Optimizing chirped laser pulse parameters for enhancing electron energy in a preformed ion channel

The direct laser acceleration (DLA) of electrons in a preformed ion channel is examined theoretically using a chirped circularly polarized (CP) laser pulse. The electron acceleration and energy gain from the direct laser beam are enhanced by the effects of linear frequency chirp and the electrostatic space charge field created in the ion channel. The electron trapping and acceleration is strengthened by the frequency chirped CP laser pulse within the created ion cavity. The presence of a preformed ion channel, on the other hand, confines oscillatory electron motion and injects it into the accelerating fields of the laser. This provides a strong betatron resonance between the electrons and electric fields of laser pulse inside the plasma-ion cavity. The chirped CP laser pulse appears to get more energy for electrons than the transformed limited laser pulse when the parameters of the chirped laser pulse and the density in the preformed ion channel are tuned. This study with a chirped CP laser pulses added a new dimension to the DLA mechanisms in a plasma-ion channel.