Spectrometer for Ice Nuclei (SPIN)

Particle detection allows for individual particle sizing and discrimination of ice and water particles using polarization change in the scattered light. The SPIN’s chamber design follows the parallel-plate geometry developed by Stetzer and the engineering team at the ETH-Zurich. Details are given in Chou et al, “Ice nuclei properties within a Saharan dust event at the Jungfraujoch in the Swiss Alps” (Atmos. Chem. Phys. 11, 4725-4738, 2011). The parallel-plate design provides easy and uniform cooling. A compact refrigeration system cools the plates directly, eliminating the need for external cooling baths and heat exchange fluids.
The SPIN consists of the following components:

• The Ice Nuclei Chamber contains the refrigerated plates with an ice layer to grow the crystals.
• The Flow Acquisition Box contains the pumps, data acquisition system, and mass flow controllers.
• The Control Box contains electronics such as pump controls.
• The Warm and Cold Refrigeration Assemblies contain the compressors that drive refrigerant into the plates.
• The Detector Box consists of the laser, two standard light-scattering detectors and two polarized light detectors. The polarized light detectors allow discrimination of ice particles from other particles.