Superconducting RF cavities activities for the MAX project

Transcription

1 1 Superconducting RF cavities activities for the MAX project OECD-NEA TCADS-2 Workshop Nantes, 22 May 2013 Marouan El Yakoubi, CNRS / IPNO

2 2 Contents 352 MHz spoke Cryomodule design 700 MHz test area 700 MHz Power couplers 700 MHz Power couplers conditioning setup Conclusions & Roadmap

3 3 Introduction MYRRHA / XT-ADS Accelerator Scheme Β g = 0.47 section of the Linac 5 cell cavity Freq = MHz Nominal accelerating voltage E acc (Β g ) = 8.5 MV/m

4 4 352 MHz Cryomodule overview 2 Beta 0.37, 352 MHz Spoke Cavities Op. Temperatures : 2 K, 5/10 K, 40/80 K Connection to Valves Box H. Saugnac (IPNO) Sliding Blocks One Thermal Shield (40K/80K) F 1200 Coupler Barometric Compensation Warm Stop Valve Supporting Frame Cavity Train Put on adjustable Posts

5 5 352 MHz Spoke Cavity Beta 0,37 H. Saugnac (IPNO) Epk Bpk Electro Magnetic Optimization : CST Mechanical Optimization : ANSYS. Mechanical/EM coupled Simulations : ANSYS Detailed Drawings OK Cavity Wall: Nb RRR>250 (thck. 3 mm) Helium Vessel Ti Grade 2 (thck. 3 mm) Optimized Parameters E acc normal operation ; 6,2 E acc fault tolerance 8,2 MV/m Optimized Parameters L acc =optimal beta x c x f [m] 0,315 E pk /E acc 4,29 Tuning Sensitivity [khz/mm] 156 B pk /E acc [mt/mv/m] 7,32 Sensitivity to Pressure [Hz/mbar] G [Ohm] 109 Lorentz Force Factor [Hz/(MV/m) 2 ] 7,6 < S P < 14 r/q [Ohm] 217 Approximated Bandwidth 150 Hz 2K for Rres=20 nω 5, b optimal < K L < -5,28

6 6 Cold Tuning System H. Saugnac (IPNO) The CTS (CEA Soleil Type) for The MAX Spoke cavities is the Same as the one Designed for the ESS Spoke Cavities. Stepping Motor Cavity elongation along its Axis Piezo Actuators Coarse Range (Stepping Motor) ~ 150 Limited by Max Stress Fine Range (Piezo) > 300 Hz Stiffness > 100 KN/mm

7 7 Power coupler H. Saugnac (IPNO) A Power Coupler 352MHz, 20 kw CW (designed), 50 W. WARM WINDOW Was manufactured, in the framework of Eurotrans and successfully tested at 8 kw (amplifier limitation) CW on a 350 MHz, beta 0.15 Spoke cavity in a Cryomodule configuration. The Design (SNS Type) will be kept as it for MAX Basis for design 2 CF16 ports for vacuum measurements. 1 port for electron emission measurement pick up 1 water cooling loop for the window Plain Copper Antenna CF 63 on cavity Thermal interception at 70 K (~15 W solid conduction) and ~ 10 K (~3 W solid conduction)

8 8 700 MHz area 700 MHz Cryomodule Cavity & tuning system Power Coupler RF source 80 kw CW Cryogenic Valves Box Power coupler RF Source 80 kw CW 160 kw DC Power Supply + IOT Cavity 5-cells β= MHz Cryomodule

9 9 Power couplers Power coupler main view Cavity (5 cells) Cavity coupling port Outer conductor (II) (I) Inner conductor / Antenna (water cooled) Ceramic (97% alumina ) disc window (water-cooled) Vacuum (III) Doorknob: Transition coaxial (power coupler) to rectangular waveguide (towards the IOT) Air

10 10 Power Couplers Heat exchanger received, vacuum tests revealed no leak. 2 Power Couplers manufactured by SCT Society And checked at IPN Orsay in May prototypes of window + antenna were brazed & delivered. 1 ceramic disc have TiN deposit (20 nm) 1 ceramic disc without deposit.

