Sample Environment - Cryogenic Vacuum
Cryogenic vacuum is obtained in a cryo-cooled volume after reaching the condensing point of the used exchange gas or left over gas particles. Values below 10-15 mbar or even lower can be reached - depending on the specific environmental conditions.
The cooldown time is defined as the period between starting the automated cooling process and reaching the guaranteed base temperature. Where pumping is also automated the time is specified for an environment with low humidity after the second cooldown. Depending on the specifics of the cryostat, microscope and magnet configurations, the cooldown time can deviate from default values.
Cryocoolers perform periodic compression and expansion of helium to remove heat from the system to be cooled. Depending on cooling power requirements, different working principles like pulse-tube (PT) and Gifford-McMahon (GM) are being used.
High Magnetic Field
Magnetic field can be generated by different means. From permanent magnets to dedicated pulsed hybrid magnets. In order to maximize the available magnetic field strength and ease of use, attocube uses specially designed superconducting magnets in all cryostats. Since the actual magnetic field strongly depends on the specific geometry, please contact our sales representative for the available options.
The temperature stability of a cryostat is specified at 1K above base temperature with active temperature control. It is defined as the maximum deviation from the temperature setpoint in a 10 minute period. Its actual value can be influenced by the chosen microscope or setup.
Sample space of a cryostat is the space designed to hold the experimental setup without affecting its cooling performance. A larger sample space is desired because it allows more complex measurements and hence makes later upgrades possible.
Cryogen-Free; Dry Cryostat; Closed Cycle Cryostat
Closed cycle cryostats, also called dry cryostats, helium-free or cryogen-free cryostats, do not require liquid cryogens (like He or N2) for cooling. Instead, helium is contained in a closed circuit, and undergoes a cyclic expansion and compression. There are two different established designs, the pulse-tube coolers, and the Gifford-McMahon (GM) coolers.