Chromatic Correlations at Injection and Related Ejection Problems in Separated Sector Cyclotrons

Injection into a cyclotron, in order to prevent emittance and phase spread dilution, requires proper couplings in the matching. One must first introduce a ¿¿/r¿ associated with an r/¿W coupling (through simplectic conditions) ; according to the angle of the accelerating dees and the choice of harmonic number the(r,r¿) acceptance may also have to be tilted. All these effects are investigated in the case of the GANIL SSC´s. At extraction corresponding correlations exist. For a resonant system, extraction may be difficult when the energy spread is large because of the large coupling induced by resonance. A precessional extraction which has been studied might in this case be more efficient. Other ways for making extraction easier are also considered. Moreover a new method of phase compression at injection into the SSC is presently under study at GANIL.