| 摘要 |
A magnet coil assembly is supported by support elements 30 within an outer vacuum container (OVC) 14, the support elements provided with a tension adjusting arrangement 50 to distort the coils in such a way that field homogeneity is improved i.e. to shim the field. The tension adjustment arrangement 50 may comprise adjusting bolts 63 which bear on the OVC and which adjust the tension in a tensile or compressive support rod 54 which passes through a hole 52 in the OVC and is attached to the magnet coil. A vacuum 62 is maintained by bellows 60; therefore the tension adjustment mechanism can lie outside the OVC. The support elements may be used to protect the coil assembly from damage in transit. Once the magnet is installed and energised, the magnetic field is measured and the tension is adjusted to distort the coils to decrease inhomogeneities. This may replace conventional shimming. |