11 11 RF power supply 17 th to 21 st Spet.2012 : the IOT has been successfully re-tested with its RF circulator in full reflection until 80 kw. The current of the circulator coil had been tuned to enable fast RF power increase (J. Lesrel ) The DC power supply can now be control through a Labview program via Ethernet (C. Joly ) 25 th sept : The coupler conditioning bench was assembled to the IOT Conditioning started in October 2012 (E. Rampnoux)

12 12 Power Couplers conditioning setup Power coupler conditioning : Experimental setup Conditioning cavity

13 RF power (W) 13 Pre -conditioning (1 kw) of the couplers E. Rampnoux & S. Berthelot Cout IN OUT Cin Cavity Time Power ramped-up to 880 W in 24 h Automatic procedure and control program validated. No multipacting detected during the low power test Vacuum leak rate remained at: mbar.l.s -1

14 RF Power (kw) 14-1 Couplers conditioning RF power conditioning couplers in CW operation 30 kw. 35 1,78E-07 RF Power RF power reaches 30 kw in 6 hours Vacuum Pressure 1,58E-07 1,38E-07 No safety system at fault 20 1,18E-07 9,80E-08 Degradation of vacuum level from 17 kw ,80E-08 5,80E ,80E ,80E-08 00: 00: 00 00: 50: 03 1: 40: 05 2: 30: 08 3: 20: 10 4: 10: 13 5: 00: 16 5: 50: 18 Time (hh:mm:ss)

15 15 Couplers conditioning RF power conditioning couplers in CW operation 42 kw. high vacuum level: Input coupler ceramic broken! 4,50E+04 November 8, ,00E+00 Hypothesis : TiN deposit have weakened the ceramic window. Heat stress Coupler conditioning with CW mode is not suitable Ongoing : Analysis under progress to understand what happened. Modification of the conditioning procedure: operating in pulsed mode, which is the safe state-of-the-art. New coupler TOSHIBA was prepared. 4,00E+04 3,50E+04 3,00E+04 2,50E+04 2,00E+04 1,50E+04 1,00E+04 5,00E+03 0,00E+00 Ps3 1,00E-01 Vide Cin 1,00E-02 Vide Cout 1,00E-03 1,00E-04 1,00E-05 1,00E-06 1,00E-07 1,00E-08 0:00:30:01:00:01:310:02:010:02:310:03:010:03:320:04:020:04:32

16 16 New TOSHIBA coupler Power Coupler manufactured by TOSHIBA Society Mechanical constructions were achieved at IPNO (D. Grolet). TOSHIBA window Electron beam welding was carried out by SAFEL society. outer envelope end of the antenna Internal antenna TOSHIBA coupler is ready and qualified

17 17 Coupler LPSC Goal: Improve the surface condition of the antenna Reduce scratch marks on the antenna. Y. Gomez Martinez, P. De Lamberterie, T. Cabanel (LPSC) R. Martret (IPNO) Before After Materiel Electro-polishing bath: Phosphoric acid + alcohol (propanol) Voltage Generator (10 V / 30 A) Results. Eliminating a thickness of 200 μm matter. Appearance close to the mirror

18 18 Pulsed test IOT Test with low pulse frequency= 1 Hz (J. Lesrel) To prevent the temperature of the RF power supply diodes exceed 30 C No disjunction of the power supply 40 kv IOT output Power meter Gate = 20 µs rise time = 1ns Pk = 64 kw Tests sent to Brucker company for validation Chanel 2 = I HV (4A/10V) Chanel 1 = U HV (40kV/10V) Current security 3.9A (not to exceed) We can work in Pulsed Wave if the rate is low

19 19 Conclusion & Roadmap The Spoke Cryomodule design is in progress. A new power coupler was prepared in short time. The IOT was tested successfully pulsed mode. Re-assembling the conditioning bench with the IOT is under progress. The power coupler conditioning will restart very soon and we plan a 2 weeks period for the test. A clean room session is foreseen for the end of June 2013: for the power coupler assembly. The Module preparation & wave guide installation will start soon. First INTEGRATED high power CRYOGENIC TEMPERATURE: Summer Goal before end 2013: reliability-oriented experiment with Digital LLRF + Cold tuning system + ADEX smart control to validate the fast fault recovery procedure.

20 20 I Would to Thank you very much for your attention

21 21

22 22 18 kw A first travelling wave (CW) conditioning at 18 kw was foreseen ,00E Ps3 Vide Cin 1,00E-05 1,00E-06 1,00E :00:0 00:00:0 00:00:0 00:00:0 00:00:0 00:00:0 00:00:00 Temps (h:mm;ss) 1,00E-08

23 23 Gate =1,8 ms with rise time = 100 µs

24 24 MAX meeting, Louvain