Thermal Anchoring in Cryostats: Copper Braid Simulation

In cryostats and cryomodules, effective thermal anchoring of components is critical for stable and efficient operation. Several methods are commonly used to achieve this, including direct attachment to cold plates, thermal exchange via gases or heat exchangers, and flexible metal braids.

This post focuses on a thermal simulation of a copper braid attached to the second stage of a Cryomech PT415 pulse-tube cryocooler. In the model, 0.5 W of heat is applied to one end of the braid, while the other end is thermally anchored to the cryocooler’s second stage.

Setup:

For cryostats and cryomodules, thermally anchoring components is very important. There are many methods of doing this, including physically attaching them to cold plates, using gases or thermal heat exchangers, or using metal braids. Below is a thermal simulation of a copper braid attached to the second plate of a PT415 cryomech pulse-tube cryostat. 0.5 Watts of power is applied to one end of the braid and the other is attached to the cryomech.

Cryomech PT415

On the second stage of the PT415, a copper braid was attached to provide thermal anchoring (see figure below). The upper end of the braid is fixed to the second-stage cold plate, while the lower end is subjected to an applied heat load of 0.5 W.

The second-stage temperature is determined from the manufacturer’s cooling curve (shown below). With the applied load, the cold plate stabilizes at 3.4 K.

Simulation Results:

The simulation shows the temperature distribution along the braid under these conditions. While the cold plate end is fixed at 3.4 K, the opposite end of the braid rises slightly to 3.67 K under the 0.5 W load.

As expected, the temperature profile depends strongly on the applied heat load. Increasing the power on the second stage would shift the operating point along the cooling curve, raising the equilibrium temperature at both ends of the braid.

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This example highlights the importance of careful thermal anchoring design in cryogenic systems. Even small heat loads can produce measurable gradients, and simulations like this are essential for predicting performance and guiding experimental setups.