  The Electron String type of Ion Sources (ESIS) was developed, constructed and
tested first in the Joint Institute for Nuclear Research. These ion sources can
be the appropriate sources for production of pulsed C4+ and C6+ ion beams which
can be used for cancer therapy accelerators. In fact the test ESIS Krion-6T
already now at the solenoid magnetic field only 4.6 T provides more than 10^10
C4+ ions per pulse and about 5*10^9 C6+ ions per pulse. Such ion sources could
be suitable for application at synchrotrons. It was also found, that Krion-6T
can provide more than 10^11 C6+ ions per second at 100 Hz repetition rate, and
the repetition rate can be increased at the same or larger ion output per
second. This makes ESIS applicable at cyclotrons as well. As for production of
11C radioactive ion beams ESIS can be the most economic kind of ion source. To
proof that the special cryogenic cell for pulse injection of gaseous species
into electron string was successfully tested using the ESIS Krion-2M.
