Due to complexities with oven, the injection experiments will require preformed H2 plasma. Laser probe experiments will gain more access and flexibility If workable, static fill H2 will allow broad control of plasma density and plasma length. Motive for preformed H2 plasma

Possible Ionization Injection Schemes at FACET Helium lithium oven boundary. Good results so far, but limited parameter control. Not well understood, but we are working on it. Evidence that when laser at high power, ionization injection was suppressed. Down-ramp injection. Very challenging. FACET II scheme requires 100 um ramp. Physics challenges to preserve emittance. Staged injector scheme Ionization injection region followed by fully ionized preformed plasma.

Why you cannot use a bounded ionization injection cell Conflicts with laser transport Experiments with bounded cell failed after 10 minutes at FFTB!

Diagram of Gas Cell Used For FFTB Experiments

Electron Beam ionized plasma seen in gas cell viewport

Plasma ion damage to downstream gas cell foil. 1”

Laser axicon H2 preformed plasma Gas Puff Ionization Injection Concept* *Requires flush and fill approximately every 1000 shots Solenoid valve gas puffer

Gas jet in 4.5” cube with view port

or less

Gas1st2ndW/cm 2 H13.6 eV2x10 14 He x10 15 Ne x10 15 Ar x10 14 Ionization impurity gas selection consider secondary ionization by e-beam