Laser-Plasma Acceleration in a Conical Plasma Channel With Longitudinally Inhomogeneous Plasma Profile

Laser-plasma acceleration is considered as a modern method of accelerating bunches using a wakefield excited by a laser pulse. This paper demonstrates the use of a longitudinally inhomogeneous increasing plasma density gradient in a conical channel to increase of the energy of a self-injected bunch. Comparison of a conical channels with homogeneous and inhomogeneous plasma and also conical and cylindrical homogeneous channels, shows a clear advantage of an inhomogeneous conical channel. The longitudinally inhomogeneous plasma helps to maintain the self-injected bunch in the wakefield acceleration phase and increases the accelerating gradient. The conical geometry prevents laser pulse expanding, and compress it. The combined effect was shown: the inhomogeneous plasma use, the effect of a conical geometry led to significant increasing the accelerating gradient and longitudinal momentum of the bunch.