The cyclotron frequency is also useful in non-uniform magnetic fields, in which ( assuming slow variation of magnitude of the magnetic field ) the movement is approximately helical-in the direction parallel to the magnetic field, the motion is uniform, whereas in the plane perpendicular to the magnetic field the movement is, as previously, circular.
22.
For \ omega _-the value of the radical is the same ( slightly less than \ omega _ c / 2 ) but it is being subtracted from \ omega _ c / 2 resulting in a small number equal to \ omega _ c-\ omega _ + ( i . e . the exact amount that the cyclotron frequency was reduced by ).
23.
Ingmar Bergstr�m, former director of the Manne Siegbahn Institute at Stockholm, was a member of the Scientific Policy Committee at CERN . He became very interested in the new technique and initiated his own trap project named SMILETRAP . The system was built and tested at Mainz and then transferred to Stockholm : The Stockholm-Mainz Ion LEvitation trap ( SMILETRAP ) has specialized in highly charged ions and thus achieves high resolving powers at the corresponding cyclotron frequencies.
