Measurement and hydrodynamic modeling of meter-scale plasma waveguides for multi-GeV electron accelerators*

In recent experiments, low density, hydrodynamic plasma waveguides from Bessel beam-induced optical field ionization were employed to achieve multi-GeV laser wakefield acceleration (LWFA)  [1]. Improving the electron energy and beam quality requires fine control of electron injection and acceleration inside the waveguide.  A full experimental characterization of the plasma waveguide evolution in 3 dimensions, along with an accurate hydrodynamic model, are therefore indispensable for channel-guided LWFAs. We present time resolved two-color interferometry-based measurements of the plasma and neutral density profiles during plasma expansion in various gases, including hydrogen, nitrogen, and argon via under various conditions. Complementary to the measurements, we present hydrodynamic simulations using the SPARC module of TurboWAVE  [2,3], which uses as the initial condition the Bessel beam heated plasma modeled by our code YAPPE [4].

1.    B. Miao, et al., Multi-GeV Electron Bunches from an All-Optical Laser Wakefield Accelerator, Phys. Rev. X 12, 31038 (2022).

2.    D. Gordon, et al., SPARC—A Simulation Model for Electrical Charges, Nav. Res. Lab., Washington, DC, USA, NRL Memo. Rep 6706 (2006).

3.    D. F. Gordon, et al., A Ponderomotive Guiding Center Particle-in-Cell Code for Efficient Modeling of Laser-Plasma Interactions, IEEE Trans. Plasma Sci. 28, 1135 (2000).

4.    L. Feder, et al., Self-Waveguiding of Relativistic Laser Pulses in Neutral Gas Channels, Phys. Rev. Res. 2, 043173 (2020).