Reliable operation of a laser plasma accelerator driven free electron laser*

Laser plasma accelerators (LPAs) have emerged as a viable alternative to traditional accelerators for various applications, thanks to their capability to generate high-brightness

beams and much higher accelerating gradients. This enables more compact designs for future light sources, such as free electron lasers (FELs). FEL technology leveraging LPA sources is

progressing swiftly, with several key milestones achieved in recent years. However, significant work remains to be done to move from proof-of-concept experiments to the dependable

operation of LPA-driven FELs. Recent initiatives at the BELLA center's Hundred Terawatt Undulator beamline, which includes an electron beam transport section leading to a 4-meter-

long, strong focusing undulator, have successfully demonstrated the consistent operation of a high-gain FEL in the SASE regime. SASE gain is detectable on 90% of shots with measured

SASE gain in excess of 1000.