BriXS – MariX WG 8,9 LASA December 13, 2017

Reference machines Three families of SC cavities could be foreseen BriXS cavities: zero beam-loading, high-current, heavily damped HOMs, Energy Recovery LERF (JLAB), in operation at 10 mA cERL (KEK), in operation at 1 mA, not yet at nominal current of 100 mA CBeta (Cornell), multi-pass ERL demonstrator, linac module tested, DR released BERLinPro (HZB), under costruction, CDR released MariX cavities Moderate beam loading, moderate current, possibly standard TESLA cavity (RF geometry) LCLS-II Booster module (not considered) If a booster module is required: Less cells, high-power, full beam-loading cERL (KEK), CBeta (Cornell) Bottom-lines TESLA/European-XFEL is mostly the reference

BRIXs linacs

CBETA, Cornell Linac Module: 6 7-cells cavities, custom cavity RF shape Design Limit beam current of 100 mA (one pass) Limit down to 40 mA for 4-passes Beam test, no ERL, low current CW, 16 MV/m gradient, up to 75 MeV 5 kW forward RF power for each cavity Commercial Solid State Amplifier, Qext 6e7 Nominal Q0 at 2e10 at 1.8 K HOM absorbers rings: Up 400 W each <12 W @ 40 mA, single cavity test Cooled at 80 K by 20 bar gHe

CBETA, Cornell 80 K heat load finally goes to LN2 one gHe/LN2 heat-exchanger for the CM 13600 m3/h subcooling pumping system 4 systems in parallel, 3400 m3/h Roots backed by 850 m3/h rotary Margin required by Q0 that is not met (not doped cavities) One of a kind module

c-ERL, KEK Linac Module: 2 9-cells cavities, TESLA shape (cells) f80 HOM damper HOM damper Linac Module: 2 9-cells cavities, TESLA shape (cells) Limit beam current of 100 mA ERL beam test done up to 1 mA CW, 15 MV/m gradient, 20 to 30 MeV Actually limited to 8 MV/m by FE Q0 > 1e10 at 2.0 K 3 Ferrite HOM absorbers per module up to 160 W dissipated power each Isolated from the cavity Cooled directly by liquid nitrogen

c-ERL, KEK Separate LN2 feed-throughs and circuitry required for HOM absorbers Poor Eacc and Q0 compared to non HOM-damped TESLA cavities One of a kind

BRIXs - comments CBETA Cornell: 2 more cavities required for 100 MeV 6 to 8 cavities string, from 10 to 13 m length Not a dramatic change but yet not the very same object … cERL KEK: For A 100 MeV final energy… linac could be assembled by 3/4 existing 2-cavity modules to stay on the safest side Much higher thermal loads Redesign vacuum vessel with 6/8 cavities in a string Once more, not critical but… Ongoing activity at KEK

LHe Cryo plant – BRIXs Parameter LCLS-II-type concept cERL-like CBETA-like Cavity temperature K 2.0 1.8 Q0 1e10 2E+10 Accelerating E field MV/m 12.5 15.4 Power, cavity W 16.6 17.2 10.1 # modules 2 8 # cavities 16 Energy, Total GeV 0.200 Cryo power, total: only cavities, no HOM heat-load kW 0.266 0.276 0.161 Cryo power, total: cavities, distribution, feed-boxes, end caps 0.326 0.436 0.221 Cryo power, with margins: +30% static, +10% dynamic (LCLS-II) 0.366 0.490 0.248 Cryo power, plant: rated capacity at cavity temperature 0.4 (+50 l/h LHe*) 0.5 (+50 l/h LHe*) 0.25 (+50 l/h LHe*) AC plug power, 4.5 K refrigerator MW 0.7 0.85 AC plug power, 1.8 K or 2.0 K refrigerator 0.1 0.15 AC plug power, water cooling AC plug power, Total: sum of above 0.9 1.1 * Liquefaction required by concurrent activities (single cavity VTs, magnet cold tests etc.)

LHe Cryo plant – BRIXs - Actual machines Cold compressors: Used above 300 W cryogenic power Typically 3,2-3,6 W@4,5K/W@1,8K FNAL CryoModule Test Facility: 500 W @ 2,0 K or 250 W @ 1,8 K 460 l/h liquefier mode 3-stage cold compressor Largest off-the-shelf unit: LINDE L/LR280 280 l/h, theoretically up to 900 W @ 4,5 K One in magnet test-stand at INFN-Salerno (200 W @ 4.5 K)

Considerations on AC plug power requirements - BRIXs Only CRYO and RF! Liquid Nitrogen plant not investigated (LHe refrigerator pre-cooling and up to 7 kW @ 80 K for HOMs) RF amplifier 16 single cavity RF SSA, 5 kW forward and 12.5 kW plug power each 0.2 MW for the two linac modules Overall Source Power – MW Linacs cryo 0.8 Linacs RF 0.2 Booster RF (2 x) Gun (2 x) 0.3 Total: sum of above 2.1 Cooling Total, with margin: to the user 2.5 Installed: electrical grid substation, considering high inductive loads 8

MARIX linac

LCLS-II, SLAC CW, 16 MV/m, 9 cells, 1.3 GHz TESLA cells, minor modifications for CW Larger pipes, dual inlets, etc. 3.8 kW forward RF power each cavity Commercial SSA, Qext 4.1e7 Q0 at 2.7e10 at 2.0 K (doped cavity) Linac Module has 8 cavities Design beam current of 100 mA upgrade foreseen to 300 mA Module string includes SC quad magnet BPM 1 HOM beam-pipe absorber Dual cryogenic feed-box

LCLS-II, SLAC 35 CMs, 280 1.3 GHz cavities 1 3.9 GHz module 2 bunch compression chicanes Linac foot-print Using the first part of original LCLS tunnel at SLAC Cutting LCLS-II at 2.4 GeV, 19 CMs: Total length approximately 500 m Without undulators, photon beam lines, user’s facility etc.

LHe Cryo plant – MARIX 1.3 GHz SC linac Parameter LCLS-II MARIX – low risk MARIX – medium risk Cavity temperature K 2.0 Q0 2.7e10 2e10 Accelerating E field MV/m 16 20 Power, cavity W 10.1 13.6 15.8 # modules 35 19* # cavities 280 152 Energy, Total GeV 4.5 2.4 3.0 Cryo power, total: only cavities kW 2.83 2.07 2.40 Cryo power, total: cavities, distribution, feed-boxes, end caps 3.64 2.64 2.97 Cryo power, with margins: +30% static, +10% dynamic (LCLS-II) 4.09 3.33 Cryo power, plant: rated capacity at cavity temperature 2 x 4 (JLAB CHL2) 1 x 4 (JLAB CHL2) AC plug power, cryogenic plant MW 9 AC plug power, water cooling 1 0.5 AC plug power, Total: sum of above 10 5 * Assuming 15 m each unit, the cryomodule string itself extends for 285 m

Considerations on AC plug power requirements - MARIX Few changes from LCLS-II MARIX 1.3 GHz SC linac Parameter Unit LCLS-II MARIX Loaded Q 4.1e7 3.25e7 Peak detuning Hz 10 30 Number of cavities 280 152 Forward RF power, with margins: cavity kW 3.7 6.0 Installed RF power: cavity 3.8 6.2 Total, AC plug power: linac, 40 % SSA efficiency MW 2.7 2.4 Source Power – MW Linac cryo 5 Linac RF 3 Electronics 2 Total: sum of above 10 Cooling 1 Total, with margin: to the user 14 Installed: electrical grid substation, considering high inductive loads 45