650 mW / 7 mm slip-on


The LSF9987 is a slip-on cooler based on the same miniature moving-magnet flexure-bearing compressor as used in the LSF9997. The 7 mm slip-on cold finger design ensures it can be integrated without the need for special IDCA integration facilities, while still retaining the performance, power density and reliability of the LSF99xx series.


  • Slip-On design
  • Baseline MTTF*: 45 000 hour
  • Compressor dimensions: 44×119 mm
  • Cold finger 7 mm
  • Mass: 1.05 kg
  • Cooling power @ 80K/23°C (Typical)**: 650 mW
  • Input power: < 18 W
  • Operating temperature range: -45/85 °C

*: See Whitepaper MTTF01_Z84.
**: See Whitepaper Qe01_Z84.

General info – LSF

The result of many years of fundamental and experimental research have been condensed into state of the art design of a very reliable miniature Stirling cooler, combining two technical breakthroughs, flexure bearings and moving magnets.

These two breakthroughs have resulted in an extremely reliable cryocooler, without sacrificing other important aspects such as affordability, compactness and weight. Flexure bearings allow for movement of the compressor pistons in axial direction, yet it features very high stiffness in the radial direction thus avoiding contact between piston and cylinder wall. This results in extremely long lifetimes, proven by lifetime tests. In these tests almost all coolers are still running well within specification after at least 20.000 operational hours.

The design of the correct flexure geometry is critical. Dedicated Finite Element Modeling techniques have been used to optimize the design and to ensure that the fatigue stress levels of the material are never exceeded. Mounting of the flexure is performed using a patented assembly procedure. The use of stationary coils and moving magnets has removed several common cryocooler failures. As the coils are placed outside the helium working gas, there is no contamination of the working gas due to potential outgassing and there is no need to use vulnerable hermetic feed throughs. On top of that, the use of moving magnets implies that there are no flying leads between the coil and the stationary world.

Thales Cryogenics LSF-range of coolers has proven to provide excellent performance under extreme conditions, combining a long life operation with affordability. This provides the perfect cooling solution for highly demanding applications such as constant surveillance, space and aircraft. As in the UP-LS series, the LSF coolers can be combined with several free displacer cold fingers, in both closed cold finger design and in dedicated IDCA design, offering the user the ability to choose the right finger in terms of cooling power and mechanical requirements.