Operating frequency in excess of 2500Hz with precision-balanced, low-mass rotors.

Gas bearings for non-contact operation, ensuring a maintenance-free service life in excess of 10 years. Absolut System benefits from a 30-year heritage acquired through the integration of OFTTECH experts (TRL 9 technology with the MELFI project).

Possibility of pre-cooling with radiators. Flexible integration capability with large-area or dispersed cooling.

Cryogenic coolers for Earth observation missions must be capable of delivering significant cooling power at an operating temperature of around 50K (for IR detection). Conventional single-stage Stirling or Pulse Tube chillers are systems that involve low-frequency moving parts (in the compressor and in the Cold Finger for the Stirling) that induce microvibrations. Although active microvibration suppression, combined with careful selection and manufacture of cooler parts, can lead to low exported microvibrations (< 100mN in all directions at all harmonics), increasingly stringent requirements on induced microvibrations at system level can lead to very complex solutions to overcome this issue (e.g. suspended coolers and radiators, flexible thermal link assemblies that degrade overall thermal performance).

The Reverse Turbo-Brayton developed by Absolut System puts exported vibrations well beyond the critical bandwidth. Our turbomachinery specialists have designed miniature high-speed rotating machines and high-efficiency recuperators to ensure efficient cooling with low vibration and high reliability using hydrodynamic gas bearing technology.

The Turbo-Brayton developed is arranged in a conventional configuration. It consists of a compression brick, a recuperative heat exchanger, usually an expansion turbine, and the thermal heat exchanger, interfaced with the customer’s application (focal plane, detector, heat shield, etc.). The compression brick can have different configurations: usually 2 compression stages, with a two-stage compressor or 2 single-stage compressors. All these components can be integrated into a compact unit, or spread over fairly large surfaces, interconnected by lengths of tubing. Refrigeration can be supplied to multiple loads at a single temperature, or at several different temperatures.