  One of the decisive issues in the design and operation of cyclotrons is the
choice of the beam extraction method. Typical methods are extraction by
electrostatic extractors and by stripping. The former method requires DC high
voltage electrodes which are notorious for high-voltage breakdowns. The latter
method requires beams of atomic or molecular ions which are notorious for rest
gas and Lorentz stripping. Here we discuss the conditions to be met such that a
beam will leave the magnetic field of an isochronous cyclotron purely by fast
acceleration.
