Model 16PT-ADR Cryogen Free Two Stage
Adiabatic Demagnetization Refrigerator System
The system consists of the
following components:
- Model 16PT cryo-cooled superinsulated helium cryostat
containing an adiabatic demagnetization refrigerator (ADR) system.
The cryostat includes a model PT405 Pulse Tube refrigerator
with internal highly conductive flexible thermal linkage to cool two
stages, the ADR support stages, a superconducting magnet and
associated leads and thermometry. It also cools two sets of radiation shields that protect the
cold assembly from the room temperature radiational heat load. The system also includes appropriate getters and provisions for
thermal anchoring of additional wiring for the end users’
experiments.
- A two stage ADR system with a gadolinium-gallium garnet (GGG)
crystal and a ferric ammonium alum (FAA) salt pill. Each pill has its own ultra low thermal conducting support
structure isolating it from the 4 K flange and the intermediate stage.
The two stages operate at a temperature of ~1 K (GGG) and 50
– 100 mK (FAA), with a typical hold time of three days below 100 mK.
- A mechanical thermal heat switch assembly for attaching and
detaching the two stages of the ADR during initial cool down, and
during its magnetization and demagnetization cycles.
-
Two ruthenium oxide thermometers with appropriate heat sunk
wiring at the various intermediate stages to monitor the temperature of the two stages of the ADR.
The two thermometers are supplied with a standard calibration data between
50 mK and 20 K.
- A 4 Tesla conductively cooled multi-filamentary
Niobium-Titanium superconducting magnet surrounding the GGG and FAA
pills. The magnet is wired with an optimized arrangement of low and high temperature
superconducting leads, and is provided with voltage taps and two
standard thermometers to monitor its cool down and operating
temperature. The magnet reaches its rated field of 4 Tesla at a nominal 10 amperes.
- A high permeability magnetic shield surrounding the magnet and
the two pills, to reduce the stray magnetic field in the vicinity of
the cold stages.
- Complete wiring, interfacing and testing of all components,
including the ADR pills, magnet, thermometry, and helium readout.
This includes a final test of the complete system, to ensure
precise dewar and ADR hold time and operation.
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Introduction
