Our range of DC cryogenic wires covers almost all cryogenic applications and environments. We offer a size of 42 SWG as standard but can offer sizes in the range of 34 to 46 SWG.
Copper has the lowest resistivity of the three materials so if you need to run significant current levels then copper would be the best option in order to avoid a drop in voltage. This comes with a trade-off. Copper has the highest thermal conductivity, especially at cryogenic temperatures. This means that copper wiring can add high heat loads to the sample, reducing the ability to achieve the lowest temperatures.
Constantan wire is a mix of copper and nickel. The resistance of the wire doesn't change with temperature making it a great fit for making thermocouples. It fits somewhere between copper and manganin, with a lower thermal conductivity than copper and lower resistivity than manganin.
Manganin is a mixture of copper, manganese, and nickel and has the lowest thermal conductivity of the three materials. At less than 1% of the thermal conductivity of copper, heat losses can be reduced by over 90% by switching from copper to manganin wiring. This makes manganin the preferred option when base temperature is key success factor.