STATUS REPORT ON VACUUM CHAMBERS (Dipole & Straight) & DIPOLE MAGNETS FOR TL-2 OF CTF3 A.K. JAIN, S.S. PRABHU, S. KOTAIAH RRCAT, INDORE (INDIA)

Vacuum Chambers

Initially, two test vacuum chambers fabricated in aluminum grade AA 6061 for qualifying machining & welding procedure. Surface finish < 0.30 microns achieved. Welding torch manuveres needed to access some portions of chamber. For third chamber, design was changed to simplify welding. Leak rate obtained ~3 x Torr – ltr / sec. Dipole Vacuum Chambers :

DIPOLE VACUUM CHAMBERS Machined & Welded Prototype Chamber Initial TrialFinal Trial

DIPOLE VACUUM CHAMBERS

END FLANGES OF DIPOLE VACUUM CHAMBERS

Fabrication & Processing : Material: AA6061–T6 is silicon magnesium based aluminium alloy. (Material is solution heat treated and artificially aged). Tooling : High-speed cutters were used. Cutters equipped with peripheral mounting, high positive rake angle (34 0 ), coated carbide inserts with 90 0 approach angle. One of three inserts had a “wiper insert” to get good surface finish. Processing : Chemical cleaning-Approved by CERN for aluminium alloy grade AA6061-T6. After chemical cleaning, jobs were hand scrapped in the lip area to remove oxide layer just before welding. Dipole Vacuum Chambers (Contd…)

TIG WELDING : Welders were qualified as per section IX of ASME code. Cleanliness and humidity level of the weld room was maintained using air conditioners, air curtains and Dehumidifiers. Base material used : AA 6061 –T6 ( containing Si- 0.6%, Mg – 1-1.2%, - Cu %) Filler wire used : AWS A5.10 ER 4043 (Containing Si–5%, Mn –0.05% Fe – 0.4% Al – rest) Shielding gas used : XL grade argon % as per IS (Grade - 1) (Impurities - Oxygen less than 1.5 ppm., Moisture less than 1.0 ppm, total hydrocarbon – NIL) Dipole Vacuum Chambers (Contd…)

Welding Parameters Peak current Amps. Back ground current 25 Amps. Pulse frequency 7 Hz. (at high position) Pulse Ratio 80% Type of arc Hard Arc Shielding gas flow rate 8 Ltrs / min Relative Humidity Less than 35%

Dipole Vacuum Chambers (Contd…) Present Status : Fabrication and welding procedures qualified. Raw material AA 6061 T6 procured. Awaiting CERN’s approval of TL-2 optics design & also magnet design. Final drawings for chamber fabrication to be taken up thereafter. Total nos. of dipole chambers ~5. Assembly of dipole chamber with bending magnet has been tried using CAD. There is no problem in the assembly.

Straight Chambers : RRCAT, Indore will deliver these chambers built out of extruded aluminum grade AA 6061 T6. This will avoid welding of chambers at the edges and their machining on a CNC vertical milling machine. Extrusion job already ordered. Extruded material expected at RRCAT ~April, Once TL-2 optics is frozen, material will be cut to required lengths, ends machined to suit the welding joints with end flanges.

Straight Chambers

DIPOLE MAGNETS FOR TL-2

Specifications  Sr. No. Parameters Values (Type-1) 35 0 Values (Type-2) Nominal Field1.3 Tesla 2Nominal current340 A 3Pole Gap45 mm ± 50 micron 4Pole width240 mm 5Coil Pocket size176 mm (width) X mm (height) 6Yoke Length465 mm(235mm) 7Magnetic Length518 mm288 mm 8Bending Angle35°17.5° 9Construction Length920 mm690 mm 10Core weight1273 kg640 Kg 11Coil weight860 kg445 Kg 12No of Pan Cakes44 13No of turns48/pancake 14Total no of turns192 15Resistance60 milli-Ohm32.5 milli-ohm 16Voltage20.4 Volts11.3 volts 17Power dissipated6.8 Kilo-watt(3.8 KW) 18Cooling water flow9.5 LPM 19Pressure drop2.4 ata1.24 ata 20No of cooling circuits44 21Water temperature rise 11  C5.8  C 22Quantity Required2 Nos.3 Nos. DIPOLE MAGNET

Magnet Core Material : 1.5 mm thick low carbon steel sheets supplied by M/s Cockrehill Sambre. B/H data and other information : H in A/m B in Tesla Variation in B %15 %2 %< 2 %1 % Coercivity – 70 A/m  Carbon content < 0.01 %  Yield Strength 120 N/mm 2  Tensile Strength 260 N/mm 2  Thickness spread < 1.5 % Dipole Magnets (Contd…)

Dipole Magnet Bottom Half Block Dipole Magnet Coil Pan Cake

DIPOLE MAGNET ASSEMBLY Overall Mechanical Details of Assembled 35  Dipole Magnet Magnet height 640 mm Magnet Width 1000 mm ( ) Magnet Length 910 mm Magnet total weight 2200 kg

CORE BLOCK FOR DIPOLE MAGNET

Fabrication Stages :  Laser Cutting of Stampings.  Stacking of stampings & pressing to form a block.  Welding of stampings to get block.  Machining of pole surface & other reference surfaces.  Assembly of two blocks along with water cooled coil pancakes.

Present Status : Engineering drawings for 35 0 bending magnet completed; Sent to CERN, but approval awaited. Quantity required 2 nos. Fabrication will start only after CERN’s approval of drawing. Engg drawings for bending magnet completed; will be shortly sent to CERN for approval. Quantity required 3 nos. R aw material for core & coil procured. Dipole Magnets (Contd…)

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