Linac Helium distribution ESS Helium Distribution 2013 01

Linac – Helium distribution ESS | Helium Distribution | 2013 -01 -09 | Torsten Koettig 1

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 ESS | Helium Distribution | 2013 -01 -09 | Torsten Koettig 2

Relevant parameters to be frozen Circuit Thermal radiation shield Supercritical helium supply VLP helium return Coupler cooling Temperatures in K Pressure in bar(a) 40 – 50 19. 5 – 19 4. 5 3 4 0. 031 4. 6 – 150 (300) <1. 5 ESS | Helium Distribution | 2013 -01 -09 | Torsten Koettig 3

Helium inventory of the Linac is 12 m 3 liquid Cryoplant flow scheme LHe tank at 1. 2 bar GHe storage at 19 bar • Helium inventory storage • Cold box 1 – 4. 5 K SC helium supply • Cold box 2 – Hybrid subcooling unit 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 Cold box 1 4. 5 K & 40 K ESS | Helium Distribution | 2013 -01 -09 | supply Torsten Koettig 4

Helium inventory and storage concept Helium inventory Equipment Helium content in liter LHe equ. Spokes CM 14 x 104 = 1456 Elliptical medium-β CM 15 x 150 = 2250 Elliptical high-β CM 30 x 197 = 5910 SC He supply line 80 mm 0. 89 x 2262 = 2010 Thermal shield supply 0. 15 x 1272 = 195 Thermal shield return 0. 12 x 1272 = 153 Total Linac + CTL 12, 000 Storage sizes 4 m 10 - 15 m 6 -8 gaseous He tanks @ 20 bar + 1 liquid helium tank 20 m 3 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 ESS | Helium Distribution | 2013 -01 -09 | Torsten Koettig 5

HP warm line Purge return line LP return line 300 K ≤ 20 bar 300 K ≤ 1. 05 bar 300 to 5 K - 1. 05 bar Thermal shield supply Thermal shield return SC helium supply Helium return Helium VLP return 40 K 50 K 4. 5 K 8 K 4 K - 19. 5 bar - 19 bar - 3 bar - 1. 2 bar - 30 mbar Valve box in CTL incl. vacuum barrier Jumper connection CM He II cooled cavities Coupler cooling return 300 K - 1. 05 bar ESS | Helium Distribution | 2013 -01 -09 | Torsten Koettig 6

Tunnel integration - location of vacuum barrier Flow scheme Distance to cold valve bodies necessary ESS | Helium Distribution | 2013 -01 -09 | Torsten Koettig 7

Cavity circuit in a log p-h-diagram (a) Δh=20 J/g 2. 0 K He II bath ESS | Helium Distribution | 2013 -01 -09 | Torsten Koettig 8

Pressure drop & heat load analysis • Tbath=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 ESS | Helium Distribution | 2013 -01 -09 | Torsten Koettig 9

SC helium supply line – normal operation Possible solutions: • Increase flow in SC He supply line • Integrate a phase separator/subcooler in front of the 2 K HEX d= 80 mm Input: q. TL= 0. 2 W/m q. JC= 0. 2 W/m LJC = 4 m Qvalves = 1 W QVac. Bar. =1 W Warm Linac Spokes Medium Beta High Beta CP ESS | Helium Distribution | 2013 -01 -09 | Torsten Koettig 10

Principle proposal– Phase separator He sat. vapor 1. 4 bara (a) • 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/dtsubcooler= 2 -3 * dm/dtcoupler) ESS | Helium Distribution | 2013 -01 -09 | Torsten Koettig 11

SC helium supply line option II - Subcooler in front of 2 K - HEX Total=>116. 5 g/s Warm Linac Spokes Medium Beta High Beta CP ESS | Helium Distribution | 2013 -01 -09 | Torsten Koettig 12

Pressure drop analysis • Tbath=2. 0 K at saturation pressure of 31. 3 mbar(a) • Precooling of the inlet SC-Helium flow to 2. 2 K (a) 2. 0 K He II bath ESS | Helium Distribution | 2013 -01 -09 | Torsten Koettig 13

VLP return line Accumulated heat load and pressure drop along the Linac 2250 1. 4 2000 d= 260 mm 1750 1 1500 1250 0. 8 1000 0. 6 750 Pressure drop in mbar Heat load at distance in W 1. 2 0. 4 500 0. 2 250 0 Warm Linac 50 Spokes 100 150 200 250 300 Distance along the LINAC in m Medium Beta High Beta 350 400 450 CP ESS | Helium Distribution | 2013 -01 -09 | Torsten Koettig 14

VLP return line - pipe diameter Pressure drop vs. VLP return pipe diameter 5 4. 5 Pressure drop along Linac in mbar 4 3. 5 3 2. 5 2 1. 5 1 0. 5 0 200 220 240 260 Diameter - gas return pipe in mm 280 300 ESS | Helium Distribution | 2013 -01 -09 | Torsten Koettig 15

Critical procedures – cool-down Example is for medium-beta elliptical cavities, ∆THe=30 K => 3 days cool down time to 40 K ESS | Helium Distribution | 2013 -01 -09 | Torsten Koettig 16

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 ESS | Helium Distribution | 2013 -01 -09 | Torsten Koettig 17

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 ESS | Helium Distribution | 2013 -01 -09 | Torsten Koettig 18