Lawrence Berkeley National Laboratory
Enhancement of Laser Injection Methods by Plasma Density Gradients
- Author(s): Fubiani, G.
- Esarey, E.
- Nakamura, K.
- Schroeder, C.B.
- Leemans, W.P.
- et al.
Plasma density down-ramps are proposed as a method for improving the performance of laser injection schemes. A decrease in density implies an increase in plasma wavelength, which can shift a relativistic electron from the defocusing to the focusing region of the accelerating wakefield. Also, a decrease in density leads to a decrease in wake phase velocity, which lowers the trappingthreshold. The specific method of two-pulse colliding pulse injector was examined using a 3D test particle tracking code. A density down-ramp of 30% led to an order of magnitude enhancement of the trapping fraction compared to the uniform plasma case, without degrading other bunch properties.