1. Overview MESA SRF system and machine design
Florian Hug
on behalf of MESA SRF team

2. Outline MESA Machine Overview MESA Cromodule Overview
Contamination issues
MESA bERLinPro
F. Hug – MESA SRF system and machine design

3. MESA Overview
MESA will be constructed in existing halls from a former MAMI experiment and in a newly erected experimental hall
Additional space for future experiments availiable
BDX possible Trade off: some project delay due to civil construction time
Picture: D. Simon
F. Hug – MESA SRF system and machine design

4. MESA Overview Beam parameters: Cryomodule parameters:
2 operation modes
Beam used for precision experiments in nuclear-/particle physics
Cryomodule parameters:
2 modules with two cavities each
Modules are under construction by RI company (exspected delivery in October/November 2017)
Parameter
Guaranteed by RI (vendor)
f0(2K) / MHz
± 0.05
Vtotal / MV
≥ 25 Q0
1.25 x 1010
PFPC / kW
≥ 15
Pdiss,stat / W
< 15
Pdiss,dyn / W
< 25
Basic Parameter
max. beam energy
105 MeV (ERL mode) 155 MeV (external beam)
max. current in ERL operation
1 mA (later 10 mA) ( pC/bunch)
Number of recirculations
2 (ERL mode) 3 (external beam)
F. Hug – MESA SRF system and machine design

5. ELBE/Stanford Cryomodules
Ordered cryomodules of the 'Rossendorf'-type (2 x 9-cell TESLA/XFEL cavities), which are in use at ELBE at company Research Instruments due to tight schedule
→ and applied some adaptations:
add tuner with piezo elements (XFEL/Saclay-type)
use sapphire windows at HOM feedthroughs
in addition: include 2K production (heat exchanger, JT-valve, phase separator) and
full cryogenic control system, all provided by the vendor in close contact with Mainz and DESY (t.b.d. by RI)
Picture: HZDR
F. Hug – MESA SRF system and machine design

6. Integration of XFEL Tuner
RI received STEP-model of the XFEL tuner by DESY
2K-phase separation of the ELBE module needed to be modified :
different bottom plate
different heating resistors
Adapted position for helium level sensor
Pictures: RI
F. Hug – MESA SRF system and machine design

7. Further Developments by JGU
Thermal calculations at HOM antenna ongoing (T. Stengler):
→ Provide optimised thermal connection design to RI
→ Limitation by heat input from cable, need for heat sink
T / K
11.4
Only 1.25 W
heat deposition in
1.8 K LHe bath
per HOM coupler
in cryo budget
1.8
Picture: T. Stengler
F. Hug – MESA SRF system and machine design

8. Further Developments by JGU
Possible solution:
Slotline on cold mass to optimize cooling
Steel wire between slotline and 300 K (bad thermal connection)
Copper bands as thermal connection between antenna and cold mass
Steel wire
1.8 K
copper strips
to load
300 K
77 K
1.8 K
slotline
copper wire
J. Sekutowicz
F. Hug – MESA SRF system and machine design

9. HIM infrastructure F. Hug – MESA SRF system and machine design

10. Contamination issues at MESA
MESA is a new accelerator, so no contamination from old machine parts are existent so far
But: extent use of liquid and gas targets for the different experiments
MAGIX (ERL experiment): Gas target (Hydrogen, later different gases)
P2 (external experiment): Liquid Hydrogen target and Hydro-Möller polarimeter atomic hydrogen at 300 mK)
Pictures: S. Aulenbacher
F. Hug – MESA SRF system and machine design

11. Possible project: MESA@bERLinPro
MESA Cryomodule
(modified ELBE type)
Position to integrate
MESA Linac Module
(5m free space available)
F. Hug – MESA SRF system and machine design

12. Summary / Outlook
MESA will be a superconducting, recirculating linac for particle and nuclear physics experiments
Two operation modes will be used - polarized external beam with up to MeV - unpolarized ERL beam with up to 1 mA (later MeV
the experiments need gas targets and poarimeters. Accelerator needs to be protected from accidental venting
The building timeline makes a project possible: bERLinPro. A grant proposal is in preparation to get funding
F. Hug – MESA SRF system and machine design

13. Thank you for your attention!
F. Hug – MESA SRF system and machine design