Trapped-ion instabilities in ion-acoustic wave

Growth of two types of sideband waves has been observed experimentally when a relatively large-amplitude ion-acoustic wave propagates in a collisionless plasma having the electron-to-ion temperature ratio Te/Ti≈20. The observed frequency spectrum and growth rate, as well as the frequency and amplitude ranges of the large-amplitude wave for which the sideband wave growth is observed are in good agreement with the theory of trapped particle instabilities. The sidebands extract the energy from the large-amplitude wave and cause it to be heavily damped.