| 摘要 |
PURPOSE:To reduce the force acting on a static magnetic field coil, by mounting a current increase rate control means for controlling the increased rate of a current per unit time before reaching a predetermined value when a static magnetic field power source starts the supply of a current to the static magnetic field coil. CONSTITUTION:A current increase rate control means 6 performs control so that the increase rate per a unit time of the current flowing to a normally conductive coil 3 before reaching a predetermined value 7 becomes a definite value by the action of an integration circuit. That is, value of di/dt is made constant, that is, brought to a linear state 9. From this, at the time of the so called rising of the apparatus, the sudden change of di/dt is eliminated and the sudden change of the force proportional to said change is prevented. Therefore, it is unnecessary to increase the strength of the support member for supporting a normally conductive coil to a necessary degree or more and the reduction of a wt. is achieved and the facilitation of planning is promoted and the lowering in system efficiency can be also prevented. Further, by this constitution, the extension of the life of the apparatus as a whole can be expected.
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