Pulse Tube Cooled 4 K Closed-cycle Refrigerators
Janis Research offers pulse tube cooled 4 K closed cycle refrigerators with sample in vacuum or sample in exchange gas.
Sample in vacuum
These pulse tube cooled 4 K closed cycle refrigerators are examples of sample in vacuum systems based on our SHI-4 Series cryocoolers.
Model PT-SHI-4 4 K pulse tube cryocooler with optional mounting stand for optical table
This is a custom-built sample-in-vacuum cryostat built upon the 1.0 W Sumitomo RP-082B2 pulse tube cryocooler. The sample area contains an 8 in diameter OFHC copper cold plate with 275 M4 helicoiled holes on a 10 mm grid. The
radiation shield is 9.5 in diameter with four fused quartz cold windows. The outer window block and radiation shield are demountable in the sample area for easy access to the cold plate. The radiation shield anchor and the cold plate
are both equipped with independent heaters and temperature sensors. The mounting stand is designed to interface with a metric optical table.
SMA feedthroughs connected to semi-rigid cables with heat sinking on the radiation shield anchor and on the cold plate deliver microwave signals to the sample area. Multipin feedthroughs allow for up to 78 individual wires to the sample area, not including the connections for the heaters and temperature sensors.
This system had an ultimate base temperature of 2 K on the cold plate and <26 K on the radiation shield anchor. The cooldown time from room temperature to <4 K on the cold plate was 95 min (60 Hz).
Special Model PTSHI-4-5
This model PTSHI-4-5 features a Sumitomo 0.5 W cooling power pulse tube for low vibration operation. The long extension is designed so the sample is positioned at the center of the poles of an electromagnet. There are two extensions with o-ring sealed windows that extend out, each 45 degrees from the cold finger extension. The orientation of these extensions matches the geometry of the electromagnet allowing optical access to the sample in field. The end of the extension can be easily removed via a taper seal (no bolts or clamp) for quick sample change. These end caps can be altered in design to fit other possible applications such as an aluminum dome for use with neutron scattering studies. This particular system had a base temperature of ~3 K. High-temperature options up to 500 K are available.
Model PTSHI-4-5 with rotating stand
This model PTSHI-4-5 features an optional rotating stand that allows the user to flip the entire cryostat upside-down. This is convenient for changing samples. The cryostat itself is rather heavy and it doesn't have any flat surface that will allow it to rest upside-down by itself. Without this rotating stand, gaining access to the sample area would be very difficult and inconvenient. This particular stand is designed to hold the cryostat 50 mm above the surface of an optical table but could be designed to hold the cryostat at any height specified by the customer.
Sample in exchange gas
These pulse tube cooled 4 K closed cycle refrigerators are examples of sample in exchange gas systems based on our SHI-950 Series cryocoolers.
As shown in the illustration, Janis Research designed a cryostat for use with easyLab's Diacell® CryoDAC-LT System high-pressure cell. (However, any of their LT cells would be suitable for the cryostat.) The photo shown is a cryostat designed for use with easyLab's OmniDAC gas membrane driven diamond anvil cell.