A simple and efficient passive vibration isolation system for large loads in closed-cycle cryostats

We present a system for passive damping of vibrations along three spatial degrees of freedom for cryostats equipped with closed-cycle coolers. The system, designed to isolate a payload of 30 kg, consists of two stages of isolation for vibrations in the vertical direction. The first isolation stage incorporates a trapezoidal beryllium copper cantilever blade. The second stage is attached to the blade via a steel wire and consists of four extension springs with an extended length of 370 mm. At 1.6 K, the stages possess vertical resonance frequencies of 2.1 and 1.3 Hz, respectively. The vertical length of the setup with a cumulative length of 580 mm also acts as a pendulum with a resonance frequency of 0.65 Hz. In the frequency band from 5 to 200 Hz, the frequency-integrated acceleration decreased from 6.7 × 10^-3 to 4.3 × 10^-5 g along the horizontal direction and from 4.3 × 10^-3 to 7.2 × 10^-5 g along the vertical direction. This corresponds to a reduction in vibrations by factors of 156 and 60, respectively. Overall, we achieve a simple, robust, and cost-efficient vibration isolation system for upgrading standard-type cryostats.