  The concept of large-radius multistage coaxial cyclotrons having separated
orbits is described, to generate proton beams of 120-2000 MeV energy at tens of
GW pulsed and hundreds of MW in continuous beam power operation. Accelerated
beam losses must be less than 0.1 W/m for the intercepted average beam power
linear density. The concept is inherently configured to actively compensate the
longitudinal and transverse space charge expansion in beam bunches. These are
based on (1) actively varying the bunch acceleration equilibrium phase while
maintaining isochronism, independently for each cyclotron turns; (2)
independently changing the acceleration voltage for each turn together with
orbit corrections that preserve isochronism; (3) independently changing the
transverse betatron oscillation tune shift, to assure non-resonant operation.
Also, (4) sextupole lenses are included to compensate for chromaticity effects.
Moreover, the concept is based on optimum uses of practical successful results
so far achieved in beam acceleration and storage techniques. This accelerator
can be used to deliver a pulsed intense source of neutrons without the use of
storage rings, and to drive the different transmutation technologies. As an
example of such a cyclotron system, we describe our approach of accelerating
single-bunch proton beams at up to 1 GeV energy, with pulsed beam power of 80
GW and bunch duration of 2 ns. The exemplar cyclotron accelerator system is
configured to be located in the shielded structure of the 6-GeV Yerevan
Electron Synchrotron. The cost of such a cyclotron system is estimated to be
approximately 40,000,000 US dollars, if implemented in Armenia at substantially
reduced labor costs.
