The use of ion sources in induction linacs for heavy ion fusion is fun
damentally different from their use in the rf linac-storage rings appr
oach. Induction linacs require very high current, short pulse extracti
on usually with large apertures which are dictated by the injector des
ign. One is faced with the problem of extracting beams in a pulsed fas
hion while maintaining high beam quality during the pulse (low emittan
ce). Four types of sources have been studied for this application. The
vacuum arc and the rf cusp field source are the plasma-types and the
porous plug and hot alumino-silicate surface source are the thermal ty
pes. The hot alumino-silicate potassium source has proved to be the be
st candidate for the next generation of scaled experiments. The porous
plug for potassium is somewhat more difficult to use. The vacuum arc
suffers from noise and lifetime problems and the rf cusp field source
is difficult to use with very short pulses. Operational experience wit
h all of these types of sources is presented.