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)

Superconducting LINAC at IUAC, Delhi CRYOGENIC SYSTEM QWR Nb Cavity ( 97 MHz) 27 Nos Ti48 +14 = 160 MeV Ti48 +14 = 300 MeV Cryo-Ops 2018 IHEP, Beijing (T S Datta)

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)

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

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 2012-13 Cryo-Ops 2018 IHEP, Beijing (T S Datta)

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, Alignment @ 4.2 K Cryo-Ops 2018 IHEP, Beijing (T S Datta)

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

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

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)

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)

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)

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)

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)

OPERATION PARAMETERS OF LINDE REFRIGERATOR WITH VARIABLE LOAD FROM LINAC Cavity Problem Refrigeration load : 280 W to 440 W Discharge Pressure : 9.75 to 11.25 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)

Preliminary Heat load ( 4.2 K) contribution by each system : Total Load ~ 430- 450 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)

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)

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

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)

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)

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)

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