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The hallmark of Sigma Systems thermal platforms is fast, reliable performance with low gradients. Heaters are carefully sized and hand fitted in a high density array to assure fast and even heating. Cryogenic coolant is carefully metered into a proprietary expanding cross section loop back expansion channel for extremely efficient, very fast, and very efficient cooling.
The Sigma proprietary cryogenic cooling channel design provides a constantly increasing volume for
the coolant as it moves through the platform. The channel volume change is coordinated with the increasing
volume of the coolant as it changes state and expands while absorbing heat. Cooling is quite uniform along
the cooling channel and the coolant is given the opportunity to absorb as much heat as possible.
Coolant cost is low because efficiency is high. Gradients are low because cooling is uniform and the cooling
channel is looped back upon itself to provide a side by side blending of the cooling effects of the beginning
and end of the channel. Large radius bends within the cooling channel reduces laminar flow and tunneling and
virtually eliminates the dry ice buildup that can accumulate with L-CO2
and competitive designs.
Sigma platforms are made of ground 6061-T6 aluminum. The working surface is exceptionally flat. Tapped holes are typically provided with "helicoil" type hardened inserts for long life under repetitive use. The exposed surfaces of the platform are anodized to preserve the flatness and resist galling and corrosion. The platforms are 100% aluminum to maximize heat transfer, reduce gradients, and avoid dissimilar metals corrosion and separation that can occur with aluminum-copper or aluminum-stainless construction.
Sigma thermal platforms are also available that use environmentally friendly mechanical refrigeration. This option is ideal for clean room environments and long soak tests or processes. Cascaded refrigeration units are capable of reaching temperatures well below -70ºC. Refrigerant is vaporized in the platform in a series of up to 24 proprietary equal length channels to keep efficiency and performance high, and thermal gradients low. To assure that compressors last a long time, Sigma offers both single stage and cascaded refrigeration and three types of refrigeration system compressors. These available choices allow us to work to your budget and your needs without running compressors at pressures that will result in early failures.
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