High Temperature Interfaces
450 K Interface
The 450 K interface is fitted with a sapphire switch and stainless steel brace to keep it robust. It is not electrically isolating. The silicon diode sensors maintain their accuracy after repeated cycling.
The 450 K interface design includes a thermal impedance which acts as a thermal isolator at very high and very low temperature (below 8 K). Therefore, this interface is not recommended for use with 4 K systems. It will increase the sample temperature by approximately 0.5 K at no load for a 4 K cooler. A heat load of 0.5 watts on the sample will raise the sample temperature by 2 K.
In the high cooling power systems this interface can be pushed up to 500 K for short periods of time (a few hours).
Temperature Ramp Rates
Using a DE-202 with 450 K interface, the following rates were obtained:
Cool down (initial) .................... 300 K to 10 K < 50 minutes
Heat up ....................................... 10 K to 450 K < 8 minutes
Cooldown (subsequent) ......... 450 K to 10 K < 50 minutes
800 K Interface
The 800 K interface design includes a thermal impedance which acts as a thermal isolator at very high temperature and very low temperature (below 8 K). So it is not recommended for use with 4 K systems. It will increase the sample temperature by approximately 1 K at no load for a 4 K cooler.
It is mechanically fragile and must be treated with care during sample installation. The 800 K interface is only supplied with ARS cryocoolers.
At 800 K, most sensors—including platinum and thermocouples—will anneal and the calibration will change from time to time. The annealing is a function of the cooldown and heat-up rate. The accuracy at the low temperature (4 to 30 K) is affected, as the response curve (dmV/dT) is generally flatter at this section of the curve.
Temperature Ramp Rates
Using a DE-202 with 800 K interface, the following rates were obtained:
Cool down (initial) ................. 300 K to 10 K < 50 minutes
Heat up .................................... 10 K to 700 K < 10 minutes
Cool down (subsequent) ..... 700 K to 10 K < 70 minutes