Generation of GeV energy electrons from laser wakefield acceleration via ionization induced injection

Laser wakefield acceleration (LWFA) is a promising approach to realize table-top accelerators. The injection process into the wakefield bubble to some extent determines the charge, divergence, energy gain as well as the energy distribution of the accelerated electrons. Traditionally, self injection using pure helium or hydrogen gas as the interaction medium was employed to accelerate the electrons. However, very high laser powers are required to achieve self injection at the low densities which are compatible with acceleration to GeV energies. Recently, a new technique, ionization induced injection, which takes advantage of the large ionization potential difference between the inner and outer shell electrons of trace atoms in the plasma, has been demonstrated to generate electron beams beyond 1 GeV at lower threshold laser powers than self injection would require [1].