  Gasdynamic electron cyclotron resonance ion sources are known for their
ability to produce huge currents of low to moderately charged ion beams with
superior quality. This is achieved by means of tens of kW of microwave heating
power, leading to high plasma density. Average power density in the plasma
chamber may reach hundreds of W/cm$^3$, which poses very high thermal load to
plasma chamber walls. A water-cooled plasma chamber has been developed for the
GISMO gasdynamic ECRIS, which is able to handle 10 kW of input microwave power
with average power density in the plasma of 250 W/cm$^3$. The plasma chamber
was manufactured and successfully tested for 200 hours.
