The Alfven ion cyclotron (AIC) mode is spontaneously excited due to a
temperature anisotropy in the ion cyclotron range of frequency (ICRF)
heating experiments in the GAMMA10 tandem mirror. The behavior of the
AIC mode is studied when the second harmonic electron cyclotron resona
nce heating is applied additionally It is confirmed experimentally, th
at the excitation of the AIC mode is determined solely by the ion pres
sure and the ion pressure distribution.