The Amica Control System

There are two specific problems complicating the operation of an autonomous instrument in Antarctica:

• The presence of unusually low ambient temperatures

• The unexpected low capacity to dissipate heat from electrical components due to air rarefaction (Dome-C is at an altitude of 3280 m corresponding to a barometric altitude of about a thousand meters higher)

These problems demand balloon/space techniques that guarantee reliable margins. For AMICA it was decided to split the system in two sections, with controls and electronics in a controlled temperature ambient (-10/+10 C°), and the camera system at the external temperature (see Fig. 4).

Figure 4. The overall AMICA control system subdivided in cold and warm ambient temperatures.

In such conditions electrical and optical flanges on the cryostat will be sealed with indium wire due to the low external temperature. The cryo-cooler head will remain open at operating temperature, which is usually higher (5/35 C°). All the control electronics (CPCI computer, detector controller, PLC master control system) and the cryo-mechanisms (vacuum pump, cryo-cooler compressor and temperature controllers) will be placed in the thermalized rack. The PLC interface to the CPCI host provides high level system control, i.e., system ON/OFF cycles, vacuum and cryocooling cycles, temperature monitoring (inside and outside the dewar), racks temperature control and cryogenic step-motors control.

Both NIR and MIR detectors are built around 4 output multiplexers and are served by an eight independent channel electronics [7] based on a CPCI-Pentium host and a SKYTECH PMC control I/F.

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