Published online by Cambridge University Press: 13 March 2009
This paper presents a paraxial theory of relativistic self-focusing of a Gaussian laser beam in plasma for a time-harmonic plane wave at arbitrary beam intensity. Since the relativistic mechanism is instantaneous, the theory is also applicable to self-focusing of laser pulses. The analysis leads to two values for the critical beam power for self-focusing, Pcr1 and Pcr2. When P < Pcr1 < Pcr2, the beam diverges. When Pcr1 <P <pcr2, it first converges, then diverges, and so on. When P > Pcr2 it first diverges, then converges, and so on.