A new kind of open-resonator for a quasioptical gyrotron-an axisymmetr
ical quasioptical cavity of oblique rotation at arbitrary angle (AQCOR
AA)-is proposed. Using scalar diffraction theory and an approximate me
thod, the field distributions in the AQCORAA are derived, and the infl
uence of rotating angle on the field distributions is analysed. The st
ored field energy in the cavity is also obtained.