Compact Cold-Atom Clock for Onboard Timebase: Tests in Reduced Gravity

We present a compact atomic clock using cold rubidium atoms based on an isotropic light cooling, a Ramsey microwave interrogation, and an absorption detection. Its technology readiness level is suitable for industrial transfer. We use a fiber optical bench, based on a frequency-doubled telecom laser. The isotropic light cooling technique allows us to cool down the atoms in 100 ms and works with a cycle time of around 200 ms. We carry out measurements in simulated microgravity and obtain narrow fringes, up to 1.25 Hz.