Transverse Density Gradients in Blowout Regime Plasma Wakefields*

Laser ionized plasma sources are useful for realizing plasma-based acceleration and focusing of relativistic electron beams.  These plasma sources often use a pulsed gas jet that fires into a vacuum environment, after which a region of the gas plume is fully ionized by the passage of a high intensity laser pulse to form the plasma source.  For most applications, a uniform density is desired within the bulk of the plasma source, however gas jet density profiles are not typically uniform when fired into vacuum.  Here we study the contribution to the wakefields of an approximately linear transverse background plasma density gradient and discuss the implications for beam dynamics in plasma lenses and plasma accelerators.  Early experimental results of a laser-ionized plasma lens in a pulsed gas jet at FACET-II are discussed.