Envelope Model Simulation of Realistic Laser Pulses at the Texas Petawatt Laser

Kathleen Weichman, University of Texas

In laser wakefield acceleration, an intense laser pulse drives a nonlinear plasma wave, generating accelerating gradients up to three orders of magnitude higher than found in conventional radio-frequency accelerators. Laser wakefield accelerators can produce sub-milliradian divergence, femtosecond-duration electron bunches over acceleration lengths of less than a meter. Quasi-monoenergetic electron spectra in excess of 2 GeV have been reported at the Texas Petawatt Laser facility1. Gaussian and near-Gaussian beam simulations predict energies higher than have been experimentally demonstrated2. Real laser pulses often exhibit intensity and phase irregularities and may deviate significantly from the ideal Gaussian profile. New methods in particle-in-cell (PIC) codes, such as the implementation of the envelope model in VORPAL3,4, have lowered the computational cost of simulating the early evolution of laser wakefields in three dimensions. Future simulations will capture the entire accelerating structure, starting with an early-time envelope model simulation, continued by a boosted frame PIC simulation5. As the first stage in a full 3-D laser wakefield simulation, we present early-time VORPAL envelope model simulations of wakefields produced by laser pulses with experimentally measured profiles from the Texas Petawatt Laser.

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Abstract Author(s): K. Weichman, A.V. Higuera, D.T. Abell, B. Cowan, N. Fazel, J.R. Cary, M.C. Downer