SIS 100 – Fast ramped superconducting magnets E. Fischer, GSI Darmstadt Meeting of the Design Study Committee for the EU contract "DIRACsecondary-Beams" for the FAIR project January 19, 2006 at GSI, Darmstadt, Germany

R&D objectives Reduction of eddy / persistent current effects ( losses)  in yoke iron, yoke structure and coil Guarantee of long term mechanical stability (≥ 2  10 8 cycles )  coil structure, fatigue / crack propagation of the conductor  coil support structure Improvement of DC-field quality  2D / 3D calculations Optimization of the conductor and the cooling system  model magnets / full length magnets Optimize cryogenic stability and magins of the conductor Related: Structure of the vacuum chamber  thin-walled stainless steel or ceramic Necessary developments EU-FP6 work GSI with :  JINR  BNN, Accel  Accel, BNN, JINR  BNN, Accel, JINR  JINR  Accel, BNN

R&D Phases according to EU-FP6 1. Milestone: report delivered

R&D Phases according to EU-FP6

EU FP6 participants: GSI, JINR, BNN, Accel Accel, BNN, GSI, JINR R&D Phases according to EU-FP6

Nuclotron R&D: loss reduction IMPROVEMENTS OF THE DIPOLE: AC LOSS REDUCTION at 4.5 K by a factor of 2

How does the prototype dipole look like ? Yoke (cold iron) Laminations (homogenisation slits, neg. shimming) glued endblocks with slits (eddy current reduction) Rogowski end profile stainless steel endplate stainless steel structure Coil standard Nuclotron cable / low loss wire 2 layer, 16 turns reduced bedstead (eddy current reduction) rigid coil structure (G11) coil ends restrained

Fixation of the aperture and redesign

Quadrupole: analogous redesign tested design with two slits and reduced construction elements redesigned lamination for larger aperture

Current dumping SIS100 dipole ring Current dump with  = 0,25 s (equivalent to – 8T/s) R dump_total is distributed along 6 resistors so that: R 1dump * I op < 1 kV V coil to ground < 500 V T max_dipole < 350 K No quench heaters No cold by pass Current dumping as for a DC magnet string Feasibility studies for the quench protection scheme

Prepreg Version  Insulation concept is similar to the Nuclotron cable insulation concept  Consists of two layers of Poly- imide on top of which two layers of Prepreg are wound  The Prepreg insulation does not harden as fast under room temperature conditions as the wet insulated Nuclotron cable, but nevertheless the possible storing time of this cable is limited Model coil: insulation R&D

All-Kapton  Insulation is similar to the insulation concept of the Rutherford cable for the LHC Dipoles  On top of two layers of normal Polyimide, two additional layers of adhesive Polyimide are wound SC cables with Prepreg insulation and comb elements

Model coil: mechanical stability  comb structure elements (G11)

Model coil: mechanical design  New winding scheme for technological improved layer transition !

 The aspects of the magnet design and its industrial realisation are considered in detail  Several technological approaches were developed Original Nuclotron cable: wet insulation system (difficult for a series production) 2 alternative insulation concepts of the Nuclotron conductor (“Prepreg” and “All-Kapton”) were developed and tested with success. The “All-Kapton” insulation improves the storage time compared to the original Nuclotron conductor and allows for easy handling during winding The concept of structural elements: For a better positioning of the conductor during winding and to improve the mechanical properties of the winding pack. Material data were collected and different structural elements were produced. Choosing G11 as a suitable material, samples of the winding pack with Prepreg and with All-Kapton insulated conductor were manufactured. The feasibility of the concept was shown. New winding concept of the coils especially in the head area was also investigated: Technological improved layer-jumps in the coil head area. Model coil: Summary

Analysis of:  SIS 100 basic design  FE Model  Results & Conclusions: w/o Prestress,w/ Ceramic Tube  1st iteration: plate with fixed support  2nd iteration: elastic bearing  Substrate: comb or block Cable and coil: FEM calculations

 The cooling tube has to carry the highest loads and is the most endangered component  Design of coil without prestress does not exceed stress limits but has a potential risk for damaging the cooling tubes during lifetime: = further studies recommended  Design with fixed prestress plate exceeds stress limits in the cooling tubes: = not recommended  Design with elastic bearing does not exceed stress limits of any component: = recommended but design not available yet  Additional fatigue test for CuNi at 4.5K recommended FEM results: cooling tube

 Results of analysis with almost homogenous mixture of epoxy/ glass demonstrate low stress level in substrate for static and pulsing loads  Substrate in block shape decreases the stresses in the cooling tubes compared to comb shaped substrate; however the block material and the fabrication method of coils with block substrate are not yet available  Sufficient material data are not available, especially at 4.5K: = more investigations necessary FEM results: comb structure

All the basics for the sis100 full length prototype dipole design and construction are obtained All necessary parameters needed for the further r&d on the sis100 quadrupoles are practically fixed The coil support structure seems to be an appropriate component to stabilize the coil and offers important advantages:  Precise positioning of the conductor with certain defined distance between conductors  More uniform distribution of loads on the CuNi tubes (no single pressure contact lines)  Easier winding process on a guiding support  Series production simplified Further actions/decisions:  Confirm design without prestress or develop suitable prestress device  Evaluate details for analyses of the coil heads  Define parameters/specification for prototype Conclusions by GSI-JINR-BNN-ACCEL