ForcesintheCaptureSolenoid.pptVIP

Forces in the Capture Solenoid Peter Loveridge P.Loveridge@rl.ac.uk STFC Rutherford Appleton Laboratory, UK 16-09-2008 Scope Have carried out a study of the magnetic forces acting on the capture solenoid coils. Will present a summary of results for: “Study-2” geometry “Helmholtz” geometry Thoughts on optimisation of field vs bore vs magnetic forces Next steps Study-2 Solenoid Baseline design from Study-2 (2001) Superconducting outer solenoid Nb3Sn CICC @ 1.9 K, generates up to 14 T Normal conducting insert Water cooled copper coil, generates up to 6 T Generates high field (20 T) in a large bore (150 mm) in order to capture pions Pion capture is related to the product of B x R In study-2, B is pushed to an absolute maximum in order to minimise the overall size (and cost) of the magnet Study-2 Solenoid Forces Cumulative axial compressive force in excess of 10,000 metric tonnes! Axial Forces between the first 5 SC coils ~balance They share a single cryostat and react against one another Forces balanced inside the cryostat Radial forces are enormous Equivalent to an internal pressure of ~1000 bar in first SC coil Large radial force = large tensile hoop stress in the coil Could be a particular problem for the (low strength) copper insert coils “Helmholtz” Split Solenoid A development of the study-2 design to include a gap at the target location So-called “Helmholtz” design Gap permits lateral access for a target “wheel” or conveyor Field quality issue – field “trough” at the target interaction region Initial studies suggest that this causes a loss in captured pions of the order ~10% Increasing the gap size further exaggerates the field trough i.e. we should reduce the gap to a minimum Currently 400 mm Note: trough in field profile generated almost entirely by contribution from insert coils “Helmholtz” Split Solenoid Forces Cumulative axial compressive force in excess of 16,000 metric tonnes! Axial Forces between the first 6 SC coils ~balance Can we house all these