Picture Descriptions for ADR Primer

Here are links to the descriptions on this page:

Description of Simple Schematic

This picture shows two simple schematic cross section views of an Adiabatic Demagnetization Refrigerator(ADR).

One of the diagrams is labelled "Operating". This first diagram illustrates the state of the ADR while it's actively cooling. This is the working part of the cycle, when the ADR is doing what it was designed to do.

The other diagram is labelled "Recycling". This other diagram illustrates the state of the ADR when it has warmed up in order to dump all the accumulated heat energy into the heat sink. While in this warm up part of its cycle, the ADR cannot provide cooling.

The parts of the ADR shown are:

Heat Sink: shown as a rectangle at the bottom end of the diagram.
Heat Switch: shown as a tube with a valve connecting the Heat Sink and the Salt Pill.
Salt Pill: shown as a rectangle (the cross section of a cyliner) inside the Magnetic Coils.
Magnet Coils: shown as rectangles (the cross section of a hollow cylinder) on either side of the salt pill.
Detectors: shown as a flat plate connected to the salt pill by a rod.

Here are those parts again, in more detail, comparing their conditions in the Operating and Recycling modes.

Heat Sink: this is where the ADR dumps all the stored heat during the "recycling" part of its cycle. The heat sink is shown the same in both diagrams. It is colored red, to indicate that it's the hottest part of the ADR. "Hot" is relative, however -- the heat sink may only be 1.3 degrees above absolute zero.
Heat Switch: this is how the ADR connects to the Heat Sink to dump the stored heat. During the "recycling" time, the heat switch makes a connection between the Heat Sink and the Salt Pill, allowing the heat to flow out of the Salt Pill. During the "operating" part of its cycle, the heat switch breaks that connection, to prevent the heat from flowing back into the salt pill.
Salt Pill: this is the heart of the ADR, which absorbs or dumps the heat. During the "recycling" part of the cycle, the salt pill (responding to a high applied magnetic field) warms up, ready to dump the stored heat into the heat sink. Therefore, in the "recycling" diagram, the salt pill is shown in red. In the "operating" part of the cycle, the salt pill (responding to a low applied magnetic field) cools down, absorbing heat from the Detectors. Therefore, in the "operating" diagram, the salt pill is shown in blue.
Magnet Coils: this is the part of the ADR that controls the behaviour of the salt pill. In the "recycling" part of the cycle, concentric ellipses surround the coils to show the high magnetic field. In the "operating" part of the cycle, those curves are missing, showing that the magnetic field is low.
Detectors: this is what the ADR was built to cool. The ADRs we build cool sensors for the astronomers here at Goddard. Their sensors are called "detectors" because they study objects out in space by detecting the light waves or infrared rays (heat waves) or other signals from those objects. In the "recycling" diagram, the detectors are shown red, to indicate that they're just as "hot" as the recycling salt pill. In the "operating" diagram, the detectors are shown blue, to indicate that they're cool.

Return to simple schematic diagram.

Description of Diagram of One Magnetic Moment

This diagram shows six little arrows. The one on the left points straight down, the one on the right straight up, the others at angles in between. The arrows represent, in a simple schematic way, the directions that the magnetic moment can point. Return to diagram of one magnetic moment.

Description of Diagram of Disordered Array of Magnetic Moments

This diagram shows a 6 by 6 array of arrows. They're pointing every which way. They represent the behavior of a disordered array of magnetic moments. The moments would not be all pointing in the same direction. They'd be pointing in all the directions that it's possible for them to point. Return to diagram of disordered magnetic moments.

Description of Diagram of Semi-Ordered Array of Magnetic Moments

This diagram shows a 6 by 6 array of arrows. Most of them are pointing straight up, but a few are pointing off at other angles. This represents the behavior of an array of magnetic moments that aren't completely disordered, but also aren't completely ordered. Return to diagram of semi-ordered magnetic moments.

Description of Diagram of Ordered Array of Magnetic Moments

This diagram shows a 6 by 6 array of arrows. They're all pointing straight up. This represents the behavior of an array of magnetic moments that is completely ordered, that is, all pointing in the same direction, all aligned with the magnetic field. Return to diagram of ordered magnetic moments.
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