20-00577 specifications.pdf

NB688000-20-00577

One closed-cycle cooling system for an existing flow cryostat system with the following specifications:

* Fully closed-cycle system, with no liquid cryogen supply needed and no need to install or operate separate helium recovery, storage, or purification systems.

* Recirculating cold helium, as coolant, must be supplied and recovered via a flexible transfer line suitable for integration with an existing Janis ST-400 flow cryostat on an existing vacuum chamber on an optical table. Must be able to attach and detach the flexible transfer line to and from the flow cryostat.

* Once cold, capable of providing a continuous service temperature (completely uninterrupted) of 4.2 K at the cold tip of the flow cryostat, subject to the heat load/cooling power specifications given below.

* ≥ 0.9 W cooling capacity at 4.2 K at the flow cryostat cold tip.

* ≥ 5 W cooling capacity at 16 K at the flow cryostat cold tip.

* ≤ 150 nm max displacement (vibration) of flow cryostat cold tip with cold tip at 4.2 K. It is suitable to demonstrate this performance with the closed-cycle system cooling a similar flow cryostat to ours (instead of directly demonstrating it on ours), since ours is integrated into a running experiment and vibrations cannot be easily measured.

* Refrigerator head for cooling recirculating helium must be operable in any orientation, and must be fully enclosed in a sound- and vibration-damping cabinet with < 2.5 ft2 laboratory floor footprint. Isolation cabinet must be readily moveable, e.g. on casters.

* Length of flexible transfer line between refrigerator head and tip of portion inserted into flow cryostat must be at least 5 feet, to allow for required reach across optical table.

* Must be possible to locate the compressor(s) ≥ 20 m from the refrigerator head and flow cryostat. Any hoses, lines, and cabling between compressor(s) and a refrigerator head must enable this.

* Water-cooled compressor unit(s).

* If the system will require permanent removal of existing internal thermometry (single PT100 resistor) and heater (for temperature control) from the cold tip of the flow cryostat, an equivalent replacement thermometer (calibrated from 300 K to 4.2 K or below) and equivalent wattage heater for the flow cryostat cold tip must be provided, suitable for continuous operation when the closed-cycle system is running.