Effects of an Axial Static Magnetic Field on Laser Wake Field Excitation and Subsequent Electron Acceleration in a Plasma

Effects of a static and uniform magnetic field are studied on the excitation of laser wake field in the plasma. The amplitude of wake field increases manifold on applying the magnetic field. The axial magnetic field acts as a guiding field and constraints the transverse movement of plasma electrons which results into a larger interaction length for electron acceleration. In presence of magnetic field, the oscillatory velocity of electron enhances by the electron cyclotron resonance, resulting to high amplitude plasma wave. If size of laser pulse is comparable to the plasma wave period, the driven plasma wave gets maximum amplitude. The large amplitude plasma wave transfers its energy to accelerate the plasma electrons at resonance. Electrons gain energy via Cerenkov resonance at later stages as Doppler shifted wave frequency approaches to cyclotron frequency of electrons. The present study is significant for radiation generation (e.g. X-rays, terahertz radiation) which may be utilized for material characterization.