Photon acceleration: three-wave interaction

Summary form only given. The possibility of photon acceleration in a plasma was studied from the viewpoint of three-wave interaction. A photon with momentum h L q phi and energy h Lophi combines with a plasmon with momentum h L q pl and energy h Lopl to give a photon with momentum h L q phf and energy h Lophf. It was observed that the interaction vertex function for the plasmon-particle can be obtained by the use of the interaction Hamiltonian between particles and longitudinal quasiparticles. Calculation of the vertex function for a specified three-wave interaction process reveals that no transition occurs if the plasma is cold and stationary. It is found that the transition probability reaches a maximum when the plasma particles move in the direction of longitudinal plasma oscillations (plasmons) along with the direction of polarization of vector potential A , resulting in the upshifting of the frequency of the outgoing photon fields