Laser Beat Accelerator
Parallel intense photon (laser, microwave, etc.) beams ¿0,k0 and ¿1,k1 shone on a plasma with frequency separation equal to the plasma frequency ¿p is capable of accelerating plasma electrons to high energies in large flux. The photon beat excites through the forward Raman scattering large amplitude plasmons whose phase velocity is equal to (¿0-¿1)/(k0-k1), close to c in an underdense plasma. The plasmon electrostatic fields trap electrons and carry them to high energies: Maximum electron energy Wmax = 2mc2[1-(¿0-¿1)2/c2(k0-k1)2]-1~2mc2(¿0/¿p)2. The multiple forward Raman instability produces smaller and smaller frequency and group velocity of photons; thus the photons slow down in the plasma by emitting accelerated electrons (inverse Cherenkov process).