Jim Kerby Fermilab With many thanks to Vladimir Kashikhin, the FNAL, KEK, and Toshiba teams. SCRF BTR Split Quadrupole ILC ML & SCRF Baseline Technical Review (ML & SCRF BTR) 19 January 2012 /20 January 2012, KEK

Split Quadrupole 18 Jan 2012KEK, SC BTR Superferric, conduction cooled magnet Constrained to Type IV CM envelope Same specs as CIEMAT design Opportunity to incorporate dipole corrector by use of trim leads (?) Magnet assembled around beam tube outside of clean room Cost ~neutral Pool boiling tests in 2011 –Need for yoke split to be better clamped? Now at KEK for 2012 conduction cooled test 2

Quadrupole Specifications 3 Integrated gradient, T36 Aperture, mm78 Effective length, mm666 Peak gradient, T/m54 Peak current, A100 Field non-linearity at 5 mm radius, %0.05 Quadrupole strength adjustment for BBA, % -20 Magnetic center stability at BBA, um5 Liquid Helium temperature, K2 Quantity required560 NbTi wire diameter, mm0.5 Number of filaments7242 Filament diameter, um3.7 Copper : Superconductor1.5 Insulated wire diameter, mm0.54 InsulationFormva r Twist pitch, mm25 RRR of copper matrix100 Critical current 4.2K, at 5T 204 A 18 Jan 2012KEK, SC BTR

4 Quadrupole Electrical Scheme All coils connected in series. 4 RTD’s to monitor the temperature. 5 voltage taps to detect the quench. 4 coil heaters connected in series and fired when the quench event is detected. Quadrupole is protected with 9 Ohm dump resistor. The peak voltage is < 1kV. 18 Jan 2012KEK, SC BTR

5 Quadrupole in T4CM Cryomodule 18 Jan 2012KEK, SC BTR

6 Quadrupole Cold Mass Assembly 18 Jan 2012KEK, SC BTR

7 Two Halves of the Quadrupole 18 Jan 2012KEK, SC BTR

8 Coil Winding (January 21, 2011] 18 Jan 2012KEK, SC BTR

9 Quadrupole Coils & Tooling 18 Jan 2012KEK, SC BTR

10 Fabricated Quadrupole Coils Four coils were initially fabricated. Coil N3 lead was damaged during test setup preparations. One more coil was fabricated to replace the damaged coil. 18 Jan 2012KEK, SC BTR

11 Quadrupole Yoke Parts 18 Jan 2012KEK, SC BTR

12 Laminated Yoke Assembly 1.Half yoke assembly in the press. 2.Half yoke final assembly 3.Yoke control assembly Yoke material – MI low carbon steel, 1.5 mm thick. 18 Jan 2012KEK, SC BTR

13 Quadrupole with Top Head Assembly Current leads Top head Quadrupole yoke Yoke halves clamping rings 18 Jan 2012KEK, SC BTR

14 Critical Current & Load Line Peak operating current 100 A. Magnet trained up to 110 A ( green line). Critical current (short sample limit) for this magnet is 185 A at the coil field 5.4 T. 18 Jan 2012KEK, SC BTR

15 Quadrupole Gradient vs. Current At 90 A current the quadrupole reached the specified peak gradient 54 T/m. 18 Jan 2012KEK, SC BTR

16 Magnetic Center Position at (10A-100A) The measured behavior was quantitatively the same at two independent body positions, and slightly exceeds the specification in X at some currents. 18 Jan 2012KEK, SC BTR

17 Quadrupole Current during Tests The body magnetic center stability was measured with BBA current profiles over a wide range of currents, up to 100 A. The center position was derived from the dipole field components assuming feed-down from the quadrupole, and could be measured reproducibly to ~ 1 µm on each current plateau of several minutes duration. 18 Jan 2012KEK, SC BTR

18 Magnetic Center Shift vs Current Quadrupole magnetic center shift at -20% current change dx<8um, dy<4 um. 18 Jan 2012KEK, SC BTR

19 Quadrupole Training Results Quadrupole was initially trained to the 95 A during first thermal cycle (interrupted by the cryo system maintenance), and to 110 A during the second thermal cycle. There were observed large voltage spikes up to 5 V, and after several power supply trip offs, was used 5 V QD threshold. Each coil has 900 turns and all quenches had mechanical nature. For the magnet protection were used strip heaters in each coil and an external dump resistor. During magnetic center position measurements was observed the time dependent effect. At -20% current change from the investigated maximum value, the magnetic center shift was less than 8 um Nevertheless, the first obtained results are very promising and close to the specified value 5 um. The main center shift was observed for dx in the X-direction, and about 2 times lower for Y. It is suspected this is due to the effect of gap fluctuations between two halves of the magnet. In the next test this gap will be modified to ensure closure. 18 Jan 2012KEK, SC BTR

20 Magnet Ready for Shipping 18 Jan 2012KEK, SC BTR Dec Now available for viewing at KEK/Cryogenic Sciences Center

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Layout: Quadrupole in KEK Dewar w/ Cryocooler 18 Jan 2012KEK, SC BTR29

Split Quadrupole: Conclusion Jan 2012KEK, SC BTR

TDR scenario for ML Magnet Split Yoke, conduction cooled magnet is proposed for the TDR baseline –Streamlines clean room operations Cleanroom sees just a pipe! –Will meet specs; fits in available T4CM volume Yoke split to be better clamped Conduction cooling test to confirm thermal performance –Cost neutral Aligment issues remaind TBD 18 Jan 2012KEK, SC BTR 31