1. Operation experience of cryogenic system and cryomodules for the superconducting linear accelerator at IUAC, New Delhi.
T S Datta
( On behalf of Cryogenics & Applied Superconductivity Group)
Inter- University Accelerator Centre. New Delhi
India
Cryo-Ops 2018 IHEP, Beijing (T S Datta)

2. Superconducting LINAC at IUAC, Delhi
CRYOGENIC SYSTEM
QWR Nb Cavity
( 97 MHz)
27 Nos
Ti = 160 MeV
Ti = 300 MeV
Cryo-Ops 2018 IHEP, Beijing (T S Datta)

3. IUAC SUPERCONDUCTING CAVITY
Accelerating Structure
200
ß = .08c
f= 97MHz,
Leff = 16 cm,
Eacc= 0.6MV
Cold Mass= 50 kg Q.Rs=18
Outer SS Jacket
LIQUID HELIUM
OUTER NIOBIUM
800 mm approx..
BEAM PORT
SLOW TUNER
CENTRAL NIOBIUM
Operating Temperature : 4.2 K and Frequency : 97 MHz
Cryo-Ops 2018 IHEP, Beijing (T S Datta)

4. IUAC SUPERCONDUCTING CAVITY
First lot ( 8 Nos) of QWR was developed at USA in Collaboration with ANL. Remaining 20 cavities were developed in house at IUAC
Performance Curve of a Cavity
Cryo-Ops 2018 IHEP, Beijing (T S Datta)
Courtesy ; P N Prakash

5. Cryo-Ops 2018 IHEP, Beijing (T S Datta)
Partial Linac was operated with one Linac Cryomodule ( LC-1) along with Buncher (SBC) , Rebuncher (RBC). and old Refrigerator ( Make CCI, USA) till 2012
SBC
Full Linac with the addition of LC-2 & LC-3 ( 16 Cavities)
and with New Refrigerator ( Linde) is under operational since 2013
CRYO MODULE
LC-1
LOW ENERGY FROM
PELLETRON
BEAM LINE
LC-2
LC-3
LN2 LINE
CRYO LINE
OLD HE REF
RBC
HIGH ENERGY
New Line
NEW HE REFIGERAOR
Cryo-Ops 2018 IHEP, Beijing (T S Datta)

6. 3 LINAC CRYO MODULES + Buncher + Re buncher
EACH
Linac MODULE
8 CAVITIES
&
1 SOLENOID MAGNET
3.0 x 1 x 1.2 m. x 1.9m
CRITICAL SPECIFICATION
CRYOSTAT VACUUM & BEAM LINE VACUUM COMMON should be better than 5x 10-8 mbar
NO MLI ( Clean environment around Cavity) : LN2 Cooled Copper Thermal Shield
COLD MASS 600 Kg, 4.2 K
Cryo-Ops 2018 IHEP, Beijing (T S Datta)

7. CRYO MODULES WITH LHE LINE & VALVE BOXES
Cryo-Ops 2018 IHEP, Beijing (T S Datta)

8. Cryo-Ops 2018 IHEP, Beijing (T S Datta)

9. Beam acceleration by all 22 Cavities in (LC-1, LC-2 & LC-3)
Year
Beam
Energy From Pelletron
(MeV)
Energy After
Linac
( MeV)
Gain
MeV
Gain/ Charge
2013
Ti+14
162
270
108
7.7
2014
275
113
8.07
2017
Ti+15
168
300
132
8.78
Improvement
Average Field : 3.5 MV/ m at 5 W Power
Cryo-Ops 2018 IHEP, Beijing (T S Datta)

10. Cryo-Ops 2018 IHEP, Beijing (T S Datta)
TOTAL LINAC COOLING WITH NEW REFRIGERATOR
LC2+LC3
LC1
RBC
SBC
Total 5 days required to cool the linac module in Batch
with liquid Helium
Cryo-Ops 2018 IHEP, Beijing (T S Datta)

