D2 CONFIGURATIONS P.Fabbricatore & S.Farinon INFN Genova  Starting from previous studies done at CERN, BNL and BLNL, possile cross sections of D2 dipole were preliminary investigated.  Among many analysed lay-outs, three configurations looked promising and we should like to have an opinion from colleagues before continuing and focussing on one configuration.  The main features of these configurations are here described.  The magnetic analyses were mainly done with Roxie, with complementary studies performed with ANSYS and COMSOL

This activity related to D2 is done in the framework o f a collaboration agreement (under definition) R&D ACTIVITIES RELATING TO HIGH LUMINOSITY LHC (HL-LHC) SUPERCONDUCTING MAGNETS between CERN and INFN (The INFN coordinator is G.Volpini). D2 is being developed by INFN Genova and the activities are organised in a Work Package: WP2 PADS Progetto Avanzato per i Dipoli di Separazione (Advanced design of the separation dipoles). Framework

Hystory (brief), Assumptions and General Approach  An iron yoke with a window frame + asymmetric coils was our starting point. We did not look at different lay-outs  First attempts were done for trying to have same angles for left and rigth branch of each coil but different number of turns (missing turns). Roxie + ANSYS large sistematic. Hypothesis soon abandoned in favour of asymmetry in angles (both  and  in the Roxie language).  Five block configuration, one layer coil analysed. Partly this is a heritage of DISCORAP project; partly comes from the need to have as many degrees of freedom as possible  We shall aim at designing feasible coils and magnet  We should like to have soon an idea of mechanics

 Integral field 35 Tm  Magnetic field from (3.5) 4T to 1.9K  Beam separation 188 mm  Coil aperture 105 mm GFR radius 35 mm  Target variations of b2 b3 b4 due to saturation< 10 units  Change of b2 b3 b4 between 6.5 and 7 TeV< 1 unit  Working point on load line max 70% (or rather lower?)  LHC outer layer conductor  Focus on geometrical harmonics and iron saturation effects Hystory (brief), Assumptions and General Approach (cont)

Missing turns ( Abandoned.. but we got sensitivity to the parameters affecting the field quality. Configurations with 58 to 64 turns were studied))

The studies with missing turns showed that in order to better control the field quality we need to have different angles  and  for right and left branches of same coil. We started from the configurations identified with missing turn approach and optimized the angles  and  for both branches of the coil with Roxie. Only three configurations appeared to be promising with 58, 59 and 63 turns. No acceptable configurations with 60,61,62 and 64 turns were found (however our systematic could miss some good lay-out). The study is indeed not yet complete, missing the analysis of stability of the configuration (how much small geometrical deviations are affecting the field quality). Optimizing asymetrically the angles

Configuration INFN_0_1 29 turns both branches 5 asymmetric blocks with turns: 11,8,4,4,2 right 12,8,4,4,1 left Iron window X =190 mm x Y= 117 mm Shimming: R=40 mm, Dx 35 mm, Dy=10 mm, hole R h =20 mm Iron ext 310 mm x 250mm B bore = A B peak = A B peak /B bore = Inductance at T 2.9 mH/m Margin to load line at 4.00 T 60.4% Margin to load line at T 70.2% Main Characteristics Dx Dy R RhRh

Input data for Roxie Configuration INFN_0_1

Load lines Configuration INFN_0_1

Field Harmonics Configuration INFN_0_1

Mag. Field Map Configuration INFN_0_1 Fringe 1 m midplane 18.6 mT

Fringe Field Configuration INFN_0_1 Fringe 1 m midplane with 10 mm cryostat wall 15.0 mT

Configuration INFN_0_1 Mechanical analysis just started. Presently the model is ready.

Configuration INFN_1_1 32 turns left branch 31 turns right 10+7,5,4,3,2 right 19,5,4,2,2 left Iron window X =180 mm x Y=95 mm Shimming: R=40 mm, hole R h =20 mm Iron ext 310 mm x 250mm B bore A B peak A B peak /B bore = Inductance at B= 4.52 T 3.52 mH/m Margin to load line at 4.00 T 51.0 % Margin to load line at 4.52 T 59.2% Margin to load line at 5.00 T 67.4 % R RhRh Main Characteristics

Configuration INFN_1_1 Detail of the coil cross section

Input data for Roxie Configuration INFN_1_1

Load lines Configuration INFN_1_1

Field Harmonics Configuration INFN_1_1

Complex!..Not impossible Courtesy of Susana Izquierdo Bermudez

Many block to block jumps

Configuration INFN_2 Main Characteristics 30 turns left branch 29 turns right 16,8,3,2 right 17,8,3,2 left Iron window X =186 mm x Y=107 mm Shimming: R=40 mm, Dx 30 mm, Dy=10 mm Iron ext 310 mm x 250mm B bore A B peak A B peak /B bore = Inductance at B= 4.57 T mH/m Margin to load line at 4.00 T 57.8 % Margin to load line at 4.52 T 67.6 % Dx Dy R

Input data for Roxie Configuration INFN_2

Load lines Configuration INFN_2

Field Harmonics Configuration INFN_2

INFN_0_1INFN_1_1INFN_2 Mag. Field bore (T) From 4 to 4.5From 4 to 5From 4 to 4.5 Blocks554 B bore /B peak Margin on load line From 60 4T to T From 51 4T to T to 67 5T From 57 4T to T Turns58= = =30+29 Comments1)4T option 2)4.5 T option 3)Lay-out 4)Coil ends 5)Connections 1)4.5 T option 2)5.0 T option 3)Lay-out 4)Coil ends 5)Connections 1)4T option 2)4.5 T option 3)Lay-out 4)Coil ends 5)Connections 6)Very good b2 to b7 7)High b8 (6 units) and b9 (9 units) Summarizing Table All Configurations