PULSAR ECLIPSING MECHANISMS - THE EFFECT OF PHOTON-BEAM-INDUCED ACOUSTIC TURBULENCE

Pulsar eclipse due to induced three-wave interactions involving low-fr equency acoustic turbulence is discussed. We consider both the case of electron acoustic waves when the ion temperature T-i is higher than t he electron temperature T-e and that of ion acoustic waves when T-e > T-i. In each case the corresponding growth rate for low-frequency acou stic waves induced by a high-frequency photon beam is evaluated. For T -i>T-e, the maximum growth rate for electron acoustic waves depends st rongly on T-i/T-e and may be comparable to that of a Langmuir counterp art for sufficiently large temperature ratio T-i/T-e. It is shown that induced scattering off electron acoustic waves can be important and c an cause pulsar eclipse. We show also that for T-e> T-i and in the sma ll-angle approximation, growth of low-frequency ion acoustic waves due to the photon beam is always slower than Langmuir waves and the corre sponding induced scattering is less effective than induced Raman scatt ering. Thus, induced Brillouin scattering involving low-frequency ion acoustic waves cannot be the main cause for pulsar eclipses.