Thermal packaging of aerospace laser assemblies using copper-water heat pipes: experimental evaluation and integration approach

Future space missions increasingly rely on high‑performance laser systems that require compact, lightweight, and highly reliable thermal management to maintain optical stability under demanding environmental conditions. This work presents a thermal packaging approach for the Advanced Laser Transmitter Assembly (ALTA), developed as a study within the Aeolus-2 program by Fraunhofer Institute for Laser Technology ILT and Airbus Defence and Space, using copper–water heat pipes as the primary passive heat transport elements. The objective is to manage distributed heat loads across a tightly constrained optical bench while meeting strict contamination control, long‑term stability, and gravity‑independent operational requirements. The methodology combines dedicated all‑metal thermal interfaces, cascaded heat‑transport concepts for extended distances, and a series of targeted experiments to assess gravity effects, bending sensitivity, and unit‑to‑unit performance variability. The results demonstrate that copper–water heat pipes enable robust, low‑gradient heat transport over complex routing paths, maintain stable performance across all relevant orientations, and preserve thermal behavior when minimum bending radii are respected. The demonstrated architecture provides a compact, passive, and contamination‑safe thermal management solution suitable for next‑generation spaceborne laser instruments and offers practical integration guidelines for implementing two‑phase heat transport in precision optical systems.