1. with the contributions of my colleagues from BI and CRG
Status of the AD’s CCC
Jocelyn TAN (BE-BI)
with the contributions of my colleagues from BI and CRG
GSI visit at CERN

2. Agenda Recap on the AD’s CCC Cryolab activities : maintenance, R&D
Plans

3. AD CCC Vacuum tank Thermal shield 840 LHe Vessel Nb shielding 1032
Safety valves
Pulse tube
+ He hose
Vacuum tank
Instrumentation
+ vacuum equip.
Thermal shield
840
LHe Vessel
Nb shielding
1032
Courtesy: A. Lees TE-CRG

4. AD CCC status before LS2 Status Limitations
Current and intensity measurement provided at end of cycle: resolution of 105 charges
Very good immunity to mechanical vibrations
Fully integrated in FESA (including automatic SQUID set-up)
Expert GUI has been developed
PLC system available to control cryogenic system
Limitations
Cryogenic availability : refill every 2.5 months
LHe circuit becomes contaminated blocking the He gas flow in the closed-circuit:
CCC could nevertheless work w/ GHe, up to ~ 7K.
Measurement display only possible at end of cycle
Due flux-jump at injection
Tested: battery power, isolation amplifiers, better calibration cable, …
Superconducting connection in DC coupling circuit kept only for limited range
Currently compensated by imposing a constant DC current

5. AD CCC status before LS2
Successful run in 2018 with similar problems of LHe reliquefaction (refill every 2.5 month)
Upgraded reliquefier performance 0.89 W W = 1.21 Wequiv. did not help!
No further performance tests possible due to cut of supplies end of 2018 until march 2019
Installed 2 x PV in pumping line protected vacuum from oil back stream (power cut)
Courtesy: T. Koettig TE-CRG

6. Investigation of performance degradation
Possible options for performance degradation were identified:
Diffusion of He through the ceramic gap and local influence of insulation vacuum mainly around the beam tube (30 MlI layers and little space)
=> excluded by an extensive leak test in May 2019
with 1 bar 293 K in the inner LHe vessel
=> Q 𝐿 <3∙ 10 −9 mbar l/s insulation vacuum to leak detector
Liquid helium vessel inner bore assembly. Configuration for integration into the BCCCA.
Cryostat insulation vacuum
LHe or GHe
Ceramic gap setup for leak testing before installation.
3 axial mechanical support rods!
Test pressure 1.5 bara x 1.25 = bar differential.
Courtesy: T. Koettig TE-CRG

7. Investigation of performance degradation
Possible options for performance degradation were identified:
Diffusion of He through the ceramic gap and local reduction of insulation vacuum mainly around the beam tube
GHe impurities due to supply or air diffusion etc. creating layer on 2nd stage HEX
Independent GHe supply
(not anymore from the central building supply 46 He)
Courtesy: T. Koettig TE-CRG

8. Investigation of performance degradation
Possible options for performance degradation were identified:
Diffusion of He through the ceramic gap and local reduction of insulation vacuum mainly around the beam tube
GHe impurities due to supply or air diffusion etc. creating layer on 2nd stage HEX
=> 2 x SV are under suspicion to be not backwards leak-tight
=> Full metal SV for cryogenic use!
=> Plan is to replace it with a combination of a RD and a bleeding valve.
Metal sealed SV
at 0.5 barg
Rupture 0.5 barg +
bleeding 0.4 barg, O-ring sealed
Courtesy: T. Koettig TE-CRG

9. Maintenance plan Maintenance kit for the compressor unit is purchased.
Run time is already (~22000 h) for compressor CP1110 with PT415
=> CP1110 Molecular Sieve Adsorber, CRYOMECH Description CP1110
Courtesy: T. Koettig TE-CRG

10. R&D on remote cooling scheme
Working principle:
Use cryocooler with closed helium circuit to deliver cooling power to remote cryostat
Heat exchangers are crucial component
Forced flow of helium gas (or 2-phase flow)
Use cold Joule-Thomson expansion valve for temperature reduction
Project goals from cryo perspective:
Increased flexibility in coolling options for different projects;
Reduce dependency on LHe availability
Possibility of placing cryocooler away from locations of high radioactivity and magnetic field
Dry cooling and gas cooling options possible
Dry cooling
He gas
Gas cooling
Status and plans:
Currently assessing performance of heat exchanger with coolling circuit connected only to first-stage of cryocooler
Total expected development for a production system of 3 to 4 years
With 2 last years of specific design for any given system

11. Advantages/changes for a future CCC
Cooling pipe with dry cooling option: no helium vessel is required
Smaller and cheaper cryostat design
No ceramic gap in contact with liquid helium
Strong pressure changes perturbations eliminated
Temperature stability
Should not be an issue with core-less CCC
Maybe require an active temperature control
Vibrations from active gas flow
Impact should be mitigated with core-less CCC
Use single-phase gas flow
To be investigated

12. Next steps for AD Study source of flux-jump at injection
Re-measure system response, and assess maximum achievable slew-rate
Replace Magnicon “Connector box” and “Power supply” by improved electronics, to be installed in a single box
Mitigate perturbations through signal processing
Install new B-train / “White Rabbit” receiver (same system as for DCCT’s)

13. Next steps for ELENA There is interest to have a CCC in ELENA
Some pre-requisites though:
Show that AD CCC can run reliably over long periods;
Wait until ELENA is fully commissioned;
If it is shown that intensity measurement is lacking, then we can proceed with an optimised design for an ELENA CCC ;
Timeline:
not before the end of 2021 at the earliest.

14. Next steps for the collaboration
Cryogenics: FAIR cryostat, new cooling scheme
SQUID: new design; outcome on rad hard tests
New CCC design: coreless ? Lead?
To be presented this Thursday at FCC week
Courtesy: T. Dodington BE-BI

15. Thank you

16. Spare Slides

17. ELENA for experiment efficiency improvement
Factors considered in the synchrotron design
Space constraints: in AD hall
e-cooler: get space + small dispersion
Tune: keep  away from resonances
Bucket to bucket beam transfer from AD
Possibility of a second extraction line
ELENA parameters
Circumference (1/6 of AD)
30.4m
Triplet-based optics
6-fold layout
Machine tunes h/v
2.3 / 1.3
Ekin range
5.3 MeV – 100 keV
Relativistic 
0.11 – 0.01
Nbunches at extraction 4
Bunch length at extraction
75 ns (rms)

18. Facility overview and layout
Transfer line
(magnetic)from AD
External source for commissioning
Electro-static line towards existing experimental area
Extraction towards new experimental area
Courtesy: C. Carli

19. ELENA Cycle Cycle length about 20 seconds ELENA parameters Ekin range
5.3 MeV – 100 keV
Frev
1.1 MHz – 100 kHz
Total Nparticles
3 – 1.8 x 107
DC current range
5.2… 0.3 A
Beam aperture
63 mm
eh,v = 15 p mm mrad
DP/P = 1x10-3
eh,v [95%]= 6/4 p mm mrad
DP/P = 2x10-4
Lbunch (max) = 1.3 m
Cycle length about 20 seconds

20. in Section 1: near septum and kicker
Integration options
1.25m drift tube
in Section 1: near septum and kicker
LPUs in Section 2