A Cryogenic Yb:YLF Amplifier Sized by Saturation Fluence and Stored Energy at 77 K

This paper presents a computed design for a cryogenically cooled Yb:YLF amplifier operating near 77 K as a high-energy, high-repetition-rate stage at 1020 nm. The sizing follows from applying the relevant intensity, thermal, nonlinear and geometric bounds at a single stated operating point, with every number produced by a deposited computation. The headline result is a saturation fluence of 1.77 J/cm2 at 77 K, a stored energy of 6.2 J in the stated crystal volume, an extracted pulse energy of 3.4 J at 55% extraction, and a repetition-rate ceiling near 34 Hz set by a 40 W cryocooler lift against the deposited heat fraction. The binding constraint is identified explicitly: cryocooler vibration coupling into beam pointing and frost or contamination on cold optical surfaces inside the vacuum housing. The design is SIMULATED, NOT MEASURED: no hardware was built for this study, and all performance figures are predictions from stated assumptions, offered as a basis for a build decision and a measurement plan.