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Cryogenics and Fluids Branch

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Text versions of this information:

• Brief: brief cycle page
• More detailed: Advanced ADR cycle page

First, a labelled drawing of the AADR:

Now, the animated drawing of the AADR:

Quibbles, Caveats, and Oversimplifications

This schematic diagram of the Advanced ADR is, of course, a simplified version of the real machine. Here are some of the details that I couldn't put in the diagram:

Number of Stages

I've shown this Advanced ADR with 3 stages. A real Advanced ADR might have more stages (for greater temperature range) or fewer (for a version that would not have as great a performance but would be less complicated to build and run).

Heat Switches

I've shown the heat switches as little hinged mechanical switches that make and break contact, like an electrical knife switch. They definitely won't be like that. The AADR team is working on designs that include gas gap switches (such as the type used on the XRS ADR) and a switch that uses the differing thermal conductivities of a superconductor in its normal and superconducting conditions.

Timing of Cycle

The relative times of the various parts of the cycle will depend on details of the finished AADR, such as the relative sizes of the salt pills, the strengths of the magnets, and the size of the heat load. In particular, heat may be transferring from the cold pill to the mid pill at the same time as it's transferring from the hot pill to the heat sink/mechanical cryocooler, unlike what I've shown in the diagram. One detail I've tried to show that is expected to be true of the working AADR is that the transfer of heat to the mechanical cooler may be a slow, drawn-out process, because many cryocoolers cannot maintain temperature with large, sudden heat loads.

Spread of Magnetic Field

I've tried to represent the magnetic field symbolically, by concentric ellipses: for an increasing field, I increased the number of ellipses and/or made them darker. The field, however, spreads out beyond the ellipses I used to represent it. For instance, the field reaches the center of the salt pil, even when the ellipses don't. Also, the field spreads out beyond the AADR. In fact, the AADR will probably need to be surrounded with a magnetic shield (probably of iron) to prevent the stray field from interfering with other nearby electronic equipment.

Curator: Mark O. Kimball NASA Official: Eric A. Silk Last Updated: 09/11/2014