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

2. 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

3. BRIXs linacs

4. 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 40 mA, single cavity test
Cooled at 80 K by 20 bar gHe

5. 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

6. 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

7. 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

8. 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

9. 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.)

10. LHe Cryo plant – BRIXs - Actual machines
Cold compressors:
Used above 300 W cryogenic power
Typically 3,2-3,6
FNAL CryoModule Test Facility:
500 2,0 K or 250 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 4,5 K
One in magnet test-stand at INFN-Salerno ( K)

11. Considerations on AC plug power requirements - BRIXs
Only CRYO and RF!
Liquid Nitrogen plant not investigated (LHe refrigerator pre-cooling and up to 7 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

12. MARIX linac

13. 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

14. 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.

15. 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

17. 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