STIMULATED RAMAN-SCATTERING OF A TRANSVERSE MAGNETIC (TM) MODE IN A STRONGLY MAGNETIZED PLASMA

A strongly magnetized plasma, e.g., the one encountered in a plasma fi lled backward wave oscillator (BWO), supports an obliquely propagating electromagnetic (EM) mode, k(0 perpendicular )(2)-omega(0)(2)/c(2))(o mega(p)(2)/omega(0)(2)-1), where omega (2)(p) much less than omega(c)( 2), omega(p)(2) much less than omega(0)(2), omega(0) and k(0) are pump wave frequency and pump wave vector, omega(p) and omega(c) are electr on plasma and cyclotron frequencies, c is the speed of light in vacuum and z and perpendicular to refer to the static magnetic field. As thi s mode acquires large amplitude it becomes susceptible to decay into a Trivelpiece-Gould (TG) mode and a sideband electromagnetic mode. The growth rate of the instability scales as gamma similar or equal to 1/4 v(osc)K(z)(k(z)/k(perpendicular to))(1/2)(omega(p)/k(1)c)(3/2), where v(osc) is the electron oscillatory velocity, k and k(1) are the wave v ectors of the low frequency electrostatic (ES) Trivelpiece-Gould mode and EM sideband wave. For typical BWO parameters the growth rate is of the order of the 10(9) s(-1) range. (C) 1997 Elsevier Science B.V.