  We discuss the principle possibility of stripping extraction in combination
with reverse bends in isochronous separate sector cyclotrons (and/or FFAGs). If
one uses reverse bends between the sectors (instead of drifts) and places
stripper foils at the sector exit edges, the stripped beam has a reduced
bending radius and it should be able to leave the cyclotron within the range of
the reverse bend - even if the beam is stripped at less than full energy.
  We are especially interested in $H_2^+$-cyclotrons, which allow to double the
charge to mass ratio by stripping. However the principle could be applied to
other ions or ionized molecules as well. For the production of proton beams by
stripping extraction of an $H_2^+$-beam, we discuss possible designs for three
types of machines: First a low-energy cyclotron for the simultaneous production
of several beams at multiple energies - for instance 15 MeV, 30 MeV and 70 MeV
- thus allowing to have beam on several isotope production targets. In this
case it is desired to have a strong energy dependence of the direction of the
extracted beam thus allowing to run multiple target stations simultaneously.
Second we consider a fast variable energy proton machine for cancer therapy
that should allow extraction (of the complete beam) at all energies in the
range of about 70 MeV to about 250 MeV into the same beam line. And third, we
consider a high intensity high energy machine, where the main design goals are
extraction with low losses, low activation of components and high reliability.
  The price that has to be paid for these advantages is an increase in size
and/or in field strength compared to proton machines with standard extraction
at the final energy.
