect TMA and CCW refrig lines at isolation valves – 3 days Purge through isolation valve port from compressor cabinets Leak check Complete system leak check – 2 days Dry out entire refrig circuit including evaporators – 4 days 8 systems simultaneously, as long as we have enough dry nitrogen flow Process will take longer if boil-off nitrogen isn’t available May take less time than initial dry down if everything has been kept clean Evacuate 2 cold and 6 cryo circuits – 2 days (8 systems simultaneously) Charge 2 cold and 6 cryo systems – 1 day (one person handling one system at a time) System is ready for cooldown Camera Systems Integration

Refrigeration preparations during Camera/IS removal Option 1: Camera is removed and set aside, with no plans to run the system Total duration of refrig work: 3 shifts Close CCW isolation valves and recover refrigerant from valve tee – 2 days (one system at a time) Disconnect lines at CCW isolation valve while under purge, capping disconnected lines – 1 day Option 2: Camera is removed to be run in the white room Total duration of refrig work: 8 shifts Recover/collect charge while camera is in the process of warming up – 1 day (all systems simultaneously) Backfill with nitrogen from compressor cabinets – 1 day Disconnect lines at CCW isolation valve while under nitrogen purge, capping disconnected lines – 1 day De-mount IS/Camera Assembly from telescope Disconnect lines at bulkhead plate while purging from isolation valves – 1 day Remove Camera from Integrating Structure and mount to Stand Connect to maintenance system umbilical lines – 1 day Assumes that maintenance system lines are in a clean, dry, leak-tight state. Maintenance system lines up to the isolation valves can be pre-evacuated. Leak check from compressor cabinets in maintenance area – 1 day Evacuate evaporator side of plumbing up to isolation valves – 1 day Charge 2 cold and 6 cryo systems – 1 day (one person handling one system at a time) System is ready for cooldown Camera Systems Integration