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Show that it makes little sense placing the dees of a cyclotron into a uniform magnetic field. Specify a rational shape of the pole pieces capable of focusing a particle beam in the centre of the dees. |
Answer» Solution :An ion entering a uniform magnetic field at an ANGLE to the lines of induction will MOVE along a helix to one of the poles of the magnet, and after some time will strike the dees and leave the bunch. To prevent LOSSES, the magnetic field should be made slightly nonuniform (in the shape of a barrel) (FIG. 28.6). It is easily seen that such a field focusses the ions, CONCENTRATING them in the middle plane.
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