Status of the CLIC DR wiggler design and production at BINP

Status of the CLIC DR wiggler design and production at BINP A.Bragin, E.Levichev, P.Vobly and S.Zaitsev Budker Institute of Nuclear Physics, Novosibirsk April 25, 2008 Outline • • • • • Wiggler parameter selection Magnetic and mechanical design Quench protection system Wiggler production status Wiggler production schedule CLIC DR emittance requirements PM emittance CLIC DR normalized emittance  as a function of the wiggler period and the field amplitude (by M.Korostelev, IBS included) PM SC (NbTi) Period length cm 10 Aperture (beam) mm 12 12 Peak field T 1.7 2.5 W length m 2 Temperature K Room 4.2 K SC emittance Wiggler parameters selection I For a sine-like wiggler model: w   0  8I   32/  3Lw   x 2w     10 I  2/5 hw  I5   10  Lw  w 2w   1/  I5      Lw  w  w  Emittance minimization requires a shorter period length and, at the same time, a higher magnetic field amplitude This is a contradictory requirement! 1/ Wiggler parameters selection II The field amplitude depends on the wiggler gap and period length as: Bw ~ exp  g /  w  Gap  field amplitude and period  emittance The gap usually is defined by external conditions (SR passing) PM technology vs SC technology 4-m-long PM damping wiggler for the PETRA III project Facility Year Bm(T) SC wiggler for the Diamond LS g(mm ) L (mm) Ay(mm) 50 500 12-14  (m m) SC CLIC DR (short) 200 2.5 20 SC CLS (Canada) 200 2.0 13.5 34 1120 9.5 DLS (UK) 200 3.5 16.4 60 1544 10 CLS-2 (Canada) 200 4.0 14 48 1000 9.5 Main principles  Short period and high field amplitude  Simple technology and easy production  Easy in tuning  Reliable (all coils are wound by a single wire  of contacts)  Magnetic forces are directed in the iron yoke  no fixing mechanical band is needed  Special quench protection system is proposed Schematic view and main parameters SC coils Iron beam-yoke Period length Vertical pole gap Beam aperture Peak field Prototype length Stored energy 5.0 cm cm 1.2-1.4 cm 2.5 T 50 cm 57 kJ Magnetic design I Magnetic flux Air – blue Iron – green Coil - red Half period y z End part Magnetic design II Field amplitude in the wiggler parts (3D) BINP Mermaid Magnetic code Units at the plots – kG and cm Longitudinal cross Transverse cross/coil Transverse cross/between coils 3-4 T 7T 5-6 T Magnetic design III Field distribution (3D) Longitudinal in central pole Transverse dB/B = ±3.5x10-4 at X = ±1 cm Longitudinal in the end part Mechanical design I General view Regular coil Iron yoke End coils to compensate the first and the second integral Corrector coils with individual PS Mechanical design II Yoke regular part Mechanical design III Magnetic forces in the regular coil SC wire contacts Iron yoke End coils to compensate the first and the second integral Corrector coils with individual PS Superconductor For many years Bochvar Institute in Moscow produces special NbTi SC wire for BINP with the following parameters: Single wire length (0.5 m) – ~2.0 km SC packing factor – 67.5 % Critical current for Т – 700 А for Т – 450 А Wire diameter – 0.9 mm SC strand thickness – 30 um In our case the current density in the SC wire is 1250 A/mm2 Critical current curve Quench protection system I A comparator measures the voltage difference between upper and low coils, which appears in case of quench If the difference appears, the heater (stainless steel strip mounded along all the coils) heats the coils by the capacitor pulse discharge, providing uniform distribution of the stored energy along the wiggler 7 Quench protection system II Voltage distribution diagrams with and without the quench protection system Magnetic measurements  Testing cryostat 700 A PS   Hall probe array (5 probes placed horizontally with 10 mm distance) Status  Wiggler development and design is completed  The wiggler manufacturing drawings passed the technological department  Parts of the spooling device are manufactured and its assembling will start in near future  We have all materials including SC wire  We have the testing cryostat, power supplies for the main coil (700 A) and for the correction coils (2 PSs 10 A)  We have all necessary equipment for magnetic measurement  The quench protection system is under development now Schedule 17.03.07 – 01.10.07: the wiggler design and starting the production of the coiler unit to test the winding technology 01.10.07 – 01.03.08: finalizing of the winding technology and starting of production of the wiggler prototype 15.11.07 – Status report including: magnetic field calculation, winding technology description, drawings of the wiggler prototype and winding tooling, description of the quench protection system 01.03.08 – 01.06.08: yoke and tooling production 01.06.08 – 15.07.08: coils production 15.07.08 – 01.08.08: wiggler installation in the cryostat 01.08.08 – 01.10.08: wiggler test and magnetic Conclusion  The short prototype of the SC wiggler for the CLIC DR is under production at BINP  Main parameters of the wiggler are: Bmax = 2.5 T with the period length of 50 mm and the pole gap of 20 mm  Such a gap allows to have the vertical beam aperture around 12-14 mm  The vertical beam aperture is defined by SR beams passing and wake fields, which may heat the vacuum chamber walls