"A high efficiency three-stage cyclotron has been proposed [1] to provide a 10 MW proton beam in the 1 GeV kinetic energy range for driving the Energy Amplifier. This accelerator complex consists of the following chain: two 15 MeV compact isochronous caylotrons (CIC) feeding a four separated sector ring cyclotron (ISSC) raising the energy up to 120 MeV. A final stage made of ten spiral separated sectors boosts the enrgy in the 1 GeV range. This paper presents some design issues. [1] N. Fiétier and P. Mandrillon, A three-stage cylotron for driving the Energy Amplifier, CERN Internal Report [CERN-AT-95-03 ET] (February 1995)"