LHC Beam Screen Heaters: System overview, consolidation needs and project planning 4 February TE-CRG/JCC (Beam Screen Heater Review) 1

System Overview: instrumentation distributed all around the tunnel 2

4 February TE-CRG/JCC (Beam Screen Heater Review) System Overview: instrumentation distributed all around the tunnel 3 Instrumentation in operation since well before All individual components have been qualified for the expected conditions, examples: Temperature sensors: 1.8 K, thermal cycling, etc. Pressure sensors: radiation and thermal cycling Active and passive electronic components: radiation & thermal cycling …

4 February TE-CRG/JCC (Beam Screen Heater Review) System Overview: Cryo-Tunnel Electronics 4 RADIATION Individual Components have been qualified for the LHC tunnel conditions Cards and complete crate radiation tolerant design has been verified in CNGS THERMAL DESIGN No active ventilation to increase reliability Validated by simulation in worst operating conditions OVERALL Survived with no damage 2008 LHC accident Unique accuracy for temperature measurements System is presently operational

4 February TE-CRG/JCC (Beam Screen Heater Review) System Overview: Beam Screen cryogenic Hardware 5 Heating cartridge is removable. Heating element: 100 ohm resistor Overheat protection: Type J Most delicate neighbour: current leads thermalization. Photos: LHC interconnects.

4 February TE-CRG/JCC (Beam Screen Heater Review) Consolidation : Reason for change 6 Cards presently deployed are capable of providing 25 W of heating power on the 100 ohm resistor of the beam screen heater. Consolidation requires to provide 200 W of heating capacity to regenerate the LHC beam screen by desorption of gas trapped on its walls. The LHC tunnel cards used by the cryogenic system provide power as follows 0-25 W: variable dc voltage W: Pulse Width Modulation (PWM) of grid voltage by using a solid state switch Card capable of supplying 200 W is not compatible with the LHC radiation environment, even if the range W is not used while there is circulating beam.  New card compatible with LHC background radiation, MOS switch and drive CNGS  Comply with additional heater protection mechanism: manual restart on either power-up or interlock The heater cartridge is designed for 500 W and is not concerned by this consolidation.

4 February TE-CRG/JCC (Beam Screen Heater Review) Consolidation Needs: Proposal 7 ParameterPresent designConsolidated design AC supplyThrough backplane (230 Vac)Independent supply (230 Vac and lower) Interlock ONENABLED when protection temperature (TP) exceeds HIGH threshold or sensor is disconnected ENABLED at start-up, at reset, when TP exceeds HIGH threshold (SOFT & HARD), or sensor is disconnected Interlock ONDISABLED automatically when TP is below LOW threshold DISABLED by manual operator request ONLY AC power controlNon RadTol (Switch degraded by TID)RadTol (validated in CNRAD) AC switchingZero crossingZero crossing, Peak or random Protection sensorthermocoupleThermocouple and resistive sensor PCB track protectionNoneFuse Power MonitorDc mode onlyAc and dc modes The new card shall be based & installed on the existing equipment Any new component shall go through a qualification campaign New ac switch for the range W The circuit schematics and main components for supplying the range W are finalized The components have been qualified in the CNRAD for up to 700 Gy Additional tests foreseen to confirm RadTol requirements

4 February TE-CRG/JCC (Beam Screen Heater Review) Beam Screen Heaters: Cost 8 The cost is not only due to the manufacturing of the electronics but also: 1.Step-down transformer: required to reduce the maximum power that can be applied onto the beam screen heaters 2.Separate power supply (e.g. new cables and mains switch): past experience suggest that this is a useful feature in order not to stop the functioning of a full crate in case of electrical failure of the heater element. 3.QA: testing with automated test bench add a task to existing manpower Electronics cost has been impacted by significant price increase of anti-fuse FPGAs manufactured by ACTEL: unit price for similar order quantities: USD in 2008 versus USD in However FPGA count per card is reduced from 4 to 2 or 1. Profit to overhaul: 500 W return module heaters that may be affected by SEU (25 cards) 100 W “high” dc current that presently use 2 channels in parallel (32 cards)

4 February TE-CRG/JCC (Beam Screen Heater Review) Beam Screen Heaters: Schedule 9 Card design require the validation of a few prototypes ideally operated in real conditions Some components may require very long delivery delays example 2007: 26 weeks delay for the ADS7807UB ADC => order ASAP Assume: PCB design, PCB manufacture & PCB/card assembly by TE-MPE-EM Punctual help for consolidating the automated test bench LabView code (BE-CO-HT) Presented schedule is the “fastest”, longer prototype testing is preferable => ordering of cards series to be delayed as permitted by LS1 schedule