11. Cryo-Ops 2018 IHEP, Beijing (T S Datta)
Cooling Philosophy of linac is changed : Because
New Refrigerator Cooling schematic different from earlier
Effective Radiation Cooling
Minor Modification on LC-2 & LC-3
Vacuum Nb
SS304L
LHe
Thermal Shield
Helium Vessel
Resonator In
Out
JT Pr
Driving Force : Dewar Pr
Cryo-Ops 2018 IHEP, Beijing (T S Datta)

12. Cooling Performance comparison between Earlier and present
No Liquid Nitrogen Precooling required
Earlier: 3 Stages
Now : 2 stages
Radiation Cooling Helps to Reduce the cavity Temperature from 210 to 175 K
Cryo-Ops 2018 IHEP, Beijing (T S Datta)

13. REDUCED WITH NEW REFRIGERATOR RF LOCKS ARE VERY STABLE
Helium Pressure fluctuation in Cryomodules
REDUCED WITH NEW REFRIGERATOR
RF LOCKS ARE VERY STABLE
CCI Refrigerator a)
Cryo-Ops 2018 IHEP, Beijing (T S Datta)

14. OPERATION PARAMETERS OF LINDE REFRIGERATOR WITH VARIABLE LOAD FROM LINAC
Cavity
Problem
Refrigeration load : 280 W to 440 W
Discharge Pressure : to bar
Mass flow rate : 53 g/s to 63 g/s
Power : 150 kW to 180 kW
Cryo-Ops 2018 IHEP, Beijing (T S Datta)

15. Preliminary Heat load ( 4.2 K) contribution by each system :
Total Load ~ W . Refrigeration capacity : 550 W ( W/0 LN2)
Cryogenic Load Distribution
of LINAC
Operating Range
Measured load of Linac
Cryo-Ops 2018 IHEP, Beijing (T S Datta)

16. Cryo-Ops 2018 IHEP, Beijing (T S Datta)
Complete Automation of Cryogen Distribution system
LN2 VESSELS
LHe & LN2 LEVEL/ Pressure In Cryomodule
He Gas
Cryo-Ops 2018 IHEP, Beijing (T S Datta)

17. Two Modes of LHe Supply Valves operation of Cryomodule
Cryo-Ops 2018 IHEP, Beijing (T S Datta)

18. Power Supply in India is not very Stable
Main system like Helium Compressor, Cold box, control system are connected through UPS and back up Generator..
Auxiliary system like chiller air supply are not with emergency power
Compressor of when water inlet temp crosses 45 C
Cryo-Ops 2018 IHEP, Beijing (T S Datta)

19. Temperature Sensor : DT- 470 Good Cavity : Fluctuation less
Temperature Reading Fluctuation
Good Cavity
Temperature Sensor : DT- 470
Fluctuation starts : Once cavity Comes out from Multipactoring Barrier
Noted
Good Cavity : Fluctuation less
Reduced by Twisted cable, Filter
Yet to be solved ????
Poor Performance
Cryo-Ops 2018 IHEP, Beijing (T S Datta)

20. Cryo-Ops 2018 IHEP, Beijing (T S Datta)
CONCLUSION
Superconducting Linac is being operational for expt with high energy heavy ion beam with almost double energy
At present Load, Linac run can be managed on running Linde refrigerator ( LR 280) without LN2 Cooling
Radiation Cooling is much more effective for the recent cryomodules and liquid nitrogen precooling stage is discarded
Helium Pressure fluctuation is reduced and RF lock is very stable
Power cut is common problem In India. Precaution are taken with UPS and back up generator
Shortly High Current Injector will be the another source for LINAC.
Cryo-Ops 2018 IHEP, Beijing (T S Datta)

21. Cryo-Ops 2018 IHEP, Beijing (T S Datta)
Thank You
Cryo-Ops 2018 IHEP, Beijing (T S Datta)