1. MICE Target Modelling Ben Shepherd February 2011

2. 2D Modelling A 2d axisymmetric model takes seconds to run (compared to hours for a 3d model) Limitations: – PMs modelled as rings (not 8 wedges) – Can’t introduce an offset

3. 3D and 2D models

4. Results – 2D model y is the distance between bottom edge of PM and bottom edge of coils Force evaluated at r = 8mm, 0.5mm away from PM outer edge Maximum force: 52.0N at y=9mm

5. Effect of increasing PM size PM outer radius: 7.5mmPM outer radius: 8.6mm

6. PM size variation results 15mm diameter  16mm diameter: 22% increase (52.0N  63.5N) PS claims a 6% increase in mass (here, page 14) but I’m not sure of the derivationhere

7. Effect of increasing coil size Coil outer radius: 15mmCoil outer radius: 25mm

8. Coil size variation results We see a ‘saturation’ effect at large radii Force is increased by 18% at r = 25mm (relative to 15mm)

9. Adding steel bobbin Added steel cylinder (0.3mm thick) to inside of coils Shunts some of the field produced by the coils Reduces force by ~33% (In reality, mild steel used with low µ - so would be OK)