Abstract
A short pulse laser of finite spot size is modeled as an amplitude modulation in time and transverse dimension. The laser exerts a time‐dependent curl‐free ponderomotive force Fp on the electrons, imparting to them a transverse velocity. When equilibrium plasma density has a gradient ∇n0⊥Fp the electron current density is irrotational, producing a quasistatic magnetic field. The relevance of the process to plasma accelerators and moving ionization fronts is discussed.