Transformation and absorption of waves in an inhomogeneous beam-plasma system

Concerns the propagation of high frequency electrostatic waves excited by an electron beam in a hot inhomogeneous plasma in a magnetic field. The gradient of the plasma density is assumed to be parallel to the magnetic field. It turns out that in the region of the plasma resonance the waves omega 12,2=1/2( omega 02+ omega c2+or- square root (( omega 02+ omega c2)2-4 omega 02 omega c2cos2 theta )) are transformed into the Langmuir waves with a significantly shorter wavelength. The latter may be strongly absorbed by the Landau damping. Thus, in a hot inhomogeneous plasma there exists a linear process leading to a plasma heating.