ESS | Helium Distribution | | Torsten Koettig Linac – Helium distribution 1

ESS | Helium Distribution | | Torsten Koettig Content Layout of the cryogenic distribution system Parameters relevant to cryogenics Helium flow scheme interface to CMs Cryoplant and helium storage Pressure drop analysis – cryo transfer line 2

ESS | Helium Distribution | | Torsten Koettig Relevant parameters to be frozen CircuitTemperatures in KPressure in bar(a) Thermal radiation shield40 – – 19 Supercritical helium supply4.53 VLP helium return Coupler cooling4.6 – 150 (300)<1.5 3

ESS | Helium Distribution | | Torsten Koettig Helium inventory storage Cold box 1 – 4.5 K SC helium supply Cold box 2 – Hybrid subcooling unit Cryoplant flow scheme Cold box 2 hosting the sub-atmospheric cold compressors (two) Cold box 2 contains the acceptance test unit at 2.0 K and 45 K Helium inventory of the Linac is 12 m 3 liquid LHe tank at 1.2 bar GHe storage at 19 bar Cold box K & 40 K supply 4

ESS | Helium Distribution | | Torsten Koettig Helium inventory and storage concept Storage sizesHelium inventory EquipmentHelium content in liter LHe equ. Spokes CM14 x 104 = 1456 Elliptical medium-β CM15 x 150 = 2250 Elliptical high-β CM30 x 197 = 5910 SC He supply line 80 mm0.89 x 2262 = 2010 Thermal shield supply0.15 x 1272 = 195 Thermal shield return0.12 x 1272 = 153 Total Linac + CTL12, m 4 m 5 Helium purchase strategy: 2 contractors with different origin of He gas Closed cycles 25% losses / year Open cycles maybe up to 50% / year Start purchasing proc. At least 1 year in advance 6-8 gaseous He 20 bar + 1 liquid helium tank 20m 3

ESS | Helium Distribution | | Torsten Koettig Thermal shield supply40 K bar Thermal shield return 50 K - 19 bar SC helium supply4.5 K - 3 bar Helium return8 K- 1.2 bar Helium VLP return 4 K- 30 mbar HP warm line300 K ≤ 20 bar Purge return line300 K ≤ 1.05 bar LP return line300 to 5 K bar Valve box in CTL incl. vacuum barrier Jumper connection CMHe II cooled cavities Coupler cooling return 300 K bar 6

ESS | Helium Distribution | | Torsten Koettig Flow scheme Tunnel integration - location of vacuum barrier 7 Distance to cold valve bodies necessary

ESS | Helium Distribution | | Torsten Koettig Cavity circuit in a log p-h-diagram Δh=20 J/g 2.0 K He II bath (a) 8

ESS | Helium Distribution | | Torsten Koettig Pressure drop & heat load analysis T bath =2.0 K at saturation pressure of 31.3 mbar(a) Precooling of the inlet SC-Helium flow to 2.2 K 2.0 K He II bath 9

ESS | Helium Distribution | | Torsten Koettig SC helium supply line – normal operation Possible solutions: Increase flow in SC He supply line Integrate a phase separator/subcooler in front of the 2K HEX d= 80 mm 10 Input: q TL = 0.2 W/m q JC = 0.2 W/m L JC = 4 m Q valves = 1 W Q VacBar. =1 W Warm Linac Spokes Medium Beta High Beta CP

ESS | Helium Distribution | | Torsten Koettig Principle proposal– Phase separator Temperature of the incoming flow varies from 4.6 K to 5.3 K along the CTL Subcooler e.g. to 1.4 bara saturation condition, use of the vapor to cool the couplers (mismatch => dm/dt subcooler = 2-3 * dm/dt coupler ) (a) 11 He sat. vapor 1.4 bara

ESS | Helium Distribution | | Torsten Koettig SC helium supply line option II - Subcooler Subcooler in front of 2 K - HEX Total=>116.5 g/s 12 Warm Linac Spokes Medium Beta High Beta CP

ESS | Helium Distribution | | Torsten Koettig Pressure drop analysis T bath =2.0 K at saturation pressure of 31.3 mbar(a) Precooling of the inlet SC-Helium flow to 2.2 K 2.0 K He II bath (a) 13

ESS | Helium Distribution | | Torsten Koettig VLP return line d= 260 mm Warm Linac Spokes Medium Beta High Beta CP 14

ESS | Helium Distribution | | Torsten Koettig VLP return line - pipe diameter 15

ESS | Helium Distribution | | Torsten Koettig Critical procedures – cool-down Example is for medium-beta elliptical cavities, ∆T He =30 K => 3 days cool down time to 40 K 16

ESS | Helium Distribution | | Torsten Koettig Safety equipment strategies Pressure test of the CM at 1.43 x MAWP 1.43 x 1.5 bara= 2.15 bara 2 stages and 2 conditions for safety equipment: LHC-CM set-up for 4.2 K: SV warm conditions at 1.5 bara SV cold liquid cond. at 1.8 bara RD at 2.1 bara 17

ESS | Helium Distribution | | Torsten Koettig Summary Design of the Linac cryogenic transfer line => 450 m Segmented CMs with individual jumper connection, exchangeable at cold Linac conditions Helium circuits for cavities, thermal shield, heat intercepts and coupler cooling Helium inventory and storage concept Pressure drop calculations for CTL Question for discussion: Location of the vacuum barrier in the jumper connection Phase separator => vapor flow to power couplers Safety equipment of the cavity circuit 18