Oval test coil for examining mechanical effects in superconducting coils

A method of investigating mechanical effects in superconducting coils has been demonstrated using an oval magnet constructed to produce high mechanical stress in a portion of a small test coil. The oval shape is maintained by an internal longitudinal strut which may be used to prestress the winding and control the longitudinal deformation. Lateral and longitudinal deflections during energization are monitored by linear variable differential transformers. Initial results show very complex deflection patterns, particularly at low field. There are indications of diamagnetic behaviour of the composite twisted multifilamentary conductor below Hc₁ and of possible conductor slippage but much remains unexplained.