A Gas-Filled Multipass Cell Compressor Sized by Per-Pass B-Integral and Total Spectral Broadening

This paper presents a computed design for a Herriott-type multipass cell that compresses 1 mJ, 250 fs pulses from an Yb amplifier toward the few-tens-of-femtoseconds range. 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 36 passes at 0.28 rad of nonlinear phase each, a total B-integral of 10.1 rad, a spectral broadening factor of 8.9, an output duration of 32 fs from 250 fs input, a throughput of 0.87 giving 0.87 mJ out, and an output peak power near 27 GW. The binding constraint is identified explicitly: ionisation at the intracell focus if the per-pass intensity is pushed, and coating damage at the mirror spots nearest the cell waist. 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.