Cryostat penetrations and services inside the cryostat Bo
Cryostat penetrations and services inside the cryostat Bo Yu July 17, 2018 Cold Electronics Workshop 2018 1
Outline • FD cryostat port layout • CE/PD feedthrough configuration • Crossing tube cable support design • APA top cable tray designs Acknowledgement • Thanks to Manhong for providing most of the models and slides. 2
Layout of the cryostat penetrations https: //edms. cern. ch/file/1834561/1/LBNF_SP_Penetrations_and_Outer_Structure. pdf The warm structure is 1. 1 m above the cryostat top plate. Penetrations for the CE/PD cables run at 1. 6 m pitch, while the APAs are at 2. 32 m pitch. So the relative position between an APA and its cable 3 penetration ports could vary +/- half APA width.
Layout of the cryostat penetrations 4
CE/PD Feedthrough Flanges and the Cross Pipe Each CE flange serves one APA (20 data and power cables), and 8 SHV connections for the APA wires and field cage terminations. The current PD signal feedthrough flange design can accommodate 20 PD cables (CAT 6, 4 pairs). 5
Proto. DUNE CE/PD Port Crossing Tube Imposed Requirement: Do not touch the thin crossing tube. Proto. DUNE experience: OD: 250 mm ID: 230 mm The crossing tube bottom openings may not be quite circular. 6
Crossing Tube Cable (CTC) Support Structure Tube alignment screws • Support the weight of the cables down to the cable tray on the APA Inner tube confines contaminates GAr Flow • Prevent back diffusion of outgassing impurities from the cables down to the LAr Cryostat crossing tube Inner tube 203 mm (8 in OD) Tip angle of the crossing tube and flange flatness are irrelevant CE cables PD cables Clamp plate 13. 5 mm GAP (SPARE) 7
Penetration Cabling Plan PD cable bundle 8 PD cables 25 mm Assume 3 bundles (4 spare cables) CE cable bundle 8 CE data/power cables 44 mm Assume 6 cable bundles (8 Spare Power and data cables) If the cable bundle is too large, the cables in the center of bundle could slip. 8
Improve the design • Proto. DUNE lessons learned: • Working on cables with the proto. DUNE CTC was difficult. • Extra personnel were needed and risky work around the APAs. • CTC cable strain relief needs updating to make it less arduous to install. Keep small hardware to a minimum. Replace the M 4 thumb screws with socket head cap screws • Will revisit the Proto. DUNE design to simplify its cable strain-relief structure (double clamping plates) without compromising the gas flow pattern (CFD analysis) • Plan for specially tools (tripod with a powered hoist, custom cable harnes? ) to assist the pulling of the cables through the penetrations. 9
DUNE Cable Feedthrough (11 -7 -2017) The middle APA to FT distance was 0. 8 m then. Now they are all 0. 4 m. 10
400 mm 660 mm 11
800 mm 400 mm 660 mm 12
Cable length: >21. 4 m 2. 5 m 1. 2 m 0. 8 m 13 m 2 m 13 m 1. 2 m 13
Current Design Proto. DUNE experiences show impact to the APA perpendicularity with unbalanced cable load. Situation could get worse for two APAs with a joint in between. Plan to include a continuous cable tray under the signal feedthrough penetrations to help balance the cable load on the APAs, and/or to store the excess cables. Do we need to transfer the load of the cable trays to the DSS beam? 4% ullage (560 mm from ceiling) 12” tray 8” tray 78 mm Field cage latch Field cage Depth of the corrugation (70 mm) 14
Mockup and trial runs of cable routing • PD cables: Ø 10 PD cables/APA – 12 PD cables on the APA with the ARAPUCA module Ø ~1. 5 days of cabling work Ø 2 people • DUNE FD will have double the cable volume compared to Proto. DUNE, and needs to be manipulated at twice the height. • CE cables: Ø 20 data and 20 power cables/APA • Available space on the cable trays on the upper APA is Ø ~2. 5 - 3 days of cabling work Ø ~2 days of dressing cables if you have for very limited. some reason to redo cabling Ø 2 people • The weight of the CE cables alone, that needs to be Lessons learned from Proto. DUNE pulled through the penetration is nearly 100 lbs. • A realistic mockup of the cryostat top to develop and practice cable arrangement procedures is necessary. • A full scale mockup of the APAs with full cable routing will also help define a more accurate cable length. 15
Summary • CERN has finalized the layout of the cryostat ports. The relative positions between the APAs and its penetrations are known. • The crossing tube cable support structure for Proto. DUNE will be further developed to support doubling of the cable volume and simplified to improve the ease of cable installation. • Concepts for the APA cable trays exist. They need to be further developed and mocked up in sufficient details to help validate the design. 16
- Slides: 16