Structure of the electrostatic wave of linear mode conversion in a magnetized plasma

When an electromagnetic wave is linearly converted into an electrostatic wave, large enhancement of the wave amplitude occurs, due to the large ratio between the group velocities. The objective of this paper is to study the structure of the electrostatic wave field when such a mode conversion takes place in a magnetized plasma, and compare the amplitude enhancement with that of an unmagnetized plasma. In a magnetized plasma, the electric field of an electrostatic wave in the plasma resonance region is in the generic case governed by a third-order differential equation first discussed by Piliya and Fedorov [Zh. Eksp. Teor. Fiz. 57, 1198 (1969)]. The validity and interpretation of this equation is discussed. Full wave solutions obtained numerically are exhibited, and compared with the unmagnetized case. In particular, scaling laws describing how the maximum electric field amplitude for given energy flux depends on the magnetic field parameters are obtained