| Line 1 was replaced by line 1 |
| - !Magnetic Forces |
| + !!Magnetic Forces |
| At line 2 added 2 lines. |
| + !Radial forces |
| + |
| At line 25 added 55 lines. |
| + |
| + !Taking the torque into account |
| + |
| + In general, the forces or not only radial but also tangential, |
| + inducing a torque onto the magnet. For estimating the forces |
| + on the fixation, we need to take into account the distance of |
| + the fixation points from the coil center. |
| + |
| + For MA7, with a mean coil radius of about 100 m and fixation points |
| + at about 150 mm from the coil center, we get the following: |
| + |
| + Ro: object distance (mm)\\ |
| + phi: angle (deg) between field direction and direction of object, for maximum force on fixation\\ |
| + Fp: force when object on magnet axis (in field direction) |
| + Ft: maximum total force on fixation |
| + |
| + ||Ro ||phi ||Ft / Fp |
| + |<600 | 0 | 1.0 |
| + | 800 | 20 | 1.04 |
| + | 1000 | 27 | 1.13 |
| + | 1200 | 32 | 1.25 |
| + |
| + |
| + |
| + ! Approximation of Forces (taken from OI Magnet Manual) |
| + |
| + As a rough guideline the following estimation can be made. |
| + For iron placed in a gradient of 500 G/m the force due to the field is equal to the mass of the object. |
| + For larger field gradients: Force = 10 * mass * gradB / 500 with Force, mass and gradB in (N, kg, Gauss/m). |
| + |
| + ! typical Field Limits for Common Devices |
| + |
| + The following devices should be kept outside these limits: |
| + |
| + |Field in Gauss| Device |
| + |1 | Motorvehicles, Elevators |
| + |10 | large steel equipment |
| + |30 | structural steel beams |
| + |
| + |
| + Fields larger than stated below might affect the following devices: |
| + |
| + |Field in Gauss | Device |
| + |1 | electro microscopes |
| + | |x-ray machines |
| + | |accurate scales |
| + | | image intensifiers |
| + |5 | pacemakers |
| + | 10 | credit cards |
| + | | watches |
| + |20| magnetic storage media (HDD) |
| + |50| magnet power supply |
| + | | Turbopumps (typically) |
| + |
| + |
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